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Cooling vest for improving surgeons' thermal comfort: A multidisciplinary designprojectThomas Langø a; Ragnhild Nesbakken b; Hilde Færevik a; Kristine Holbø a; Jarl Reitan a; Yunus Yavuz c;Ronald Mårvik c

a SINTEF Health Research,, Trondheim,, Norway b Department of Product Design, Norwegian University ofScience and Technology (NTNU),, Trondheim,, Norway c National Centre for Advanced LaparoscopicSurgery, St. Olav's Hospital,, Trondheim,, Norway

Online Publication Date: 01 February 2009

To cite this Article Langø, Thomas, Nesbakken, Ragnhild, Færevik, Hilde, Holbø, Kristine, Reitan, Jarl, Yavuz, Yunus and Mårvik,Ronald(2009)'Cooling vest for improving surgeons' thermal comfort: A multidisciplinary design project',Minimally Invasive Therapy andAllied Technologies,18:1,20 — 29

To link to this Article: DOI: 10.1080/13645700802649383

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Minimally Invasive Therapy. 2009; 18:1; 20–29

ISSN 1364-5706 print/ISSN 1365-2931 online © 2009 Informa UK LtdDOI: 10.1080/13645700802649383

ORIGINAL ARTICLE

Cooling vest for improving surgeons’ thermal comfort: A multidisciplinary design project

ThOmaS LaNgø1, RagNhILD NeSbaKKeN2, hILDe FæRevIK1, KRISTINe hOLbø1, JaRL ReITaN1, YUNUS YavUz3, & RONaLD måRvIK3

1SINTEF Health Research, Trondheim, Norway, 2Department of Product Design, Norwegian University of Science and Technology (NTNU), Trondheim, Norway, and 3National Centre for Advanced Laparoscopic Surgery, St. Olav’s Hospital, Trondheim, Norway

Abstracta laparoscopic surgeon sometimes experiences heat-related discomfort even though the temperature situation is moderate. The aim of this project was to design a cooling vest using a phase change material to increase thermal comfort for the surgeon. The project focused on the design process to reveal the most important parameters for the design of a cooling vest that could be demonstrated in a clinical setting. We performed an entire design process, from problem analysis, situation observations, concept for a prototype, temperature measurements, and a final design based on clinical testing. The project was conducted by a multidisciplinary team consisting of product designers, engineers, physiologists, and surgeons. We carried out four physiological demonstrations of one surgeon’s skin temperatures and heart rate during different laparoscopic procedures. a commercially available cooling vest for firemen and two proof-of-concept prototypes were tested alongside a reference operation without cooling. To aid the final design, one person went through a climate chamber test with two different set-ups of cooling elements. The final design was found to improve the conditions of our test subject. It was found that whole trunk cooling was more effective than only upper trunk cooling. a final design was proposed based on the design process and the findings in the operating room and in the laboratory. although the experiences using the vest seemed positive, further studies on several operators and more surgical procedures are needed to determine the true benefits for the operator.

Key words: Design, cooling vest, heat stress, laparoscopic surgery

Introduction

heat stress inflicts increased body temperature and sweating and is known to cause problems such as discomfort, dehydration, impaired mental performance and even hyperthermia in extreme situations (1). Surgeons have reported to experience heat-related discomfort during long surgical proce-dures due to increased physical and mental effort and poor ergonomic working conditions (2–3) combined with an inability to evaporate sweat through protective surgical clothing. Thus the work performance of the surgeon might be impaired.

Personal cooling systems are common methods for relieving thermal discomfort for lines of work with

extreme temperatures or limited possibilities for body heat dissipation. The use of a cooling system can result in increased work productivity and comfort in addition to safer work conditions (4). Cooling agents, such as water, air, gel, ice or phase change material (PCm), are commonly utilized in these systems to prevent heat stress. PCms cause a reduction in increased body temperature by absorption of excess body heat. most heat stress studies have been conducted in extreme temperature situations with environment temperatures > 35C, whereas the surgeon is only exposed to room temperatures around 25C. There-fore few studies regarding heat stress within the surgical field can be found in the literature.

Correspondence: T. Langø, SINTeF health Research, Department for medical Technology, 7465 Trondheim, Norway. Fax: +47 900 70 800. e-mail: Thomas.Lango@sintef.no

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Design of cooling vest for surgery 21

The overall goal of this project was to design an efficient and comfortable cooling vest for surgery using PCm elements to relieve the thermal stress for the operator. Key focus areas of the design project were efficient cooling, adequate moisture transport, mobility according to task and overall comfort. Physiological temperature measurements were used to examine the heat stress situation during surgery and to study the effect of a commercially available cooling vest. Optimal place-ment of PCm elements on the body was examined in an environmental chamber and designed on the basis of thermoregulation in the human body and the physics of thermoregulation. The laboratory measurements were conducted to provide an indication of whether the design project was achieving the goals of reduced thermal stress and improved comfort. User tests for mobility during surgery were carried out to ensure a comfortable fit for different body sizes and shapes. The vest was designed and tested in laparoscopic surgery, simply because the project leader and initiator of the idea is a laparoscopic surgeon. Nevertheless, we believe that other clinical disciplines, perhaps, are in more need of cooling, e.g. orthopaedics and surgeons wearing lead coats due to radiation exposure during surgery. The project was carried out by a product design student working together with researchers and clinicians in a multidisciplinary team including physiologists, medical technology engineers, surgeons and product designers. It should be emphasized that only one test subject was used. heat sensation varies between subjects, but the main part of this project was the design process itself. The clinical tests were used as an indication of success, or reference, for achieving a proper design process and progression. a larger study involving many subjects is needed to perform a scientific evaluation of the clinical effect of the final design of the cooling vest.

Material and methods

Design approach

We based our development of a cooling vest on a design approach that contained the phases described in the list below. The description is general to some degree, and only steps relevant for our project are included. Specifics for the cooling vest design process are outlined with italic font where appropriate.

Problem description – Information retrieval from •different sources, such as literature, trying to

understand the field, laparoscopic surgery, and extract core problems with emphasis on the challenge at hand, heat stress.Observation and problem analysis – by observing •the real environment, laparoscopic surgery in the operating room, it is possible to analyse in more detail the challenges described in the literature and by other observers, medical technology engineers. a designer also gains insight into logistics, which must be considered in the later concept design.Interviews with users – These are carried out to •obtain a deeper understanding of the problem from experienced users, laparoscopic surgeons, i.e. surgeons with more than 1000 procedures and who are in a teaching position.Idea and concept generation – We combined •our knowledge gained from the previous steps with insight on different materials and physio-logical aspects specific for the user situation, laparoscopic surgery, to generate ideas to solve the problem, heat stress. Ideas and concepts generated in this phase are discussed with both engineers, physiologists, and surgeons to make sure that promising concepts are considered carefully. exist-ing products, cooling vest for firemen, are considered if they seem eligible, at least for comparison with developed prototypes.early prototype design – a first prototype of a •solution is designed based on the concept generation that seems to hold most promise to solve the core problem for the user. Functionality and logistics are important parameters at this stage, although appearance and user perception can already be considered.Testing and evaluation – The prototype design is •tested in a real environment to get initial feedback on the concept and feedback on parameters that determine the functionality of the design. Several parameters are logged for evaluation and as a basis for the next phase.Redesign and second prototype development – •This is more an adjustment of the design based on the immediate feedback from the real environment test. The functionality of the design is important and must be adjusted to optimally fit the users’ requirements in this redesign.Testing and evaluation in laboratory for controlled •experiments – This is used as a basis for the final design. In the laboratory, various parameters can be controlled to a greater degree than in a real situation, e.g. temperatures in the operating room, and this allows for a more careful check of which parameters are most important in the final changes that might need to be completed.

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22 T. Langø et al.

Final design and evaluation – In this final phase, •such parameters as appearance and the users’ perception of the prototype are important, also those which have not been involved in the project.

This scheme ensured a development solving the user-specific problem and constantly improving the prototypes.

Phase Change Material

The PCm material used in this study consisted of glaubersalt (Climsel C28, Climator ab, Sweden), which has a melting point of 28C and latent heat capacity 180 kJ · kg-1. The effect of glaubersalt is three times that of e.g. Outlast microcapsules in fabric. glaubersalt was chosen because of the high capacity for cooling. Phase-change materials are characterized by their ability to absorb energy when they change from a solid to a liquid state and to release heat as they return to the solid phase. PCm used in clothing should go through the phase change at temperatures close to the thermally neutral temperature of the skin, 28–32C. During the phase change, the temperature does not change, and thus PCm can stabilise body temperature. To optimize cooling performance of PCm in clothing the further design process focused on careful positioning of PCm, minimizing total insulation and facilitating moisture transport.

Test clothing

The regular clothing worn by the surgeon in the operating theatre consisted of shoes, socks, cotton underwear including a t-shirt, cotton trousers and a surgeon’s protective smock (clothing a, Figure 1a). heat stress wearing this clothing was compared with the situation when a commercially available cooling vest completely covered with glaubersalt elements (ComfortCooling, Kinna, Sweden; total weight 2.0 kg)

was added to the protective clothing system (clothing b, Figure 1b). Clothing with two experi-mental cooling vest concepts (clothing C and D, Figure 1C and D) were then compared with clothing a and b. For the design of a new cooling vest, all excess fabric was removed from the existing vest. Then, the number and position of the elements were systematically changed, while the effect on heat stress and freedom of movement was evaluated. The cooling vest concept C was worn directly on skin under the surgical shirt.

Measurements

Local skin temperatures were measured on the chest, abdomen, anterior thigh, neck, upper and lower back and biceps using YSI-400 thermistors (Yellow Springs Instruments, Yellow Springs, Oh, USa) with an accuracy of 0.15C. Temperatures were logged every 60 seconds and heart rate was monitored using a Polar Sports Tester (Polar electro, Kempele, Finland). In addition, the surgeon gave an evaluation of experienced subjective thermal comfort approxi-mately every ten minutes. The evaluation scheme included questions on experienced temperature, perception of skin wetness and thermal comfort and the surgeon answered with a modified version of the Nielsen questionnaire (5) shown in Table I. The standard scale was simplified because of the surgeons’ working condition. For the same reason, it was difficult to obtain values from the surgeon precisely every ten minutes. hence, we calculate average values, instead of showing the measurements as a function of time, and present the last measurement after 90 minutes.

Set-up for prototype evaluation in the operating room

exposure characteristics, clothing properties and work intensities (heart rate) were assessed for the real work situations for the surgeon in the operating

Figure 1. Regular clothing for laparoscopic surgery (a), comercially available cooling vest for firemen (b), prototype 1 (C), and prototype 2 (D) of cooling vest.

A. B. C. D.

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Design of cooling vest for surgery 23

theatre during surgery at St. Olavs hospital, Trondheim, Norway. For all test procedures, the same operating room was used. The temperature in the room was externally controlled within 3°C of normal room temperature. a 55 year-old male surgeon was the test subject for the four experiments in the operating theatre. The procedures were three gastric bypasses and one adrenalectomy. gastric bypass was selected as test procedure because of long-lasting operations and the extended use of tasks known to create heat stress such as dissection and suturing.

The various OR tests were:

Temperature progression was examined under •normal conditions, without cooling. The gastric bypass procedure lasted three hours at room temperature (mean value 22.7°C) (clothing a).The procedure lasted 78 minutes and was con-•ducted with a commercially available cooling vest for fire fighters (ComfortCooling a, b, Sweden) during an adrenalectomy. Room temperature was approximately 23.5°C (clothing b).The initially developed prototype cooling vest was •used during a gastric bypass procedure lasting two hours with a room temperature of 21.7°C. The surgeon wore the prototype directly on the skin under the surgical shirt (clothing C).The final functional prototype was worn during •a gastric bypass operation lasting almost four hours. Room temperature was approximately 23.7°C (clothing D).

Sweat production was measured by the difference in the weight of the surgeon’s clothes before and after the procedures. Surgeons drink liquid during the procedure, and, hence, body weight is not a suitable parameter to determine sweat production. Furthermore, the outermost sterile coat does not

allow significant evaporation of moisture, making the weight of clothes a suitable parameter to calculate the sweat production. Nevertheless, with only one subject and four procedures, this parameter only provides an indication for the design process.

Set-up for prototype evaluation in the laboratory

Laboratory measurements were carried out to aid the design process. In particular, the hypothesis for the laboratory tests was that if cooling elements were strategically placed on the most sensitive body segments the total number of cooling elements needed would decrease. This would be favourable in terms of weight and mobility and provide uncovered skin areas for sweat evaporation.

In the laboratory all parameters could be moni-tored under controlled environmental conditions in order to examine the effect of different positioning and amount of PCm on physiological responses. In addition, we focused on determining parameters that affect the design regarding the key problem areas, such as overall comfort, mobility, cooling, and moisture transportation. Two different concepts were tried: One with 14 cooling elements on the whole trunk (whole trunk cooling WTC), the second with nine elements only on the upper part of the trunk (upper trunk cooling UTC) (Figure 2). The surgical clothing was weighed before and after the test. Core temperature and local temperatures (chest, chest outside of element, upper and lower abdomen, shoulder, upper back, middle back and lower back, anterior thigh, upper arm and forehead) were measured. Four moisture sensors (type hIh-3605-b-CP, honeywell, USa) were attached at chest, abdomen, upper back and lower back and a Polar Sports Tester (Polar electro, Finland) measured the heart rate. body weight

Table I. Subjective evaluation ratings.

Subjective ratings

Clothing

A B C D

Thermal comfort 2.61.3 (4) 2.50.8 (3) 2.21.3 (3) 1.00.6 (1)

Thermal sensation 3.30.5 (4) 2.50.5 (3) 2.30.5 (3) 2.00 (2)

Skin wetness 4.71.0 (6) 3.40.5(4) 3.00 (3) 3.00 (3)

Subjective evaluation1 of thermal comfort, thermal sensation and skin wetness for a surgeon wearing the protective clothing a, b, C or D. values are means and SD of measurements made every ten minutes during the first 90 minutes of the operations. values in parentheses denotes ratings at 90 minutes.1) Ratings for thermal comfort: 0 (neutral); 1 (comfortable); 2 (slightly uncomfortable); 3 (uncomfortable); 4 (very uncomfortable); 5 (extremely uncomfortable). Ratings for thermal sensation: 0 (neutral); 1 (slightly warm); 2 (warm); 3 (hot); 4 (very hot); 5 (extremely hot). Ratings for wetness of skin: 1 (more dry than normal); 2 (normal dryness); 3 (chest and back slightly wet); 4 (chest and back wet); 5 (body wet); 6 (body wet; clothing sticks to the skin).

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24 T. Langø et al.

was determined before and after the tests. Sweat production was measured by the difference in body weight before and after the experiments.

The test protocol inside the chamber started with 20 minutes moderate exercise on a treadmill (Woodway Treadmills, USa) (Figure 3a), followed by simulated laparoscopic tasks: Cutting, moving objects around in a training box (Figure 3b) and leaning over a table to create an uncomfortable static posture, each lasting several minutes. The protocol ended with another 20 minutes moderate exercise on the treadmill. as for the clinical tests, the test subject in the laboratory was asked to give subjective ratings of thermal sensation (for body, feet, hands, head and neck), sweat rate, thermal comfort as well as skin sensation and preferred environment temperature.

Results

Surgery

Table I shows the results of subjective evaluation of thermal comfort, thermal sensation and skin wetness. Since the clothes were evaluated during real

operations, the duration of the exposures varied. The results are therefore shown only for 90 minutes, which was the shortest duration time. Compared with the regular clothing (clothing a) the subjective ratings of thermal comfort and sensation, and also skin wetness, improved when cooling vests with PCm were introduced into the clothing. While perceived skin wetness increased by time for clothing a, it was stable throughout the exposure when wearing clothing C. also values after 90 minutes exposure are reduced for the clothing with PCm, shown by the ratings 6 (body wet, clothing sticks to the skin), 4 (chest and back wet), and 3 (chest and back slightly wet) for clothing a, b and C, respectively.

It was apparent from the clinical trials that the regular clothing generates serious discomfort related to wetness and temperature. The experience from the operating theatre encouraged further improvements in the use of PCm in the surgeon’s protective clothing. The effect of PCm on subjective evaluation of wetness was noticeable when the commercially available cooling vest (b) was used, as well as the initial experimental vest concept (C). however, the surgeon stated that vest b was not acceptable due to reduced freedom of movement and stiffness. Our

WTC

UTC

Figure 2. Placement of PCm elements during laboratory test 1 (WTC) and laboratory test 2 (UTC). Test 1 (WTC) was performed with 14 cooling elements on the whole trunk, while test 2 (UTC) was conducted with nine cooling elements on only the upper part of the trunk.

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Design of cooling vest for surgery 25

challenge was to design a cooling vest that paid attention to the freedom of movement that had been achieved by vest concept C and also contained a sufficient amount of cooling elements to maintain satisfactory cooling capacity. It was also a challenge to provide spacing between the cooling elements and thus reduce the barriers to the evaporation of sweat.

The effects of cooling elements covering the whole trunk (WTC), or the upper trunk (UTC) under the controlled environmental conditions in the laboratory demonstrated that increasing the number of cooling elements by 56% (from nine to 14) doubled the drop in mST from 1.3°C to 2.6°C (Figure 4). although mean skin temperature fell more and stayed at the lower level for a longer period of time with concept WTC compared to UTC, the test subject rated thermal comfort and thermal sensation more positively for UTC than for clothing WTC. Relative humidity (% Rh) was 20% lower in clothing UTC than with WTC. moreover, less sweat was produced and more sweat evaporated through UTC than with WTC (217 g and 189 g, respectively; measured as difference between total sweat production and the amount of sweat accumulated in the clothing).

The design of the final vest concept D (total weight 1.8 kg) (Figure 5a–D) was chosen on the basis of the results from the operating theatre and laboratory tests. The final experimental vest concept was designed using a permeable, thin material that facilitates heat and moisture transport. The vest is closely fitting since there are no PCm elements on the sides of the trunk, providing better freedom of movement.

The elements are configured in strips, with three or four elements in a row and small spaces between them. They are positioned on areas of high thermal sensitivity and where body heat transport can be facilitated by regulating blood flow through variations in vasomotoric tonus. Clothing D was evaluated during a gastric bypass operation that lasted almost four hours. Perceived sweat rate was chest and back slightly wet (rating 3), thermal sensation was perceived as warm (rating 2) and thermal comfort was perceived as comfortable (rating 1) after 90 minutes exposure (Table I).

Design process

a comparison of the physiological and subjective measurement data from the four clinical tests indicates that the cooling vest lowers heart rate, sweat rate, and increases thermal comfort more than the commercially available cooling vest. The vest also seems to provide the surgeon with a physiological improvement compared to no cooling regarding sweat rate and thermal sensation (Table I). Neverthe-less, it should be noted that the results are based on a concept analysis; design of a cooling vest for surgery, using thermal tests for reference values only, and that further studies are needed to statistically prove the potential clinical benefits. Nevertheless, the indications of our findings are positive and can be summarized as follows:

The surgical situation generates discomfort •related to heat and sweat.

A. B.

Figure 3. Photos from typical settings during the laboratory tests: Treadmill walking (a) to increase body temperature and simulation of surgical movements (b).

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26 T. Langø et al.

The commercially available cooling vest was not •suited for laparoscopic surgery.The initial prototype worked better than the •commercially available cooling vest.The new design seems to increase thermal •comfort and reduce perceived sweatiness for the surgeon.

Discussion

The tests during laparoscopic surgery showed that surgeons are subjected to temperature conditions that can cause thermal discomfort. The discomfort

experienced by the surgeon is evident through increased sweating and heart rate and a high level of perceived discomfort. The sensation of thermal discomfort might lead to decreased performance, e.g. in concentration and decision making. moreover, the commercially available cooling vest was not suited for the surgical situation. It caused the surgeon’s body temperature to rise and generated a higher sweat rate compared to heat generated without cooling. This commercial vest was originally designed for fire fighters and might give sufficient cooling for shorter periods of time under extreme temperature exposures. however, the thick insulation material in the vest hinders evaporation of sweat, which is the

34.5

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33.5

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31.01 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 101106 111 116

Mea

n s

kin

tem

per

atu

re (

°C)

Time (min)

Whole trunk cooling Upper trunk cooling

Figure 4. mean skin temperatures for laboratory tests during whole trunk cooling (grey) and using only upper trunk cooling (black).

A. B. C. D.

Figure 5. Prototype 3 of cooling vest, the final version in the design project. (a) User wearing the vest. (b) view from back. (C) Front view. (D) Cooling elements inside vest.

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Design of cooling vest for surgery 27

main mechanism for body cooling, and is therefore not suitable in the work situation of the surgeon.

The concept background for the first prototype was to have cooling elements close to the body, centred along the spine and on the chest in front, and use a minimum of textiles to allow high degree of moist transport. The initial prototype resulted in increased cooling and, hence, a decreased mean skin temperature (mST). elements were wrapped in a thin, micro-fibre textile and were positioned closer to the skin compared to the commercially available vest. however, the surgeon complained about uneven distribution of cooling elements and a desire for more cooling.

The final functional model was designed according to these findings with a more even distribution of elements for higher comfort and a uniform thermal relief. It also contained a higher number of elements for increased cooling effect.

The final experimental cooling concept for the surgeon (D) resulted in improved subjective evalua-tion of perceived wetness of skin and clothing, improved thermal sensation of clothing and improved thermal comfort, compared with the surgeon’s regular clothing. The trunk was cooled sufficiently to reduce the activation of sweating. The resulting improved perceived thermal comfort has also been observed by other studies that have demonstrated an inverse relationship between perception of sweatiness and thermal comfort (6,7) which found that feeling of comfort is inversely related to perception of sweatiness. The cooling elements provided an even distribution of temperature over the whole trunk, while skin temperature varied between different areas of the trunk in the regular suit. Such a uniform distribution of skin temperature is perceived as more thermally comfortable than a non-uniform temperature distribution (8). The total weight of fabric and glaubersalt elements of the final vest concept (D) was only slightly reduced compared with that of the commercially available cooling vest (b), 1.8 kg and 2.0 kg, respectively. although the commer-cially available vest also provided improved thermal sensation and thermal comfort, the final vest concept D allowed for improved moisture transport and evaporation. This was achieved through spacing between cooling elements and the use of materials with improved moisture permeability. The design provided a close fit between cooling elements and skin to facilitate heat transport. a recent study has also demonstrated the significance of fit on the effect of cooling garments (4).

The laboratory tests support the clinical findings in indicating that both amount of cooling and element placement influence the cooling effect. These

findings were incorporated in the final design. Together with changes in material qualities and garment configuration, our final cooling vest was noticeably improved compared to the commercially available cooling vest. The glaubersalt elements generated a clear and instant drop in temperature when applied. This drop varied between 2°C and 5.2°C. after this period, the temperature remained stable for some time before rising again. If heat stress is high, these periods will be shorter and the temperature will have a faster increase rate. Similarly, increasing the cooling element area prolonged both heat sink and stable period before successive temperature increase. environment temperature, work intensity, clothing insulation, and breathing proper-ties affect the cooling capacity of the elements in addition to individual heat tolerance. Local tempera-tures in areas not covered by PCm decreased even though no direct cooling was applied. This suggests that local skin cooling also creates a peripheral cooling effect. This influence of localized cooling on other body areas has been reported previously (1,9).

Our findings suggest that all segments on the trunk influence the total thermal responses of the body for the surgeon’s moderate temperature situation. Therefore increasing the total amount of elements on the trunk increases the cooling effect. an even distribution of elements on the trunk is also more comfortable than cooling in constrained areas, provided that sweat evaporation is not inhibited. Others have also demonstrated that cooling vests can decrease body temperature and sweat rate and increase performance and thermal comfort for a user (6,9–12).

Final prototype design

The findings from the clinical and laboratory tests were used to examine cooling effect and evaluate concepts in an iterative design process. This process included analysis of user context, production, market, material quality and aesthetics as well as prototype testing and user trials, upon which a final cooling concept was suggested (Figure 5a–D). The final cooling vest is designed in permeable, thin materials to facilitate heat exchange and moisture transport. a synthetic fibre shirt under the vest ensures moisture transport away from the body and comfort for the user. Silver fibres in the shirt accelerate heat exchange and prevent unwanted odour. The vest has a close fit that is easy to adjust to different body sizes. This ensures effective cooling without restricting the surgeon’s movement. The element arrangement considers physiological aspects such as heat production, sweat production and

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28 T. Langø et al.

evaporation and thermal sensitivity in the upper body. The elements are configured in strips with three or four elements in a row with a small space between. This gives an even cooling effect while at the same time providing sweat transport. Inserting and removing PCm cooling elements is also faster with this configuration.

Surgical clothing

The use of a sporting shirt under the cooling vest proved advantageous as it keeps the surgeon dry and comfortable while temperature is rising. The cotton shirt worn today is comfortable while dry, but comfort declines rapidly when sweating. Comfort is one of the most important aspects of clothing and the perceived comfort of a garment depends on its temperature and moisture characteristics. The user’s perception of the thermal situation is extremely important in a surgical setting. If the surgeons feel better, their work performance will most likely improve. Small physiological improve-ments might constitute a significant difference in this situation, which demands a high degree of precision and concentration.

Further work

The design project resulted in a final prototype that seems to improve the thermal comfort for surgeons experiencing thermal discomfort during a procedure. however, since only one person was tested in the clinical setting and one in the laboratory analysis, statistical conclusions cannot be made, but the designed concept seems promising. Further studies should be conducted with several users to determine parameters such as element size, thickness, placement and amount of cooling. User testing of functional aspects such as size, adjustability, wearing comfort, element size, and shape for optimal cooling and comfort should be investigated. The use of material and thermoregulatory qualities can also be further optimized in the vest.

Conclusions

a design process was performed and a new cooling vest for surgeons was developed. The cooling vest seemed effective and was perceived as comfortable when the cooling elements were evenly applied and moisture transport is provided. The cooling system has some physiological benefits in terms of lower mean skin temperature and decreased sweat rate.

however, the thermoregulatory advantages of the cooling vest are most prominent in increasing the personal comfort of the surgeon. Further studies are needed to determine whether the clinical effects of the cooling vest are significant. The cooling elements generate an immediate drop in skin temperature, lower sweat rates, and constitute a small decrease in core temperature depending on the thermal situation. For the surgical situation, whole trunk cooling seems more effective than only upper trunk cooling. The physiological tests performed during the design process contributed by providing important parameter measurements that indicated how the prototypes needed to be changed for achieving optimal conditions for the end user. In summary, we experienced that this cross-disciplinary design project, involving surgeons, designers, physiologists, and engineers, was able to develop a working concept of an early product prototype, based on problem analysis and design process methodology in a surgical setting.

Acknowledgements

We greatly appreciate research assistant Ingrid Wist Langmoen at the Department of engineering Design and materials (NTNU, Norway) for her help during the climatic chamber work. We also wish to thank professors andré Liem and Trond are øritsland at the Department of Product Design (NTNU, Norway) for their advice during the concept development.

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