Is Intraoperative Flap Perfusion a Predictive Factor for Postoperative Flap Revision of Anterolateral Thigh Flaps and Fibula Free Flaps in Microvascular Head and Neck Reconstruction?

Abstract

Background: The prediction of postoperative flap revision by intraoperative flap perfusion measurement in microvascular head and neck reconstruction could improve postoperative flap monitoring.

Purpose: The study purpose was to measure the association between intraoperative flap perfusion and postoperative flap revision.

Study design, setting, sample: This study was conducted as a retrospective cohort study at the Department of Oral and Maxillofacial Surgery at the University Hospital RWTH Aachen, Germany. The sample was composed of subjects reconstructed with anterolateral thigh flaps or fibula free flaps in the head and neck region between 2011 and 2022. Exclusion criteria were an age below 18 years, incomplete data records, and flap revision within 12 hours postoperatively.

Predictor variable: The predictor variable was flap perfusion measured intraoperatively as blood flow, hemoglobin concentration, and hemoglobin oxygen saturation.

Main outcome variable: The main outcome variable was postoperative flap revision coded as yes or no.

Covariates: Covariates were sex, age, flap type, flap ischemia duration, mean arterial blood pressure, and catecholamine dose.

Analyses: Covariates were compared for perfusion parameters by Mann-Whitney test. Subjects with and without flap revision were compared for covariates by χ² test or Mann-Whitney test and for perfusion parameters by Mann-Whitney test and multivariable regression analysis, and cut-off values for predicting flap revision were determined using receiver operating characteristics. P > .05 was considered significant.

Results: The sample (median age 66 [IQR 18] years) was composed of 239 (93%) subjects without and 18 (7%) subjects with flap revision. Blood flow at 8 mm and hemoglobin oxygen saturation at 2 mm tissue depth were lower, and hemoglobin concentration at 8 mm tissue depth was higher in subjects with flap revision (P = .008; P = .030; P = .001). The cut-off values for blood flow, hemoglobin oxygen saturation, and hemoglobin concentration for predicting flap revision were <76.5 arbitrary units, <64.5%, and >34.5 arbitrary units (area under the curve 0.687, 0.653, 0.728; P = .10, P = .014, P < .001; sensitivity 72, 89, 83%; specificity 70, 44, 53%; PPV 15, 11, 12%; NPV 97, 98, 98%).

Conclusion and relevance: Intraoperative flap perfusion was associated with postoperative flap revision related to cut-off values (highest predictive accuracy for blood flow). Prospective confirmatory studies are necessary.