Conventional versus miniaturized cardiopulmonary bypass: A systematic review and meta-analysis

Abstract

Objective: A meta-analysis of randomized controlled trials was performed to compare the effects of miniaturized extracorporeal circulation (MECC) and conventional extracorporeal circulation (CECC) on morbidity and mortality rates after cardiac surgery.

Methods: A comprehensive literature search was conducted using Ovid, PubMed, Medline, EMBASE, and the Cochrane databases. Randomized controlled trials from the year 2000 with n > 40 patients were considered. Key search terms included variations of "mini," "cardiopulmonary," "bypass," "extracorporeal," "perfusion," and "circuit." Studies were assessed for bias using the Cochrane Risk of Bias tool. The primary outcomes were postoperative mortality and stroke. Secondary outcomes included arrhythmia, myocardial infarction, renal failure, blood loss, and a composite outcome comprised of mortality, stroke, myocardial infarction and renal failure. Duration of intensive care unit, and hospital stay was also recorded.

Results: The 42 studies eligible for this study included a total of 2154 patients who underwent CECC and 2196 patients who underwent MECC. There were no significant differences in any preoperative or demographic characteristics. Compared with CECC, MECC did not reduce the incidence of mortality, stroke, myocardial infarction, and renal failure but did significantly decrease the composite of these outcomes (odds ratio, 0.64; 95% confidence interval [CI], 0.50-0.81; P = .0002). MECC was also associated with reductions in arrhythmia (odds ratio, 0.67; 95% CI, 0.54-0.83; P = .0003), blood loss (mean difference [MD], -96.37 mL; 95% CI, -152.70 to -40.05 mL; P = .0008), hospital stay (MD, -0.70 days; 95% CI, -1.21 to -0.20 days; P = .006), and intensive care unit stay (MD, -2.27 hours; 95% CI, -3.03 to -1.50 hours; P < .001).

Conclusions: MECC demonstrates clinical benefits compared with CECC. Further studies are required to perform a cost-utility analysis and to assess the long-term outcomes of MECC. These should use standardized definitions of endpoints such as mortality and renal failure to reduce inconsistency in outcome reporting.

Keywords: AKI, acute kidney injury; CABG, coronary artery bypass graft; CECC, conventional extracorporeal circulation; CI, confidence interval; CPB, cardiopulmonary bypass; FFP, fresh-frozen plasma; ICU, intensive care unit; IL-6, interleukin-6; IL-8, interleukin-8; MECC, miniaturized extracorporeal circulation; MI, myocardial infarction; OR, odds ratio; POAF, postoperative atrial fibrillation; RBC, red blood cells; RCT, randomized control trial; cardiac surgery; cardiopulmonary bypass; coronary-artery bypass grafting; meta-analysis; minimal extracorporeal circulation.

Graphical abstract

PRISMA chart showing literature search method and the results.

Figure 1

Forest plot for mortality rate in comparing CECC and MECC. MECC, Miniaturized extracorporeal circulation; CECC, conventional extracorporeal circulation; M-H, Mantel-Haenszel; CI, confidence interval; CABG, coronary artery bypass graft; df, degrees of freedom.

Figure 2

Forest plot for stroke outcomes comparing CECC and MECC. MECC, Miniaturized extracorporeal circulation; CECC, conventional extracorporeal circulation; M-H, Mantel-Haenszel; CI, confidence interval; CABG, coronary artery bypass graft; df, degrees of freedom.

Figure 3

Outcomes of patients who underwent conventional extracorporeal circulation (CECC, n = 2154) versus those who underwent miniaturized extracorporeal circulation (MECC, n = 2196). No difference in mortality, stroke, myocardial infarction, and renal failure has been reported. ICU, Intensive care unit; CABG, coronary artery bypass graft;

Figure E1

Funnel plot assessing mortality for publication bias comparing CECC and MECC. SE, Standard error; OR, odds ratio; CABG, coronary artery bypass graft.

Figure E2

Funnel plot assessing stroke outcome for publication bias comparing CECC and MECC. SE, Standard error; OR, odds ratio; CABG, coronary artery bypass graft.

Figure E3

Funnel plot assessing arrythmia for publication bias comparing CECC and MECC. SE, Standard error; OR, odds ratio; CABG, coronary artery bypass graft.

Figure E4

Funnel plot assessing composite outcome for publication bias comparing CECC and MECC. SE, Standard error; OR, odds ratio; CABG, coronary artery bypass graft.

Figure E5

Funnel plot assessing mean blood loss outcome for publication bias comparing CECC and MECC. SE, Standard error; MD, weighted mean difference; CABG, coronary artery bypass graft.

Figure E6

Funnel plot assessing myocardial infarction outcome for publication bias comparing CECC and MECC. SE, Standard error; OR, odds ratio; CABG, coronary artery bypass graft.

Figure E7

Funnel plot assessing renal failure outcome for publication bias comparing CECC and MECC. SE, Standard error; OR, odds ratio; CABG, coronary artery bypass graft.

Figure E8

Forest plot for postoperative arrhythmia in CECC and MECC. MECC, Miniaturized extracorporeal circulation; CECC, conventional extracorporeal circulation; M-H, Mantel-Haenszel; CI, confidence interval; CABG, coronary artery bypass graft; df, degrees of freedom.

Figure E9

Forest plot for composite outcomes in CECC and MECC. MECC, Miniaturized extracorporeal circulation; CECC, conventional extracorporeal circulation; M-H, Mantel-Haenszel; CI, confidence interval; CABG, coronary artery bypass graft; df, degrees of freedom.

Figure E10

Forest plot for mean blood loss comparing CECC and MECC. MECC, Miniaturized extracorporeal circulation; CECC, conventional extracorporeal circulation; SD, standard deviation; IV, instrumental variables; CI, confidence interval; CABG, coronary artery bypass graft; df, degrees of freedom.

Figure E11

Forest plot for myocardial infarction comparing CECC and MECC. MECC, Miniaturized extracorporeal circulation; CECC, conventional extracorporeal circulation; M-H, Mantel-Haenszel; CI, confidence interval; CABG, coronary artery bypass graft; df, degrees of freedom.

Figure E12

Forest plots for rate of renal failure comparing CECC and MECC. MECC, Miniaturized extracorporeal circulation; CECC, conventional extracorporeal circulation; M-H, Mantel-Haenszel; CI, confidence interval; CABG, coronary artery bypass graft; df, degrees of freedom.