COMPARISON OF EFFECTS OF 95-PERCENT AND 90-PERCENT OXYGEN SATURATIONSIN RESPIRATORY-DISTRESS SYNDROME

Aims-To determine if decreasing arterial blood saturation from 95% to 90% could cause vasoconstriction of the pulmonary vasculature and dila tation of a patent ductus arteriosus in preterm newborn infants with r espiratory distress syndrome (RDS). Methods-Doppler echocardiographic studies were compared at 95% and 90% pulse oxygen saturation (SpO(2)) in 13 preterm infants aged 61.7 (4.3) hours with RDS and Doppler echoc ardiographic evidence of tricuspid regurgitation. Results-The mean (SD )Doppler echocardiographic indices determined at 95% were heart rate ( 146 (3.60) beats per minute), acceleration time of the velocity wave f orms of the pulmonary artery (PAAT) (51.8 (2.5) milliseconds), ratio o f PAAT to right ventricular ejection time (ET) (0.26 (0.02)), diameter of the ductus arteriosus (2.6 (0.6) mm), pulmonary blood flow (0.33 ( 0.03) 1/minute) and the left ventricular shortening fraction (SF)(0.4 (0.02)%). The ascending aorta flow velocity wave form was used for the calculation of pulmonary blood flow. The right ventricular to right a trial systolic pressure gradient calculated using the peak velocity of the tricuspid regurgitation jet was 26.7 (7.4) mm Hg. Conclusions-A d ecrease from 95% to 90% SpO(2) did not have any effect on the pulmonar y circulatory haemodynamics nor the ductus arteriosus.