Obesity-associated hypoventilation in hospitalized patients: prevalence, effects, and outcome

Am J Med. 2004 Jan 1;116(1):1-7. doi: 10.1016/j.amjmed.2003.08.022.

Abstract

Background: Severe obesity is associated with hypoventilation, a disorder that may adversely affect morbidity and mortality. We sought to determine the prevalence and effects of obesity-associated hypoventilation in hospitalized patients.

Methods: Consecutive admissions to internal medicine services were screened over a 6-month period. In all eligible subjects with severe obesity (body mass index > or =35 kg/m2), we administered a sleep questionnaire, and performed neuropsychological, arterial blood gas, and pulmonary function testing. Hospital course and mortality at 18 months was also determined.

Results: Of 4,332 admissions, 6% (n = 277) of patients were severely obese, of whom 150 were enrolled, 75 refused to participate, and 52 met the exclusion criteria. Hypoventilation (mean [+/- SD] arterial partial pressure of carbon dioxide [PaCO2], 52 +/- 7 mm Hg) was present in 31% (n = 47) of subjects who did not have other reasons for hypercapnia. Decreased objective attention/concentration and increased subjective sleepiness were present in patients with obesity-associated hypoventilation compared with in severely obese hospitalized patients without hypoventilation (simple obesity group; mean PaCO2, 37 +/- 6 mm Hg). There were higher rates of intensive care (P = 0.08), long-term care at discharge (P = 0.01), and mechanical ventilation (P = 0.01) among subjects with obesity-associated hypoventilation. Therapy for hypoventilation at discharge was initiated in only 6 (13%) of the patients with obesity-associated hypoventilation. At 18 months following hospital discharge, mortality was 23% in the obesity-associated hypoventilation group as compared with 9% in the simple obesity group (hazard ratio = 4.0; 95% confidence interval: 1.5 to 10.4].

Conclusion: Hypoventilation frequently complicates severe obesity among hospitalized adults and is associated with excess morbidity and mortality.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Bicarbonates / blood
  • Body Mass Index
  • Carbon Dioxide / blood
  • Colorado
  • Comorbidity
  • Confidence Intervals
  • Critical Care / statistics & numerical data
  • Female
  • Follow-Up Studies
  • Hospitals, Teaching
  • Humans
  • Hypoventilation / complications
  • Hypoventilation / diagnosis
  • Hypoventilation / mortality*
  • Length of Stay / statistics & numerical data*
  • Long-Term Care / statistics & numerical data
  • Male
  • Middle Aged
  • Neuropsychological Tests / statistics & numerical data*
  • Obesity / complications
  • Obesity / diagnosis
  • Obesity / mortality*
  • Obesity, Morbid / complications
  • Obesity, Morbid / diagnosis
  • Obesity, Morbid / mortality*
  • Outcome Assessment, Health Care
  • Patient Admission / statistics & numerical data
  • Proportional Hazards Models
  • Psychometrics / statistics & numerical data
  • Sleep Apnea Syndromes / complications
  • Sleep Apnea Syndromes / diagnosis
  • Sleep Apnea Syndromes / mortality*
  • Survival Analysis

Substances

  • Bicarbonates
  • Carbon Dioxide