Lack of association between body weight and mortality in patients on veno-venous extracorporeal membrane oxygenation

To analyse the association of body weight with hospital mortality of adult patients supported with veno-venous extracorporeal membrane oxygenation (VV ECMO).

Retrospective analysis of the international Extracorporeal Life Support Organization (ELSO) registry. Univariate and multivariable logistic regression analyses were used to estimate the odds ratio (OR) of hospital death for each body weight quartile. Adjustment was made for demographic, physiologic and ECMO-related characteristics. We undertook a similar analysis for the subgroup of patients with confirmed H1N1 infection on VV ECMO.

The study group consisted of 1,334 adult patients supported with VV ECMO between 2005 and 2011 with a median (Q1, Q3) body weight of 80 kg (69, 101 kg). Univariate analysis identified increased body weight to be associated with a reduced risk of death. In multivariable analysis, only age greater than 53 years, primary diagnosis other than pneumonia and intubation time longer than 3 days prior to initiation of ECMO were independent risk factors for mortality, whereas the association between high body weight and adjusted risk of death (OR 0.73, 95 % CI 0.52–1.04, P = 0.08) was no longer statistically significant. The body weight of the 196 patients with confirmed H1N1 infection was significantly higher than that of the remaining study group. Body weight was not significantly associated with risk of death for these patients either (univariate OR for Q4 vs. Q1: 0.75, 95 % CI 0.33–1.72, P = 0.49).

Increased body weight was not a risk factor for hospital mortality in adult patients who required support with VV ECMO. High body weight should therefore not be regarded as a contraindication to initiation of VV ECMO in adult patients. Data collection and reporting that include patient height in addition to body weight would facilitate future research into the association of obesity with outcome of ECMO patients.