UBC Graduate Research

Thermal Cautery for Low Resource Settings Adibi, Mohammad Amin; Esfandiari, Hooman; Dowling-Medley, Jennifer; Satti, Sampath; Sterling, Samantha May 6, 2016

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P a g e  |    6 May 2016   An Engineers in Scrubs Design Project | Amin Adibi, Hooman Esfandiari, Jennifer Dowling-Medley, Sampath Satti, Samantha Sterling INTERNATIONAL HEAT THERMAL CAUTERY FOR LOW RESOURCE SETTINGS  P a g e  | i  Table of Contents Executive Summary .................................................................................................................................... iv 1. Introduction ......................................................................................................................................... 5 1.1 Background .................................................................................................................................. 5 1.2 Project Timeline ........................................................................................................................... 5 2 Design Process Phase I: Identification ................................................................................................ 6 2.1 Needs Finding ............................................................................................................................... 6 2.1.1 Strategic Focus ..................................................................................................................... 6 2.1.2 Needs Statement Development.......................................................................................... 9 2.2 Needs Screening ......................................................................................................................... 12 2.2.1 Disease State Fundamentals .............................................................................................. 12 2.2.2 Treatment Options .............................................................................................................. 15 2.2.3 Stakeholder Analysis .......................................................................................................... 16 2.2.4 Market Analysis ................................................................................................................... 17 2.2.5 Needs Filtering ................................................................................................................... 18 2.2.6 Preliminary Needs Specifications ...................................................................................... 19 3 Design Process Phase II: Invention ................................................................................................... 20 3.1 Concept Generation ................................................................................................................... 20 3.1.1 Ideation & Brainstorming .................................................................................................. 20 3.1.2 Concept Screening .............................................................................................................. 21 3.2 Concept Selection ...................................................................................................................... 26 3.2.1 Prototyping ........................................................................................................................ 26 3.2.2 Final Concept Selection ..................................................................................................... 32 4 Design Process Phase III: Implementation ....................................................................................... 34 4.1 Development Strategy & Planning ........................................................................................... 34 4.1.1 Intellectual Property Strategy ........................................................................................... 34 4.1.2 Research & Development Strategy ................................................................................... 34 4.1.3 Clinical Strategy .................................................................................................................. 35 4.1.4 Competitive Advantage & Business Strategy ................................................................... 36 5 Conclusion .......................................................................................................................................... 37 6 References ......................................................................................................................................... 38 7 Appendices ......................................................................................................................................... 40 P a g e  | ii  7.1 Brainstorming & concept maps ................................................................................................ 40 7.2 Power draw testing data ........................................................................................................... 41 7.3 Thermocouple calibration ......................................................................................................... 43 7.4 Finite Element Simulations of Heat Transfer in Tip .................................................................. 43 7.5 Handpiece and tip CAD .............................................................................................................. 46  Table of Figures Figure 1: Project Timeline ............................................................................................................................. 6 Figure 2: Tasks Timeline ............................................................................................................................... 6 Figure 3: Team Technical Skills .................................................................................................................... 7 Figure 4: Team Soft Skills ............................................................................................................................. 8 Figure 5: Acceptance Criteria ...................................................................................................................... 8 Figure 6: Problem identification ................................................................................................................. 11 Figure 7: Effect of temperature on the denaturation and crosslinking of the Albumin protein in an egg white ............................................................................................................................................................ 13 Figure 8: Comparison of existing products according to cost and functionality .................................... 17 Figure 9: “Must have” features ................................................................................................................ 19 Figure 10: "Nice to have" features ............................................................................................................ 19 Figure 11: An overview of the generated concept maps. .......................................................................... 21 Figure 12: Working principles of the selected general concepts. ............................................................ 22 Figure 13: Selected power generation protocols. .................................................................................... 22 Figure 14: Updated Needs Specifications ................................................................................................. 23 Figure 15: Updated "nice to have" features ............................................................................................. 24 Figure 16: The selected concepts for coagulation. ................................................................................... 26 Figure 17: Teflon spray-coated tip & machined Teflon rod tip ................................................................. 28 Figure 18: Works-Like Prototype Circuit Configuration ........................................................................... 28 Figure 19: Efficiency (left) and tissue damage (right) testing of thermal cautery system ..................... 30 Figure 20: Works-Like prototype (left) and its microcontroller-heating element response curve (right) .................................................................................................................................................................... 32 Figure 21: Final Design ................................................................................................................................ 33 Figure 22: Original concept map................................................................................................................ 40 Figure 23: Reorganized concept map (power) ......................................................................................... 40 Figure 24: Reorganized concept map (feasibility) ................................................................................... 41 Figure 25: Soldering iron power draw....................................................................................................... 42 Figure 26: Temperature contour plot of Incoloy heating element and tissue ....................................... 44 Figure 27: 3D temperature gradient plot after 30s application of 10W heating element to tissue ....... 45 Figure 28: Temperature contour plots for various Teflon coat thicknesses after 30s with metal tip at 110C ............................................................................................................................................................. 45 P a g e  | iii   Table of Tables Table 1: Preliminary Needs Screening ......................................................................................................... 9 Table 2: Matrix decision chart criterion definition ................................................................................... 10 Table 3: Matrix decision chart ................................................................................................................... 10 Table 4: Comparison of existing coagulation methods ........................................................................... 16 Table 5: Preliminary Needs Specifications ................................................................................................ 20 Table 6: Updated needs criteria. Additions and changes are in italics.................................................... 24 Table 7: Concept screening chart (Pugh chart). ....................................................................................... 25 Table 8: Purpose of Prototyping the Thermal Cautery System ............................................................... 27 Table 9: Tip temperature testing results .................................................................................................. 30 Table 10: Teflon Configuration and Heat Up/Down Results ..................................................................... 31 Table 11: R&D Milestones ........................................................................................................................... 34 Table 12: R&D Technical Challenges .......................................................................................................... 34 Table 13: Stakeholder Analysis Summary .................................................................................................. 36 Table 14: ESU Power Draw......................................................................................................................... 41 Table 15: Tissue properties ........................................................................................................................ 43 Table 16: Material Parameters ................................................................................................................... 43    P a g e  | iv  Executive Summary International Heat, a team of five graduate students, spent the past four months designing a thermal cautery system capable of being used for open abdominal surgery in low resource settings. Throughout those four months, the team followed the design process outlined in Biodesign: The Process of Innovating Medical Technologies [1]. Potential project ideas were presented to the entire Engineers in Scrubs class.  International Heat formed from a desire to create a device with the potential to significantly impact the quality of medical care in third world countries. This report details the team’s progression starting with defining the team’s mission statement and strategic focus, to the needs finding process, to needs screening and creation of preliminary needs specifications, to concept generation and screening, to interviewing clinicians who provided feedback leading to the update of the needs statement and needs specifications, and then final concept selection.  We describe the prototyping of and evaluation of two separate concepts in order to ultimately choose thermal cautery as well as extensive feasibility testing we performed to see if thermal cautery had the potential to be a viable alternative to an electrosurgical unit. Finally, we provide a potential development strategy which could be implemented to bring the thermal cautery unit to market.   P a g e  | 5  1. Introduction 1.1 Background The state of healthcare in a third world country such as Uganda is vastly different than what a person would expect to find in America or Canada. Healthcare in Uganda works on a referral basis; patients begin at a small regional clinic and, if necessary, get transferred to the next highest level, ultimately terminating in the national referral hospital located in Kampala. Most of the lower level medical facilities lack the capacity to perform surgery of any kind, while those regional medical centers that do have an operating room for emergencies may only have the bare minimum of equipment [2]. Additionally, Uganda has incredibly unreliable grid power. Hospitals experience power surges which can damage equipment plugged into the wall and also have unpredictable outages that can last anywhere from a few hours to a few days. Generators might be able to maintain critical systems, such as an anesthesia machine, but surgeries are often either postponed or, if the procedure has already begun, done in the dark mostly with unpowered systems [3].      Electrosurgical units (ESU) are a common surgical tool in the western medicine. An ESU uses a high frequency electrical current to heat up and cauterize bleeding tissues. During surgery, this minimizes bleeding, keeping the surgical field visible and reducing the need for blood transfusions.  However, while Ugandan medical centers often have a donated ESU, the clinicians could lack the expertise to use it, the facility might not be capable of repairing a simple malfunction, and the medical center might not have access to the required accessory parts.  For example, an ESU used in VGH requires a disposable handpiece and disposable tips.  Ugandan hospitals lack the funds to keep buying consumables as well as the administrative setup to order disposable supplies on a regular basis. An ESU also requires a large amount of reliable grid power, which as previously discussed is far from guaranteed in a third world setting.       This report details the journey of International Heat, a team devoted to creating a viable thermal cautery system for a third world setting.  Thermal cautery does not require as much power as an ESU and can therefore be run via a small backup battery in the event of a power outage.  The device itself is reasonably priced, and there is no ongoing maintenance cost due to consumables. This report will walk the reader through the team’s reasoning for design decisions through the process of needs finding, needs screening, concept generation, concept screening, prototyping, and a proposed development strategy. 1.2 Project Timeline Initial MedTech Cafes were held in the last few months of 2015. At the first MedTech Cafe for each division, surgeons and clinicians presented problems they believed could have potential engineering solutions. At the second MedTech Cafe for each division, the Engineers in Scrubs students presented literature reviews performed on each topic. Team formation and project selection began in January, at which point the class went through stages of problem identification, needs finding, needs screening, concept generation and selection, and finally prototyping and building. The term ended P a g e  | 6  with final presentations on April 7, 2016, which the final report due on May 6, 2016.  Major project milestones are illustrated in Figure 1 below, and the duration of individual tasks is shown in Figure 2.   Figure 1: Project Timeline  Figure 2: Tasks Timeline 2 Design Process Phase I: Identification 2.1 Needs Finding 2.1.1 Strategic Focus After all four MedTech Cafe sessions (two to hear the clinicians present their problems, and two to show the clinicians our own preliminary literature reviews), all of the soon-to-be members of International Heat united under a common goal: to make a difference.  In order to develop a meaningful strategic focus, the five of us first determined a mission, then identified assets of individual team members, and finally defined acceptance criteria to guide project selection.  P a g e  | 7  The team agreed that our main priority was to find a means of benefiting society through the implementation of engineering solutions.  We also agreed that our end goal was to have a workable solution capable of working in a real world situation.  To that end, International Heat defined the team mission as follows: 1. Produce a positive impact on the healthcare system, and for patients and providers in particular. 2. Generate high quality solutions for low resource settings. 3. Address problems in the medical field that have previously been overlooked due to economic non-viability. 4. Create products that are affordable for the target markets. Based on our mission, priorities, and common goals, International Heat decided to tackle a problem proposed by the Branch of International Surgery, as this would allow us to create a solution geared towards low resource settings. International Heat then took time to evaluate the assets and expertise brought in by individual team members, as we wanted to ensure our team was sufficiently diverse to tackle a wide range of problems.  International Heat consists of three MASc candidates and two PhD candidates, with undergraduate degrees from a wide range of universities and programs.  Figure 3 shows a summary of the technical backgrounds of the various members.   Figure 3: Team Technical Skills  International Heat believes it also worthwhile to identify any weaknesses in the team knowledge base, as this promotes self-awareness of areas for improvement as well as allows the team to make a more informed choice of which problem to focus on.  In general, those with more mechanical Team Expertise Mechanical Engineering •microfluidics •CAD/FEA Electrical Engineering •coding •circuit design Biomedical Engineering •anatomy •biomechanics •biomaterials •medical imaging Chemical Engineering Geomatics P a g e  | 8  engineering-oriented backgrounds considered circuit building and signal processing to be individual weaknesses, while the two electrical engineers had only minimal knowledge of biomechanics and mechanical design.  However, having such a diverse team allowed other team members to fill in those knowledge gaps.  The lack of advanced fabrication skills ended up being the primary weak point in team expertise; however, this constraint allowed us to narrow down our project choices in an informed manner.  International Heat also boasts a plethora of soft skills and areas of expertise, including but not limited to:   Figure 4: Team Soft Skills The final step in developing the team’s strategic focus was to define acceptance criteria. These acceptance criteria (detailed in Figure 5)   provided the basis of the initial evaluation of potential project.   Figure 5: Acceptance Criteria Publication Leadership Technical Writing Ethics Documentation Oral Presentations Communication •There are many ways to go about implementing change in the healthcare system.  Often the solution lies in increased or different training methods or changes in SOP that produce more instructive documentation or yield a lower amount of energy usage.  However, due to time constraints and the difficulty of effecting policy-wide changes without backing from hospital administration, International Heat chose to focus only on those solutions which could potentially be solved with engineering. Engineering solution to the proposed problem •International Heat has an incredibly diverse breadth of expertise but, as discussed earlier, there are some topics of which we have only minimal knowledge.  Therefore, some projects will inevitably fit better than others.  In addition, we wanted to be sure to select a project that could be designed and implemented without going over budget (roughly $2500 CAD).  Finally, the problem needed to be solvable using only those resources available to the team. Match with technical expertise and resources •The team also operated under a time constraint; four months to select a project and engineer a solution is a relatively short period of time.  Taking on a project which would require significantly more time to complete would prevent us from presenting the clinicians with a feasible idea at the end of the course. Reasonable progress in four months •The team was adamant that the proposed project result in something that could be physically built.  Besides allowing the team to set a clear end goal, this criterion ensured that the team would have something tangible to hand to clinicians at the end of the course. Prototypable •International Heat wanted the problem to have the potential for high impact.  The team saw high impact defined in two separate ways.  First, the team wanted to choose a project that could potentially help a large number of people. Second, the team wanted to choose a project that might help only a small number of people, but the project would have a drastic and potentially life-saving impact on those people.  Ultimately, we decided that these two ideas were not mutually exclusive and chose to incorporate them together. High impact  P a g e  | 9  With the strategic focus determined, International Heat moved on to the next step in the design process: problem identification and preliminary needs screening. 2.1.2 Needs Statement Development Many different problems were presented at the MedTech Cafes. International Heat performed preliminary needs screening based on our defined acceptance criteria in order to narrow down the choice of projects, as illustrated by Table 1 below. As the acceptance criteria represented International Heat’s minimum requirements for the chosen project, projects that did not meet all criteria were quickly eliminated from consideration. Each category was assessed in a binary fashion- either the project did or did not meet that particular criterion.  The “Electricity” problem involved a need to power medical devices in third world countries during unpredictable power outages; we eliminated this project because we didn’t have the resources available to make any sort of worthwhile progress in four months.  EQUEQ, or Early Quit and Unwrapped Equipment, asked to find a solution to the rooms of unused donated equipment found in third world hospitals.  Clinicians there often do not know how to use or maintain such equipment, and will therefore stop using the equipment altogether. International Heat believed that this project was beyond the scope of the course, as it seemed that the best solution would involve training and policy changes at the administrative level.  Finally, the sterilization project involved higher quality control to reduce contamination in sterile environments in low resource settings; this project was also eliminated due to a lack of sufficient team knowledge as well as belief that significant progress would take longer than the four month scope of the course.  The team then moved on to perform a more thorough exploration of the needs of the last four projects.  Table 1: Preliminary Needs Screening Criteria Engineering Resources Time Prototypable High Impact Electricity ? x x ? ✓ EQUEQ x x x x ✓ Sterilizer ✓ x x ✓ ✓ Hernia Spoon ✓ ✓ ✓ ✓ ? Endoscope ✓ ✓ ? ✓ ✓ Tourniquet ✓ ✓ ? ✓ ✓ Electrocautery ✓ ✓ ? ✓ ✓   P a g e  | 10  After investigating each need and problem, International Heat created a matrix decision chart, seen in Table 2 and Table 3, to delve more deeply into the project needs as well as see how closely each project fit the team’s acceptance criteria.  Table 2 illustrates how each criterion was defined as well as the weight we assigned to each criterion.  Each member of International Heat used these guidelines to fill in a matrix decision chart individually, and then team scores were averaged for each box.  The result of this process is seen in Table 3. Table 2: Matrix decision chart criterion definition CRITERIA Patient Impact  Social Impact Provider Impact  Interest & Skill Treatment Gap Feasibility Profitable WEIGHT 30% 20% 15% 15% 7.5% 7.5% 5% 5 (best) lifesaving millions faster, better, easier skill match, interest no solutions  clinical prototype possible $millions 3  quality of life, outcome ~1000s 2/3 of above 1/2 of above no imple- mented solutions proof of concept possible $thousands 1 (worst) minimal or unclear impact <1000 0 of above 0/2 of above existing solutions  could not prototype $<1000  Table 3: Matrix decision chart Project Patient Impact Social impact Provider Impact Team factors Gap Feasible Profit Total (/5) Decision Hernia spoon 1.8 1.8 3.2 1.8 2.4 4.6 1.2 2.2 no ESU 3.9 4 4.4 3.4 2.7 3.1 3.6 3.8 consider Tourniquet 3.4 2.2 3.6 3 1.6 3.6 2.4 3.0 no Endoscope 3.3 3.8 4.2 3.2 2.2 3.6 3.8 3.5 consider  The two highest scoring projects were the electrocautery/electrosurgery project and the endoscope project.  International Heat re-evaluated the criteria for both projects in a binary fashion; team members voted for which of the two projects they believed would fit each criterion better, and P a g e  | 11  scores were again averaged together. With the results basically tied, the team held a roundtable discussion and scrutinized how well each project matched team interests and expertise.  Ultimately, International Heat chose to move forward with the electrosurgery project.  With the general project area selected, International Heat moved on to the next step: focused problem identification. Our investigations into the conditions of third world hospitals, the principles of operation of typical ESUs, and the necessity of having a way to cauterize blood during surgery led the team to the following major conclusions, seen in Figure 6.   Figure 6: Problem identification  With the initial focused problem identification done, International Heat then crafted a suitable needs statement which would ultimately guide the remaining design process.  In designing the needs statement, the team took a “Problem, Population, Outcome” approach:   Problem: A means to safely and reliably perform electrosurgery.  Affected Population: Medical centers, clinicians, and patients in low resource settings, such as third world countries.   Desired Outcome: Low long term operational costs. Reliable operation in variable power conditions.  •Lack of single-use replacement components.  •Maintenance cost. •Lack of knowledge of repair and maintenance. Conventional electrosurgery equipment is often abandoned. While third world hospitals often have the ESUs themselves (generally through donation) certain issues can cause the clinician to abandon them. •Power surges cause damage to equipment plugged into grid. •Outages interrupt surgery. Power supply issues. As discussed previously, third world countries have unreliable grid power which can experience unpredictable power surges as well as outages. •Blood loss increases the need for blood transfusions. In third world settings, there is a high risk that the transfused blood will have HIV or other blood-borne diseases. This risk increases as more units of blood are required.  •Difficult to visualize surgical field. Blood flows freely from cut vessels, making it extremely difficult for the surgeon to find what exactly he’s supposed to be cutting. •Must perform surgery fast. Surgeons move quickly to minimize blood loss, but faster surgery can often result in more mistakes. •Poorer patient outcomes. Higher risk of blood loss, disease from transfusion, surgical mistake, and infection.  Lack of electrosurgery can have significant clinical consequences. P a g e  | 12  This approach led International Heat to the following preliminary needs statement:  A means by which electrosurgery can be performed safely and reliably in low resource settings that has low long-term operational costs and can operate reliably during power fluctuations. 2.2 Needs Screening 2.2.1 Disease State Fundamentals Devices that coagulate tissue during surgery are not specific to any one pathology, but rather are used as a tool to prevent bleeding during surgical procedures. Excessive bleeding is not desirable as it obscures the surgeon’s view [5] [6] [3] and increases patient blood loss. In sub-Saharan Africa, increased blood loss during surgery is especially undesirable as there are high rates of blood-borne infection in donated blood used in transfusions [7]. Understanding the biology and physics of coagulation is an important consideration when determining possible methods by which coagulation could be achieved.   Coagulation is the process of phase change of blood from liquid to a gel/solid. Coagulation of blood is desirable to maintain homeostasis and avoid hemolytic shock. Naturally, the coagulation of blood is mediated by a cascade of chemical reactions known as the coagulation cascade. Coagulation involves platelet activation, aggregation and polymerized fibrin at the site of blood loss. Coagulation is required during open as well as laparoscopic surgery to maintain blood in circulation and reduce loss. The natural coagulation process is supplemented during surgery by physical modalities that deliver energy to the tissue such as electrosurgery, cautery and RF ablation.  Broadly, the effects of coagulation as well as cutting observed in biological tissue is mediated by heat irrespective of the modality used. Zervas and Kuwayama [8]  found that lesions produced by various modalities such as  induction heating, electrosurgery, and direct application of heat were similar when normalized by the increase in temperature at the surface. Understanding the effect of heat and temperature on tissues is critical to understanding the process of coagulation.  Effect of Temperature on Cells and Tissue  Homeostasis Normal body temperature is 37°C and homeostasis is maintained throughout the body by the circulatory system consisting of blood and the blood vessels. An increase in the temperature up to 5°C is observed during infections as the body’s natural response.   Between  40°C and 60°C  An increase of local temperature to 50°C can lead to cell death in approximately 6 minutes. Lacourse et al have observed that a local temperature of 60°C can lead to instantaneous cell death is [4]. However, cell death cannot be correlated with coagulation in this temperature range.   P a g e  | 13  Between 60°C and 100  Two simultaneous processes of protein denaturation and dehydration occur inside the cell in this temperature range.   Protein denaturation Unfolding and subsequent crosslinking of proteins leads to the formation of a coagulum, in a process referred to as “coagulation” or “white coagulation”. White coagulation is the result of a process similar to the coagulation of the proteins in the egg white when heated. There exists a well-defined temperature below which coagulation is not possible even at long time scales. The image below denotes the effect of temperature on the coagulation of the egg whites. A clear distinction is seen at the 60°C temperature mark.   Figure 7: Effect of temperature on the denaturation and crosslinking of the Albumin protein in an egg white Dehydration or desiccation:  The cells gradually lose water through the damaged cellular wall. The loss of water is driven through evaporation catalysed by heat rather than a bulk phase change as seen above 100°C. In desiccation, the cells are shrunken and shriveled with elongated nuclei with the cellular detail being preserved. This effect is produced by the loss of water from the cells, without extensive coagulation of proteins.  A combination of desiccation as well as protein coagulation leads to the shrinkage of blood vessels (vasoconstriction) leading to coagulation.   Between 100°C and 200°C: When the intracellular temperature increases beyond 100°C, the intracellular water boils forming steam without having the necessary time to evaporate. Formation of steam inside the cell causes an increase in volume reading to rupture of the cell membrane It is suspected that the explosive force results in acoustical vibrations that contribute to the cutting effect through the tissue.  P a g e  | 14  Above 200°C: The process of “carbonization” occurs at temperatures beyond 200°C leading to a breakdown of organic molecules. The breakdown leads to carbon molecules such as soot, and referred to as “black coagulation” due to the black/brown appearance.  Modelling heat transfer through biological tissue  To better understand the physics of heat transfer, we performed simulations as well as an analysis of the physics involved to understand the heat transfer in tissue. These results would enable us to come up with specifications to evaluate and compare possible solutions.   Parabolic heat transfer equation:  ∇ · q(x, t) + kα ∂T/∂t (x, t) = S(x, t)  q(x, t) is the thermal flux k thermal conductivity  α = k/ρc ρ being the density c the specific heat  S(x, t) is a heat source at a given point  Fourier law of heat conduction:  Fourier’s law state that the thermal flux is proportional to the negative gradient of temperature in space. This law implies that there is greater transfer of heat from steeper gradient.   q(x, t) = −k ∇T (x, t)  Combining the parabolic heat transfer equation as well as Fourier’s law,   ∇ · q(x, t) + kα ∂T/∂t (x, t) = S(x, t) −k ∇ · ∇T (x, t) + kα ∂T/∂t (x, t) = S(x, t) − ∇2T (x, t) + 1/α ∂T/∂t (x, t) = 1 /k  S(x, t)  S(x,t) denotes all the sources and sinks of heat, such as the heat applied from the probe, and cooling effects due to blood perfusion.   The solution of this equation results in 3 dimensional space with symmetry assumptions and a point source of heat leads to “heat balls” or 3D spherical contours of temperature centered around the point source of energy. In practical scenarios, symmetry assumptions do not hold, as well as the energy source cannot be approximated to a point. Additionally, blood perfusion and heterogeneity in the tissue environment result in heat sinks and anisotropy in density and thermal conductivity. As a P a g e  | 15  result, an accurate analytic solution is not viable. Instead, an FEM simulation of the same can be performed to capture most of these considerations. Ideally, for tip design this would mean that to maximize heat transfer to the tissue for a given amount of energy, one would select a material with the relatively high density and specific heat (resulting in a large thermal mass) and a high thermal conductivity (resulting in greater heat transfer to tissue). Care would have to be taken to ensure that the thermal is not so high that the tip takes a lot of time and energy in the initial heat-up, however.  2.2.2 Treatment Options Various medical devices exist on the market for coagulation during surgery. They use various modalities to generate heat locally, which causes coagulation.   The first recorded use of endogenous energy during surgery for the purposes of coagulation was a fire heated cautery to remove lesions as well as reduce the incidence of infections during amputations. The use of thermal cautery required extensive heating apparatus, was not sterile and caused a lot of tissue damage due to necrosis because of the lack of temperature control. The development of ligatures (thread used to tie blood vessels) by Ambroise Pare in the 1600s reduced reliance on thermal cautery. However, ligatures could only be used on larger blood vessels and took longer time to apply.   The use of electrical energy to cut and coagulate tissue was proposed in the late 1800s and developed into a medical device by Dr. William Bovie. The device consists of an electrosurgical generator as well as a handpiece for the targeted application of the energy in the form of a high frequency electric current. A high frequency is used as it causes local heating of tissue causing coagulation without neuromuscular stimulation. The use of a handpiece necessitated a grounding pad for the return path of the current. With increasing safety risks and adverse events associated with improperly applied ground pads, the return path for current was included in the handpiece itself. This was called a “bipolar electrosurgery” device to distinguish it from the “monopolar electrosurgery” technique requiring grounding pads.   To avoid the risk arising out of high frequency electrical signals from electrosurgery interfering with implanted electronic devices such as cardiac pacemakers, as well as greater control over energy delivery to the tissue, ultrasonic and laser scalpels were developed which also have the capability to coagulate blood by causing local heating. These were compared in terms of functional parameters in Table 4.         P a g e  | 16   Table 4: Comparison of existing coagulation methods  Scalpel  Electrosurgery (mono & bi) Ultrasonic Scalpel Laser Blood loss High Low Low Low Tissue damage, healing Least damage, Best healing Moderate-high damage, Worse healing Moderate-low damage, Better healing Most damage, Worse healing Surgery time Least Moderate-high increase Moderate-low increase Longest  Cut & coag Cut only Both Brand dependent Both Cost Least (<$10) Moderate ($10-50k) Moderate ($10-50k) Highest (>$50k) 2.2.3 Stakeholder Analysis To perform an analysis of the stakeholders involved a device that would perform coagulation during surgery, we adopted the activity based theory pioneered by Vygotsky et al [9]. Activity theory considers the relationship and interplay between a subject, object and the community to achieve a certain outcome of an activity. Relationships between the different entities could include the rules being followed, as well as interfacing instruments. The activities analysed spanned the lifetime of the device and included 1. Purchasing process 2. Device usage in the OR 3. Sterilization Purchasing Process The process of device purchase involves multiple stakeholders, primarily the surgeon operating the instrument. From conversations with Lawrence Buchan of Arbutus Medical, it was understood that the decision making process regarding the purchase is driven by the surgeons. In the case of the drill cover, some surgeons purchase it out of their own pocket. Interacting with the surgeon in the purchasing process, would be the administrators on the hospital board as well as the government or NGOs if the device is ordered on a large scale, or donated.  Training the surgeon to familiarize them with the concept of electrocautery would be a major challenge due to the lack of penetration of cautery tools in Uganda, according to Dr. Piotr Blachut of USTOP (Uganda Sustainable Trauma Orthopaedic Program). The presence of tangible metrics as well as well-defined end points could catalyse the decision making process.   Sterilization Before a medical device can be used during a surgery, it needs to be subject to a thorough sterilization process to reduce the incidence of infections during recovery. Personnel sterilizing the medical device are therefore important stakeholders in ensuring its proper working. In developed P a g e  | 17  countries like Canada, sterilization is performed by the MDRD (Medical Device Reprocessing Department) with dedicated staff and established protocols. In Uganda however, the nurses are responsible for sterilization in most hospitals. Nurses interact with technicians and the device manufacturers to establish rules for sterilization as well as the equipment used such as autoclaves.   Cauterization The most important activity in the device life cycle is cauterization during surgery. The surgeon is primary driving the activity with the assistance of staff in the OR (Operating Room). The activity is being performed on the patient with the aim of reducing the blood loss during surgery. The definition of a sterile field and its boundaries are critical to the safe completion of this activity. Most specifications related to the medical device arise out of this activity, such as battery backup, amount of manageable blood loss as well as sterile field considerations. The ergonomics and usability of the device depends on the rules of interaction between the surgeon and the support staff. For example, the coagulation settings could be changed by a nurse outside the sterile field on a console, while the surgeon retains the final control using a handpiece that is sterilizable is placed inside the field. The time consideration for both the surgeon as well as the operating room as a resource necessitates an always ready standby state for the device. 2.2.4 Market Analysis  Figure 8: Comparison of existing products according to cost and functionality Figure 8 shows existing FDA-approved products available for cautery on the market. Products at the lower end of the price spectrum primarily rely on heat, while electrosurgery, laser and ultrasound cautery are the more expensive solutions.  Bovie electrocautery pens are disposable devices that heat a platinum or kanthal alloy tip of ultra-low resistance up to 1000 degree centigrade by passing a DC current through it. Though the product is affordable ($20), the device itself has an extremely low thermal capacity (mass of heating element*temperature of heating element). As a result, the device is only suitable for use in superficial applications such as lesion removal, minor hemostasis, ophthalmology and dermatology.   P a g e  | 18  Thermal Cautery Unit (TCU) by Geiger medical technologies improves on the disposable thermal cautery pens by increasing the thermal mass of the heating element. As a result, it is intended for use in wetter environments and applications such as urology, plastic surgery, ENT and general hemostasis. The TCU does not control the temperature of the tip, but applies a preset amount of energy. Heat transfer in the tissue depends factors such as the nature of the tissue as well as blood perfusion. Hemostatix is a heated scalpel tool intended to cauterize along with cutting. Though it does have additional functionality of cutting along with coagulation, it cannot only coagulate unlike electrosurgery generators which allow the user to switch between cut and coagulation modes or a combination of the two.   Heat Probe (HPU20) is marketed by Olympus for endoscope applications. It consists of a heating element in the form of a resistor encased in a biocompatible coating along with a channel for liquid irrigation for applications in gastrointestinal surgery. The resistance of the heating element was continuously measured to estimate the temperature by exploiting the temperature dependence of resistance.   Electrosurgery units such as the Aaron series marketed by Bovie and Covidien retail for greater that $10,000 and are able to perform tissue cutting, coagulation as well as a combination of the two. These units are capable of achieving bloodless fields by enabling coagulation in bloody environments as well as application of suction and irrigation tools. They require a reliable electrical supply without fluctuations and have a high standby power consumption.   Though developed countries have access to multiple modalities to achieve coagulation, most of them are not suitable for use in Uganda due to resource constraints. Resource constraints include economic constraints such as limited budgets, support resources constraints such as unreliable power supply, broken autoclaves and personnel constraints such as a low per capita number of doctors and surgeons necessitating quick surgeries. Current devices have been designed for hospitals in industrialized countries and cannot be modified to suit the ground realities in Uganda. Doing so would only result in a weak stop gap solution which is not scalable, as well as fragile. A robust solution can only be developed by taking into account the special needs in low resource settings and evaluating all possible solutions against them. 2.2.5 Needs Filtering After discussion with various stakeholders, a literature survey and problem identification, a list of specific criteria were arrived at. Various concepts would be evaluated against these criteria. These needs criteria were derived, as well as influenced the needs statement and the problem statement. For example low resource settings necessitated the need for power independence as well as the device being multi-use with no consumables.  The criteria were divided into two categories depending on whether they were critical towards addressing the need or were simply desirable.  P a g e  | 19   Figure 9: “Must have” features  Figure 10: "Nice to have" features 2.2.6 Preliminary Needs Specifications According to the “must-have” and “nice to have” features identified through the needs filtering process, a preliminary needs specifications list was drafted. This was integral to ensure that it would be possible to quantify or qualify whether or not our novel device met the needs we outlined, and to what degree.  •Discussion with the surgeons informed us that the existing need was a reliable means to achieve coagulation of tissue and not cutting. Even though means to cut tissue using electrosurgery exist in first world settings like Canada, surgeons prefer to use scalpels due to low tissue damage and familiarity. As a result, the criteria for filtering and comparing solutions would only consider the ability to coagulate and not cut tissue. Ability to coagulate blood vessels during surgery •A major problem faced by surgeons in Uganda towards using electrosurgery tools for cauterization is the lack of a reliable power supply. Hence, the ability of a solution to provide backup power is critical. A lower limit of the time for  which the device runs  on backup power was reached after discussion with clinicians as well an analysis of the average time taken for multiple surgeries. Power independent for 2+ hours •Sterilization protocols in Uganda are not as stringent or complied with as the ones in first world countries. As a result, any solution has to be amenable to a simple sterilization step. For example, the device casing must incorporate smooth surfaces and eliminate grooves. It must be fluid resistant to allow compatibility with sterilization steps such as immersion in a solution of formaldehyde.  Easily autoclave-able (for any components within surgical field) No consumables •Having a low power consumption as normalized against the volume/area of coagulation achieved would be desirable but not critical, as a higher battery capacity could be used if the concept having a high power consumption coagulates more effectively. Low power •It is desirable to develop a device that is low-cost when it is being used in a system where the per capita spending on healthcare is $108 per annum (Uganda). The economic benefit of coagulation during surgery is intangible as the benefits include a decrease in infection rates due to transfusion and faster recovery times. Due to the lack of epidemiological data, the precise economic benefit afforded by a coagulation device cannot be quantified and as a result, any considerations for the price of the device can only be guiding metrics and not rigid pass/fail criteria. Low upfront cost (~$300)  •Precise delivery of energy in space is desired to coagulate only those vessels losing blood while not affecting those the healthy ones. The disadvantages to losing a large volume of blood far outweigh those of a large spread of tissue damage in the current scenario. Therefore, a high level of precision is desired but not required. High level of precision •The need for a means to coagulate is the one that is primarily being addressed. A solution also has the added benefit of being able to cut tissue without large design modifications would be desirable. Ability to cut •The amount of output power required to coagulate tissue is organ specific. General abdominal and liver surgeries would result in bloodier environments than surgeries of the extremities and would require a greater output power. It would be desirable to provide control of the output power to the surgeon for greater control over the coagulation achieved. Adjustment of coagulatory power P a g e  | 20  Table 5: Preliminary Needs Specifications Need Metric Threshold Ability to coagulate blood vessels No blood release on application of pressure Pass/Fail Grid independent Battery backup measured in Watt-Hour < 60 kJ (17 W-h) Sterilizable MDRD Approval Pass/Fail No consumables Lifetime and reliability analysis of parts. Time in years. >2 years Low tissue damage Area of tissue discolouration (cm2 ) < 120% of tissue damage by ESU Low power consumption Watts < Power consumption of ESU (60W) No safety hazard Flammability of paper drapes and gloves at operating temperature for a duration of 1 minute Pass/Fail 3 Design Process Phase II: Invention 3.1 Concept Generation 3.1.1 Ideation & Brainstorming In order to come up with as many potential ideas as possible capable of addressing the defined need statement, International Heat organized a brainstorming session. This allowed for the rapid-fire generation of ideas. We agreed to abide by certain guidelines to manage the idea generation and documentation. The ideas had to have a logical link to the need statement; however, every group member was free to express any idea he/she had without taking into account how feasible or practical it is. We then categorized the ideas into concepts required to address the need statement and mapped the concepts using several different principles of organization. A high-level overview of the concept classification is illustrated in Figure 11. Please refer to Appendi for the complete concept maps based on our three organizing principles: modality, power requirements, and feasibility.  Amongst the different modalities of possible solutions, we eliminated the entire group of chemically-oriented concepts due to lack of sufficient expertise within the team as well as the inaccessibility of cauterizing chemical compounds. Because our target users are hospitals in low resource countries, the amount of power a particular solution required became a key limiting factor when choosing concepts. For this arrangement, we grouped concepts based on the estimation of how much power a particular solution might require.  According to our need statement, the system must be capable of operation even in situations when the power surges, disappears, and just generally acts unreliable. P a g e  | 21  Working with this guiding principle, it became clear that many of our generated concepts were completely reliant on reliable grid power; we eliminated these concepts accordingly. Finally, we organized concepts based on our estimation of the feasibility of the solution. Feasibility criteria were defined based on the availability of resources, team expertise, the ability to execute the project within the timeframe of the course, inherent synergy with the need statement, and level of complexity.   Figure 11: An overview of the generated concept maps. 3.1.2 Concept Screening After reorganizing the concept maps several times and eliminating non-viable solutions, we performed a thorough review on all remaining ideas. Through round-table discussion, the team selected the main concepts capable of fully addressing the need statement. A review of existing methods of coagulation in clinical settings also guided the team towards viable concepts. Ultimately, the team selected four general concepts for blood/tissue coagulation: monopolar ESU, bipolar ESU, thermal cautery, and ultrasonic scalpels (Figure 12). ESUs operate on the basis of delivering high frequency electrical signals (on the order of 5000 HZ) to the tissue of interest. Because the signal has such a high frequency, risk of ventricular fibrillation is minimized. High frequency electrical impulses are converted into local heat, causing tissue coagulation.  These systems are divided into monopolar and bipolar units. A monopolar ESU operates by delivering a high density electrical impulse via a single probe that must make physical contact with the tissue of interest. The electrical pulse travels through the patient's body and to a grounding pad placed on the opposite side of the patient’s body. A bipolar unit makes use of two adjacent probes, one for transmitting the electrical impulse and the other for receiving, eliminating the need for a grounding pad. Although a bipolar ESU provides a higher level of coagulation control and causes less tissue damage, the system is more expensive than its monopolar counterpart.  Thermal cautery units cause tissue coagulation by directly applying heat via physical contact with the tissue. These systems generally consist of a heat generator running off of a DC power supply. Because thermal cautery uses only DC current, it is safe to use on patients with pacemakers, while an P a g e  | 22  ESU carries some risk. Ultrasonic scalpels also exist in the market that produce local tissue heat by making use of a piezoelectric actuator, which produces ultrasonic frequency vibrations. These scalpels are considerably more expensive than either the ESU or thermal cautery and are rarely used in clinical settings.  Figure 12: Working principles of the selected general concepts. Due to the nature of the project, power generation and consumption were also incredibly important points to consider. To that end, the team discussed various methods of powering a device while keeping in mind the capacity of a power generator, possible interference with the sterile field, and the ability to provide consistent power even during outages and surges. Based on this analysis, the team selected two main power generation protocols (Figure 13).  Figure 13: Selected power generation protocols. P a g e  | 23  At this point in the need exploration process, it became evident that we required further input from clinical experts in order to inform our concept selection process. International Heat was fortunate to have access to information and advice from several different clinicians; this input proved instrumental in the subsequent design and testing processes. The clinical collaborators who lent their expertise to the thermal cautery project include:   Dr. Piotr Blachut: Orthopaedic surgeon; USTOP c0-founder   Dr. Robert Taylor: Orthopaedic surgeon; Branch of International Surgical Care founder  Dr. Brian Westerberg: Otolaryngologist; Branch for International Surgical Care director  Cindy Findlater: MDRD Coordinator at Vancouver General Hospital Meeting with these experts provided key insight into the working conditions and available resources of a typical regional medical center in Uganda, driving us to revise our need specifications [3] [10]:   Figure 14: Updated Needs Specifications With assistance from the clinicians, the team also generated a list of “nice-to-have” features: •Too costly. •Precedent of reusing disposable  parts in Uganda regardless of intended use. •Supply chain issues: lack of administrators to order and reorder materials, and inherent difficulty in shipping to Uganda.  Avoid consumables and disposables.  •A hand held device is best- light and easy to maneuver. •Foot pedal option not strictly necessary. Be ergonomically sound. •Cutting can be (and generally is) done with conventional scalpels, eliminating the need for a system which can both cut and coagulate.  Choose coagulation over cutting. •Capable of providing enough power to finish an ongoing surgery, even if power went out right at the beginning. •No elective operations are generally started in this situation, trauma and other emergent surgeries will still need to be performed.  Have a backup battery. •Autoclave and/or bleach are generally the only available methods for disinfection and sterilization.  •No nooks, crannies, or areas not capable of being cleaned with dishcloths.  •Avoid a solution where batteries would need to be sterilized. Most medical centers wouldn’t have sterilization equipment suitable for batteries. Be easily sterilized.  P a g e  | 24   Figure 15: Updated "nice to have" features Based on the clinicians’ opinions and our own investigations, International Heat revised the need statement to its current incarnation.  A means by which to perform coagulation during open surgery that does not require consumables and that can be powered for the length of a surgery by a battery. Similarly, the team updated the needs criteria to reflect feedback from the collaborators (Table 6). Table 6: Updated needs criteria. Additions and changes are in italics. Must Haves Nice to Haves Ability to coagulate blood vessels during surgery (independent of cutting) Easy maintenance and assembly  Grid-independent for 2 hours Low upfront cost (up to a few thousand dollars)  Ability to be sterilized with bleach and steam autoclave  Ability to cut No consumables Adjustment of coagulatory power  Moving on from here, International Heat needed to integrate these changes and apply them to the process of concept solution. Using a Pugh chart, the team was able to quantify comparisons among the possible final concepts. The first step was to establish the baseline concept, the ESU as used by surgeons in Canada. By definition, each criterion corresponding to the baseline concept recieved a score of zero. Against this baseline, the possible solution concepts were judged in each criterion to be better than, worse than, or equal to the corresponding baseline criterion. All criteria were weighted according to their relative importance, where a weight of five signified the most important criteria and a weight of one signified the least important. Each criterion score was multiplied with the weight of that particular criterion, and then those values were added up for each column. Table 7 illustrates this process.   •some surgeons prefer to cut this way. •would need to be independent of the coagulation function (ie. two separate modes) Be capable of cutting as well. •This enables the surgeon to adjust the amount of coagulation based on the type of operation. •Variation of ESU coagulation settings is 20-40W depending on type of surgery.  Control the delivered temperature. •Upfront cost of a couple hundred dollars up to a few thousand dollars, with little to no maintenance cost. •If hospitals see value in device they might be willing to pay more as long as cost is within reason. Be affordable. P a g e  | 25  The potential concepts are listed on the horizontal axis and the desired criteria on the vertical axis. From this analysis, the highest ranked concepts emerged:  Thermal cautery unit (power supplied by external generator).   Monopolar ESU (power supplied by external generator).   Bipolar ESU (power supplied by external generator).  Table 7: Concept screening chart (Pugh chart).  1: Conventional monopolar ESU, as seen in Canadian hospitals, chosen as baseline concept 2: Ultrasonic scalpel systems 3: Thermal cautery units ( hand-held internal battery  vs externally supplied design)  4: Monopolar ESU (hand-held internal battery  vs externally supplied design) 5: Bipolar ESU (hand-held internal battery  vs externally supplied design)  International Heat held a round table discussion to further evaluate these three concepts. By considering existing devices, current literature, and potential feasibility, two final candidate concepts were chosen, as illustrated in Figure 16 below. The first selected concept was a power adaptor and regulator capable of being coupled with the existing monopolar ESUs and which would be remain outside of the sterile field (ie. UPS – Uninterruptible Power Supply). The second selected concept consisted of a thermal cautery system with a backup battery which would remain outside the sterile field, illustrated in Figure 16.  P a g e  | 26   Figure 16: The selected concepts for coagulation.  3.2 Concept Selection 3.2.1 Prototyping 3.2.1.1 Materials & Methods Moving forward from concept screening, two concepts emerged as being potentially viable solutions to the need for coagulation during open surgery in low resource settings. Although some concern had been raised by the clinical advisors with regard to the efficacy and safety or thermal cautery, it was decided that it would be rash to discard this idea completely without first determining if these concerns could be mitigated through design features. With this in mind, the prototyping process was used to determine essential functional parameters of the thermal cautery system, and whether through prototype iteration it would be possible to design a device that adequately met the previously defined needs.  These essential functional parameters are detailed in Table 8.  The UPS concept was not explicitly prototyped as its appropriateness and functionality was considered to be well-established, where the design challenge lay more in creating a UPS that was low cost and robust in a low resource environment. Later, the focus shifted away from this concept as it became apparent that similar products were already in development [11].      P a g e  | 27  Table 8: Purpose of Prototyping the Thermal Cautery System Concern Parameter Test Strategy Efficacy of method Optimal operating temperature range. Test soldering iron between 70-150C on beef liver. Speed and efficiency of coagulation at operating temperature Time and power used to coagulate a 3cm line with soldering iron on beef liver Efficacy of design Temperature control system Ability of custom control circuit to heat tip within +/-5% of input Non-stick tip configuration Qualitative assessment of various Teflon configurations with soldering iron on beef liver  Appropriateness in low resource OR Power consumption Compare soldering iron power to ESU in different operating modes Heat-up/ down speed to/from operating temperature Time from 0130C, time from 13050C Clinician preference Verbal feedback, email correspondence Safety Fire risk Hold hot tip against glove, drape and cotton for 60s Tissue damage (spread) Cross-sectional inspection of coagulation vs. ESU at 40W  In order to establish the viability of thermal cautery, two prototypes were used. For the majority of the testing, a modified Hakko FX-888D temperature-controlled soldering iron was used (Hakko Corporation, Osaka, Japan). This model employs a ceramic cartridge heater in series with a stainless steel tip, where tip temperature control is achieved through a calibrated thermocouple sensor placed in the heater with an external console for user input and display. This model in particular was selected as its operating principle was the same as that which was planned to be used in the novel thermal cautery system. This allowed for testing of parameters such as time to heat up/down and power consumption to be done with the soldering iron with reasonable assurance that these results would be representative of subsequent prototypes. This prototype also allowed for the establishment of the physics of the process of coagulation, including the optimal temperature and tip shape and composition, which facilitated the design of the next-step prototype. Previously, these had been unknown quantities due to the lack of available literature and complexity of creating a representative simulation.    During the preliminary testing it was noticed that the stainless steel soldering iron tip stuck to the tissue surrogate, interfering with use of the device. To circumnavigate this, it was proposed that a non-stick material be used either wholly or as a coating on the existing tip, where the trade-off between smooth operation and effectiveness of heat transfer to the tissue had to be balanced. Teflon (PTFE - polytetrafluoroethylene) was selected as the non-stick material as this is a material that is robust, has a sufficiently high melting temperature, and is already used in a number of similar P a g e  | 28  medical devices, such as the Olympus Heat Probe. Ceramic, which was also considered as a non-stick surface was not selected due to concern with regard to chipping. Three configurations of Telfon were tested, as seen in Table 10. For the spray, consumer-grade Dupont Teflon Dry-Film Lube was used, while for the tape Plumbshop Teflon Tape was used (both Canadian Tire Co., Toronto, ON). The Teflon rods were machined from PTFE rods (McMaster-Carr, Aurora, OH).   Figure 17: Teflon spray-coated tip & machined Teflon rod tip Fresh-frozen beef liver was used as a tissue surrogate during the final testing. This type of meat was selected as it provided the best opportunity to test the device in a blood-filled environment and on blood vessels of varying sizes. Other meats and cuts were tested, such as pork chops and steak, but these were found to be too dry and bloodless to be representative of an open surgical procedure. For all tests requiring a comparison to existing ESU technology, a BRAND device was used on the 40W monopolar coagulation setting. This setting was chosen based on input from clinical advisors, who indicated that this was a typical setting used during liver resection.  Power consumption was measured using a RioRand Plug Power Meter, while tip temperatures were measured with a type k thermocouple. Coagulation was defined by the presence of a visible change in tissue colour or texture and a lack of blood or fluid exuding from the area during squeezing.   Figure 18: Works-Like Prototype Circuit Configuration P a g e  | 29  The second prototype was used to explore design challenges such as circuit and microprocessor design, as well as handpiece ergonomics. Once the critical physical parameters such as operating temperature and tip design had been established through the testing of the soldering iron prototype, this prototype was tested to assure functionality of the control circuit and to obtain subjective feedback from potential users of the device. This prototype involved a silicone-insulated 3D printed PLA (polylactic acid) handpiece, Teflon-coated stainless steel tip, ceramic cartridge heater with imbedded type k thermocouple, an Arduino Uno R3 microprocessor (Arduino, Somerville, MA) and an LCD for user display/input.  3.2.1.2 Testing Results & Discussion  Preliminary testing with the soldering iron revealed that the average power consumption of the soldering iron was 15-16W regardless of operating mode in the operating temperature range (standby or with tip held in room temperature water). Because the soldering iron uses a cartridge heater, the power draw follows a square wave on/off pattern, cycling between ~5W and 32W, with a very brief period instance of higher wattage during initial heat-up.  In reality, power consumption must be greater in the presence of a heat sink and with increased temperature settings, but no substantial difference was ascertained due to experimental limitations with the power measurement device. Thus, a worst-case scenario of 16W was assumed for all power calculations involving the soldering iron.  This can be compared to the ESU, which consumed either 11W on standby or 85-90W during use on the 40W power setting (and 40-45W at the 20W setting). Assuming 20minutes of straight use (a reasonable worst-case scenario for liver or breast surgery [3]), this would mean that the thermal cautery device would use 19.2 kJ of energy, while an ESU would use 54-.0108.0 kJ, depending on the power setting used. As a point of illustration, this means that the thermal cautery device could theoretically be powered for the length of a surgery using an iPhone 5 battery (19.6kJ) [12]. This means that the thermal cautery device should more than satisfy the need to be operational for a single surgery entirely from battery.  Through the testing of various tip temperatures, it was found that the minimum temperature to produce any visible coagulation was 110C on the liver cortex. More effective coagulation occurred in the 130-150C temperature range, where 150C was required to produce adequate coagulation in the very bloody inner regions of the liver. As the tip temperature increased the local tissue damage increased. Tissue damage that could be visualized appeared to extend to a similar depth as the ESU (negligible), but appeared to spread less laterally beyond the tip margins. This is partially illustrated in Figure 19, where it should be noted that the soldering iron tip was wider than that of the ESU.   P a g e  | 30    Table 9: Tip temperature testing results Setting J for ~3cm Effectiveness (heavy bleed) Tissue damage (charring, spread) ESU (40W) 450  (5s @ 90W) Adequate Charring, spread beyond margins of tip Soldering iron 110C 144  (9s @ 16W) Inadequate No charring; tight spread Soldering iron 130C 80  (5s @ 16W) Somewhat adequate No charring; tight spread Soldering iron 150C n/a Adequate Some charring, tight spread   Figure 19: Efficiency (left) and tissue damage (right) testing of thermal cautery system Efficiency of the thermal cautery system was comparable to that of the ESU in terms of time taken to coagulate a 3cm coagulate a 3cm line at 130C, but used substantially less power to perform this same task, as seen in   Table 9. Interestingly, increasing tip temperature did not necessarily result in increased power draw as the decreased time taken to perform the task outweighed any slight difference in energy required to heat the element to a higher temperature.  Following this, the effect of the different Teflon tip application methods were tested at the nominal operating temperature (130C). As seen in Table 10, the thicker Teflon layers (tape and rod) provided so much insulation that the outer end of the tip could not reach the desired operating temperature without concern that the inner layer touching the heating element or stainless steel tip would begin ESU TC – 130C ESU TC – 130C TC – 110C P a g e  | 31  melting. As a result of this, these design options were discarded. The spray was able to heat up to temperature with no measurable delay as compared to the uncoated tip, and was able to provide a sufficiently non-stick surface for operation of the device. The major disadvantage of this coating was that it rubbed off quite easily, and became ineffective after prolonged use. This issue would likely be circumvented by using industrial application methods as opposed to a consumer grade product. Table 10: Teflon Configuration and Heat Up/Down Results  Coagulatory effectiveness Heat-up to 130C Non-stick? Cool-down to 50C No Teflon effective Immediate (<5s) No 1:46 Teflon Spray effective Immediate (<5s) Yes, but rubs off easily 2:16 Teflon Tape Only if held for >10s Not achieved  (max 90C) Yes n/a Teflon Rod none Not achieved n/a n/a  Cool-down time was also a concern from a safety perspective. Using the Teflon coating slowed the cool-down slightly due to its insulating properties, but overall the cool-down time was not increased substantially. Though flammability testing revealed that fire or melting of gloves was not a concern (no melting, holes or smoke from paper drapes, cotton or gloves after 60s at 130C), the 2 minute cool-down time might be a concern with respect to accidentally touching the device against skin. To circumvent this, a shielded stand with metal heat sink base has been proposed to both protect the OR staff and to increase the cool-down time.  Moving on from the basic soldering iron prototype, the basic “works like” thermal cautery system was successfully implemented and presented to the clinical advisors, shown in Figure 20. In this prototype, the control system was able to be run from a laptop, where a narrow control of temperatures within the device operating range was achieved, as seen in Figure 20. Currently, the next aim is to operate this prototype as a stand-alone, using the LCD screen and panel and refine the geometry of the handpiece and tip according to clinician input.  P a g e  | 32    Figure 20: Works-Like prototype (left) and its microcontroller-heating element response curve (right) A finite element simulation was also performed on the current tip and heating cartridge to determine the effect of changing the Teflon thickness and to determine the heat distribution in the current configuration. Unsurprisingly, the thicker the Teflon coat, the worse the heat transfer to tissue (where thicknesses in excess of 0.2mm limited transfer quite severely). In terms of time, holding the tip in one location beyond 10 seconds would result in some carbonization in the tissue. Further details may be found in Appendix 7.2 and 7.5. 3.2.2 Final Concept Selection While a successful “works like” prototype was implemented, this device differs substantially from one that would satisfy the previously detailed needs. Following establishment of basic operating parameters in this prototype, the next step would be work towards prototyping features that are essential to the ideation of the final concept. P a g e  | 33   Figure 21: Final Design  Ideally, the final iteration of this device that could be approved by the necessary regulatory bodies and sent to clinicians in Uganda would have a number of features not explored in the present prototypes. First and foremost, all components of the handpiece would be designed such that full immersion in water and bleach during standard Ugandan sterilization procedures would not damage the device. This would involve ensuring proper material selection, selection of robust internal electronic components and sealing of sensitive areas of the handpiece, as is currently the case with ESU handpieces. Similarly, the control box would be constructed of a more liquid-resistant, easy to clean material, so that it could be stored in the OR and wiped clean between uses. The handpiece would also be designed such that it could be easily disconnected from the control box for sterilization. These differences would satisfy the requirement that the device be easily sterilized in a low resource environment.  With regard to the tip itself, it would either be designed as a non-removable part of the entire handpiece or as a reusable piece that could be interchanged. This choice would depend on further input from clinical experts and testing of the device through sterilization. Further consideration would also be given to the geometry and material selection on the tip from a heat transfer efficiency perspective.  Another distinct change from the prototype to the final product would be the inclusion of and selection of an appropriate battery in series with the wall plug, within the control box. Battery selection would depend upon cost, size vs. desired capacity. Similarly, other components within the device would be upgraded to more refined and robust ones that are more suited to a medical device. These changes would mean that the final device would satisfy the need to be ergonomic, non-reliant on wall power for 2 hours, and robust.  P a g e  | 34  4 Design Process Phase III: Implementation 4.1 Development Strategy & Planning 4.1.1 Intellectual Property Strategy The concept of thermal cautery and most of the individual components of the proposed device have been vastly published upon in the prior art and thus cannot be considered novel. For this reason and on the advice of our intellectual property adviser, Mr. Brad Wheeler of the UBC University-Industry Liaison Office (UILO), we plan to file IP around the entire system. Such narrow patent would more serve to attract potential investors and promote the device in fundraising pitches, rather than protecting against potential infringements.   Our preliminary patent search using Google Patent did not uncover active patents that would limit our freedom to operate. However, a professional search of the prior art is warranted and will be done through UBC UILO to determine the landscape of active patents in this area and to establish the freedom to operate. Appropriate measures, including modifications to product design or licensing would be considered if freedom to operate was not established. 4.1.2 Research & Development Strategy Careful consideration and planning is paramount to the development of the production device, that is the product that will be delivered to the customer. Defining high level R&D milestones, and recognizing anticipated technical challenges in the order of priority will inform detailed planning of an effective R&D strategy. As shown in Table 11, we have identified 8 critical milestones towards the development of the final product. As it can be appreciated from the table, the two first milestones have already been met.    Table 11: R&D Milestones R&D Milestones Proof-of-concept that thermal cautery can be used to coagulate blood vessels during open surgery First working prototype for effective coagulation in tissue in vitro First working prototype for effective coagulation in large animal models First working prototype for safe coagulation in large animal models First working prototype that is easy and safe to handle in the OR First working prototype that performs safely and effectively in humans Pre-production device for testing manufacturing method Scalable production device  We then used the aforementioned milestones to identify and rank anticipated technical challenges that need to be addressed at various stages of product development. In doing so, we focused on major challenges related to safety, effectiveness and ease of use of the proposed thermal cautery solution. These challenges, ranked in the order of importance, are presented in Table 12. Table 12: R&D Technical Challenges P a g e  | 35  # Technical challenge 1 Ensuring electrical safety for in-human applications 2 Ensuring adequate heat capacity in case of excessive bleeding 3 Determination of a (set) of optimal tip temperature(s) 4 Developing process for making durable non-stick coatings 5 Designing optimum tip shape for general abdominal and trauma surgery 6 Designing a holder or a cooling down mechanism to avoid heat-related safety/inconvenience for the surgeon  Based identified milestones and technical challenges, we plan to develop a detailed R&D plan - with the help of experience product development consultants - to determine the engineering tasks as a well as the required resources, testing methods and time.  4.1.3 Clinical Strategy Our product has been designed for low-resource settings with a strategic focus on Uganda; as such, it is necessary to base our regulatory strategy upon the regulatory framework of developing nations, and specifically Uganda.   In Uganda, pharmaceuticals are regulated by the National Drug Authority (NDA). Judging based on WHO’s 2014 Global Atlas of Medical Devices [13] and NDA’s own website, it is unclear whether any regulation of medical devices is currently in place. Our previous literature review in Fall 2015 had uncovered a 2009 draft guideline by the NDA, entitled Draft Guideline for Registration of Medical Devices for Human Use in Uganda [14], although at the time of preparing this report, it appears that the aforementioned guideline has been taken off NDA’s website and it remains unclear whether the guideline has been adopted or not.   The draft guideline envisioned three tracks for medical device registration applications, based on whether the device is licensed in any of the Global Harmonization Task Force (GHTF) country members, and whether it has been manufactured in accordance with one of the recognized Quality Management Systems (QMS). Accordingly, if a medical device is registered in a GHTF country, that is if it has a 510k clearance or a pre-market approval in US, a CE mark in the EU, or a device license in Canada, Australia or Japan, it becomes eligible for approval in Uganda under a Track 1 application. If the device is not licensed in GHTF members, but has been manufactured under ISO13485, ISO13488, or Good Manufacturing Practice (FDA’s 21 CFR part 820) it can be approved under Track 2. Approval applications for devices that are neither licensed in a GHTF country nor manufactured in compliance of a recognized QMS, would require preclinical data as well as manufacturer’s declaration of conformity with GHTF Essential Principles of Safety and Performance.  Whether or not the draft guidance document has been adopted in Uganda, we plan to go down an FDA clearance route, as FDA clearance is accepted in the majority of developing world, and ensures patient safety, through the required conformity to GMP.    P a g e  | 36  Our proposed thermal cautery device seems to be classified as a 510(k)-eligible Class II device by the FDA, as all the thermal and electro-cautery devices have been [15]. Accordingly, we plan to have the device cleared under 510(k), as our device seems to be substantially equivalent to the Olympus Heat Probe Unit HPU20, a thermal cautery device previously cleared by the FDA through 510(k) [16].  As a part of our R&D process, we plan to conduct Good Laboratory Practice-compliant preclinical studies in large animal models to assess safety (both acute and chronic) and effectiveness of the device. The generated preclinical data will be submitted to the FDA as a part of the 510(k) application. It will be at the discretion of the FDA whether or not to ask for clinical data for a 510(k) clearance, although one would notice in upwards trend in the these requests. In either case, upon successful preclinical results, we plan to conduct a pilot clinical trial of the device in the form of a registry. Although a pivotal randomized controlled trial (RCT) would not be necessary for a 510(k) submission, in recent years more and more medical device companies take it upon themselves to assess their devices in RCTs, either to support new reimbursement code applications or as an effective marketing strategy. However, as our device is mainly geared towards low-resource settings, we would expect to avoid expensive RCTs to reduce final product cost, as long as they are not dictated by regulatory agencies.  4.1.4 Competitive Advantage & Business Strategy Uganda has a population of 37.5 million, and a per capita total health expenditure of $108. Both public and private hospitals operate in the country. The public sector manages 48 district hospitals, 14 provincial hospitals and 2 regional hospitals, while the private sector runs 88 district hospitals [13]. To pain a better picture of the current availability of medical equipment in Uganda, it is worthwhile to note that the entire public sector own only 2 CT-scanners, 3 mammography units and no MRIs [13]. It is these hospital that would benefit most from our innovations, and accordingly, they would be the focus of our marketing strategy.   The most important consideration in development of the reimbursement and marketing strategies is to identify the payer and the entity that makes purchasing decisions. In Uganda, traditionally, the ministry of health had been procuring medical devices in bulk and distributing it among regional hospitals. However, in the past two years, the ministry has allocated developmental funds for infrastructure directly to regional hospitals to buy medical equipment they require, with some input from the health infrastructure division and national advisory committee on medical equipment (NACME) [13].  Accordingly, our product should be marketed to hospitals themselves, as well as the involved government bodies, that is the health infrastructure division and the NACME.   Table 13 shows the value propositions that we have developed for the stakeholders. Value propositions will be focused towards hospitals (buyers), surgeons (end users) and the government bodies which can influence hospital purchase decisions.  Table 13: Stakeholder Analysis Summary   Stakeholder Value proposition P a g e  | 37  Surgeons Easier procedures (improved field of view), improved care. Hospital Easier procedures for surgeons. Reduced need for future treatment. Government Reduced need for future treatment; improved care; reduced long-term cost 5 Conclusion The journey International Heat has taken over the past four months has been invaluable as we applied principles of engineering and biodesign to create a solution for a real world problem. We believe that thermal cautery has the potential to be a viable replacement for electrosurgical units in the third world, as the device is inexpensive to manufacture, requires no consumables, and is potentially power enough to coagulate blood vessels cut during open abdominal surgery.  As the official course comes to a close, we would like to take the opportunity to thank all of the people who helped us through the process. A huge thank you goes out to all of the clinical collaborators who fielded our questions, tested our product, and answered countless emails.  Dr Piotr Blachut, the orthopedic surgeon who proposed the original problem at the MedTech Cafe; Dr Robert Taylor, a member of the Branch for International Surgical Care who provided valuable insight on working conditions in Uganda; Dr Brian Westerberg, the head of the Branch for International Surgical Care who provided insight on clinical expertise; and Cindy Findlater, the head of the Medical Device Reprocessing Unit at Vancouver General Hospital who gave the team crucial information on the sterilization procedures found in smaller Ugandan hospitals. International Heat would also like to thank everyone who made this course such an enriching experience. The other Engineers in Scrubs students; teaching assistants Michèle Touchette and Tiffany Ngo; and finally the course instructors who guided us through the entire process: Dr Mike Van der Loos, Dr Dave Wilson, and Dr Roger Tam.    P a g e  | 38  6 References  [1]  S. Zenios, J. Makower and P. Yock, Biodesign: The Process of Innovating Medical Technologies, Cambridge, UK: Cambridge University Press, 2010.  [2]  R. Kavuma, "Uganda's Healthcare System Explained," The Guardian, 1 April 2009.  [3]  R. H. Taylor, Interviewee, Electrosurgery in low resource settings. [Interview]. 16 February 2016. [4]  J. Lacourse, W. Miller, M. Vogt and S. Selikowitz, "Effect of high-frequency current on nerve and muscle tissue," IEEE Trans Biomed Eng, vol. 32, pp. 82-86, 1985.  [5]  P. Blachut, Interviewee, Electrosurgery in low resource settings. [Interview]. 5 February 2016. [6]  B. Westerberg, Interviewee, Electrosurgery in low resource settings. [Interview]. 5 February 2016. [7]  W. Schneider, The History of Blood Transfusion in Sub-Saharan Africa, Athens, OH: Ohio University Press, 2013.  [8]  N. Zervas and A. Kuwayama, "Pathological characteristics of experimental thermal lesions: comparison of induction heating and radiogrequency electrocoagulation," J Neurosurg, vol. 37, pp. 418-422, 1972.  [9]  G. Bedny and D. Mesiter, The Russian Theory of Activity: Current Application to Design and Learning, Series in Applied Psychology, Psychology Press, 1997.  [10]  C. Findlater, Interviewee, Sterilization in low resource settings. [Interview]. 16 February 2016. [11]  G. Craig, "This Nigerian student developed Neva, an emergency power backup for Suregons in the OR," Techpoint Nigeria, 14 October 2015.  [12]  Batteries Plus LLC, "Battery for Apple iPhone 5 Cell Phone," Duracell, 2016. [Online]. [Accessed 1 May 2016]. [13]  S. Wanda, A. Wondimagegnehu and J. Mwoga, "Global Atlas of Medical Devices: Uganda," World Health Organization, Geneva, Switzerland, 2014. [14]  National Drug Authority, "Draft Guideline for Registration of Medical Devices for Human Use in Uganda," National Drug Authority, Mbarara, Uganda, 2009. [15]  The Food and Drug Administration, "Product Classification Database," [Online]. Available: http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPCD/PCDSimpleSearch.cfm. [Accessed 2 P a g e  | 39  May 2016]. [16]  The Food and Drug Administration, "510(k) Summary Olympus Heat Probe Unit HPU-20," Dept. of Health & Human Services, Food and Drug Adminstration, Rockville, MD, 1998.     P a g e  | 40  7 Appendices  7.1 Brainstorming & concept maps  Figure 22: Original concept map  Figure 23: Reorganized concept map (power) P a g e  | 41   Figure 24: Reorganized concept map (feasibility) 7.2 Power draw testing data Table 14: ESU Power Draw   P a g e  | 42   Figure 25: Soldering iron power draw P a g e  | 43   7.3 Thermocouple calibration  7.4 Finite Element Simulations of Heat Transfer in Tip Table 15: Tissue properties Parameter Value Young’s Modulus (N/m2)  2.7E5 Poisson’s ratio  0.4 Thermal conductivity (W/mK) 0.512 Density (kg/m3)  1060 Specific heat (J/kgK)  3600 Electrical conductivity (S/m) 0.33 Table 16: Material Parameters   P a g e  | 44  Parameter Tissue Teflon Incoloy (nickel alloy) Water Stainless steel Thermal conductivity (W/mK) 0.512 0.25 12 0.6 70 Density (kg/m3)  1060 2200 7250 1000 7700 Specific heat (J/kgK)  3600 970 500 4200 502   Figure 26: Temperature contour plot of Incoloy heating element and tissue P a g e  | 45   Figure 27: 3D temperature gradient plot after 30s application of 10W heating element to tissue  Figure 28: Temperature contour plots for various Teflon coat thicknesses after 30s with metal tip at 110C     P a g e  | 46  7.5 Handpiece and tip CAD    

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