Outcomes of morbidly obese patients receiving invasive mechanical ventilation: a nationwide analysis.
BACKGROUND
Critically ill, morbidly obese patients (BMI≥40 kg/m2) are at high risk of respiratory failure requiring invasive mechanical ventilation (IMV). It is not clear if outcomes of critically ill, obese patients are affected by obesity. Due to limited cardiopulmonary reserve, they may have poor outcomes. However, literature to this effect is limited and conflicted.


METHODS
We used the Nationwide Inpatient Sample from 2004 to 2008 to examine the outcomes of morbidly obese people receiving IMV and compared them to nonobese people. We identified hospitalizations requiring IMV and morbid obesity using International Classification of Diseases, 9th Revision, Clinical Modification codes. Primary outcomes studied were inhospital mortality, rates of prolonged mechanical ventilation (≥96 h), and tracheostomy. Multivariable logistic regression was used to adjust for potential confounding variables. We also examined outcomes stratified by number of organs failing.


RESULTS
Of all hospitalized, morbidly obese people, 2.9% underwent IMV. Mean age, comorbidity score, and severity of illness were lower in morbidly obese people. The adjusted mortality was not significantly different in morbidly obese people (OR 0.89; 95% CI, 0.74-1.06). When stratified by severity of disease, there was a stepwise increase in risk for mortality among morbidly obese people relative to nonobese people (range: OR, 0.77; 95% CI, 0.58-1.01 for only respiratory failure, to OR, 4.14; 95% CI, 1.11-15.3 for four or more organs failing). Rates of prolonged mechanical ventilation were similar, but rate of tracheostomy (OR 2.19; 95% CI, 1.77-2.69) was significantly higher in patients who were morbidly obese.


CONCLUSIONS
Morbidly obese people undergoing IMV have a similar risk for death as nonobese people if only respiratory failure is present. When more organs fail, morbidly obese people have increased risk for mortality compared with nonobese people.
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI.
Gagan
G
Kumar
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI.
Tilottama
T
Majumdar
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI; Department of Medicine, Division of Pulmonary and Critical Care Medicine, Clement J. Zablocki VA Medical Center, Milwaukee, WI.
Elizabeth R
ER
Jacobs
Division of Critical Care Medicine, Orlando Regional Medical Center, Orlando, FL.
Valerie
V
Danesh
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI.
Gaurav
G
Dagar
Division of Cardiology, University of Arkansas for Medical Sciences, Little Rock, AR.
Abhishek
A
Deshmukh
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI.
Amit
A
Taneja
Department of Medicine, Division of Pulmonary and Critical Care Medicine, Medical College of Wisconsin, Milwaukee, WI. Electronic address: rnanchal@mcw.edu.
Rahul
R
Nanchal
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016638:Critical Illness / Q000401:mortality* / Q000628:therapy*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000150:complications*; D011379:Prognosis; D012121:Respiration, Artificial; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D014481:United States; D055815:Young Adult