Vacuum assisted venous drainage does not increase trauma to blood cells

Although gravity drainage has been the standard technique for cardiopulmona ry bypass (CPB), the development of minimally invasive techniques for cardi ac surgery has renewed interest in using vacuum assisted venous drainage (V AVD). Dideco (Mirandola, Italy) has modified the D903 Avant oxygenator to a pply a vacuum to its venous reservoir. The impact of VAVD on blood damage w ith this device is analyzed. Six calves (mean body weight, 71.3 +/- 4.1 kg) were connected to CPB by jug ular venous and carotid arterial cannulation, with a flow rate of 4-4.51 L/ min for 6 h. They were assigned to gravity drainage (standard D903 Avant ox ygenator, n = 3) or VAVD (modified D903 Avant oxygenator, n = 3). The anima ls were allowed to survive for 7 days. A standard battery of blood samples was taken before bypass, throughout bypass, and 24 h, 48 h, and 7 days afte r bypass. Analysis of variance was used for repeated measurements. Thrombocyte and white blood cell counts, corrected by hematocrit and normal ized by prebypass values, were not significantly different between groups t hroughout all study periods. The same holds true for hemolytic parameters ( lactate dehydrogenase [LDH] and plasma hemoglobin). Both peaked at 24 hr in the standard and VAVD groups: LDH, 2,845 +/- 974 IU/L vs. 2,537 +/- 476 IU /L (p = 0.65), respectively; and plasma hemoglobin, 115 +/- 31 mg/L vs. 89 +/- 45 mg/L (p = 0.45), respectively. In this experimental setup with prolo nged perfusion time, VAVD does not increase trauma to blood cells in compar ison with standard gravity drainage.