Super Obesity in the Medical Intensive Care Unit

Studies exploring the effect of body mass index (BMI) on outcomes in the intensive care unit (ICU) have yielded mixed results, with few studies assessing patients at the extremes of obesity. We sought to understand the clinical characteristics and outcomes of patients with super obesity (BMI > 50 kg/m²) as compared to morbid obesity (BMI > 40 kg/m²) and obesity (BMI > 30 kg/m²).

A retrospective review of patients admitted to the Los Angeles County + University of Southern California medical intensive care unit (MICU) service between 2008 and 2013 was performed. The first 150 patients with BMI 30 to 40, 40 to 50, and 50+ were separated into groups. Demographic data, comorbid conditions, reason for admission, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, serum bicarbonate, and arterial carbon dioxide pressure (Pco ₂) at admission were collected. Hospital and ICU length of stay (LOS), discharge disposition, mortality, use of mechanical ventilation (invasive and noninvasive), use of radiography, and other clinical outcomes were also recorded.

There was no difference in age, sex, and APACHE II score among the 3 groups. A pulmonary etiology was the most common reason for admission in the higher BMI categories (P < .001). There was no difference in mortality among the groups. Intensive care unit and hospital LOS rose with increasing BMI (P < .001). Patients admitted for pulmonary etiologies and higher BMIs had an increased ICU and hospital LOS (P < .001). Super obese patients used significantly more noninvasive mechanical ventilation (NIMV, P < .001). There were no differences in the use of invasive mechanical ventilation across the groups.

Super obese patients are most commonly admitted to the MICU with pulmonary diagnoses and have an increased use of noninvasive ventilation. Super obesity was not associated with increased ICU mortality. Clinicians should be prepared to offer NIMV to super obese patients and anticipate a longer LOS in this group.