# Evaluating Predictive Value of Plasma Free Hemoglobin (PFH) in ECMO for COVID-19, Non-COVID-19 Pulmonary, and Cardiac Patients

## TL;DR

This study examines how plasma-free hemoglobin levels during ECMO treatment relate to survival in patients with conditions like COVID-19 and heart failure.

## Contribution

The study identifies late spikes in plasma-free hemoglobin as a potential predictor of mortality in ECMO-treated COVID-19 patients.

## Key findings

- Expired COVID-19 patients had higher plasma-free hemoglobin levels in the final days of ECMO.
- Cardiac patients had the highest overall plasma-free hemoglobin levels regardless of survival.
- Late plasma-free hemoglobin spikes correlated with mortality in ECMO-treated patients.

## Abstract

Background and Objectives: Extracorporeal membrane oxygenation (ECMO) can support patients with severe cardiopulmonary failure, but it poses risks such as hemolysis, leading to complications. Plasma-free hemoglobin (PFH) is a hemolysis biomarker, with elevated levels linked to mortality. This study evaluates PFH and ECMO survival in COVID-19, non-COVID-19 pulmonary, and cardiac patients, focusing on late PFH spikes. Materials and Methods: We retrospectively analyzed 122 ECMO patients treated at our tertiary hospital (January 2020–December 2021). Patients were categorized by indication: post-COVID-19, non-COVID-19 pulmonary, or cardiac. We classified patients as Expired (died during ECMO or ≤30 days post-ECMO) or Survived (>30 days post-ECMO). Data included demographics, ECMO duration, and PFH values at 24 h and during the last 3 and 5 ECMO days. Groups were compared using two-tailed t-tests, with p < 0.05 indicating significance. Results: COVID-19 patients survived after significantly longer ECMO duration than non-COVID-19 pulmonary and cardiac patients. Expired COVID-19 patients had higher PFH values during the last 3 and 5 days of ECMO compared to survivors. Cardiac patients had the highest overall PFH levels regardless of mortality. No significant differences in PFH trends were observed between non-COVID-19 pulmonary and cardiac patients. Conclusions: Late PFH spikes correlated with mortality in COVID-19 patients, suggesting the utility of measuring late PFH spikes in ECMO management. Additionally, COVID-19 pulmonary patients survived when undergoing ECMO significantly longer than both groups, while VA ECMO was more prone to hemolysis. However, technical cannulation differences and frequent use of an Impella pump in cardiac patients may increase blood stress and PFH values.