Positive end-expiratory pressure improves respiratory function in obese but not in normal subjects during anesthesia and paralysis

Paolo Pelosi, Irene Ravagnan, Gabriella Gíuratí, Mauro Panigada, Nicola Bottino, Stefano Tredici, Giuditta Eccher, Luciano Gattinoni

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
Pages (from-to)1221-1231
Number of pages11
JournalAnesthesiology
Volume91
Issue number5
DOIs
Publication statusPublished - Nov 1999

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Positive-Pressure Respiration
Paralysis
Anesthesia
Thoracic Wall
Lung
Respiratory System
Pressure
Oxygen
Respiratory Mechanics
Helium
Operating Rooms
Carbon Dioxide
Intensive Care Units
Arterial Pressure
Body Mass Index
Catheters
Gases

Keywords

  • Mechanical ventilation, obesity
  • Postoperative period

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Cite this

Positive end-expiratory pressure improves respiratory function in obese but not in normal subjects during anesthesia and paralysis. / Pelosi, Paolo; Ravagnan, Irene; Gíuratí, Gabriella; Panigada, Mauro; Bottino, Nicola; Tredici, Stefano; Eccher, Giuditta; Gattinoni, Luciano.

In: Anesthesiology, Vol. 91, No. 5, 11.1999, p. 1221-1231.

Research output: Contribution to journalArticle

Pelosi, Paolo ; Ravagnan, Irene ; Gíuratí, Gabriella ; Panigada, Mauro ; Bottino, Nicola ; Tredici, Stefano ; Eccher, Giuditta ; Gattinoni, Luciano. / Positive end-expiratory pressure improves respiratory function in obese but not in normal subjects during anesthesia and paralysis. In: Anesthesiology. 1999 ; Vol. 91, No. 5. pp. 1221-1231.
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abstract = "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.",
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AU - Pelosi, Paolo

AU - Ravagnan, Irene

AU - Gíuratí, Gabriella

AU - Panigada, Mauro

AU - Bottino, Nicola

AU - Tredici, Stefano

AU - Eccher, Giuditta

AU - Gattinoni, Luciano

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N2 - 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.

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