Plastic Surgery Research Council

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The Effect of Intraoperative Temperature on Microvascular Thrombosis
John T. Smetona, MD1, Kyle Gabrick, MD1, Jacob Dinis, BS2, Fouad Chouiari, BS1, Michael Alperovich, MD1, Marc Walker, MD1, Henry Hsia, MD1, J Grant Thomson, MD1.
1Yale New Haven Hospital, New Haven, CT, USA, 2Quinnipiac University Frank H Netter School of Medicine, North Haven, CT, USA.

Purpose:
The trauma literature provides evidence of a correlation between hypothermia and mortality. Anesthesia guidelines require intraoperative temperature monitoring and prevention of hypothermia (T < 36 C). There has been less concern with mild intraoperative hyperthermia for plastic surgery patients. However, previous data from our institution suggest that intraoperative hyperthermia is associated with increased rates of microvascular thrombosis in free tissue transfer. We present a series of free tissue transfers to further assess for correlation between intraoperative hyperthermia and microvascular thrombosis.
Methods:
A retrospective chart review was conducted of 416 consecutive patients with 686 free flap breast reconstructions treated at Yale New Haven Hospital from 2013 to 2018. Bivariate analysis was used to compare rates of intraoperative flap thrombosis as function of temperature. Multivariate regression analysis was also performed to control for confounders in the assessment of intraoperative thrombosis requiring revision, post-operative venous thrombosis, and post-operative arterial thrombosis as a function of temperature.
Results:
Patients with intraoperative temperature greater than 99.5 F had a 14% rate of intraoperative microvascular thrombosis, while patients with an intraoperative Tmax of less than 99.5 had a 7% rate of thrombosis on bivariate analysis. Multivariate regression analysis showed that the rate of intraoperative revisions increased by 1.54 x for each increase of Tmax by one degree F. Post-operative venous thrombosis increased by 3.07x for each degree F increase in Tmax; and post-operative arterial thrombosis showed a change of .824x which was not statistically significant (P .682). Of note, smoking was found to be a very strong predictor of post-operative venous thrombosis (odds ratio 9.27, p.037).
Conclusions:
These data suggest that intraoperative hyperthermia is associated with increased microvascular thrombosis. We invite similar assessments of free flap failure rates a function of intraoperative temperature from other centers across the country to determine whether guidelines for intraoperative management of patient temperature should be modified when free tissue transfer is performed.


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