Abstract
31 lambs were delivered by C-section at 120 days gestational age and divided randomly into 6 groups (G1-6) of 4-7 lambs. Gl lambs were killed before the first breath. G2-6 were supported with 100% O2 at 30 breaths/min and 30/2 cm H2O on infant ventilators. Frequent blood gases and tidal volumes (TV) were measured. All lambs were in respiratory failure by 28.6 min (pH=6.93±.01; PO2, 30.6±1.8; pCO2, 108±3). G2 lambs were killed before NST and G3-6 lambs were treated with 50 mg/kg NS by tracheal instillation. G3-6 lambs were killed 10 min, 40 min, 1.5 hr and 3 hr post NST, respectively. All lambs responded dramatically to NST; mean maximal responses were: pH, 7.29±.02 at 1.25 hr; pO2, 196±20 at 5.6 min; and pCO2, 39±4 at 58 min post NST. Responses of lambs in different groups were uniform. Pressure-volume curves (P-V) were measured using the left lung, an alveolar wash (AW) was recovered from the right upper lobe (RUL), and the RLL was fixed by perfusion at constant pressure for histology. P-V curves improved following NST. Surface tension (ST) measurements of AW samples were 31±1 dynes/cm before NST and fell to 6.3±2.8 at 10 min post NST, before rising to 21.7±4.6 by 3 hr post NST. ST correlated with PO2 (p<0.001) but not pCO2 or TV at sacrifice. A grid count of % distal air space (%A) in tissue sections showed dramatic improvement in aeration with NST; %A correlated with pCO2 and TV at sacrifice (p<.05).
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Jacobs, H., Ikegami, M., Jobe, A. et al. 1670 NATURAL SURFACTANT THERAPY (NST): CLINICAL AND BIO-PHYSICAL CORRElATES IN PREMATURE LAMBS. Pediatr Res 15 (Suppl 4), 721 (1981). https://doi.org/10.1203/00006450-198104001-01688
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DOI: https://doi.org/10.1203/00006450-198104001-01688