Unveiling Impact of VV ECMO on COVID-19 Patients: Study evaluates Respiratory Rescue

The Extracorporeal Life Support Organization has documented the application of venovenous extracorporeal membrane oxygenation (VV ECMO) in over 17,000 patients suffering from refractory respiratory failure due to confirmed COVID-19. Recent retrospective cohort study investigated echocardiographic findings in mechanically ventilated COVID-19 patients with acute respiratory distress syndrome (ARDS), specifically comparing outcomes between those receiving venovenous extracorporeal membrane oxygenation (VV ECMO) and those who were not. Conducted in a single-center ICU from March 2020 to June 2021, the study analyzed data from 242 patients who underwent echocardiography within 72 hours of ICU admission. Among the participants, 145 (60%) received VV ECMO. Key findings highlighted significant differences in physiological parameters between the two groups. The median arterial oxygen partial pressure to fractional inspired oxygen ratio (PaO2/FiO2) was notably lower in the ECMO group (76 mmHg) compared to the non-ECMO group (98 mmHg), indicating greater severity of respiratory distress in patients requiring ECMO support. Initial echocardiographic assessments revealed no significant differences in left ventricular systolic dysfunction (LVSF) between the groups (10% vs. 15%, p = 0.31) but indicated a higher prevalence of acute cor pulmonale (ACP) in the ECMO cohort (41% vs. 26%, p = 0.02).

Follow-Up Assessment

During the ICU stay, follow-up echocardiograms demonstrated an increased incidence of right ventricular (RV) systolic dysfunction in ECMO patients (55% vs. 34%, p = 0.001) and a rise in the frequency of ACP (51% vs. 26%, p = 0.002). The study quantified mortality odds ratios, finding RV systolic dysfunction (OR 1.99) and ACP (OR 2.95) on follow-up echocardiograms were significantly associated with higher ICU mortality rates.

Conclusions and Future Research

The overall conclusion emphasized a high prevalence of echocardiographic abnormalities, particularly right ventricular dysfunction and ACP, found more frequently among VV ECMO patients. Furthermore, the persistence of RV dysfunction was notably linked to worse clinical outcomes, highlighting the critical role of regular echocardiographic evaluation to guide management in this patient population. The study underscores the need for further research to understand the trajectory of cardiac dysfunction in severely ill patients affected by COVID-19, particularly those on VV ECMO, and its implications for patient outcomes.

Key Points

1\. \*\*Study Design and Population\*\*: The research involved a retrospective cohort study conducted in a single-center ICU between March 2020 and June 2021, focusing on mechanically ventilated COVID-19 patients with acute respiratory distress syndrome (ARDS). It analyzed data from 242 patients, with 145 (60%) receiving venovenous extracorporeal membrane oxygenation (VV ECMO) within 72 hours of ICU admission.

2. \*\*Physiological Findings\*\*: The study revealed significant differences in physiological parameters between the VV ECMO and non-ECMO groups. The median arterial oxygen partial pressure to fractional inspired oxygen ratio (PaO2/FiO2) was significantly lower in the ECMO cohort (76 mmHg) compared to the non-ECMO group (98 mmHg), indicating worse respiratory distress among patients receiving ECMO.

3. \*\*Initial Echocardiographic Assessment\*\*: Initial echocardiographic evaluations did not show significant differences in left ventricular systolic dysfunction (LVSF) (10% in ECMO vs. 15% in non-ECMO). However, acute cor pulmonale (ACP) was more prevalent in the ECMO group (41%) compared to the non-ECMO group (26%), with a statistically significant difference (p = 0.02).

4. \*\*Follow-Up Findings\*\*: Follow-up echocardiograms indicated a marked increase in right ventricular (RV) systolic dysfunction in the ECMO group (55% compared to 34% in non-ECMO, p = 0.001) and a higher incidence of ACP (51% for ECMO vs. 26% for non-ECMO, p = 0.002) during the ICU stay.

5. \*\*Mortality Associations\*\*: The study quantified mortality odds ratios, showing that RV systolic dysfunction (odds ratio 1.99) and ACP (odds ratio 2.95) were significantly associated with increased ICU mortality rates based on findings from follow-up echocardiograms.

6. \*\*Conclusions and Research Implications\*\*: The conclusions highlighted a high prevalence of cardiac abnormalities, particularly right ventricular dysfunction and ACP, in patients on VV ECMO. The persistency of RV dysfunction linked to worse clinical outcomes emphasizes the importance of regular echocardiographic monitoring. The study calls for additional research to explore the long-term effects of cardiac dysfunction in severely ill COVID-19 patients and the implications for patient outcomes when managed with VV ECMO.

Reference –

D. Morales Castro et al. (2024). Echocardiographic Findings In Critically Ill COVID-19 Patients Treated With And Without Extracorporeal Membrane Oxygenation.. *Journal Of Cardiothoracic And Vascular Anesthesia*. https://doi.org/10.1053/j.jvca.2024.08.007.