Effects of remifentanil-based general anaesthesia with propofol or sevoflurane on muscle microcirculation as assessed by near-infrared spectroscopy.

Abstract BACKGROUND: Although anaesthetics are known to alter microcirculation no study has, to our knowledge, documented changes in human skeletal microcirculatory function during general anaesthesia. METHODS: Forty-four patients undergoing maxillofacial surgery at a university hospital were prospectively randomized to receive general anaesthesia with remifentanil combined with propofol or sevoflurane. Muscle microcirculation was investigated with near-infrared spectroscopy (NIRS) before general anaesthesia was induced and 30 min later. An NIRS device (NIMO, Nirox) was used to quantify calf deoxyhaemoglobin [HHb], oxyhaemoglobin [HbO2], and total haemoglobin [HbT] concentrations, coupled to a series of venous and arterial occlusions to measure calf blood flow, muscle oxygen consumption, calf vascular resistance, microvascular compliance, and haemoglobin resaturation rate (RR). RESULTS: In both the groups, general anaesthesia induced marked changes in muscle microcirculation: the tissue blood volume increased (+33% in remifentanil-sevoflurane and +45% with remifentanil-propofol groups), microvascular resistance decreased (-31% and -38%, respectively), and the post-ischaemic haemoglobin RR decreased (-48% and -36%, respectively). In the remifentanil-propofol group, the muscle blood flow increased (P0.001), whereas in the remifentanil-sevoflurane group microvascular compliance and muscle oxygen consumption decreased (P0.01). CONCLUSIONS: Remifentanil-based general anaesthesia with propofol or sevoflurane altered the muscle microcirculation in different ways. Quantitative NIRS, a technique that takes into account the optical tissue properties of the individual subject, can effectively measure these changes non-invasively.