Examination of tissue oxygen saturation (StO2) changes associated with vascular pedicle occlusion in a rat Island flap model using near-Infrared spectroscopy.

Abstract

The purpose of this study was to perform continuous StO(2) monitoring of rat island flaps during pedicle vessel occlusion using near-infrared spectroscopy (NIRS) in order to collect experimental data for StO(2) flap monitoring under optimized conditions. Twenty rats were used in this study. The 3 × 3 cm(2) epigastric skin island flaps were elevated on either side. The animals were randomly assigned to two groups; an arterial occlusion group (n = 10) and a venous occlusion group (n = 10). The StO(2) values of the flaps were observed for over 30 min for the pedicle artery or venous occlusion, followed by an additional 30 min release. The baseline StO(2) value was 78.4% ± 3.2% in the arterial occlusion group, compared to 78.5% ± 5.8% in the venous occlusion group, with no significant differences (P > 0.05). The StO(2) values decreased immediately after arterial occlusion, whereas a temporal StO(2) increase was initially observed after venous occlusion, followed by a StO(2) decrease. The StO(2) values decreased 27.3% ± 7.1% after arterial occlusion and 28.4% ± 19.1% after venous occlusion at 30 min after pedicle vessel clamping (P > 0.05). The StO(2) values were 0.4% ± 5.8% lower than baseline 30 min after arterial release (P > 0.05), while 18.9% ± 11.3% lower than baseline 30 min after venous release (P < 0.01). NIRS can be used to indicate StO(2) changes in flaps with the pedicle vessel occlusion and differentiate between pedicle artery and vein occlusion. Further investigations are needed to obtain definitive evidence associated with predicting the degree of flap viability and determine the practical use of this technique.