A meta-analysis of deep hypothermic circulatory arrest versus moderate hypothermic circulatory arrest with selective antegrade cerebral perfusion

Abstract

Introduction: A recent concern of deep hypothermic circulatory arrest (DHCA) in aortic arch surgery has been its potential association with increased risk of coagulopathy, elevated inflammatory response and end-organ dysfunction. Recently, moderate hypothermic circulatory arrest (MHCA) with selective antegrade circulatory arrest (SACP) seeks to negate potential hypothermia-related morbidities, while maintaining adequate neuroprotection. The present meta-analysis aims to compare postoperative outcomes in arch surgery using DHCA or MHCA+SACP as neuroprotective strategies.

Methods: Electronic searches were performed using six databases from their inception to January 2013. Two reviewers independently identified all relevant studies comparing DHCA with MHCA+SACP, as defined by a recent hypothermia temperature consensus. Data were extracted and meta-analyzed according to pre-defined clinical endpoints.

Results: Nine comparative studies were identified for inclusion in the present meta-analysis. Stroke rates were significantly lower in patients undergoing MHCA+SACP (P=0.0007, I(2)=0%), while comparable results were observed with temporary neurological deficit, mortality, renal failure or bleeding. Infrequent and inconsistent reporting of systemic outcomes precluded analysis of other systemic outcomes.

Conclusions: The present meta-analysis indicated the superiority of MHCA+SACP in terms of stroke risk.

Keywords: Deep hypothermic circulatory arrest; antegrade cerebral perfusion; meta-analysis; moderate hypothermic circulatory arrest.

Figure 1

Aortic arch surgery is a complex operation that requires specialised neuroprotective strategies to prevent cerebral injury. Hypothermic circulatory arrest, in conjunction with antegrade cerebral perfusion, offers surgeons a bloodless operating field while reducing and sustaining cerebral metabolic demand

Figure 2

Comparison of cardiopulmonary bypass time for patients undergoing DHCA (blue) or MHCA+SACP (orange) for aortic arch surgery. ^†Data from Wiedemann (2012) not evaluated statistically due to lack of reported data; ^‡Misfeld et al. reported a mean of 22±2 °C as deep hypothermia

Figure 3

Forest plot of the odds ratio (OR) of post-operative stroke in aortic arch surgery using deep hypothermic circulatory arrest alone (DHCA) or using moderate hypothermic circulatory arrest with selective antegrade cerebral protection (MHCA+SACP) as cerebral protection mechanisms. Misfeld et al. reported a mean of 22±2 °C as deep hypothermia. Exclusion of Misfeld et al. does not alter the overall significance of results (OR, 1.91, 95% CI, 1.23-2.97; P=0.004; I²=0%). The estimate of the OR of each trial corresponds to the middle of the squares, and the horizontal line shows the 95% confidence interval (CI). On each line, the number of events as a fraction of the total number randomized is shown for both treatment groups. For each subgroup, the sum of the statistics, along with the summary OR, is represented by the middle of the solid diamonds. A test of heterogeneity between the trials within a subgroup is given below the summary statistics. M-H, Mantel-Haenszel

Figure 4

Forest plot of the odds ratio (OR) of post-operative temporary neurological deficit in aortic arch surgery using deep hypothermic circulatory arrest alone (DHCA) or using moderate hypothermic circulatory arrest with antegrade cerebral protection (MHCA+ACP) as cerebral protection mechanisms. Misfeld et al. reported a mean of 22±2 °C as deep hypothermia. Exclusion of Misfeld et al. does not alter the overall significance of results (OR, 0.77, 95% CI, 0.28-2.14; P=0.62; I²=49%). The estimate of the OR of each trial corresponds to the middle of the squares, and the horizontal line shows the 95% confidence interval (CI). On each line, the number of events as a fraction of the total number randomized is shown for both treatment groups. For each subgroup, the sum of the statistics, along with the summary OR, is represented by the middle of the solid diamonds. A test of heterogeneity between the trials within a subgroup is given below the summary statistics. M-H, Mantel-Haenszel

Figure 5

Forest plot of the odds ratio (OR) of post-operative mortality in aortic arch surgery using deep hypothermic circulatory arrest alone (DHCA) or using moderate hypothermic circulatory arrest with selective antegrade cerebral protection (MHCA+SACP) as cerebral protection mechanisms. Misfeld et al. reported a mean of 22±2 °C as deep hypothermia. Exclusion of Misfeld et al. does not alter the overall significance of results (OR, 0.1.56, 95% CI, 1.10-4.79; P=0.09; I²=36%). The estimate of the OR of each trial corresponds to the middle of the squares, and the horizontal line shows the 95% confidence interval (CI). On each line, the number of events as a fraction of the total number randomized is shown for both treatment groups. For each subgroup, the sum of the statistics, along with the summary OR, is represented by the middle of the solid diamonds. A test of heterogeneity between the trials within a subgroup is given below the summary statistics. M-H, Mantel-Haenszel

Figure 6

Funnel plot for the meta-analysis of permanent neurological deficit comparing DHCA vs. MHCA+SACP as neuroprotective strategies in all 9 included studies. Log of odds ratio comparing PND (vertical axis) is presented against the standard error (SE) of the log of OR (horizontal axis). The SE inversely corresponds to study size. Asymmetry of the plot can indicate publication bias