Figure 59-8 The effects of sodium bicarbonate on aortic blood pressure (PAO), heart rate, and hematocrit level. Notice that hypotension occurred after administration of sodium bicarbonate. The hematocrit level decreased as fluid was "pulled" into the intravascular space to compensate for the hypovolemia that was present since birth. Raising the pH decreased the peripheral vasoconstriction produced by the preexisting acidosis. Giving albumin increased the aortic pressure to normal. On the basis of the final hematocrit level, the initial blood volume was approximately 30% less than predicted. (Adapted from Phibbs RH: Problems of neonatal intensive care units. In Lucey JF [ed]: Report on the 59th Ross Conference on Pediatric Research, 1969, Columbus, OH.)