Oliguria in the premature baboon with hyaline membrane disease: a manifestation of multisystem immaturity?

To assess the temporal relationship between fluid balance and cardiopulmonary function in hyaline membrane disease (HMD), serial measurements were made of pulmonary gas exchange (Pa/A O2, PaO2, PaCO2), ventilation indices (FIO2, Ppeak, Pmin, frequency), blood pressure (BP), heart rate (HR), and fluid balance ratio (FBR) in 11 premature (140-day gestation) baboons with HMD treated with positive-pressure ventilation and continuous distending airway pressure (PPV/PEEP) for 11 days. All animals had radiographic and clinical evidence of HMD. Pa/AO2 fell initially, and, in spite of increase in Paw, remained below 0.2 for the first 42 hours. In the same time frame, the animals became progressively oliguric with FBR falling from 0.48 to 0.17 and remaining at that level through hour 43. Tachycardia and hypotension were also present during this period. The onset of the recovery phase at hour 42 was associated with concurrent improvement in Pa/AO2, fall in HR and BP, and the onset of diuresis. These data suggest that, at this development age in the immature baboon, recovery from HMD is associated with improved function of multiple organ systems. The apparent similarities in the "adaptive" timetable support the hypothesis that events associated with delivery and survival of the immature fetus result in accelerated maturation.