# Kidney protection during surgery on the thoracoabdominal aorta: a systematic review

## TL;DR

This systematic review evaluates perfusion techniques used during thoracoabdominal aorta surgery to protect the kidneys and reduce mortality.

## Contribution

The study provides a benchmark for kidney protection using left heart bypass with crystalloid perfusion and highlights gaps in evidence for other techniques.

## Key findings

- Left heart bypass with cold crystalloid perfusion shows low dialysis and mortality rates.
- Deep hypothermic circulatory arrest and partial cardiopulmonary bypass lack high-quality evidence.
- Acute kidney injury remains a significant issue, calling for improved perfusion strategies and data reporting.

## Abstract

Acute kidney injury (AKI) is a common consequence of surgical repair of the thoraco-abdominal aorta (TAA). Perfusion techniques aim to facilitate renal protection through oxygenation or hypothermia. This systematic review assesses renal and mortality outcomes by perfusion techniques to evaluate their ability to provide effective kidney protection.

PubMed, Web of Science, ClinicalTrials.gov and ClinicalTrialsRegister.EU were searched to identify relevant studies published from 1995 to 2024. Following quality assessment and data extraction, outcomes of the highest quality studies were used to synthesize a narrative discussion.

Thirty-eight studies were analysed, featuring three extracorporeal strategies: left heart bypass (LHB; n = 22), cardiopulmonary bypass with deep hypothermic circulatory arrest (DHCA; n = 11) and partial cardiopulmonary bypass (pCPB; n = 10). Three categories of selective renal perfusion (SRP) strategy were identified: warm blood, cold blood and cold crystalloid. Five studies of ‘very high’ and ‘high’ quality demonstrate a 0–13.6% incidence of post-operative dialysis and 5.0–13.3% risk of operative mortality following LHB with cold crystalloid SRP. No studies in support of DHCA or pCPB provided a high quality of evidence.

Left heart bypass with crystalloid SRP provides a benchmark for rates of dialysis and mortality following TAA repair. However, AKI remains significant, emphasizing the need for continued innovation in SRP, and a greater understanding of overlooked risk factors. DHCA and pCPB are supported by low-quality evidence, meaning that prospective research is necessary to enable fair comparison. Finally, consensus on data reporting is recommended to improve the quality of future studies in this area.

Surgical repair of the thoraco-abdominal aorta (TAA) is associated with a high incidence of post-operative acute kidney injury (AKI) and accompanying risks of renal replacement therapy (RRT) and early mortality [1–10].