The optimal hematocrit value during cardiopulmonary bypass: a meta-analysis

Zhou Qin; Sun Yan-hua; Ji Bing-yang

doi:10.13498/j.cnki.chin.j.ecc.2017.04.07

Abstract：Objective Initiation of cardiopulmonary bypass( CPB) inevitably leads to hemodilution, there is thus wide varia-tion in practice with regard to the minimum safe acceptable hematocrit ( Hct) during cardiac surgery. To search the ideal Hct during CPB, we screened all relevant published randomized controlled trials to perform a meta-analysis for Hct during cardiopulmonary by-pass. Methods We searched PubMed, EMBASE, the Cochrane Controlled Clinical Trial register, WANFANG and CNKI databases for published articles. Randomized controlled trials were included when the research provided data of different clinical endpoints accord-ing to various Hct values during CPB. We choose a fixed-effects model when the trials showed low heterogeneity, otherwise a random-effects model was used. The quality of studies were assessed by modified Jadad scale. Results Four studies were included in this meta-analysis. The overall pooled relative risk(RR) for cardiac complications was 0.408, 95% confidence interval (CI)=[0.257-0.646], and the z-score for overall effect was 3.82( P =0.00) . The standardized mean difference( SMD) of the MAP and urine volume were-0.288 and 0.474, respectively. with the 95%CI=[-0.564 -0.012] and [0.171-0.778]. The z-score for overall effects were 2.04( P=0.041) and 3.06( P =0.002).Conclusion Compared with relatively high Hct value in CPB, lower Hct could reduce cardiac com-plications after surgery, although there were no significant differences in the outcomes of blood transfusion, renal failure, neurological dysfunction, as well as chest tube drainage and length of ICU stay . Further studies involving optimal Hct value are expected to be in-vestigated if we want to find out a critical point at which the patients do not need blood transfusion and their organ functions suffer least.