Comparison of deep and nondeep hypothermia in thoracic and thoracoabdominal aortic surgery: A systematic review and...

Deep hypothermic circulatory arrest (DHCA) remains a cornerstone technique for neuroprotection and end-organ preservation during ascending aorta and arch surgeries. However, its benefits and risks compared with non-DHCA strategies in thoracic and thoracoabdominal aortic aneurysm (TAAA) repair are uncertain owing to conflicting evidence and variable institutional practices.

A systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis and Cochrane guidelines. PubMed, Embase, and Cochrane Library were searched for comparative studies evaluating DHCA and non-DHCA techniques for open thoracic and TAAA repair. Random-effects models were applied to calculate pooled effect estimates. Effect sizes were risk ratio (RR) for binary end points and mean difference for continuous end points, both with 95% confidence intervals. Statistical significance was set at P < .05. Between-study heterogeneity was estimated using the I² statistic. Metaregression analyses were used to explore the sources of heterogeneity.

Nine observational studies, including 1041 patients, were analyzed. DHCA use was associated with a significantly lower risk of spinal cord injury (RR, 0.44; P = .012) compared with non-DHCA. However, DHCA was also associated with prolonged postoperative ventilation time (RR, 1.34; P = .003). No significant differences were observed in overall mortality, length of hospital and intensive care unit stay, stroke, or renal complications. Metaregression identified patient age as a moderator of length of stay variability, with older cohorts demonstrating longer recovery periods.

DHCA is associated with a lower risk of spinal cord injury during TAAA repair without increasing mortality or stroke risk, although it is associated with longer ventilation times.