2.1 Literature search and study selection
Figure 1 showed the flow chart of the literature search, and we identified total 665 articles, from which 452 were excluded after reading the titles, abstracts and full texts. Finally, 9 RCTs were included in this meta-analysis.(Figure1)
2.2 The characteristics of the 9 RCTs
The 9 RCTs included 452 patients treated with CPB. The characteristics of intervention measures, outcome indicators, and number of participants of 9 RCTs were shown in Table1.
Table 1. Characteristics of the included RCTs.
According to Cochrane's systematic evaluation manual, the methodological quality of the 9 clinical studies included in the study was evaluated for items such as random method, allocation concealment, blind method, withdrawal from missed visits and selective reporting (Figure 2).
2.3 Results of meta-analysis
2.3.1 The length of ICU stay. Four RCTs reported the length of ICU stay. There was no statistical heterogeneity among the studies (P = 0.10;I2 = 89%),and the random effect model was selected for the analysis. The results showed no significant difference in the length of ICU stay between the HES group and the albumin group(MD = 0.70; 95%CI:-0.14 to 1.55;P =0.10) (Figure 3A). Therefore, the use of albumin and HES as priming fluid for CPB in cardiac surgery had a similar effect on the length of stay in ICU. (Figure 3A).
2.3.2 Ventilation time. Two RCTs reported the ventilation time. There was no statistical heterogeneity among the studies (P = 0.12; I2 = 60%),and the random effect model was selected for analysis. The results showed no significant difference between the HES group and the albumin group (MD = 2.31 ;95%CI-3.93 to 8.55; P = 0.47) (Figure 3B). Therefore, the use of albumin and HES as priming fluid for CPB in cardiac surgery had a similar effect on ventilation time. (Figure 3B)
2.3.3 The length of hospital stay. Two RCTs reported the length of hospital stay. Two was statistical heterogeneity among the studies (P = 0.48; I2 = 0%), and the random effect model was selected for analysis. The results showed no significant difference between the HES group and the albumin group (MD = -0.31;95% CI: -2.00 to 1.37; P = 0.71) (Figure 3C).
2.3.4 Crystal volume. Three RCTs reported crystal volume. There was no statistical heterogeneity among the studies (P = 0.60; I2 = 0%), and the random effect model was selected for analysis. The results showed no significant difference between the HES group and the albumin group (MD = 0.26;95% CI: -0.09 to 0.61; P = 0.15) (Figure 3D).
2.3.5 Fresh frozen plasma. Three RCTs reported fresh frozen plasma. There was statistical heterogeneity among the studies (P = 0.66;I2 =0%),and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (SMD = 0.25;95%CI:-0.08 to 0.59; P = 0.14) (Figure 3E).
2.3.6 Platelet input. Two RCTs reports platelet input. There was no statistical heterogeneity among the studies (P = 0.75;I2 = 0%),and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =-0.17;95% Cl:-0.59 to 0.26;p = 0.45) (Figure 3F).
2.3.7 Blood loss. Five RCTs reports blood loss. There was no statistical heterogeneity among the studies (P = 0.23;I2 =29%),and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =0.31;95% Cl:-0.01 to 0.63;p = 0.06) (Figure 4A).
2.3.8 Platelet count. Five RCTs reported platelet count. There was no statistical heterogeneity among the studies (P = 0.18; I2 = 37%), and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =-0.21;95% cl: -0.54 to 0.11; p = 0.20) (Figure 4B).
2.3.9 Hemoglobin value. Five RCTs reported hemoglobin value. There was no statistical heterogeneity among the studies (P = 0.96; I2 = 0%), and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =0.1;95% CI: -0.15 to 0.36; P = 0.42) (Figure 4C).
2.3.10 Fibrin. Three RCTs reported fibrin. There was no statistical heterogeneity among the studies (P = 0.91; I2 = 0%), and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =0.12;95% CI: -0.19 to 0.44; P = 0.45) (Figure 4D).
2.3.11 APTT. Four RCTs reported APTT. There was no statistical heterogeneity among the studies (P = 0.83; I2 = 0%), and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =1.13;95% CI: -2.06 to 4.32; P = 0.49) (Figure 4E).
2.3.12 PT. Three RCTs reported PT. There was no statistical heterogeneity among the studies (P = 0.10; I2 = 0%), and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =0.10;95% CI: -0.21 to 0.40; P = 0.52) (Figure 4F).
2.3.13 Urea. Two RCTs reported hemoglobin urea. There was no statistical heterogeneity among the studies (P = 0.58; I2 = 0%), and the random effect model was selected for analysis. The results showed statistical difference between the HES group and the albumin group (MD =-0.46;95% CI: -0.81 to -0.11; P = 0.01) (Figure 5A).
2.3.14 Creatinine. Three RCTs reported creatinine. There was no statistical heterogeneity among the studies (P = 0.09; I2 = 51%), and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =0.09;95% CI: -0.32 to 0.50; P = 0.66) (Figure 5B).
2.3.15 Urine volume. Five RCTs reported urine volume. There was no statistical heterogeneity among the studies (P = 0.14; I2 = 43%), and the random effect model was selected for analysis. The results showed no statistical difference between the HES group and the albumin group (MD =0.11;95% CI: -0.26 to 0.48; P = 0.55) (Figure 5C).