High-flow total body perfusion with severe hemodilution and normothermia in infants weighing less than 10 kg--safe limits of hemodilution in cardiopulmonary bypass in infants.

Cardiopulmonary bypass with 17 to 57 per cent dilution of hemoglobin for repair of ventricular septal defect (VSD) was applied to 26 infants weighing less than 10 kg at normal temperature. The higher flow rate was required to compensate the reduced oxygen carrying capacity and to maintain an adequate arterial pressure in proportion to a decrease of hemoglobin value. Perfusion index resulted in 3.0 to 6.5 L/m2/min in this series. When the dilution ratio of hemoglobin became more than 50 per cent and high flow rate was required, however, oxygen transfer ratio decreased remarkably on account of inadequate oxygen delivery and imparied venous return. In these cases, it was difficult to remove the diluent immediately after the operation in spite of powerful diuretic therapy. The results of the present study indicate that the safe limits of hemodilution is 50 per cent in cardiopulmonary bypass at normal temperature in infants.