The relationship between cerebral and somatic oxygenation and superior and inferior vena cava flow, arterial oxygenation and pressure in infants during cardiopulmonary bypass

Abstract

We investigated blood flow and regional oxygenation (rSO2) during cardiopulmonary bypass (CPB). Twenty infants (mean (SD) age 5 (3) months, weight 5.4 (1.6) kg) were prospectively studied. Total CPB and superior vena cava (SVC) flow were measured using Transonic Bypass Flowmeters, inferior vena cava (IVC) flow derived arithmetically and rSO2 measured using Near Infra-Red Spectroscopy. Mean SVC flow was 51.3 (14.8) ml.kg-1. min-1 and mean IVC flow 62.5 (19.0) ml.kg-1.min -1. Mean cerebral rSO2 was 71 (11)% and somatic rSO 2 55 (13)%. Cerebral and somatic rSO2 showed no correlation with SVC and IVC flow. Cerebral rSO2 showed a positive correlation with PaCO2, mean arterial pressure (MAP) and haematocrit (p < 0.0001). Somatic rSO2 showed a positive correlation with MAP and haematocrit (p = 0.01, p = 0.02). In conclusion, the distribution of blood flow during CPB varies. The most important factor affecting this is PaCO2. Cerebral and somatic oxygenation are unaffected by flow but significantly influenced by MAP, haematocrit and PaCO2. © 2009 The Authors.