Does flow character of cardiopulmonary bypass make a difference?

The influence of pulsatile bypass flow on the performance of the cardiovascular system, fluids and blood balance, acid-base equilibrium, and splanchnic function was investigated. One hundred patients scheduled for elective coronary artery bypass grafting were randomly divided into a group of standard perfusion (NP) and a group of pulsatile perfusion (PP). At the end of the operation, similar cardiac performance developed in both groups that was higher than before bypass: left ventricular stroke work index after bypass, 56.8 +/- 2.7 gm/beat per square meter in the NP group and 56.7 +/- 2.6 gm/beat per square meter in the PP group (not significant). Further determinations did not differ among the groups. After discontinuation of cardiopulmonary bypass, bypass grafts flow measured using an electromagnetic probe did not differ among the groups. During the postbypass period, mean arterial pressure and systemic vascular resistance were similar (mean arterial pressure 86.8 +/- 1.6 mm Hg in the NP group and 88.5 +/- 1.7 in the PP group; systemic vascular resistance 817 +/- 33 dyne.sec/cm5 in the NP group and 881 +/- 34.5 in the PP group), as were further determinations. However, severe hypotension requiring the administration of vasoconstrictors was observed more frequently in PP group of patients (20 versus 6%; p < 0.05). Fluid balance determined at the second postoperative day was similar among the groups (+1307 +/- 239 ml in the NP group and +1535 +/- 266 ml in the PP group). Blood loss was 1122 +/- 120 ml in the NP group and 1263 +/- 119 ml in the PP group during the first postoperative day (p = 0.407). Urine output during bypass was lower in the PP group (261 +/- 25 versus 341 +/- 26 ml/hr; p = 0.028). The creatinine clearance was 96.4 +/- 10.3 ml/min in the NP group and 92.6 +/- 7.0 ml/min in the PP group (not significant); amylase and lipase clearance did not differ among the groups. Finally, no significant difference was detected in arterial lactic acid determinations and acid-base balance assessment between the groups postoperatively. Thus equivalent cardiovascular hemodynamics, a good control of fluids and blood balance, acid-base equilibrium, and a satisfactory protection of the function of kidneys and pancreas were obtained with both types of perfusion.