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Published on: October 27, 2020
Role of Hypothermia in Adult Cardiac Surgery Patients: A Systematic Review and Meta-analysis
Riccardo Giuseppe Abbasciano1, Marinos Koulouroudias1, Thomas Chad1
1Department of Cardiovascular Sciences, Clinical Sciences Wing, Glenfield Hospital, University of Leicester, Leicester, United Kingdom.
Insights
Systemic hypothermia during cardiac surgery offers uncertain organ protection. Low-quality evidence suggests potential increased mortality and no significant benefit for brain injury, especially in high-quality trials.
Area of Science:
- Cardiovascular Surgery
- Critical Care Medicine
- Translational Medicine
Background:
- Systemic hypothermia is a debated organ protection strategy in cardiac surgery.
- Evidence regarding its efficacy and safety remains inconclusive.
Purpose of the Study:
- To systematically review and meta-analyze randomized controlled trials (RCTs) assessing systemic hypothermia for organ protection in adults undergoing cardiac surgery with cardiopulmonary bypass.
Main Methods:
- A comprehensive search of major databases (Cochrane, MEDLINE, Embase) identified 48 RCTs with 6,690 patients.
- Risk of bias assessment was conducted using Cochrane methodology.
- Random-effects meta-analysis was employed to evaluate outcomes like mortality and brain injury.
Main Results:
- The overall quality of included studies was low, primarily due to methodological limitations.
- Meta-analysis showed uncertainty regarding hypothermia's benefits versus normothermia for mortality and brain injury.
- Sensitivity analyses of high-quality trials indicated increased mortality with hypothermia, with no significant effect on brain injury.
Conclusions:
- Current evidence supporting an organ-protective effect of systemic hypothermia in adult cardiac surgery is of low quality and inconsistent.
- Further high-quality research is needed to clarify the risks and benefits.
Objective:
To review studies that assessed systemic hypothermia as an organ protection strategy in adults undergoing cardiac surgery with cardiopulmonary bypass.
Design:
A systematic review and meta-analysis.
Setting And Participants:
Randomized controlled trials, irrespective of blinding, language, publication status, and date of publication, were identified by searching the Cochrane Central register of Controlled Trials, MEDLINE, and Embase until November 2020. Risk of bias assessment was performed according to Cochrane methodology. Treatment effects were expressed as risk ratios and 95% confidence intervals. Heterogeneity was expressed as I2.
Interventions:
Systemic hypothermia.
Measurements And Main Results:
Forty-eight trials enrolling 6,690 patients were included in the analysis. Methodologic quality of the studies included was low, mostly due to insufficient allocation concealment or blinding. Random-effects meta-analysis did not resolve uncertainty as to the risks and benefits for hypothermia versus normothermia for key primary and secondary outcomes, including mortality (1.21, 0.94 to 1.56, I2 = 0%) and brain injury (0.87, 0.67 to 1.14, I2 = 0%). Sensitivity analyses restricted to trials at low risk of important bias demonstrated higher mortality with hypothermia (1.70, 1.05 to 2.75, I2 = 0%), with little or no treatment effect on brain injury (1.01, 0.69 to 1.49, I2 = 0%). There was no interaction between cardioplegia temperature and the effects of cardiopulmonary bypass temperature on outcomes. There was insufficient evidence to assess the effects of hypothermia in noncoronary artery bypass graft surgery.
Conclusion:
The existing evidence for an organ-protective effect of hypothermia in adult cardiac surgery is of low quality and inconsistent.
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