# Retrograde inferior vena cava perfusion reduces the risk of acute kidney injury depending on the oxygen extraction ratio. A retrospective cohort study

## TL;DR

Retrograde inferior vena cava perfusion during aortic surgery may lower the risk of acute kidney injury by improving oxygen extraction in the lower body.

## Contribution

The study demonstrates that RIVP reduces AKI risk depending on oxygen extraction ratio, not just oxygen delivery.

## Key findings

- ACP + RIVP was associated with a 73% lower risk of AKI compared to ACP alone.
- Oxygen extraction ratio during RIVP correlated strongly with reduced postoperative creatinine levels.
- Oxygen delivery alone did not correlate with improved kidney outcomes.

## Abstract

Total aortic arch replacement surgery (TARS) for Acute type A aortic dissection is associated with high incidence of postoperative acute kidney injury (AKI), at least partly due to the lower body ischemia during circulatory arrest. This study aimed to evaluate whether retrograde inferior vena cava perfusion (RIVP) reduces the risk of AKI by providing oxygenated blood to the lower body.

This retrospective study utilized a medical recording system to screen patients who underwent TARS from January 1 to December 31, 2019. Patients were assigned to receive antegrade cerebral perfusion (ACP) only or ACP + RIVP during circulatory arrest. The primary outcome was postoperative AKI. Oxygen delivery, consumption, and extraction ratio during RIVP were also determined.

Of all included 87 patients, postoperative AKI occurred in 35 (40%), of whom 23 (53.5%) were in the ACP, and 12 (27.3%) were in the ACP + RIVP (P = 0.013). In regression analysis, ACP + RIVP was associated with lower risk of AKI than ACP alone (adjusted OR 0.229; 95% CI 0.071–0.746). RIVP at a pressure of 22.5 ± 3.8 mmHg delivered 0.98 ± 0.34 ml/min/kg of oxygen to the lower body, and the partial oxygen pressure decreased from 359 ± 57 mmHg in RIVP blood to 64 ± 30 mmHg in returning blood. Oxygen extraction ratio was 44 ± 16%, which correlated negatively with peak postoperative creatinine levels (r = −0.58, P = 0.01) and creatinine increase (r = −0.61, P = 0.009). No correlations were found between oxygen delivery and postoperative creatinine or creatinine increase.

RIVP may reduce the risk of postoperative AKI in a manner that depends on the tissue oxygen extraction ratio.