# Impact of initial hematocrit levels during direct procurement and perfusion on the likelihood of primary graft dysfunction in donation after circulatory death heart transplantation

## TL;DR

This study examines how hematocrit levels during heart perfusion affect transplant outcomes, finding no significant benefit from higher levels.

## Contribution

The study provides new insights into the clinical impact of hematocrit levels during heart perfusion in transplantation.

## Key findings

- Higher hematocrit levels did not reduce primary graft dysfunction.
- Higher hematocrit was linked to increased postoperative support requirements.
- No significant difference in graft dysfunction was observed between hematocrit groups.

## Abstract

Optimizing perfusion parameters when using ex vivo heart perfusion systems is critical for maximizing organ quality and extending perfusion duration. Hematocrit (HCT) of the perfusate may influence oxygen delivery and perfusion dynamics, yet its clinical significance remains uncertain.

In this retrospective single-center study, we utilize regression models to explore the relationship between hematocrit (HCT) of the device perfusate during normothermic machine perfusion (using the Transmedics Organ System [OCS]) and recipient outcomes following transplantation. Cohorts with HCT <15% packed cell volume [PCV] were compared with those with HCT ≥15% PCV.

Among 74 recipients, moderate and severe primary graft dysfunction (defined as needing extracorporeal machine oxygenation post-transplant) did not differ significantly between cohorts. Mean inotrope scores 48 hours post admission were significantly higher in recipients with higher perfusate HCT. The ICU length of stay in the higher HCT group was numerically high but did not achieve statistical significance.

Higher perfusate HCT was not associated with reduced PGD and may be linked to increased postoperative support requirements. These findings raise important questions about optimal HCT levels for ex vivo perfusion and warrant further prospective investigation.