Specific Bypass Conditions Determine Safe Minimum Flow Rate

Tissue oxygen index derived from near-infrared spectroscopy is a useful real-time monitor for detecting inadequate cerebral perfusion during cardiopulmonary bypass. Minimal safe pump flow rate varies according to the conditions of bypass: using pH stat management and with an hematocrit of either 20% or 30%, a flow rate as low as 10 mL · kg−1 · min−1 is safe for as long as 2 hours at a temperature of 15°C. However, under the same conditions at 34°C, a flow rate of 10 mL · kg−1 · min−1 is very likely to be associated with neurologic injury.