Blood pressure and microvascular free flap perfusion in head and neck reconstruction- a retrospective analysis.

[PURPOSE] The influence of blood pressure on microvascular free flap perfusion is not fully understood and remains an ongoing topic of debate, as flap perfusion is both a prerequisite for flap viability and a parameter frequently used for postoperative flap monitoring. The aim of this study was to investigate the influence of blood pressure on microvascular free flap perfusion.

[METHODS] Perfusion measurement data obtained with the Oxygen-2-see (O2C) analysis system intraoperatively and postoperatively in 244 patients who underwent microvascular reconstruction of the head and neck region with a fasciocutaneous free flap (FFF) or perforator free flap (PFF) between 2011 and 2020 were analyzed retrospectively. Blood pressure values (i.e., systolic (SBP), diastolic (DBP), and mean arterial blood pressure (MBP)) and perfusion parameters (i.e., flap blood flow, hemoglobin concentration, and hemoglobin oxygen saturation) were evaluated to reveal potential associations.

[RESULTS] Postoperative flap blood flow was associated with SBP, DBP, and MBP in PFFs (r = 0.245, p = 0.006; r = 0.239, p = 0.008; r = 0.295, p < 0.001, respectively). These associations also persisted in multivariable analysis (p = 0.036; p = 0.024; p = 0.004, respectively). Postoperative hemoglobin oxygen saturation was associated with SBP and MBP in PFFs (r = 0.253, p = 0.005; r = 0.189, p = 0.036, respectively). The association with SBP also persisted in multivariable analysis (p = 0.005).

[CONCLUSION] Microvascular free flap perfusion in PFFs, specifically postoperative flap blood flow and hemoglobin oxygen saturation, is influenced by blood pressure. This suggests that blood pressure might be an adjustable variable for the control of flap perfusion and should be considered as a confounding variable for flap monitoring based on flap perfusion in PFFs.