Patients with severe acute respiratory distress syndrome (ARDS) who have higher ventilator ratios (VRs), tidal volumes, heart rates (HRs), and esophageal pressure swings (PES) during a sweep gas off trial (SGOT) are less likely to attain safe liberation from venovenous extracorporeal membrane oxygenation (VV-ECMO). Two observational studies were conducted in the medical-surgical intensive care unit (ICU) at Toronto General Hospital in Toronto, Ontario, Canada, among adults who were weaned from VV-ECMO for severe ARDS. Results of the analysis were published in the journal Chest.

The investigators sought to evaluate whether safe liberation from VV-ECMO can be predicted at a patient’s bedside. Of the 2 observational studies, the first was a retrospective study that was conducted between January 2012 and September 2016, and the second was a prospective physiologic study conducted between July 2018 and June 2019. The second analysis included esophageal PES measurements, which had become routine practice at that time.

The 2 studies enrolled consecutive patients 18 years and older who were diagnosed with ARDS, supported, and then liberated from VV-ECMO. The primary study outcome was unsafe liberation from VV-ECMO, which was defined as the development of at least 1 of these criteria within 48 hours of decannulation: (1) VV-ECMO recannulation; (2) escalation of mechanical ventilation (MV) settings; (3) use of rescue therapies; or (4) new, worsening hemodynamics requiring the addition of any vasoactive agents with no evidence of hypovolemia or sepsis.


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Over the course of both studies, a total of 83 patients were weaned from VV-ECMO, with 25% (21 of 83) of them not fulfilling criteria for safe liberation. In the retrospective study, higher tidal volume per predicted body weight (odds ratio [OR], 1.58; 95% CI, 1.05-2.40; P =.03) and higher HR (OR, 1.07; 95% CI, 1.01-1.13; P =.02) at the end of SGOT were significantly associated with an increased likelihood of unsafe liberation when adjusted for age (OR, 1.02; 95% CI, 0.95-1.09; P =.63) and sequential organ failure assessment (SOFA) score (OR, 1.16; 95% CI, 0.86-1.56; P =.34).

Change in VR exhibited an imprecise association (OR, 2.71; 95% CI, 0.93-7.92; P =.06) with unsafe liberation from VV-ECMO when adjusted for age (OR, 1.03; 95% CI, 0.96-1.10; P =.42), SOFA score (OR, 1.11; 95% CI, 0.81-1.51; P =.52), and HR (OR, 1.07; 95% CI, 1.01-1.13; P =.02).

In the prospective analysis, individuals with unsafe liberation from VV-ECMO exhibited significantly higher inspiratory effects (esophageal PES of 9 [range, 7-13] vs 18 [range, 7-25] cmH2O, respectively; P =.03) and worse outcomes (ie, longer duration of MV, ICU stay, and hospitalization).

The investigators concluded that additional studies are warranted to confirm the clinical impact of the current findings and to optimize the management of weaning from artificial respiratory support during the use of VV-ECMO.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures. 

Reference

Al-Fares AA, Ferguson ND, Ma J, et al. Achieving safe liberation during weaning from VV-ECMO in patients with severe ARDS: the role of tidal volume and inspiratory effort. Chest. Published online June 16, 2021. doi:10.1016/j.chest.2021.05.068