The effect of high or low oxygen affinity red cells on tissue oxygenation and myocardial function in hypoxic newborn...

In order to compare high and low oxygen affinity blood under conditions of severe respiratory failure, the effects of a high or low P50 were evaluated in two groups of newborn lambs (P50, 20 mmHg versus 30 mmHg), under conditions of hypoxic hypoxia (Fio2, 10%) and hypercapnic hypoxia (Fio2, 10% and Fico2, 10%). Data on cardiovascular function, blood gas parameters, and tissue oxygenation were collected under normoxic conditions and during severe hypoxia. During hypoxic hypoxia, a higher arterial oxygen content was noted in the high affinity group throughout the experiment; however, there were no significant differences detected in the remainder of the parameters studied. During hypercapnic hypoxia, the position of the oxygen dissociation curve did not cause any significant differences. When, however, hypercapnic hypoxia was compared to hypoxic hypoxia, there was a significant increase in cardiac output and myocardial contraction during hypercapnia.