Cooling Vest May Reduce Heat Stress During Surgery

Cooling Vest May Reduce Heat Stress, Improve Thermal Comfort, and Preserve Cognitive Performance of Surgeons While Performing Surgery

The investigators will propose a randomized cross-over trial using a uniform and strongly balanced 4-period design in which will include four operations for each surgeon. Surgeons will be randomized to 1 of 4 sequences: ABBA, BAAB, AABB or BBAA. The design is "uniform" in that each treatment appears the same number of times within each sequence (uniform within sequence) and if each treatment appears the same number of times within each period (uniform within each period). It is strongly balanced with respect to first-order carryover effects because each treatment precedes every other treatment, including itself, the same number of times

The subjects will be randomly assigned to use either the CoolSource™ cooling vest (worn between scrubs) and a conventional surgical gown for each of 4 surgeries. Sequence of treatments within the subjects will be randomized (ABBA, BAAB, AABB or BBAA), and determined using the PLAN procedure in SAS, such that each surgeon will wear vest and non-vest twice. The sequencing will not be shared with any study personnel. Allocation for each case will be concealed with a web-based system that will be accessed only shortly before surgery. The investigators will target an ambient temperature of 21°C ± 1°C, and try to maintain the same temperature of each of the four study cases for each surgeon. The CoolSource vest holds six reusable cooling packs located bilaterally on the shoulders, angled flank along the base of the rib cage, and along each side of the spine, mid-back. The vest will be donned over hospital-issued scrubs after all temperature sensing devices have been applied and before surgical hand scrubbing. The subjects will wear the vest throughout surgery, and for a few additional minutes while postoperative assessments are made (details below). The weight of the disposable cooling vest is 1 kg which is evenly distributed over both shoulders. The cooling packs have an insulated cover to reduce condensation or sweating while seated inside the vest pocket. The flexible frozen reusable cooling packs will be inserted into each of the six pockets and the vest belt will be tied to hold the cooling packs securely. The disposable cooling vests will be discarded after each case, and the cooling packs returned to a freezer.

Surgeons first performed one surgery with the cooling vest. On another day, they then performed one surgery without the cooling vest. Then on another day, they performed another surgery without the cooling vest. Then they finally performed one surgery with the cooling vest.

Surgeons first performed one surgery without the cooling vest. On another day, they then performed one surgery with the cooling vest. Then on another day, they performed another surgery with the cooling vest. Then they finally performed one surgery without the cooling vest.

Surgeons first performed one surgery with the cooling vest. On another day, they then performed another surgery with the cooling vest. Then on another day, they performed one surgery without the cooling vest. Then they finally performed another surgery without the cooling vest.

Surgeons first performed one surgery without the cooling vest. On another day, they then performed another surgery without the cooling vest. Then on another day, they performed one surgery with the cooling vest. Then they finally performed another surgery with the cooling vest.

Evaluate that wearing a cooling vest during surgery reduces surgeons' mean-body temperature and preserves their cognitive performance.

Immediately after surgery, while still gowned, surgeons will rate their thermal comfort on a 0-10 Likert scale, with 0 representing extreme cold, 5 being thermal comfort, and 10 representing extreme heat. Two points on the 11-point Likert scale will be considered a clinically important difference.

The first secondary outcome will be the mean core temperature for a case, calculated as the time-weighted average over the taken measurements. The surgeon's core body temperature will be monitored by a validated wireless wearable iThermonitor WT701 biosensor which estimates core temperature within ±0.5⁰C (Pei et al., 2018). The sensor will be applied to the surgeon's right axilla 15-20 minutes prior to the surgical hand scrub performed at the start of surgery and secured with an adhesive cover. A small patch of axillary hair will be clipped or shaved as necessary.

The second secondary outcome will be the mean skin temperature for a case, calculated as the time-weighted average over the taken measurements. Mean skin temperature will be estimated from skin temperature from the back of the upper chest, deltoid arm, thigh, and calf using the formula [MSTR = 0.3 chest + 0.3 arm + 0.2 thigh + 0.2 leg or 0.3(chest + arm) + 0.2(thigh + 0.2 leg)] (Ramanathan, 1964). Skin temperature will be continuously measured using wireless patches, TempTraq, which meet professional accuracy standards for digital thermometers (ASTM E1112-00). The sensors will remain affixed with adhesive dressing on the surgeon's body surface throughout surgery and approximately 10 minutes required for post-operative testing.

Surgeons' cognitive performance was assessed with the Cleveland Clinic Cognitive Battery (C3B, Cleveland, OH), a ten-minute-long self-administered computer tablet program that tests visual memory (episodic learning and delayed memory, range 0 - 70) and processing speed (information processing speed and incidental memory, range 40 - 120). Testing will take place right after surgery with surgeons still gowned. The surgeons will sit with the iPad touch screen placed on a desk in front of them for approximately 10 minutes to complete the cognitive test.

Surgeon' Perceived Ergonomic Workload Measured With the Borg Rating of Perceived Exertion (RPE) Scale.

Immediately after surgery, while still gowned, surgeons will rate their perceived exertion on the Borg scale which ranges from 6 (no exertion) to 20 (maximal exertion).

Surgeon' Perceived Fatigue Measured as 0 Representing Not Fatigued at All, 5 Moderately Fatigued, and 10 Total Fatigue & Exhaustion

Perceived fatigue will be rated on a 0-10 ROF scale, with 0 representing not fatigued at all, 5 moderately fatigued, and 10 total fatigue & exhaustion. Two points difference on either scale will be considered a clinically important difference.

Immediately after surgery, while still gowned, surgeons' perception and amount of sweat-soaked scrub clothing will be rated using a Likert scale from 0 = "not wet at all" to 10 = "fully drenched."

Inclusion Criteria: Surgeons who perform elective major orthopedic surgery such as total hip and knee arthroplasties scheduled for 90 to 150 minutes at the Cleveland Clinic Main Campus. Orthopedic surgeons ages of 25-65 years old, as body temperatures may be lower and less stable in the elderly (Waalen & Buxbaum, 2011), who operate frequently enough to participate in four cross-over cases. Surgical helmet system is consistently worn for each of the surgeon's four cases, if used in the first case. Exclusion Criteria: Surgical cases that require surgeons to sit on stools during the procedure, which may impact temperature and energy expenditure. - Surgeons who report having a recent illness within 24 hours prior to the surgery, symptoms producing a febrile condition; Surgeons who worked the previous evening. Surgeons who wear lead X-ray gowns.

Collaborative proposal approved by the trial Executive Committee. Data use agreement will be required. Address requests to Daniel Sessler at DS@CCF.org.