Influence of Breathing Pattern, Sleep States, and Maturation on Functional Residual Capacity (Frc) in Newborn Infants

Abstract

P e d i a t r i c s , Oregon Health Sciences Univ., P o r t l a n d , OR. Moment a n a l y s i s (MA) of MBNW could i n theory be a good method o f q u a n t i f y i n g v e n t i l a t i o n inhomogeneity i n young c h i l d r e n s i n c e i t r e q u i r e s only q u i e t b r e a t h i n g of oxygen f o r <2 minutes and t h e r e s u l t s a r e independent of b r e a t h i n g p a t t e r n o r lung volume. We have developed t h e software r e q u i r e d f o r on-line MA of MBNW and have performed d u p l i c a t e s t u d i e s on 36 h e a l t h y c h i l d r e n (H) and 10 w i t h c y s t i c f i b r o s i s (CF) ages 3-6 y e a r s . Outcome v a r i a b l e s included FRC, moments 0 , 1 , 2 and moment r a t i o s Mi/% and M2/% I n H t h e r e were no s e x r e l a t e d d i f f e r e n c e s i n FRC o r moment r a t i o s w h i l e a b s o l u t e moments tended t o be h i g h e r i n boys (p<.05,MO). Int r a s u b j e c t c o e f f i c i e n t of v a r i a t i o n (CV%) was < l o % f o r a l l v a r ia b l e s . I n t e r s u b j e c t CV% f o r M1/%=8%, M2/%=13%, and FRC=18%. A modified Shwachman (S) s c o r e was used t o q u a n t i f y lung involvement i n CF w i t h a s c o r e o f 75 being t h e b e s t p o s s i b l e . The CF group v a r i e d from no lung involvement t o s e v e r e d i s e a s e , S s c o r e 30-75. Mean FRC was no d i f f e r e n t i n CF v s H while mean M1/M0 and M2/% were b o t h higher i n CF, 2.59 v s 2.32 and 13.04 v s 9.31, p< .001. 7 of 1 0 CF had moment r a t i o s >95th p e r c e n t i l e of H. The 3 w i t h v a l u e s i n t h e normal range had higher S s c o r e s than t h e 7 w i t h abnormal v a l u e s , mean 65 v s 47, p<.001. Moment r a t i o s i n CF showed a good c o r r e l a t i o n w i t h S s c o r e s ; f o r i n s t a n c e Ml/%=3.35 -.01.S s c o r e r=.67, pC.01. We conclude t h a t MA of MBNW has promise a s a t e s t of lung f u n c t i o n i n young c h i l d r e n s i n c e t h e method is non-invasive, low i n v a r i a b i l i t y , and appears t o have t h e s e n s i t i v i t y r e q u i r e d t o d e t e c t mild v e n t i l a t i o n inhomogeneity. During behavioural a c t i v e s l e e p (AS) a s compared t o q u i e t s l e e p ( Q S ) , a 30.z decrease i n lung volume has been r e p o r t e d i n term newborns. T h i s study was designed t o determine whether such changes i n lung volume a r e r e l a t e d t o changes i n s l e e p s t a t e s o r t o changes i n b r e a t h i n g p a t t e r n . The r o l e o f maturation was a l s o a ss e s s e d . We used t h e helium d i l u t i o n method t o measure FRC. Neurophysiologic c r i t e r i a were used t o i d e n t i f y s l e e p s t a t e s . Movements of c h e s t and abdomen were monitored.Results (1 _+ SD; FRC= o f -t h e i e 26 newborn i n f a n t s , FRC happened to-be meastked when b r e a t h i n g showed two completely o p p o s i t e p a t t e r n s : OUT o f phase and IN-phase b r e a t h i n g . FRC "OUT" (1.38 +_ 0.25 ml/cm) was lower than FRC "IN" (1.56 t 0.25 ml/cm...

Relationship Between Functional Residual Capacity and Oxygen Desaturation During Short Central Apneic Events During Sleep in “Late Preterm” Infants

“…The O 2 -technique can overestimate FRC by about 10% when the tidal volume is low but is highly reproducible (19). Hence, bearing in mind this systematic overestimation, our overall mean FRC value of 31.2 Ϯ 9.6 mL kg Ϫ1 is within the wide range reported in previous studies (using a variety of other methods) of infants of similar ages and body masses (7,23). Part of the difference with previous studies may result from different techniques and populations.…”

“…Although we took care to limit variability, the intrasubject coefficient of variation for FRC was 13.7 Ϯ 11.1%, which corresponds to somewhat lower reproducibility than previously reported with the He technique (8%) (4 ). We failed to observe a sleep state effect on FRC values as previously reported (7,11,23,24), probably because we only measured FRC during regular breathing pattern. In contrast, less recent studies found that the FRC was lower in AS (determined by the behavior and/or from electro-oculograms but without EEG data) (2,10).…”

“…We found that FRC was negatively correlated with the frequency of overall apneic events during AS but not during QS. Although a decrease in lung volume following frequent apneic episodes or irregular breathing periods has been observed (3,23,24); this is the first time (to the best of our knowledge) that a sleep-state dependent relationship has been established between FRC and frequent, short apneic events.…”

Reference values for residual volume, functional residual capacity and total lung capacity. ATS Workshop on Lung Volume Measurements. Official Statement of The European Respiratory Society

“…A large number of studies have reported values for FRC in healthy infants using both helium dilution [23,[26][27][28][29][30][31][32][33] and plethysmographic techniques [34][35][36][37][38][39][40][41][42][43]. Many of these studies have confined measurements to the neonatal period, thereby precluding calculation of prediction equations based on body weight or length.…”

Measuring tidal volume and functional residual capacity change in sleeping infants using a volume displacement plethysmograph

“…FRC change with different sleep states has been explored by a number of groups with conflicting results [19][20][21][22][23]. Only STOKES et al [23] explored the concept of FRC variability using the respiratory jacket.…”