Near-infrared spectroscopy to assess microvascular dysfunction: A prospective pilot study in cardiac surgery patients.

Abstract Purpose The diagnosis of microvascular dysfunction remains challenging after cardiac surgery. We hypothesized that peripheral near-infrared spectroscopy (NIRS) monitoring in combination with a vascular occlusion test could reliably assess postoperative microvascular dysfunction in that setting. Materials and Methods Twenty-two patients undergoing cardiac surgery with cardiopulmonary bypass and 10 healthy volunteers were prospectively investigated. Relevant NIRS parameters (regional tissue oxygen saturation, desaturation, and resaturation rates) were recorded the day before surgery (D-1), at the arrival in the intensive care unit (postoperative day [POD] 0) and on POD 1 and POD 2. Results No difference in NIRS parameters was found at baseline between healthy volunteers and cardiac surgical patients. Absolute values of regional tissue oxygen saturation significantly increased at POD 0 and POD 1 when compared with D-1: 78% (75%-81%) and 75% (73%-78%) vs 68% (64%-72%), P − 1 (0.08-0.14) and 0.15% · s − 1 (0.08-0.22) vs 0.14% · s − 1 (0.10-0.17), P = .233, and resaturation rate, 0.76% · s − 1 (0.41-1.11) and 0.77% · s − 1 (0.53-1.02) vs 0.79% · s − 1 (0.61-0.97), P = .453. The use of postoperative norepinephrine infusion did not change the results. Conclusions Peripheral NIRS monitoring in combination with a vascular occlusion test failed to assess cardiopulmonary bypass–induced microvascular dysfunction.