Mild hypothermia is associated with improved outcomes in patients undergoing microvascular head and neck reconstruction

Objective: Microvascular free tissue transfer has become the standard for reconstruction for large defects. With long operative times and an increased surface area exposed, transient hypothermia is common, but it is unclear how this impacts surgical outcomes. This study evaluated the impact of core body temperature on free tissue flap outcomes in patients undergoing microvascular reconstruction. Study design: Retrospective data analysis. Setting: Mount Sinai Hospital; NYC, NY; 2007–2016. Subjects and methods: Demographic information, mean/minimum/maximum body temperatures, and the presence of flap complications (venous thrombosis, arterial insufficiency, flap death, wound infection/dehiscence, fistula, chyle leak, hematoma/seroma) of 519 free tissue transfer patients were documented. Binomial logistic regression was used to examine associations between the presence of flap complications and mean temperature. Statistical analysis used SPSS, with p-values ≤0.05 deemed statistically significant. Results: 393 soft-tissue and 125 osteocutaneous flaps were included. 19.8% (n = 103) patients had the presence of ≥1 flap complication, while 80.2% (n = 416) did not. Average temperature for all patients was 36.12 ± 0.84 °C, with minimum at 34.43 ± 0.97 °C and maximum at 37.24 ± 1.23 °C. After controlling for several factors including: tumor stage, radiation, diabetes, BMI, age, sex, and flap type, there was a significant association between flap complications and mean intraoperative temperature (Exp(B) = 1.559, p = 0.004). Conclusion: Higher intraoperative temperatures were associated with worse outcomes. A mild relative hypothermia may improve flap outcomes in this population. This represents the largest study to date evaluating the impact of intraoperative temperature on free tissue transfer outcomes.