Document Detail

Respiratory restriction and elevated pleural and esophageal pressures in morbid obesity.
MedLine Citation:
PMID:  19910329     Owner:  NLM     Status:  MEDLINE    
To explore mechanisms of restrictive respiratory physiology and high pleural pressure (P(Pl)) in severe obesity, we studied 51 obese subjects (body mass index = 38-80.7 kg/m(2)) and 10 nonobese subjects, both groups without lung disease, anesthetized, and paralyzed for surgery. We measured esophageal and gastric pressures (P(Es), P(Ga)) using a balloon-catheter, airway pressure (P(AO)), flow, and volume. We compared P(Es) to another estimate of P(Pl) based on P(AO) and flow. Reasoning that the lungs would not inflate until P(AO) exceeded alveolar and pleural pressures (P(AO) > P(Alv) > P(Pl)), we disconnected subjects from the ventilator for 10-15 s to allow them to reach relaxation volume (V(Rel)) and then slowly raised P(AO) until lung volume increased by 10 ml, indicating the "threshold P(AO)" (P(AO-Thr)) for inflation, which we took to be an estimate of the lowest P(Alv) or P(Pl) to be found in the chest at V(Rel). P(AO-Thr) ranged from 0.6 to 14.0 cmH2O in obese and 0.2 to 0.9 cmH2O in control subjects. P(Es) at V(Rel) was higher in obese than control subjects (12.5 +/- 3.9 vs. 6.9 +/- 3.1 cmH2O, means +/- SD; P = 0.0002) and correlated with P(AO-Thr) (R(2) = 0.16, P = 0.0015). Respiratory system compliance (C(RS)) was lower in obese than control (0.032 +/- 0.008 vs. 0.053 +/- 0.007 l/cmH2O) due principally to lower lung compliance (0.043 +/- 0.016 vs. 0.084 +/- 0.029 l/cmH2O) rather than chest wall compliance (obese 0.195 +/- 0.109, control 0.223 +/- 0.132 l/cmH2O). We conclude that many severely obese supine subjects at relaxation volume have positive P(pl) throughout the chest. High P(Es) suggests high P(Pl) in such individuals. Lung and respiratory system compliances are low because of breathing at abnormally low lung volumes.
Negin Behazin; Stephanie B Jones; Robert I Cohen; Stephen H Loring
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-11-12
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  108     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2010-01-07     Completed Date:  2010-03-17     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  212-8     Citation Subset:  IM    
Dept. of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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MeSH Terms
Esophagus / physiopathology*
Lung / physiopathology*
Lung Compliance
Middle Aged
Obesity, Morbid / physiopathology*
Pleural Cavity / physiopathology*
Pulmonary Gas Exchange*
Respiratory Mechanics*
Young Adult
Grant Support

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

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