Oxygen transport and utilization during rest and progressive exercise in chronic nonpulsatile blood flow was reviewed. In a chronic nonpulsatile animal model, (1) basal oxygen consumption of a 4-month old calf was 6.3 ± 0.3ml/kg/min
(2) PvO2 decreased when the pump flow rate was reduced (29.6 ± 1.0, 28.3 ± 1.2, and 23.8 ± 0.9 mmHg at 120, 100, and 90 ml/kg/min of pump flow, respectively)
(3) serum lactate concentration increased significantly at 90 ml/kg/min of pump flow compared with other rates of pump flow. These results suggest that a critical flow level to maintain oxidative metabolism in the calf with chronic nonpulsatile flow exists between 90 and 100 ml/kg/min, and PvO2 at the critical flow rate was between 24 and 28 mmHg. Exercise data showed a significant correlation between O2 delivery and the maximal O2 consumption at each nominal flow rate, and suggested that a maximum of 78% of the oxygen delivered can be extracted and utilized during maximal exercise in animals with chronic nonpulsatile blood flow. These data suggest that chronic nonpulsatile blood flow is not a limi]ting factor for oxygen transport during rest and progressive exercise. However, further studies are needed to directly compare oxygen transport properties in pulsatile and nonpulsatile blood flow models.