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


CONCLUSIONS
Hypoventilation frequently complicates severe obesity among hospitalized adults and is associated with excess morbidity and mortality.
Nowbar
Sogol
S
University of Colorado Health Sciences Center, Denver, Colorado, USA.
Burkart
Kristin M
KM
Gonzales
Ralph
R
Fedorowicz
Andrew
A
Gozansky
Wendolyn S
WS
Gaudio
Jon C
JC
Taylor
Matthew R G
MR
Zwillich
Clifford W
CW
D000328:Adult; D000368:Aged; D001639:Bicarbonates / Q000097:blood; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000097:blood; D003120:Colorado; D015897:Comorbidity; D016001:Confidence Intervals; D003422:Critical Care / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006784:Hospitals, Teaching; D006801:Humans; D007040:Hypoventilation / Q000150:complications / Q000175:diagnosis / Q000401:mortality*; D007902:Length of Stay / Q000706:statistics & numerical data*; D008134:Long-Term Care / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D009765:Obesity / Q000150:complications / Q000175:diagnosis / Q000401:mortality*; D009767:Obesity, Morbid / Q000150:complications / Q000175:diagnosis / Q000401:mortality*; D017063:Outcome Assessment, Health Care; D010343:Patient Admission / Q000706:statistics & numerical data; D016016:Proportional Hazards Models; D011594:Psychometrics / Q000706:statistics & numerical data; D012891:Sleep Apnea Syndromes / Q000150:complications / Q000175:diagnosis / Q000401:mortality*; D016019:Survival Analysis
D001639:Bicarbonates; D002245:Carbon Dioxide