BLOOD TRANSFUSION REQUIREMENTS IN CARDIAC SURGERY

BLOOD TRANSFUSION REQUIREMENTS IN CARDIAC SURGERY

By

Amr Ibrahim Abd El-Aal Hassan*, El-Husseiny El-Husseiny Gamil¹, Hossam Fouad Fawzy² and Yousry Zaki Al-Zohairy³

¹Department of Cardiothoracic Surgery, Faculty of Medicine, Al-Azhar University

²Department of Cardiothoracic Surgery, Faculty of Medicine, Tanta University

³Department of Clinical Pathology, Faculty of Medicine, Al-Azhar University

*Corresponding Author: Amr Ibrahim Abd El-Aal Hassan

E-mail: amribrahim288@yahoo.com

ABSTRACT

Background: The effect of restrictive blood transfusion in comparison to liberal red cell transfusion strategy on clinical outcome in cardiac surgery remains undetermined.

Objectives: The aim of this work is to evaluate the restrictive blood transfusion strategy versus the liberal strategy in open heart surgery in terms of vital organ functions (heart, brain, lung, and kidney) and mortality.

Patients and Methods: After approval of Institutional ethical committee and obtaining written informed consent from the patient, in this multicenter randomized prospective study, we assigned 100 adult cardiac surgery patients with Euro score I of 6 or more to a restrictive red cell transfusion trigger (transfuse if hemoglobin level was <7.5g/dl starting from the induction of anesthesia) and liberal red cell transfusion trigger (transfuse if hemoglobin level was <9.5g/dl in the operative room or intensive care unit or <8.5g/dl in the ward). The primary outcome was composite of any cause death, myocardial infarction, stroke, or new onset renal failure with dialysis by discharge from hospital or by day28 whichever came first.

Results: There was a significant decrease in RBC transfusion in the restrictive group intraoperative, in the postoperative day (1), and in the ward stay. There was significantly less fresh frozen plasma transfused in the restrictive group during the ward stay only. There were a significant decrease in ventilator time, ICU stay, chest tube drainage, and rapid AF occurrence in the restrictive.

Conclusion: The restrictive transfusion strategy showed efficacy and safety in decreasing transfusion requirements in cardiac surgery, thus decreasing morbidities and mortality associated with blood transfusion. It also showed cost effectiveness.

Key words: Blood transfusion requirements, Cardiac surgery, Cardiopulmonary bypass, Preoperative anemia.

INTRODUCTION

     During cardiac surgery, ongoing blood loss and hemodilution as a result of cardiopulmonary bypass (CPB) cause low hemoglobin (HB) levels. Transfusion of red blood cells (RBC) is the current standard practice for perioperative anemia, but RBC transfusion is not without risks (El-Hilali et al., 2016 and Vlot et al., 2019).

     The prevalence of patients undergoing cardiac surgery who received blood components is unknown, with values varying from 10-95% (Ferraris, 2015). Such diversity is partly due to different local practices and institutional protocols (Tagliari et al., 2019).

     The incidence of perioperative blood transfusion ranges from 40% to as high as 90% and is dependent on the complexity and duration of surgery, prevalence of pre-existing anemia, and age of the patient. However, blood transfusions have risks, including cardiac and respiratory complications, e.g. transfusion-related acute lung injury, transfusion-associated circulatory overload, transfusion-related immunomodulation, transmission of microorganisms causing infections, hemolytic reactions, renal and neurologic complications, and increased hospital length of stay (Tempe and Khurana, 2018). Safely reducing exposure to red blood cell transfusion can prevent transfusion-related adverse effects, conserve the blood supply, and reduce costs (Carson et al., 2016 and Delaney et al., 2016). Untreated anemia, however, is also associated with adverse effects, particularly in patients having cardiac surgery who are susceptible to anemia-induced tissue hypoxia (Docherty et al., 2016 and Garg et al., 2019).

     This prospective randomized study was designed to investigate the effect of restrictive transfusion strategy on decreasing transfusion requirements in cardiac surgery in comparison to the liberal strategy without adding extra risks on the patient outcome.

PATIENTS AND METHODS

     This was a randomized prospective study that included one hundred patients of moderate to high risk of death undergoing cardiac surgery on cardiopulmonary bypass from multiple Egyptian cardiac centers (multicenter study) after obtaining approval of institutional ethical committee and obtaining written informed consent from the patient.

     These patients were randomly divided into two equal groups: Group I (Restrictive transfusion group): Patients received a red cell transfusion if their hemoglobin isGroup II (Liberal transfusion strategy): Patients received a red cell transfusion if their hemoglobin concentration was

Inclusion Criteria: Age 18 or older, and European System for Cardiac Operative Risk Evaluation (EuroSCORE) of 6 or more.

Exclusion Criteria: Patients who were unable to receive or who refused blood products, patients who were involved in the autologous pre-donation program, and pregnancy or lactation (a negative pregnancy test was obtained prior to randomization for pre-menopausal females).

     Both investigational groups were followed during their hospitalization from the induction of anesthesia up to discharge or 28 days postoperatively (whichever came first). There after a contact was continued for 6 months postoperatively.

     All Patients in both groups were subjects of the following:

1.  Pre-operative: Demographics, Medical/Cardiac History, Preoperative laboratory data (within 30 days): HB, HCT, platelets, INR, PTT, creatinine, CK-MB and/or troponin.

2.  Intra-operative: Intraoperative laboratory data: HB (pre/during CPB and chest closure), HCT (pre/during CPB and chest closure), lowest arterial and central venous PO2 (pre/during CPB and chest closure), lowest arterial and central venous SO2 saturation (pre/during CPB and chest closure), minimum pump flow (during-CPB), and platelets (within 2 hours of chest closure).

3.  Post-operative: Postoperative laboratory data: HB, HCT, platelets, creatinine, CK-MB and/or troponinwere assessed on postoperative days 1,2,3,5,7,9 and 11 per protocol (unless discharge occurred earlier) and otherwise as clinically indicated. A 12-lead ECG was performed 24 hours after surgery and at hospital discharge or on day 4-6 postoperatively, whichever comes first.

Statistical analysis of the data:

     Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. (Armonk, NY: IBM Corp). The Kolmogorov- Smirnov, Shapiro and D’agstino tests were used to verify the normality of distribution of variables, Comparisons between groups for categorical variables were assessed using Chi-square test (Fisher or Monte Carlo). Student t-test was used to compare two groups for normally distributed quantitative variables while Mann Whitney test was used to compare between two groups for not normally distributed quantitative variables.

     Data wer presented as mean ± SD, for quantitative data and as frequency and percentage for qualitative data. Significance was considered when ≤ 0.05.

RESULTS

     There was a statistically significant difference between the two groups as regards the age (Table 1).

Table (1):   Demographic data

Data were represented as Mean ± SD

     There was a statistically significant difference between both groups as regards the pre CPB and during chest closure hemoglobin level (Figure 1).

Figure (1):  Intra operative HB and HCT

     Regarding intraoperative blood and blood products transfusion, blood transfusion occurred in 12 patients (24%) in the restrictive group compared to 26 patients (52%) in the liberal group, with statistically significant difference between both the studied groups. Plasma transfusion occurred in 2 patients in the restrictive group and 4 patients in the liberal group with no significant difference between both groups as regards plasma transfusion. Platelets transfusion occurred in 3 patients in the liberal group. No cryoprecipitate transfusion in both groups. There were no significant differences as regards plasma, platelets transfusion in both of the study groups (Table 2).

Table (2):   Intraoperative blood and blood products transfusion parameters

Data were represented as numbers (No) and percentage (%)

     Regarding transfusion parameters postoperatively (day 0), whole fresh blood was transfused in 4 patients (8%) in the liberal group. Packed RBCs was transfused in 3 patients (6%) in the liberal group. Plasma transfusion occurred in 3 patients (6%) in the restrictive group and in 5 patients (10%) in the liberal group. Platelets transfusion occurred in 4 patients (8%) in the restrictive group compared to 7 patients (14%) in the liberal group. Cryoprecipitate was transfused in only 3 patients (6%) in the liberal group.

     There were no statistically significant differences between both the study groups as regards blood and blood products transfusion in postoperative day 0 (Table 3).

Table (3):   Blood and blood products transfusion parameters (Day 0)

Data were represented as numbers (No) and percentage (%)

     Regarding transfusion parameters postoperatively (day one), packed RBCs were transfused in 7 patients (14%) in the liberal group. Fresh frozen plasma was transfused in only one patient (2%) in the restrictive group. Platelets transfusion occurred in only one patient in the liberal group. No cryoprecipitate transfusion in any of the two studied groups. There was a statistically significant difference between the two study groups as regards PRBCs transfusion postoperativelyin day one (Table 4).

Table (4):   Blood and blood products transfusion parameters (Day 1)

Data were represented as numbers (No) and percentage (%)

     Regarding transfusion parameters in the ward stay, packed RBCs was transfused in 6 patients (12%) in the liberal group. FFP was transfused in only 1 patient (2%) in the liberal group. Regarding transfusion parameters in the ward stay, there were statistically significant differences between the two studied groups as regards PRBCs transfusion and FFP transfusion (Table 5).

Table (5):   Blood and blood products transfusion parameters (ward stay)

Data were represented as numbers (No) and percentage (%)

     Regarding the postoperative outcomes, ICU stay in the restrictive group was ranging from 1 to 6 days with a mean of 2.21 ± 0.81, while in the liberal group was ranging from 2 to 28 days with a mean of 3.4 ± 3.85 with a statistically significant difference between the two studied groups. Total chest tube drainage in the restrictive group was ranging from 250 to 1000 cc with a mean of 499 ± 171.8 while in the liberal group was ranging from 250 to 1500 with a mean of 730.0 ± 303.8, with a statistically significant difference between the two studied groups. Ventilator time in the restrictive group was ranging from 3 to 24 hours with a mean of 8.96 ± 4.15, while in the liberal group was ranging from 4 to 240 hours with a mean of 18.70 ± 35.89, with a statistically significant difference between the two studied groups. Total hospital stay in the restrictive group was ranging from 5 to 11 days with a mean of 6.88 ± 1.44, while in the liberal group was ranging from 5 to 30 days with a mean of 9.0 ± 5.19, with no significant difference. Rapid AF occurred in 3 patients (6%) in the restrictive group compared to 11 patients (22%) in the liberal group, with a statistically significant difference between the two studied groups regarding the occurrence of rapid AF.

     There was no significant difference between the study groups as regards the neurological events. Regarding the renal problems, there were no cases with acute kidney injury in the restrictive group compared to 4 patients (8%) in the liberal group, with no significant difference. Regarding death from any cause, there were 4 patients (8%) died in the liberal group, one of them died from renal failure, other one from suture line endocarditis, and two cases with sudden cardiac arrest. No significant difference between the two studied groups as regards death due any cause (Table 6).

Table (6):   Postoperative outcomes

Data were represented as Mean ± SD

DISCUSSION

     Restrictive and liberal transfusion strategies are both effective and safe techniques for blood transfusion in patients with an elevated perioperative risk of death who were undergoing cardiac surgery with cardiopulmonary bypass according to this study. In the restrictive threshold group, there were fewer patients receiving red cell transfusion than in the liberal threshold group. Also, fewer units of allogeneic red cells were transfused in the restrictive threshold group than in the liberal group.

     Our findings were consistent with those found in Mazer et al. (2018) who found that a restrictive transfusion threshold (hemoglobin˂7.5 g/dl) was non inferior to a liberal transfusion strategy (hemoglobin˂9.5 d/dl in the operating room or ICU, and ˂8.5 g/dl on the ward) as regarding death and major disabilities (myocardial infarction, stroke, and new onset renal failure with dialysis) in patients undergoing cardiac surgery with moderate to high risk of death. These results were achieved with fewer units of RBCs being transfused.

     Van Boven et al. (2015) stated that there was no difference between restrictive and liberal transfusion during cardiac surgery regarding either mortality rate or perioperative complications which run in lines with our results.

     Garg et al. (2019) found in their study that there was no difference between restrictive and liberal groups regarding mortality rate which was in agreement with our results.

     Docherty et al. (2016) revealed in their study that the use of liberal transfusion improves outcome in cases of surgery for acute coronary syndrome which conflicting with our results.

     Murphy et al. (2015) documented in their study that, in the restrictive strategy of transfusion, there was increased mortality within three months postoperatively which conflicted with our results without significant difference between both of the transfusion strategies (restrictive or liberal), but regarding post-operative morbidity was in agreement with our results.

     The current study did not involve low risk patients. Also, it did not answer the question of whether even lower transfusion triggers might also be as safe and effective as the thresholds used in this study.

CONCLUSION

     The restrictive transfusion strategy showed efficacy and safety in decreasing transfusion requirements in cardiac surgery, thus decreasing morbidities and mortality associated with blood transfusion. It also showed cost effectiveness.

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