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' gestation). 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% oxygen. Each inflation was followed by a positive end-expiratory pressure 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 MCVP 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. The observed cardiovascular changes produced by this procedure are considered clinically relevant when managing premature infants with a high risk of intraventricular haemorrhage.