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Cutaneous microcirculation during operations with a cardiopulmonary bypass. BACKGROUND: Cutaneous microcirculation (cMC) is influenced by many factors. In cardiac surgery, most operations are performed with a cardiopulmonary bypass (CPB) and cardiac arrest induced by cardioplegic solutions. OBJECTIVES: Aim of this study was to examine a correlation between cMC and hemodynamic parameters in patients undergoing heart surgery with two different cardioplegic solutions. METHODS: 20 patients were included and divided into Histidine-Tryptophane-α-Ketoglutarate solution- (HTK, n = 10) and blood cardioplegia- (BCP, n = 10) groups. With initiation of CPB, cMC was continuously monitored with Laser-Doppler-Perfusion (LDP) until termination of CPB. Additionally, we measured hemoglobin-concentration (HbC) with a Blood-Parameter-Monitoring-System. RESULTS: LDP pulsation was almost equal before and after CPB and decreased during aortic cross clamping. The following factors influenced LDP: central venous pressure (CVP), mean arterial pressure (MAP), total peripheral resistance (TPR) and flow of the heart-lung machine. We measured relative LDP and HbC (RLDP; RHbC). Five and 25 min after administration of cardioplegia, RLDP (1.22±0.8; 1.17±0.94) and RHbC (0.92±0.06; 0.96±0.09) in the HTK-group were lower than in the BCP-group: RLDP (1.58±1.11; 1.58±2.2) and RHbC (1.00±0.05; 0.99±0.13). HTK-patients with a body surface area (BSA) <2 m2 showed a lower RLDP (0.75±0.50), than patients over 2 m2 (RLDP = 1.64±0.97). CONCLUSIONS: The cMC is influenced by CPB. Cutaneous LDP monitoring is a non-invasive method, for estimating hemodynamics intraoperatively.