Surgical humidification (HumiGardTM) improves tissue temperature during open spinal surgery: a first in-human randomised controlled trial

Background: Tissue exposed to theatre air is susceptible to evaporative heat and moisture loss. The resulting local hypothermia and desiccation disrupts the internal milieu of the patient and may lead to delayed healing and increase the risk of surgical site infections (SSIs). HumiGard for orthopaedic surgery was developed to deliver warmed, humidified air to an open surgical incision site to mitigate heat and moisture loss from an open wound. This study aims to evaluate the efficacy of surgical humidification in preventing local tissue cooling and desiccation during open spinal procedures by delivering warmed, humidified air (37 ℃, 100% relative humidity) over the surgical site. Methods: Twenty-eight patients undergoing elective 1-2 level open spinal decompression were equally randomised to receive standard of care (Control) or HumiGard [n=8 for version 1 (V1), n=6 for version 2 (V2)]. The primary outcome was the temperature of the incision site measured at fifteen-minute intervals using a thermal camera. Results: Surgical wounds in open spinal surgeries cooled significantly, with an average temperature of 32.7±4.0 ℃ at 15 min post-incision and 28.5±0.9 ℃ at 90 min (P<0.01). Intra-operative application of HumiGard facilitated the maintenance of wound temperature near or within the normothermic range (~37 ℃), with an average of 35.4±3.9 (15-min) and 33.5±0.9 ℃ (90-min) with HumiGard V1 and 38.4±1.7 (15-min) and 36.8±1.5 ℃ (90-min) with HumiGard V2. At 15-min post-incision, the average wound temperature with HumiGard V2 was 5.7 ℃ higher than the Control group (P<0.001). This thermal advantage persisted throughout the procedure, resulting in a mean wound temperature difference of 8.3 ℃ compared to the Control group at 90-min (P=0.03). Supplementary observations by surgeons indicated that, with the use of HumiGard tissues appeared subjectively more hydrated, with improved redness, suggesting better preservation of tissue integrity throughout the procedure. Conclusions: This first in-human randomised controlled trial (RCT) demonstrated that a significant drop in local tissue temperature occurs in the surgical wound during open orthopaedic surgery. Intraoperative use of HumiGard mitigated this issue by delivering localised warmth and humidification, thereby maintaining physiological tissue temperatures throughout open orthopaedic procedures without disrupting the surgical workflow. Trial Registration: ANZCTR: ACTRN12620001321932; UTN: U1111-1257-0011.