Document Detail

Nasal versus oronasal raised volume forced expirations in infants--a real physiologic challenge.
MedLine Citation:
PMID:  22328241     Owner:  NLM     Status:  MEDLINE    
Raised volume rapid thoracoabdominal compression (RTC) generates forced expiration (FE) in infants typically from an airway opening pressure of 30 cm H(2)O (V(30)). We hypothesized that the higher nasal than pulmonary airway resistance limits forced expiratory flows (FEF(%)) during (nasal) FE(n), which an opened mouth, (oronasal) FE(o), would resolve. Measurements were performed during a brief post-hyperventilation apnea on 12 healthy infants aged 6.9-104 weeks. In two infants, forced expiratory (FEFV) flow volume (FV) curves were generated using a facemask that covered the nose and a closed mouth, then again with a larger mask with the mouth opened. In other infants (n = 10), the mouth closed spontaneously during FE. Oronasal passive expiration from V(30) generated either the inspiratory capacity (IC) or by activating RTC before end-expiration, the slow vital capacity ((j) SVC). Peak flow (PF), FEF(25), FEF(50), FEF(25-75), FEV(0.4), and FEV(0.5) were lower via FE(n) than FE(o) (P < 0.05), but the ratio of expired volume at PF and forced vital capacity (FVC) as percent was higher (P < 0.05). FEF(75), FEF(85), FEF(90), FVC as well as the applied jacket pressures were not different (P > 0.05). FEFV curves generated via FE(o) exhibited higher PF than FV curves of IC (P < 0.05); PF of those produced via FE(n) were not different from FV curves of IC (P > 0.05) but lower than those of (j) SVC (P < 0.05). In conclusion, the higher nasal than pulmonary airways resistance unequivocally affects the FEFV curves by consistently reducing PF and decreases mid-expiratory flows. A monitored slightly opened mouth and a gentle anterior jaw thrust are physiologically integral for raised volume RTC in order to maximize the oral and minimize nasal airways contribution to FE so that flow limitation would be in the pulmonary not nasal airways.
Mohy G Morris
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2012-02-10
Journal Detail:
Title:  Pediatric pulmonology     Volume:  47     ISSN:  1099-0496     ISO Abbreviation:  Pediatr. Pulmonol.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-07-12     Completed Date:  2012-12-04     Revised Date:  2013-08-15    
Medline Journal Info:
Nlm Unique ID:  8510590     Medline TA:  Pediatr Pulmonol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  780-94     Citation Subset:  IM    
Copyright Information:
Copyright © 2012 Wiley Periodicals, Inc.
Department of Pediatrics, Pulmonary Medicine Section, College of Medicine, University of Arkansas for Medical Sciences, Arkansas Children's Hospital, Little Rock, Arkansas 72202-3591, USA.
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MeSH Terms
Airway Resistance / physiology*
Child, Preschool
Forced Expiratory Flow Rates / physiology*
Inspiratory Capacity
Mouth / physiology*
Nose / physiology*
Respiratory Function Tests / methods
Grant Support
5K23-HL004475/HL/NHLBI NIH HHS; K23 HL004475-05/HL/NHLBI NIH HHS

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