Document Detail

Positive end-expiratory pressure improves respiratory function in obese but not in normal subjects during anesthesia and paralysis.
MedLine Citation:
PMID:  10551570     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Morbidly obese patients, during anesthesia and paralysis, experience more severe impairment of respiratory mechanics and gas exchange than normal subjects. The authors hypothesized that positive end-expiratory pressure (PEEP) induces different responses in normal subjects (n = 9; body mass index < 25 kg/m2) versus obese patients (n = 9; body mass index > 40 kg/m2). METHODS: The authors measured lung volumes (helium technique), the elastances of the respiratory system, lung, and chest wall, the pressure-volume curves (occlusion technique and esophageal balloon), and the intraabdominal pressure (intrabladder catheter) at PEEP 0 and 10 cm H2O in paralyzed, anesthetized postoperative patients in the intensive care unit or operating room after abdominal surgery. RESULTS: At PEEP 0 cm H2O, obese patients had lower lung volume (0.59 +/- 0.17 vs. 2.15 +/- 0.58 l [mean +/- SD], P < 0.01); higher elastances of the respiratory system (26.8 +/- 4.2 vs. 16.4 +/- 3.6 cm H2O/l, P < 0.01), lung (17.4 +/- 4.5 vs. 10.3 +/- 3.2 cm H2O/l, P < 0.01), and chest wall (9.4 +/- 3.0 vs. 6.1 +/- 1.4 cm H2O/l, P < 0.01); and higher intraabdominal pressure (18.8 +/-7.8 vs. 9.0 +/- 2.4 cm H2O, P < 0.01) than normal subjects. The arterial oxygen tension was significantly lower (110 +/- 30 vs. 218 +/- 47 mmHg, P < 0.01; inspired oxygen fraction = 50%), and the arterial carbon dioxide tension significantly higher (37.8 +/- 6.8 vs. 28.4 +/- 3.1, P < 0.01) in obese patients compared with normal subjects. Increasing PEEP to 10 cm H2O significantly reduced elastances of the respiratory system, lung, and chest wall in obese patients but not in normal subjects. The pressure-volume curves were shifted upward and to the left in obese patients but were unchanged in normal subjects. The oxygenation increased with PEEP in obese patients (from 110 +/-30 to 130 +/- 28 mmHg, P < 0.01) but was unchanged in normal subjects. The oxygenation changes were significantly correlated with alveolar recruitment (r = 0.81, P < 0.01). CONCLUSIONS: During anesthesia and paralysis, PEEP improves respiratory function in morbidly obese patients but not in normal subjects.
P Pelosi; I Ravagnan; G Giurati; M Panigada; N Bottino; S Tredici; G Eccher; L Gattinoni
Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesiology     Volume:  91     ISSN:  0003-3022     ISO Abbreviation:  Anesthesiology     Publication Date:  1999 Nov 
Date Detail:
Created Date:  1999-11-24     Completed Date:  1999-11-24     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1221-31     Citation Subset:  AIM; IM    
Istituto di Anestesia e Rianimazione, Università di Milano, Ospedale Magiore, Istituto di Ricovero e Cura a Carattere Scientifico, Milan, Italy.
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MeSH Terms
Abdomen / physiopathology,  surgery
Airway Resistance / physiology
Body Mass Index
Lung Volume Measurements
Middle Aged
Neuromuscular Blockade*
Obesity / physiopathology*,  surgery
Oxygen / blood
Positive-Pressure Respiration*
Pulmonary Alveoli / physiology
Pulmonary Atelectasis / prevention & control
Pulmonary Gas Exchange / physiology
Respiratory Function Tests
Respiratory Mechanics / physiology*
Surgical Procedures, Operative
Reg. No./Substance:

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

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