CARDIOVASCULAR CHANGES DURING SUSTAINED LUNG INFLATIONS IN PREMATURE NEWBORN LAMBS

We studied the effect of sustained inspiratory inflations (SI) on the cardiovascular system by measuring mean central venous pressure (MCVP) , mean arterial blood pressure (MABP) and heart rate (HR), before and during sustained lung inflations in premature lambs (128-133 days' ges tation). SI consisted of four inflations of 5 a at a peak inspiratory pressure of 35 cmH(2)O, with a mixture of 5% carbon dioxide and 95% ox ygen. Each inflation was followed by a positive end-expiratory pressur e of 5 cmH(2)O for 5 s. Percentage change from baseline was -3.88% for MABP and -2.55% for HR during the first inflation. The changes in MCV P fluctuated with each inflation (mean 9.61%;p < 0.01 versus baseline) and deflation (mean -3.87%; p < 0.05 versus baseline). These changes were dependent on the time after birth and the pressure used for ST. T he observed cardiovascular changes produced by this procedure are cons idered clinically relevant when managing premature infants with a high risk of intraventricular haemorrhage.