The newborn's ability to compensate for a sudden increase in respiratory load remains unclear. The mouth occlusion pressure (Pmo) and the effective elastance (E'rs) were determined in 58 neonates ranging in gestational age from 28 to 41 wk. These results were compared with the esophageal pressure change (ΔPes) and with lung elastance (EL) obtained during regular breathing. Since E'rs = Pmo/ΔPes x EL, E'rs is proportional to an active component, Pmo/ΔPes and a passive component, EL. Although EL is 1.10 ± 0.31 (mean ± SD) cmH2O/ml at 28 wk gestation, this value decreases to 0.20 ± 0.04 cmH2O/ml at full-term. The active component Pmo/ΔPes changes in the opposite direction. It is 0.92 ± 0.25 at 28 wk gestation, indicating that there is no load compensation in the very premature infant. It increases to 2.06 ± 0.50 in the full-term newborn, reflecting a linear increase in the ability for load compensation with advancing gestational age. The E'rs is largely determined by EL and is, therefore, not a good measure to compare load compensating ability. The quotient Pmo/ΔPes, being independent of tidal volume, lung maturation, and growth, reflects load compensating activity better than E'rs.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Applied Physiology Respiratory Environmental and Exercise Physiology|
|State||Published - Jan 1 1982|
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