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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.