# A retrospective pilot crossover study of protocolized transition from inhaled nitric oxide to inhaled epoprostenol in adult cardiothoracic surgery

## TL;DR

This study shows that switching from inhaled nitric oxide to inhaled epoprostenol after cardiothoracic surgery is safe and feasible, with minimal impact on oxygenation and stable hemodynamics.

## Contribution

The study introduces a protocolized transition between two inhaled pulmonary vasodilators in real-world postoperative cardiothoracic care.

## Key findings

- All patients completed the transition without adverse events or interruptions.
- Hemodynamic stability was maintained with no significant changes in pulmonary artery pressures or cardiac output.
- Small but statistically significant decreases were observed in SvO₂ and SpO₂ after the transition.

## Abstract

Inhaled pulmonary vasodilators (iPVDs), including inhaled nitric oxide (iNO) and inhaled epoprostenol (iEPO), are commonly used in the perioperative management of right ventricular dysfunction, pulmonary hypertension, and hypoxemia in cardiothoracic surgery. While randomized trials have shown clinical equivalence between iNO and iEPO, few studies have evaluated protocolized transitions between these agents in heterogeneous postoperative surgical populations. This retrospective pilot study aimed to assess the feasibility, physiologic stability, and oxygenation effects of a unidirectional transition from iNO to iEPO in a real-world cardiothoracic intensive care setting.

We conducted a retrospective analysis of 77 adult patients who underwent cardiothoracic surgery and were transitioned from iNO to iEPO using a standardized crossover protocol in a single tertiary-care cardiothoracic intensive care unit. Hemodynamic and oxygenation parameters were collected before and after transition. The primary outcomes were changes in mean arterial pressure, pulmonary artery pressures, central venous pressure, cardiac output, mixed venous oxygen saturation (SvO₂), and peripheral oxygen saturation (SpO₂). Paired t-tests were used to compare pre- and post-crossover values.

All patients completed the transition without interruption or adverse clinical events. Hemodynamic parameters remained stable across the transition. Statistically significant reductions were observed in SvO₂ (71.3% to 69.6%, p = 0.0059) and SpO₂ (98.2% to 97.7%, p = 0.0007), though the absolute differences were small. No significant changes were observed in pulmonary artery pressures, MAP, CVP, or cardiac output.

In this pragmatic, retrospective pilot study, protocolized transition from iNO to iEPO was safe, feasible, and well tolerated in a diverse cardiothoracic surgical population. The findings support iEPO as a cost-conscious alternative to iNO in the postoperative setting, with preserved hemodynamic stability and minimal changes in oxygenation. These results contribute to the growing evidence base for implementing standardized iPVD protocols in real-world practice.