Document Detail

Influence of vagal activity on the neonatal ventilatory response to hypoxemia.
MedLine Citation:
PMID:  4047758     Owner:  NLM     Status:  MEDLINE    
The sustained increase in ventilation (V1) that occurs during acute hypoxemia in adults is not characteristic of the neonate as V1 falls to or below baseline values soon after onset of the hypoxic stimulus. Associated with this decline in V1 is a decrease in tidal volume, lung compliance, inspiratory duration, and an increase in functional residual capacity and respiratory frequency. We hypothesized that hypoxemia induced small airway constriction and pulmonary time constant inequalities resulting in a frequency dependent fall in lung compliance and tidal volume and retention of lung volume. In seven newborn subhuman primates, responses to acute hypoxemia were measured prior to and after administration of atropine methyl bromide to prevent vagally mediated narrowing of peripheral airways. The increase in frequency and fall in inspiratory duration characteristic of the ventilatory decline during hypoxemia was eliminated by the drug but functional residual capacity and lung compliance were unaffected. Also, the initial rise in V1 was blunted or blocked in all subjects. Bilateral vagotomy caused V1 to fall significantly requiring oxygen supplementation but responses to hypoxemia were still biphasic in nature. These findings suggest that cholinergically mediated mechanisms in the airways do not alter effective lung distensibility related to respiratory rate. Acetylcholine may be important at the peripheral chemosensor since cholinergic blockade eliminated the initial ventilatory increase.(ABSTRACT TRUNCATED AT 250 WORDS)
W A LaFramboise; D E Woodrum; R D Guthrie
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Pediatric research     Volume:  19     ISSN:  0031-3998     ISO Abbreviation:  Pediatr. Res.     Publication Date:  1985 Sep 
Date Detail:
Created Date:  1985-11-06     Completed Date:  1985-11-06     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0100714     Medline TA:  Pediatr Res     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  903-7     Citation Subset:  IM    
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MeSH Terms
Animals, Newborn / physiology*
Anoxia / physiopathology*
Atropine Derivatives
Functional Residual Capacity
Macaca nemestrina
Respiration* / drug effects
Tidal Volume
Vagus Nerve / physiopathology*
Grant Support
Reg. No./Substance:
0/Atropine Derivatives; 31610-87-4/methylatropine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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