1. Lako S, Daka A, Nurka T, Dedej T, Memishaj S
Blood use and risk factors for red cell transfusion in patients undergoing coronary artery bypass surgery
Lako S, Daka A, Nurka T, Dedej T, Memishaj S

2. Introduction
The use of allogeneic red blood cells (RBC) transfusions is common in cardiac surgery, with reported transfusion rates ranging from 5 to 90 %.
Despite advantages, RBC transfusion is associated with well- described adverse outcomes.
Transfusion of RBCs, during or after coronary artery bypass operations, is not only associated with an increased perioperative mortality and morbidity, however; it also results in a longer ICU stay, total hospital stay and increased costs.
Even the long-term results are influenced by perioperative RBC transfusions. Koch et al. found a significantly reduced 6-month and late survival in patients undergoing CABG with transfusion of RBCs.

3. Introduction
Not all patients are at the same risk for transfusion requirement.
Several preoperative patients' characteristics (variables) were identified that were associated with increased red cell transfusion rates including: cardiopulmonary bypass pump (CBP), female sex, older age, low body weight (BMI), number of grafts, combined cardiac interventions, low haemoglobin concentration.
Identifying factors that can predict adults at high risk of receiving red blood cell transfusion during or after coronary artery bypass graft (CABG) surgery, may aid in more efficient blood banking practices and may tailor blood conservation strategies for these adult patients.
The classification of coronary artery bypass graft patients on the basis of attributes known preoperatively and by conduits used yields subsets of patients with distinctly different transfusion requirements and in-hospital outcomes.

4. Objectives
This survey aimed at assessing the incidence of blood use and the impact on red blood cell transfusion of: cardiopulmonary bypass (CBP), gender, age, BMI, number of grafts, combined cardiac interventions, and preoperative hemoglobin concentration in patients who undergo coronary artery bypass graft (CABG) surgery.

5. Patients and Methods
This study involved 164 patients (138 men and 26 women) who underwent CABG surgery at the Department of Cardiac Surgery at the American Hospital, Tirana, Albania, over a period of 2 years spanning January 2011 to December Patients with primary hematologic disease were not included in this study. Also not included were patients with DIC and HIT II after surgery.
Of the 164 patients, 116 underwent CABG surgery with use of Cardiopulmonary bypass-CBP (on-pump) and 48 underwent CABG surgery without CBP (off-pump). The surgery was either isolated (129/164 cases) or combined with other cardiac surgery (35/164 cases).

6. Patients and Methods
Patients were reviewed for their preoperative demographic, clinical (coronary artery disease severity and co-morbidities) and laboratory variables and then followed to record their postoperative data and outcomes.
One surgical team operated on all of the patients in this study.
All the patients included in the study were managed according to the hospital's current policies regarding preoperative preparation, intraoperative surgical and anesthetic management and postoperative care.
Packed red blood cells (PRBC) are transfused according to the needs of each patient. At our clinic, blood transfusion was used to maintain Hct > 25% and hemoglobin (Hb) > 8.0 g/dL during cardiac surgery.
PRBC transfusions were assessed by the total number of transfusions received intra and post-operatively.

7. Statistical Methods
This prospective cohort study involved consecutive patients who underwent elective or emergency CABG surgery.
The data are summarized as the mean ± SD values. The differences between the data were assessed by the Student’s t-test and p values ​​≤ 0.05 were considered statistically significant.
In clinical practice, anemia is diagnosed if the blood concentration of hemoglobin (Hb) is abnormally low. The World Health Organization (WHO) has defined anemia as Hb < 13 g/dL for men and < 12 g/dL for women. Cutoff for age = 62 years (median values ​​used as dividing points). BMI was calculated by dividing the individual patient's weight in kilograms by the individual patient's height in meters squared. Following World Health Organization guidelines, patients were divided into groups based on BMI and included normal weight (BMI < 25), overweight (BMI 25 to 29), and obese (BMI ≥ 30)
SPSS 20.0 software (IBM, 2011) was used for statistical analysis.

8. Patients and Methods
The average age of the patients was 61.8 ± 9.0 years (range, years). Figure 1 illustrates the patient distribution according to age.

9. The preoperative demographics and hematological data

10. 1. Results – The Incidence of blood use
During and after surgery, 79.9 % of patients (131/164) received Packed Red Blood Cells (PRBC).
In total, 334 units of PRBC were used.
The average number of PRBC units per patient was 2.0 (range, 0–8 units).
PRBC were not transfused in 20.1% (33/164) of patients, whereas 101 of 131 patients (77.0%) to whom PRBC were transfused received only 1-3 units of PRBC.

11. 2. Results – Impact of CBP on blood transfusion
1. On-pump patients received more PRBC than off-pump patients did. Specifically, 87.06% (101/116) of on-pump patients received PRBC as compared to 62.5% (30/48) of off-pump patients. On average, on-pump patients received 2.4 units versus 1.0 units of PRBC received by off-pump patients (p < 0.001).
CBP
Number of patients
Blood Transfusion
The average number of PRBC units SD
P value
On-pump
Off-pump
116 48
101 (87.0 %)
30 (62.5%)
2.4
1.0
1.7
< 0.001

12. 2. Results – Impact of gender on blood transfusion
80.7% (21/26) of women and 79.7% (110/138) of men received PRBC. Female patients received 2.2 units of PRBC during surgery, whereas male patients received 2.0 units of PRBC (p = 0.1). 2. Female patients received more PRBC than male patients did, although it was not statistically significant.
Gender
Number of patients
Transfused patients
The average number of PRBC units SD
P value
Female
Male 26
138
21 (80.7%)
110 (79.7%)
2.2
2.0
1.6
0.1

13. 2. Results – Impact of age on blood transfusion
3. Patients aged >62 years were transfused more often than younger patients were. In patients aged > 62 years (50.6%) received an average 2.3 units of PRBC, while patients aged ≤ 62 years (49.3%) received an average 1.7 units of PRBC (p < 0.001).
Age
Number of patients
Transfused patients
The average number of PRBC units SD
P value
> 62
≤ 62 83 81
68 (81.9%)
63 (77.7%)
2.3
1.7
1.5
0.019

14. 2. Results – Impact of BMI on blood transfusion
4. Overweight and obese BMI patients (>25 kg/m2) received less PRBC than normal BMI patients (≤25 kg/m2) patients did. Specifically, 85.7% (48/56) of normal BMI patients received PRBC as compared to 51.8% (56/108) of overweight and obese BMI patients. On average, normal BMI patients received 2.3 units versus 1.8 units of PRBC received by overweight and obese BMI patients (p = 0.003).
BMI (kg/m2)
Number of patients
Transfused patients
The average number of PRBC units SD
P value
<25
≥25 56
108
48 (85.7%)
56 (51.8%)
2.3
1.8
1.6
0.003

15. 2. Results – Impact of the number of grafts on blood transfusion
5. A larger number of grafts is associated with increased use of PRBC. Specifically, 88.6% (70/79) of 4-6 grafts patients received PRBC as compared to 71.7% (61/85) of 1-3 grafts patients. Surgery involving 4–6 grafts, 48.17% of patients, required 2.5 units of PRBC. 1.6 units of PRBC were required in the surgeries that required 1–3 grafts, 51.82% of patients, (p < 0.001).
Graft Numbers
Number of patients
Transfused patients
The average number of PRBC units SD
P value
1-3
4-6 85 79
61 (71.7%)
70 (88.6%)
1.6
2.5
1.5
<0.001

16. The average number of PRBC units
2. Results – Impact of combined cardiac surgical interventions on blood transfusion
6. Other cardiac surgical interventions (MVR, AVR) were associated with greater use of blood transfusion than isolated surgery (without other cardiac surgical intervention). Patients who underwent and other cardiac surgical interventions (21.3%) received an average 2.6 units of PRBC, while patients who underwent no other cardiac surgical intervention (78.6%) received an average 1.9 units of PRBC (p < 0.022).
Surgery
Number of patients
Transfused patients
The average number of PRBC units SD
P value
Isolated CABG
Combined CABG
129 35
102 (79.0%)
29 (82.8%)
1.9
2.6
1.5
2.1
0.022

17. 2. Results – Impact of preoperative anemia on blood transfusion
7. Preoperative Anemia is associated with greater use of blood transfusion.
41.4 % of patients with preoperative anemia. Specifically, 93.7% (45/48) of patients with preoperative anemia received PRBC as compared to 74.1% (86/116) of patients without anemia.
On average, patients with preoperative anemia received 2.7 units versus 1.7 units of PRBC received patients without preoperative anemia (p < 0.001).
Hemoglobin gr/dl
Number of patients
Transfused patients
The average number of PRBC units SD
P value
Anemia
Normal 48
116
45 (93.7 %)
86 (74.1 %)
2.7
1.7
1.9
1.4
< 0.001

18. Conclusions
The incidence of blood transfusion among patients undergoing coronary artery surgery has been reported to be between 27 % and 92 %. In our study, blood transfusion was required for 79.9 % of patients with a mean number of 2 units per patient.
We found that on-pump (versus off-pump), age ≥ 62 years, BMI < 25 kg/m2, a large number of grafts, associated heart disease, and preoperative anemia were significant predictors of blood transfusion for patients undergoing coronary artery surgery.
Preoperative anemia, use of CBP pump, number of grafts, are the most significant predictor of blood transfusion.
The next predictor of transfusion in CABG surgery was sex. Female gender was identified as a risk factor for blood transfusion in patients undergoing CABG surgery. This has been noted in both on- pump and off-pump surgery. In our study, female patients used more PRBC units comparing to male, but was not statistically significant. The number of female patients was relatively limited (26/164).
Preoperative patients' characteristics can predict the need for perioperative blood component transfusion in cardiac surgical operations. Prediction models based on preoperative variables may facilitate blood component management and improve the efficiency of ordering blood before operations for patients undergoing CABG surgeries in order to assist blood banks in improving responsiveness to clinical needs .

19. Limitations
The limitations of our study are the inclusion of scheduled and non-scheduled (urgent) patients; the latter has an increased risk for blood transfusion.
Likewise, patients who underwent CABG and cardiac catheterizing (coronarography procedure) in the same admission were at risk for transfusion.
The number of female patients was relatively limited (26/164).
We did not consider other variables such as the duration of surgery, the surgeon and anesthesiologist.

20. Thank you!