Fewer patients with obesity receiving ECMO for ARDS died than those without obesity

Key takeaways:

• A lower rate of death was observed among ICU patients with vs. without obesity on extracorporeal membrane oxygenation.
• This outcome was found even after propensity score matching.

Obesity reduced the odds for ICU mortality among patients with acute respiratory distress syndrome receiving extracorporeal membrane oxygenation, according to results published in American Journal of Respiratory and Critical Care Medicine.

Darya Rudym

“We showed that patients with obesity who needed [ECMO] for ARDS had better survival than patients without obesity,” Darya Rudym, MD, pulmonologist and assistant professor of medicine at NYU Langone Health, told Healio. “We hope that the findings from this study would empower bedside clinicians to consider ECMO as the means of support in their patients with obesity who have severe forms of ARDS and not preemptively withhold ECMO from those who may very well benefit from it.”

In an international, multicenter, retrospective cohort study, Rudym and colleagues assessed 790 patients (mean age, 44.2 years; 63.8% men) with ARDS receiving ECMO to determine the impact of obesity (BMI 30 kg/m²; n = 320) on ICU mortality.

Researchers analyzed this relationship using multivariable logistic regression that accounted for age, sex, days of invasive mechanical ventilation prior to intubation, pre-cannulation positive end-expiratory pressure, pH, PaO₂/FiO₂, use of neuromuscular blocking agents, inhaled nitric oxide, prone positioning and renal replacement therapy, as well as propensity score matching.

Notably, the cohort of patients with obesity had a greater proportion of women (41.2% vs. 32.8%), and a smaller average Acute Physiology and Chronic Health Evaluation II score (22.2 vs. 23.9; P = .028) compared with the cohort without obesity.

When comparing ICU death rates, fewer patients with obesity died than patients without obesity (24.1% vs. 35.3%; P < .001), and researchers observed reduced odds for mortality among those with obesity in the adjusted multivariable model (adjusted OR = 0.63; 95% CI, 0.43-0.93).

This analysis also demonstrated lower odds for ICU mortality with each 1 kg/m² increase in BMI (OR = 0.97; 95% CI, 0.95-1).

In addition to obesity, researchers found reduced odds for mortality with younger age, fewer invasive mechanical ventilation days before ECMO, increased PEEP, increased pH and a lack of inhaled nitric oxide or renal replacement therapy prior to ECMO.

Outcomes other than mortality, such as ICU stay length, hospital stay length, ECMO duration and mechanical ventilation duration, were comparable between those with vs. without obesity.

Notably, at 90 days patients without vs. with obesity showed a lower median number of ventilator-free days (50 days vs. 60 days; P = .05) and hospital-free days (22 days vs. 40 days; P = .012), according to researchers.

Even after propensity score matching (n = 199 with obesity and without obesity each), researchers continued to find decreased chances for ICU mortality among those with vs. without obesity (22.6% vs. 35.2%).

“We hope our study will advocate for inclusion of patients with obesity in future clinical trials,” Rudym told Healio.

Reference:

• NIH-funded study supports use of ECMO for critically ill patients with obesity. https://www.nih.gov/news-events/news-releases/nih-funded-study-supports-use-ecmo-critically-ill-patients-obesity. Published Aug. 28, 2023. Accessed Aug. 28, 2023.