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Recovery from hypopnea in preterm lambs: Effects of breathing air or oxygen
Author(s) -
Hutchison Alastair A.
Publication year - 1987
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.1950030507
Subject(s) - medicine , anesthesia , hyperoxia , ventilation (architecture) , hypopnea , oxygen , respiratory rate , room air distribution , apnea , breathing gas , arterial blood , breathing , heart rate , blood pressure , lung , chemistry , polysomnography , mechanical engineering , physics , organic chemistry , engineering , thermodynamics
The aim of this study was to determine if resuscitation from hypopnea when breathing oxygen resulted in a slower recovery than that seen when breathing room air. Hyperoxia, in preterm human neonates and lambs, decreases minute ventilation (V̇ I ), but no study has shown this effect during recovery from apnea or hypopnea, a common clinical setting. Thus, recovery from hypopnea was studied in eight unanesthesized preterm lambs, breathing spontaneously via an endotracheal tube placed into a tracheostomy. Hypopnea, defined here as a decrease in V̇ I from baseline greater than 50%, was induced by instillation of distilled water onto the larynx. After a baseline 30 sec when V̇ I heart rate, and arterial blood gas were measured, a standard hypopnea stimulus was given over 30 sec. The lambs then breathed air or oxygen during a 2‐min recovery period, which started with 15 sec of artifical ventilation. The degree of recovery at 2 min was less in the oxygen (O 2 ) breathing group: V̇ I (ml/kg/min) = 381 ± 27 in air and 270 ± 18 in O 2 , P < 0.01; pH = 7.38 ± 0.005 in air and 7.34 ± 0.008 in O 2 , P < 0.01; arterial carbon dioxide tension (Pa CO 2mrnHg) = 45.0 ± 1.3 in air and 49 ± 1.3 in O 2 P < 0.01; base excess = 2.1 ± 0.6 in air and 1.1 ± 0.5 oxygen, P < 0.01. By 2 min a return to baseline values of V̇ I , pH, and Pa CO 2was noted only in the air breathing group, where the arterial oxygen tension also returned to normal. The heart rate recoveries at 2 min were not different and, in both groups, were less than their baseline values. Resuscitation with O 2 in contrast to room air, delays ventilatory recovery from hypopnea. Pediatr Pulmonol 1987; 3:317–323 .