Pulsatility does not change cerebral oxygenation during cardiopulmonary bypass

Background: To determine the effect of pulsatility during cardiopulmonary b ypass (CPB) on cerebral oxygenation, we measured oxyhaemoglobin (HbO(2)), d eoxyhaemoglobin (Hb) and oxidised cytochrome aa3 (CtO(2)) with near-infrare d spectroscopy (NIRS) in 14 patients electively scheduled for cardiac surge ry. Methods: Cerebral oxygenation was measured during steady state CPB at a cor e temperature of 32 degrees C. Non-pulsatile Row and pulsatile flow were pe rformed for 10 min each. Results: After 14 min of CPB, HbO(2), Hb and CtO(2) were significantly belo w prebypass values. HbO(2) and CtO(2) did not alter with changing flow patt erns. Hb significantly increased both during the period of nonpulsatile (me dian: -0.7 vs. 0.25 mu mol/ 1; P<0.05) and pulsatile flow (median: 0.25 vs. 0.5 mu mol/l; P<0.001). This increase was independent of flow pattern. Conclusions: Neither oxygenated haemoglobin, nor intracellular oxygenation, represented by CtO(2), indicated a beneficial effect of pulsatile perfusio n during hypothermic CPB. These results, however, are only valid for short time effects within 10 min before rewarming from CPB and patients without R ow-limiting stenoses of the carotid artery. (C) Acta Anaesthesiologica Scan dinavica 44 (2000).