A novel thermal compression device for perioperative warming: a randomized trial for feasibility and efficacy

Abstract

Background: Inadvertent perioperative hypothermia (IPH) leads to surgical complications and increases length of stay. IPH rates are high with the current standard of care, forced air warming (FAW). Our hypothesis is that a prototype thermal compression device that heats the popliteal fossa and soles of the feet, with lower leg compression, increases perioperative temperatures and reduces IPH compared to the current standard of care.

Methods: Thirty six female breast surgery patients, at a tertiary academic hospital, were randomized to the device or intraoperative FAW (stage I) with a further 18 patients randomized to the device with a single heating area only (stage II, popliteal fossa or sole of the feet). Stage I: 37 patients recruited (final 36). Stage II: 18 patients recruited (final 18).

Inclusion criteria: general anesthesia with esophageal monitoring for over 30 min, legs available and able to fit the device and no contraindications to leg heating or compression. The intervention was: Stage I: Investigational prototype thermal compression device (full device group) or intraoperative FAW. Stage II: Device with only a single heating location. Primary outcomes were perioperative temperatures and incidence of IPH. Secondary outcomes were local skin temperature, general and thermal comfort scores and presence of perioperative complications, including blood loss.

Results: Mean temperatures in the full device group were significantly higher than the FAW group in the pre-operative (36.7 vs 36.4 °C, p < 0.001), early intraoperative (36.3 vs 35.9 °C, p < 0.001), intraoperative (36.6 vs 36.2 °C, p < 0.001) and postoperative periods (36.8 vs 36.5 °C, p < 0.001). The incidence of IPH in the device group was also significantly lower (16.7% vs 72.0%, p = 0.001). Thermal comfort scores were significantly higher in the full device group and hypothermia associated wound complications were higher in the FAW group.

Conclusions: The thermal compression device is feasible and has efficacy over the FAW. Further studies are recommended to investigate clinically significant outcomes.

Trial registration: clinicaltrials.gov ( NCT02155400 ).

Keywords: Forced air warming; Perioperative normothermia; Perioperative warming; Thermal compression.

Conflict of interest statement

Ethics approval and consent to participate

This study and its protocol were approved by Stanford University’s Internal Review Board. Protocol ID 28535.

Consent for publication

Not applicable.

Competing interests

PLSM, AR and BTK are inventors on US patent 14/197,518 currently owned by Stanford University which describes this invention.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

Fig. 1

Shows the trial enrollment, allocation, follow-up and analysis according to the CONSORT standards. Groups are full device, forced air warming (FAW) group, popliteal group and sole group

Fig. 2

Artistic rendition of the prototype device. Figure 2 displays an artistic rendition of the prototype device identifying the areas of heating and compression within the lower leg sleeve. The heating elements are located at the popliteal fossa and sole of the foot strapped in close contact to the patient. Beneath the heating elements, in each location, are temperature feedback probes that feed back to the individual heating unit for that region. There is also a sequential pneumatic calf compression sleeve component fitted to the patient’s lower legs in between the two heating areas

Fig. 3

Perioperative Temperatures. Figure 3 shows the temperature benefit of the full device over the FAW. The mean patient temperatures (temp) with standard error are shown for the full device (n = 18) and FAW (n = 18) treatment groups. Each phase is shown including pre op (preoperative), intra op (intraoperative) and post op (postoperative). Patient in the full device group had higher mean temperatures in each phase of surgery compared to the FAW group where patient became hypothermic soon after induction

Fig. 4

Comparison in the same patient. Figure 4 shows the temperatures (temp) recorded when the same patient underwent the same surgery on each breast at separate times. Once the patient was in the full device group and the other she was in the FAW group. Each phase is shown including pre op (preoperative), intra op (intraoperative) and post op (postoperative). The patient had higher temperatures in the full device group compared to when she was in the FAW group where she became hypothermic soon after induction

Fig. 5

Case studies of surgery with patient turning. Figure 5 shows the temperatures (temp) recorded when two different patients underwent mastectomy with reconstruction using a pedicled latissimus dorsi muscle flap. Each phase is shown including pre op (preoperative), intra op (intraoperative) and post op (postoperative). The down arrows indicate times when the patient was completely undraped, turned over, re-prepped and draped. The triangle indications the FAW was transferred with the patient into and used through admission to the PACU. Each turn led to a reduction in mean temperature, however the patient with the full device maintained normothermia despite being turned over twice. The patient in the FAW group did not maintain normothermia

Fig. 6

Perioperative temperatures in single heating treatment groups. Figure 6 shows the importance of heating in both areas for efficacy. The mean patient temperatures (temp) with standard error are shown for the full device (device, n = 18), FAW (n = 18), popliteal (pop fossa, n = 9) and sole (sole of foot, n = 9) groups. Each phase is shown including pre op (preoperative), intra op (intraoperative) and post op (postoperative). Both individual heating treatment groups had higher mean preoperative, early intraoperative and overall intraoperative temperatures compared to FAW although as a group the mean was still hypothermic after induction

Fig. 7

Compression is needed for device efficacy. Figure 7 shows the importance of the lower leg compression for full device efficacy. Each phase is shown including pre op (preoperative), intra op (intraoperative) and post op (postoperative). The temperatures (temp) recorded were hypothermic on induction and failed to rise until it was realized the lower leg compression had not been turned on. After turning on the patient’s temperature began to rise