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W e tested the hypothesis t h a t n e t L+R duct shunt contributes t o PBF surge i n premature lambs during the f i r s t hour of l i f e (Pediat. Res., 8:433, 1974) and t o high PBF seen l a t e r i n lambs with severe HMD (Pediat. Res., 5:393, 1975). Total PBF, r i g h t v e n t r i c u l a r output (RVO) and duct shunt were measured during f i r s t hours of l i f e i n 1 lamb with and 1 without HMD. A t 129-130d g e s t a t i o n , a pre-calibrated electromagnetic flow transducer with non-occlusive zero was implanted on the main pulmonary a r t e r y (PA) t o measure RVO; a s i m i l a r transducer was implanted on the postductal portion of the common PA t o measure PBF. Duct shunt was calculated a s the d i f f e r e n c e between PBF and RVO.Lambs were returned t o the amniotic cavity f o r 7-8d and then delivered by C-Section a t 137d gestation.I n each lamb, PBF rose sharply from < 50 t o peaks of 487 and 473 mllkglmin, respectivel y , a t 22 and 29 min of age and then s t a b i l i z e d a t lower l e v e l s >y 1 h r of age. RVO stayed a t high l e v e l s u n t i l a f t e r the PBF surge, then f e l l t o s t a b l e l e v e l s by 1 h r of age. During the F i r s t 4 h r , net L+R duct shunt accounted f o r 28 t o 68% of PBF :means 54 and 52%). These data suggest t h a t L-tR duct shunt cont r i b u t e s appreciably t o PBF during the PBF surge and a t age 1-4 l r . L+R duct shunt may be a major source of the high PBF x e v i o u s l y reported i n lambs with HMD. (RDS) in premature i n f a n t s i s associated with a deficiency of pulmonary s u r f a c t a n t . Disaturatec phosphatidylcholine (DSPC) i s the major phospholipid component oi s u r f a c t a n t . W e have u t i l i z e d the osmium t e t r o UCLA School of Medicine. D e~t . of P e d i a t r i c s . Los Anneles. Calif The acute and chronic e f f e c t s of URIs on lung function have not been adequately studied i n children. Four normal (N) and a l l e r g i c (A) children, 9-15 years i n age were studied prospect i v e l y a t baseline, a t the time of URI and 2, 4 , and 9 months following URI. Lung function s t u d i e s included maximal expirato flow-volume curves and the response of flows t o a helium-oxygen gas mixture (VisoV) , exercise and isoproterenol. A t baseline, 1 N.and 5 A had minor abnormalities i n flows measured a f t e r 50% (Vmax 50) and 75% ( k a x 75) o f t h e v i t a l capacity had been exhaled. A t t h e time of t h e URIs, 12/14 subjects had elevated Visoo; 8 had a f a l l i n FEV1, i m a x 50 and \;max 75; 9 subjects demonstrated a g r e a t e r than 10% f a l l i n flows with exercise ( t h i included a l l 4 N), but ~i s o ? was abnormal i n only 3/12 subjects post-exercise. With isoproterenol, FEVl did not change i n any s u b j e c t but Vmax 50 and Vmax 75 increased i n 10 s u b j e c t s ; ~i s o i ' was abnormal i n 4 s u b j e c t s . Two months following URI, small ailway obstruction and bronchial hyperreactivity were s t i l l evident i n nearly 1/2 of t h e s u b j e c t s , but t h e abnormaliti...

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