Effect of intravenously administered norepinephrine on early postoperative tissue perfusion of radial free forearm flaps in the head and neck region - retrospective analysis in the context of continuous flap monitoring.

BACKGROUND

Postoperative flap monitoring following microvascular head and neck reconstruction can be conducted by continuous flap tissue perfusion measurement with an attached surface probe using the Oxygen-to-see (O2C) analysis system. However, intravenously administered norepinephrine may influence flap tissue perfusion and affect the reliability of predefined absolute thresholds used for the detection of vascular flap compromise. This study aimed to evaluate the association between early postoperative flap tissue perfusion and norepinephrine in radial free forearm flaps (RFFF).

METHODS

Data of patients undergoing head and neck reconstruction with an RFFF from 2020 until 2022 were retrospectively analyzed. Flap tissue perfusion was measured continuously for 8 h postoperatively with an attached surface probe using the O2C analysis system. Intravenously administered norepinephrine dose and blood flow and hemoglobin oxygen saturation as well as flow resistance (ratio of mean arterial blood pressure and flap blood flow) were analyzed for associations.

RESULTS

The study included 12 patients (5 men and 7 women). Blood flow and hemoglobin oxygen saturation were not associated with norepinephrine (B=-110.509, p = 0.583 and B=-12.500, p = 0.912). In addition, flow resistance was not associated with norepinephrine (B = 0.292, p = 0.825).

CONCLUSIONS

Early postoperative tissue perfusion of RFFFs, measured during continuous flap monitoring with attached surface probes for the O2C analysis system, showed no association with norepinephrine with regard for blood flow and hemoglobin oxygen saturation. This supports the reliability of absolute thresholds used to detect vascular flap compromise during continuous postoperative monitoring of RFFFs with the O2C analysis system, albeit additional studies with substantial sample sizes and longer monitoring intervals are required to validate these findings.