Changes in the microvascular reactivity during spinal anesthesia

Abstract

PurposeAnesthesia alters microcirculation and tissue oxygen saturation (StO2). We sought to examine changes in StO2 using near-infrared spectroscopy and a vascular occlusion test (VOT) during spinal anesthesia. MethodsThis prospective observational study was included 51 patients without comorbidities who underwent elective surgery under spinal anesthesia. We measured the StO2 in the lower extremity during VOT before and after intrathecal injection. ResultsThe baseline, minimum, and maximum StO2 values during VOT significantly increased after intrathecal injection (baseline StO2 from 68.6 ± 7.3% to 77.1 ± 10.1%, minimum StO2 from 39.7 ± 14.9% to 48.8 ± 17.6%, and maximum StO2 from 74.2 ± 7.5% to 80.2 ± 10.0%, all P < 0.0001). The occlusion slope and ischemic stimulus did not significantly change after intrathecal injection. The reperfusion slope was 1.38 ± 0.69%/sec before intrathecal injection and significantly decreased to 1.15 ± 0.61%/sec after intrathecal injection (P = 0.0001). ConclusionsOur results showed that despite an increased perfusion, reperfusion rate was significantly decreased by spinal anesthesia. Further studies are required to confirm how these contradictory results (improving oxygenation while reducing microvascular reactivity) actually affect the clinical impact of spinal anesthesia on microvascular function.