. Columbia University College of Physicians and Surgeons, Babies H o s p i t a l , Departments of P e d i a t r i c s , Surgery, Pathology and I n s t i t u t e f o r Human Nutr i t i o n , New York.To t e s t t h e hypothesis t h a t distending p r e s s u r e produced by t h e r e s p i r a t o r y muscles determines p o s t n a t a l growth of lung parenchyma, we s t u d i e d u n i l a t e r a l diaphragmatic p a r a l y s i s i n k i t tens. Twelve 10-12 week o l d k i t t e n s underwent l e f t thoracotomy. In 6 , u n i l a t e r a l phrenectomy was done v i a t h e thoracotomy; t h e o t h e r 6 served a s controls. Five t o 7 weeks l a t e r , body weight had increased by 49% i n the phrenectomized group and by 47% i n t h e c o n t r o l s (NS). However f u n c t i o n a l r e s i d u a l capacity by helium d i l u t i o n under ketamine hydrochloride a n a e s t h e s i a was lower i n t h e phrenectomized group (35 2 4 ml versus 58 + 9 m l i n t h e c o n t r o l s , P C .001). As measured by b i l a t e r a l p l e u r a l balloons, mean transpulmonary p r e s s u r e i p s i l a t e r a l t o t h e phrenectomy was lower than mean transpulmonary pressure c o n t r a l a t e r a l t o t h e phrenectomy (P<.05). I n postmortem s t u d i e s , growth of contral a t e r a l lungs r e l a t i v e t o i p s i l a t e r a l lungs was g r e a t e r i n the phrenectomized animals than i n t h e c o n t r o l s , as shown by r a t i o s of contralateral/ipsilateral wet lung weight (1.44 versus 1.34, P< .005), maximum i n f l a t i o n volume (1.53 versus 1.33, P< .005) and t o t a l p r o t e i n content (1.45 versus 1.26, P< .002). Ratios of t o t a l proteinlDNA and RNA/DNA were unchanged. W e conclude t h a t p o s t n a t a l growth of lung parenchyma by c e l l p r o l i f e r a t i o n i n t h e c a t depends on pulmonary distending pressure. This study was designed to obtain normative data for FRC, dynamic (CLd) and specific lung compliance (CLs) during the first years of life. Thirteen boys and 9 girls f r e e of respiratory disease were studied. Age, height, weight and ventilatory r a t e respectively ranged from 2 -52 months, 55 -96 cm, 4.9 -16 Kg and 22 -55Imin.Studies were performed during chloral hydrate induced sleep. Infants breathed through a mouth piece or a face mask. FRC was determined by the closed circuit helium dilution technique using a 2.2 1 water sealed spirograph.Added dead space was subtracted from the measured volume and values were converted to BTPS. Measurement of tidal flow and volume through a heated pneumotachograph and of esophageal pressure with an air filled balloon catheter allowed for calculation of CLd as A V/ A P a t zero flow. FRC, CLd and CLs respectively ranged from 110 -430 ml, 8.1 -34.7 ml/cm H 0 and .051 -.I10 ml/cm H20/ml FRC. FRC and CLd were signif?cantly correlated with height, age, weight and ventilatory r a t e while CLs was not. CLd was also significantly correlate with FRC. Multiple linear regression analysis showed that: I-the only significant predictive ...
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