Blood gas strategies and management during pediatric cardiopulmonary bypass

Blood gas management during hypothermic cardiopulmonary bypass may be corrected by pH stat or alpha stat strategy. The pH stat philosophy is to maintain the blood pH constant at any temperature. Carbon dioxide must be introduced to the oxygenator in order to maintain the pH and pCO2 during hypothermic cardiopulmonary bypass. Conversely, during alpha stat blood gas management pH is maintained according to 37 degrees C despite the patient temperature. Alpha stat management preserves intracellular pH and autoregulation of cerebral vasculature by following the natural shift of the oxyhemoglobin dissociation curve. In-line blood gas analysis is a practical tool in assessing adequate blood gas management, because this technology provides immediate detection for modification of air/oxygen/carbon dioxide parameters. Results from several studies favor the pH stat strategy during neonatal cardiopulmonary bypass. This strategy increases tissue oxygenation and cerebral blood flow while cooling. Data also suggest that pH stat management results in better outcomes with shorter ventilation times and intensive care unit stays after pediatric cardiac surgery.