Effect of Hypothermic Cardiopulmonary Bypass on Blood Viscoelasticity in Pediatric Cardiac Patients

Abstract

The objective of this study was to determine the changes in blood viscoelasticity during and after pediatric cardiopulmonary bypass (CPB) procedures. Twelve pediatric cardiac patients, subjected to hypothermic (22-28 degrees C) CPB procedures were enrolled in this study. Viscosity and elasticity were measured at strains of 0.2, 1.0, and 5.0 using a Vilastic-3 Viscoelasticity Analyzer. Arterial blood samples (1 ml each) were taken before CPB, on normothermic CPB, hypothermic CPB, and 1 and 24 hours after CPB. Compared with the pre-CPB levels (0.0464 +/- 0.007 Poise), viscosity at a strain of 1.0 was significantly lower during normothermic CPB (0.0305 +/- 0.006 Poise, p < 0.01), hypothermic CPB (0.03 +/- 0.0007 Poise, p < 0.01), and 1 hour after CPB (0.0334 +/- 0.006 Poise, p < 0.01). Viscosity at a strain of 1.0 24 hours after CPB (0.0525 +/- 0.01 Poise, p = NS) was slightly higher than pre-CPB levels. Elasticity at a strain of 1.0 was significantly altered during normothermic CPB (0.0016 +/- 0.0007 Poise, p < 0.01), hypothermic CPB (0.0015 +/- 0.0007 Poise, p < 0.01), and 1 hour after CPB (0.0017 +/- 0.0005 Poise, p < 0.01) compared to the pre-CPB levels (0.0048 +/- 0.0001 Poise). Elasticity at a strain of 1.0 24 hours after CPB (0.0068 +/- 0.003 Poise, p = 0.06) was significantly higher compared to the pre-CPB level (0.0048 +/- 0.0001 Poise). Viscoelasticity at strains of 0.2 and 5.0 had patterns similar to those seen with a strain of 1.0. Viscosity and elasticity at strains of 0.2, 1.0, and 5.0 were significantly altered during normothermic and hypothermic CPB and 1 hour after CPB. Viscoelasticity of blood was slightly higher 24 hours after CPB at all strains. Further investigation of the effects of hypothermic CPB on blood viscoelasticity and the outcomes of pediatric cardiac patients are warranted.