Effect of blood conservation protocol on the utilisation of blood and outcome of patients undergoing open heart surgery

Abstract

Introduction

Cardiac surgery is fraught with increased consumption of blood and blood products. Various strategies for blood conservation have been described. Our aim was to study the impact of a structured blood conservation protocol (BCP) on the utilization of blood and patient outcome.

Methods

Retrospective analysis of prospectively collected data comparing adult patients undergoing open heart surgery with BCP with those undergoing surgery without BCP. The primary objective was to compare the amount of blood utilized and the hematocrit at discharge. The secondary objective was to compare the parameters of patient outcomes. The level of significance was set at 0.05.

Results

The proportion of patients requiring transfusion (19.1% [9/47] vs 58.9% [33/56]; p < 0.001) and the quantity of blood transfused (12 units vs 45 units; p 0.003) in the BCP group was significantly lower. Interestingly, the hematocrit level at discharge was comparable between the groups (30.9 (4.8) versus 31.8 (2.4), p-0.671). The average cost incurred for transfusing blood in the BCP group was ₹ 370.2 as compared to ₹1165.1 in the other (p < 0.001). BCP reduced the odds of overall blood transfusion by 79.8% (OR 0.202 (0.084-0.485); p < 0.001) and intraoperative blood transfusion by 95.3% (OR 0.047 (0.010-0.213); p < 0.001). The morbidity and mortality were comparable between the groups.

Conclusion

Implementing a structured blood conservation protocol in patients undergoing open heart surgery significantly reduces the need for blood transfusion. It also has a promising impact on patient recovery after surgery and significant positive cost implications.

Keywords

Blood conservation protocol Blood transfusion Retrograde autologus priming

Introduction

Cardiac surgery is a resource-intensive speciality and is fraught with increased consumption of blood and blood products.¹ This is often attributed to the use of cardiopulmonary bypass and the various strategies used to run the pump, high-pressure vascular suture lines which have a higher propensity to bleed and frequent use of anticoagulation. Blood is a precious resource, and its transfusion is known to increase patient morbidity and mortality and has significant cost implications.^2–6

Immediate, early, and late adverse outcomes of blood transfusion have already been described.^2–5,7 Techniques like using anti-fibrinolytic agents, retrograde autologous priming, miniaturization of cardiopulmonary bypass circuit, minimizing on-pump hemodilution and restrictive strategy of blood transfusion in the postoperative period have been described to reduce the utilization of blood.^1,3,5,8–14

Most of the studies performed to evaluate the risk factors that lead to an increase in blood transfusion and its effect on patient outcomes are retrospective in nature. The few large prospective studies performed, evaluate the effect of a particular strategy of blood conservation on patient outcomes. And it has been observed that retrospective studies demonstrate worse outcomes with transfusion, probably related to the selection bias.¹⁵

We have designed this study to prospectively assess the impact of a structured blood conservation protocol on the utilization of blood in the treatment of patients undergoing cardiac surgery and study their immediate outcomes. Also, to compare it with patients undergoing cardiac surgery without a blood conservation protocol.

Aims and objectives

The study aimed to assess the effect of structured blood conservation protocol on the consumption of blood and the outcome of patients undergoing open heart surgery. The primary objective was to compare the amount of blood used and hematocrit level at discharge between adult patients who underwent open heart surgery with blood conservation protocol versus those who underwent surgery without blood conservation protocol. The secondary objectives were to compare the effect of blood conservation protocol on the postoperative recovery (vasoactive inotrope score, duration of inotrope use, duration of mechanical ventilation, duration of ICU stay, and duration of hospital stay), cost implications, morbidity (surgical site infection, stroke, requirement of dialysis) and mortality. Also, the strength of association and relation of the various components of the blood conservation protocol on the significant patient outcome parameters was studied.

Methodology

The study was performed in the Department of Cardiothoracic and Vascular Surgery, Sri Sathya Sai Institute of Higher Medical Sciences, Bangalore, India, after ethical committee approval (ECR/1407/Inst/KA/2020).

Type of Study: Retrospective analysis of prospectively collected data

Study Period: June 2022 to November 2022

Nul Hypothesis: H₀ – No difference in the units of blood used in adult patients undergoing open heart surgery with blood conservation protocol versus without blood conservation protocol

Sample Size: The sample size was calculated based on the study by Hou et al. The effect size was 0.6 and standard deviation was 1.0. The alpha error was set at 5% and the power of the study was 80%. The minimum number of participants required in each group was calculated to be 44.¹⁰

Inclusion criteria

All adult patients aged more than 18 years undergoing open heart surgery were included in the study.

Exclusion criteria

1. Blood prime used in the cardiopulmonary bypass circuit.

2. Cyanotic congenital heart disease

Blood conservation protocol

Two operating surgeon out of the six at our centre performed surgery using blood conservation protocol, which included

Intraoperative blood conservation strategy

Patients were administered Epsilon amino caproic acid (50 mg/kg) before performing sternotomy. After cannulation, retrograde autologous priming was performed and the volume of the same was recorded. Myocardial protection was achieved using St Thomas cardioplegia or Modified Del Nido blood cardioplegia (Blood from the reservoir with Del Nido cardioplegia). No hemofilter was used. After weaning from cardiopulmonary bypass, the blood remaining in the reservoir, oxygenator and arterial line was returned back to the patient and this volume was recorded. The threshold for adding blood on cardiopulmonary bypass was a hematocrit of less than 24. After completion of protamine, Epsilon amino caproic acid (50 mg/kg) was administered again.

Postoperative blood transfusion threshold

Blood was transfused in the postoperative period if the hematocrit was less than 27%.

Surgery without blood conservation protocol

Four operating surgeons out of the six at our centre performed surgery without blood conservation protocol, which included

Intraoperative strategy

Pre-sternotomy and post-protamine epsilon amino caproic acid was used at surgeon’s discretion. Retrograde autologous priming and post-cardiopulmonary bypass transfusing the blood remaining in the oxygenator and pump were performed at surgeon’s discretion. Cardioplegia options for myocardial protection included St Thomas cardioplegia, Del Nido cardioplegia and modified Del Nido blood cardioplegia (blood from the reservoir with Del Nido cardioplegia). No hemofilter was used. The threshold for adding blood on cardiopulmonary bypass was a hematocrit of less than 24.

Postoperative blood transfusion threshold

Blood was transfused in the postoperative period if the hematocrit was less than 27%.

Data collection

All the data were collected prospectively and recorded in Microsoft Excel (Version 16.65).

Statistical analysis

Data were entered into Microsoft Excel (Version 16.65) and analyzed using the statistical software SPSS (Version 28.0). The Kolmogorov-Smirnov test was used to check the normality of the data. Normal data were represented as mean ± standard deviation and descriptive statistics of skewed data were represented as median (interquartile range). Categorical data were expressed as proportions. Student t-test was used to compare continuous data between normally distributed variables and the independent-sample Mann-Whitney U test was used to compare the continuous variables between the two groups with skewed distribution. Pearson Chi-square test was used to compare categorical variables between the two groups. Univariate and multivariate logistic regression was used to study the association of the need for blood transfusion with risk factors. Univariate and multivariate linear regression was used to study the relation of significant continuous outcome variables with risk factors. Kaplan-Meier plots were used to study the time to discharge after surgery and the Mantel-Cox log-rank test was used to compare the difference between the groups. Patient death was censored. The level of significance was set at 0.05.

Results

From June 1, 2022, to November 30, 2022, a total of 582 patients underwent cardiac surgery at our unit. The inclusion criteria were met by 103 patients, with 47 (46.6%) patients undergoing cardiac surgery with blood conservation protocol and 56 (53.4%) patients undergoing cardiac surgery without blood conservation protocol. The remaining patients were excluded as 209 patients underwent off-pump coronary artery bypass grafting, 126 patients were less than 18 years of age, 113 patients had cyanotic congenital heart disease and 31 patients required blood priming.

The characteristics of patients at baseline were similar in the two groups (Table 1). Both groups were comparable in terms of age, gender, case range, disease severity, and functional class. The weight, BSA and baseline hematocrit were also similar in the two groups.

Table 1.

Preoperative and intraoperative parameters of the two groups of patients. Normal data is represented as mean ± SD and skewed data as median (IQR) and categorical data as proportion.

Parameter	BCP (n = 47)	NON-BCP (n = 56)	Significance
Preoperative
Age (years)	33 (22)	30 (23)	0.357
Gender	Male – 18	Male – 27	0.312
Gender	Female – 29	Female – 29
Weight (Kg)	50.38±12.03	45.45±12.23	0.070
BSA (m²)	1.47±0.19	1.40±0.24	0.056
Diagnosis	ACHD – 22	ACHD – 24	0.399
	VHD – 22	VHD – 32
	Myxoma – 3
Functional class	NYHA – II – 46	NYHA – II – 55	0.707
Functional class	NYHA – III – 1	NYHA – III – 01
LVEF (%)	60 (0)	60 (0)	0.179
RVSP (mmHg)	35 (30)	45 (32)	0.316
PAH	Absent – 8	Absent – 9	0.732
	Mild – 23	Mild – 22
	Moderate – 10	Moderate – 6
	Severe – 6	Severe – 1
RV dysfunction	Absent – 43	Absent – 53	0.898
	Mild – 2	Mild – 2
	Moderate – 2	Moderate – 1
Intraoperative
Surgery	ASD closure – 19	ASD closure – 18	0.393
	AVSD repair – 1	AVSD repair – 2
	VSD closure – 2	VSD closure – 4
	Myxoma excision – 3	Valve repair – 5
	Valve Replacement - 18
	Valve repair – 4	Valve replacement - 27
AoXCl time (min)	66 (51)	74 (48)	0.483
CPB Time (min)	100 (59)	113 (61)	0.339
CPG type	Blood cardioplegia – 32	Blood cardioplegia – 0
	St thomas – 15	St thomas – 25
	Del nido – 0	Del nido – 31
CPG volume	1140 (660)	1350 (1540)	0.114
Prime volume	1150 (100)	1150 (196)	0.383
Add crystalloid	500 (625)	500 (551)	0.170
RAP	47 (100%)	14 (25%)	<0.001
RAP volume	200 (20)	0 (75)	<0.001
Transfuion of residual oxygenator and pump blood	47 (100%)	12 (21.4%)	<0.001
Volume of residual oxygenator and pump blood transfused	500 (100)	0	<0.001
On-pump urine output	1100 (550)	1000 (875)	0.503
Minimum temperature	28 (4)	28 (0)	0.009

Patients in both groups were comparable in terms of the surgeries performed and the time taken to perform the procedure (clamp time and the cardiopulmonary bypass time). RAP was performed in all patients undergoing surgery with BCP compared to only 25% of patients undergoing surgery without BCP (p < 0.001) and there was also a significant difference in the volume of RAP done in the two groups (p < 0.001). Similarly, the proportion of patients in whom the remaining pump volume was transfused back to the patient was significantly more in the BCP group (100% vs 21.4%; p < 0.001) (Table 1).

The pre-CPB hematocrit and the first hematocrit after going on-pump were comparable between the two groups, however, the subsequent blood gas samples taken on the pump showed significantly lower hematocrit in the group without the BCP (26% vs 23%, p – 0.022). There was a significant difference in the number of patients requiring the addition of blood on CPB in patients undergoing surgery without BCP (4.3% vs 50%; p < 0.001). The median lowest hematocrit on-pump was significantly lower in patients not undergoing RAP (26% vs 22.5%: p–0.003). Post-operative blood transfusion requirement was comparable between the two groups (14.8% vs 17.8%; p < 0.483). Both groups had comparable postoperative mediastinal drainage. Only 19.1 % of patients undergoing cardiac surgery with BCP required blood transfusion during the course of their hospital stay compared to 58.9% of patients undergoing surgery without BCP (p < 0.001). 12 units of blood were used in the BCP group compared to 45 units in the other (p < 0.001). The preoperative, postoperative and discharge hematocrit levels in both groups were comparable (Table 2).

Table 2.

Comparison of hematocrit (hct) and amount of blood transfusion between the two groups at various stages of their treatment. Normal data is represented as mean ± SD and skewed data as median (IQR) and categorical data as proportion.

Parameter	BCP (n = 47)	NON-BCP (n = 56)	Significance
Preoperative hematocrit (%)	40.34±5.06	39.48±5.56	0.400
First pump hematocrit (%)	27 (4)	26 (7)	0.128
Lowest pump hematocrit (%)	26 (4)	23 (6)	0.022
Post protamine hematocrit (%)	32 (7)	32 (7)	0.420
First ICU hematocrit (%)	36 (8)	37 (6)	0.546
Post operative Day1 hematocrit (%)	32.1 (7.8)	32.1 (3.9)	0.817
Post operative Day2 hematocrit (%)	30.6 (5.1)	31.3 (3.0)	0.671
Discharge hematocrit (%)	30.9 (4.8)	31.8 (2.4)	0.503
Intraoperative blood use	2 (4.3%)	28 (50%)	<0.001
Intraoperative blood use amount	1 Unit-1	1 Unit −26	<0.001
Intraoperative blood use amount	2 Units −1	2 Units −2
Postoperative blood use	7 (14.8.0%)	10 (17.8%)	0.483
Postoperative blood use amount	1 Unit-5	1 Unit −7	0.520
	2 Units −2	2 Units −1
	3 Units −0	3 Units −2
Both intraoperative and postoperative blood usage	0	5 (8.9%)	0.048
Total postoperative drain	125 (183)	130 (215)	0.902
Total patients requiring blood	9 (19.1 %)	33 (58.9%)	<0.001
Total blood units used	1 Unit-6	1 Unit −24	0.003
	2 Units −3	2 Units −7
	3 Units −0	3 Units −1
	4 Units −0	4 Units −1

The median vasoactive inotrope score in the first 24 h after the surgery was higher in patients not following BCP (5 vs 10; p-0.043), however, the duration of inotrope use was comparable in the two groups. The postoperative cardiac recovery (LV function, RV function and pulmonary hypertension) was comparable between the groups. The duration of mechanical ventilation and ICU stay was comparable, whereas the median hospital stay was shorter in patients undergoing surgery with BCP (Table 3). Kaplan-Meier plots demonstrate a significant difference in the duration of hospital stay between the two groups (p–0.008). Subgroup analysis showed a trend of longer hospital stay within the two groups if the patient had received blood transfusion (p–0.004) (Figure 1). Linear regression demonstrated a trend towards the number of units of blood transfused to be the only risk factor for prolonged hospital stay (p – 0.053).

Table 3.

Comparison of parameters of patient recovery, morbidity and mortality between the two groups. Skewed data is represented as median (IQR) and categorical data as proportion.

Parameter	BCP (n = 47)	NON-BCP (n = 56)	Significance
Inotrope score (maximum) first 24 h	5 (5)	10 (5)	0.043
Duration of inotropes use (hours)	16 (6)	18.5 (22)	0.165
Post operative LVEF (%)	60 (0)	60 (0)	0.440
Post operative RVSP (mmHg)	25 (19)	25 (15)	0.849
Post operative PAH	Absent – 27	Absent – 27	0.274
	Mild – 16	Mild – 25
	Moderate – 4	Moderate – 2
		Severe - 2
Post operative RV dysfunction	Absent – 38	Absent – 46	0.455
	Mild – 8	Mild – 8
	Moderate – 1	Moderate – 2
Duration of ventilation (hours)	7 (5)	8 (7)	0.667
Duration of ICU stay (days)	1 (1)	1 (1)	0.135
Duration of hospital stay (days)	4 (2)	4 (3)	0.027
Fever	0	2 (3.6%)	0.293
SSI	0	1 (1.8%)	0.544
Stroke	0	1 (1.8%)	0.544
Preop creatinine	0.68 (0.25)	0.62 (0.25)	0.858
Postop creatinine	0.74 (0.28)	0.75 (0.34)	0.832
Creatinine difference	0.06 (0.15)	0.06 (0.18)	0.544
Death	0	1 (1.8%)	0.544

Figure 1.

(a)Kaplan-Meier plots demonstrating a significantly shorter duration of hospital stay in patients following BCP. (b) - Subgroup analysis in the BCP group, demonstrating longer time to discharge in patients who received blood transfusion.

Two patients had a postoperative fever, one had a surgical site infection, and one had an ischemic stroke, and all these patients underwent surgery without BCP, however, this occurrence was not statistically significant. The preoperative, and postoperative creatinine levels were comparable between the groups and none of the patients required renal replacement therapy (Table 3). There was one mortality, the patient underwent ASD closure without BCP and had a thrombotic stroke which had a hemorrhagic transformation followed by brainstem herniation. This patient had received 3 units of blood transfusion.

The cost of 1 unit of packed red blood cells in India as per the Indian Red Cross Society database is ₹ 1450.¹⁶ Excluding the overhead charges of storage and administration of blood, the average cost incurred for transfusing blood in the BCP group was ₹ 370.2 as compared to ₹1165.1 in the other (p < 0.001)

Univariate logistic regression demonstrated utilisation of BCP reduced the odds of overall blood transfusion by 79.8% (OR 0.202 (0.084-0.485); p < 0.001) and intraoperative blood transfusion by 95.3% (OR 0.047 (0.010–0.213); p < 0.001). There was no significant impact of BCP, however, on postoperative blood transfusion. (Table 4). Multivariate logistic regression analysis identified the lowest hematocrit on pump and postoperative mediastinal drainage as risk factors for blood transfusion. Every 1% increase in the lowest on-pump hematocrit reduced the odds of blood transfusion by 28.3% (OR 0.717 (0.581–0.884); p-0.002) (Table 5).

Table 4.

Multivariate logistic regression to identify the risk factors for intraoperative blood transfusion. OR – Odds Ratio CI – Confidence Interval.

Univariate logistic regression for assessing the relation of BCP with blood transfusion
Variable	OR	95% CI lower	95% CI upper	P value
Overall blood transfusion	0.202	0.084	0.485	<0.001
Intraoperative blood transfusion	0.047	0.010	0.213	<0.001
Post operative blood transfusion	0.844	0.294	2.423	0.752

Table 5.

Univariate and multivariate logistic regression to identify the risk factors for postop blood transfusion. OR – Odds Ratio CI – Confidence Interval.

Multivariate logistic regression for overall blood use
Variable	OR	95% CI lower	95% CI Upper	p Value
Preoperative hematocrit	0.981	.866	1.110	0.981
BSA	0.177	0.014	2.219	0.179
RAP	0.147	0.006	3.543	0.238
Blood CPG	0.978	0.265	3.612	.0.973
Transfusion of residual pump blood	1.960	0.081	47.466	0.679
Minimum temperature	0.785	0.531	1.161	0.225
Lowest hematocrit. on pump	0.717	0.581	0.884	0.002
Post operative drainage	1.004	1.001	1.008	0.014

Discussion

Patients undergoing cardiac surgery are among the highest recipients of blood transfusion, with most of the hospital blood supply used by this group.¹ Our study demonstrates the impact of a structured blood conservation protocol on the consumption of blood and patient outcome.

Blood utilization

Also, the volume of blood transfused in this group was significantly lower than that in the comparison group (12 units vs 45 units). It was interesting to note that with comparable baseline BSA and preoperative hematocrit levels, a similar profile of surgeries being performed and a restrictive postoperative blood transfusion strategy in the BCP group, the hematocrit at discharge was comparable between the groups (30.9 vs 31.8). This suggests blood can truly be conserved in cardiac surgery.

Intraoperative blood conservation strategies

Retrograde autologous priming of the CPB circuit is recommended by both the STS and EACTS as a measure to prevent hemodilution on the pump and conserve blood during surgery.^3,5 Hou and associates showed a significant decrease in transfusion requirement in patients who underwent RAP compared to those who underwent surgery without RAP (26.7% vs 83.3%;p < 0.01).¹⁰ In our study, all patients of the BCP group underwent RAP and it was identified as a significant risk factor for transfusion during the course of the patient’s treatment on univariate analysis (p < 0.001). Sun et al observed a significant reduction in the risk of intraoperative transfusion after RAP (0.39, 95% CI 0.29, 0.53; p < 0.00,001).⁸ We observed that patients undergoing RAP had significantly higher levels of nadir hematocrit on CPB (26% vs 22.5%; p-0.003), which indirectly reduced the utilisation of blood on the pump as confirmed on multivariate analysis. These findings are in line with previous studies and corroborate the role of RAP in the conservation of blood during cardiac surgery.

Ranucci and associates demonstrated excessive hemodilution and the lowest hematocrit (especially below 25%) achieved on-pump were independent risk factors for morbidity, even in the absence of blood transfusion.¹² Implementation of measures to avoid excessive hemodilution like doing RAP, administering blood cardioplegia, using miniaturised circuits, reducing priming volume and performing surgery under normothermia have been suggested to reduce the risk of bleeding and the need for blood transfusion.^3,5,12 In our study, patients following the BCP had a nadir hematocrit of 26% compared to 23% in the other group. We too identified low hematocrit on-pump as the predictor for intraoperative blood administration.

After waning off CPB, by transfusing the perfusate remaining in the oxygenator and the aortic line tubing, we were able to transfusion about 500 mL of autologous blood to the patient. This let us achieve a post-protamine hematocrit comparable to the other group, where 50% of patients received intraoperative transfusion.

STS and EACTS guidelines recommend the use of antifibrinolytics therapy (tranexamic acid and epsilon aminocaproic acid) as a measure to reduce blood loss and blood transfusion during cardiac procedures (Class I, Level A)^3,5,14 All patients in the BCP group received the same, however, due to erratic use of antifibrinolytics in the comparison group, the contribution of antifibrinolytics in conserving blood due BCP could not be ascertained.

Postoperative blood conservation strategy

Mazer and associated demonstrated a restrictive strategy of blood transfusion after cardiac surgery was not inferior to a liberal strategy in terms of patient outcome.¹ However, a decrease in the proportion of patients receiving transfusion was observed and transfusion was identified as an independent risk factor for late mortality (72.6% vs 52.3%).^1,17 Clinical patient management guidelines for patients undergoing cardiac surgery now recommends a restrictive allogeneic blood transfusion strategy for perioperative blood conservation (Class I, Level A).^3,5 In our study, a hematocrit trigger of 27% was used in both groups for postoperative blood transfusion and the utilisation of blood was found to be comparable (14.8% vs 17.8%). Post-operative mediastinal drainage was the only predictor of postoperative transfusion.

Patient recovery

We observed a lower inotrope requirement in patients following the BCP, however, the duration of inotrope use and time of mechanical ventilation was comparable between the groups. Although the duration of ICU stay was similar, patients in the BCP group had a significantly shorter time to discharge from the hospital. Interestingly, patients who received transfusions showed a trend towards a longer hospital stay within the BCP group.

Morbidity and mortality

Blood transfusion has been associated with an increased risk of infection secondary to immunosuppression, ischemic complications like stroke and myocardial infarction, renal dysfunction requiring hemodialysis, increased incidence of atrial fibrillation and mortality.^{2,4,7,18–21} Studies have demonstrated a two times higher mortality risk at 5 years in patients who received perioperative transfusion and this risk is seen to extend beyond a decade after the surgery.^2,21 Murphy and colleagues found patients undergoing transfusion had 3 times higher odds of infection and ischemic complication. They also observed transfused patients were less likely to be discharged from the hospital (hazard ratio [HR], 0.63; 95% CI, 0.60 to 0.67) and more likely to have mortality after discharge (0 to 30 days: HR, 6.69; 95% CI, 3.66 to 15.1; 31 days to 1 year: HR, 2.59; 95% CI, 1.68 to 4.17;1 year: HR, 1.32; 95% CI, 1.08 to 1.64)⁴ Our study did not detect a difference in the rate of occurrence of these complications between the two groups, however, a longer follow-up is required to truly determine the same.

Cost implication

The cost of blood and blood products differs in various countries. For one unit of packed red blood cells, the cost in India is ₹ 1450¹⁶ compared to $210⁶ in the USA and £ 130⁴ in the UK. This excludes overhead charges of storage, additional laboratory testing, administration of blood and cost incurred in managing complications associated with transfusion. Murphy and associates found transfusion was associated with an increased relative cost of admission (any transfusion, 1.42 times [95% CI,1.37 to 1.46], varying from 1.11 times for 1U to 3.35 times for 9 U).⁴ As the transfusion requirements in the BCP group were less, we observed that the expenditure per patient towards blood transfusion was significantly less compared to patients undergoing surgery with BCP.

Importance of a structured blood conservation protocol

Our study highlights the importance of a structured protocol for utilising blood conservation approaches as compared to unsystematically applying the same. A structured BCP comprising simple strategies significantly reduced the consumption of blood and had a positive impact on patient outcomes. The STS now recommends the institution of a comprehensive multimodality blood conservation program led by a multidisciplinary team of health care providers to be part of any patient blood management program to limit the utilization of blood.³

Limitation

It was a retrospective analysis of prospectively collected data. The data was skewed, and a larger sample would be required to normalise the distribution. The study was not adequately powered to study the study population’s risk factors for low hematocrit on-pump. The use of antifibrinolytics in the control group was not uniform and hence was difficult to ascertain its effect on the utilization of blood and it was a confounding factor.

We appreciate that different surgeons in the two groups is another confounding factor. However, the two groups were comparable with regard to the preoperative characteristics of the patients (diagnosis and functional class), the type of operative procedure performed, operative times and postoperative blood loss. Although these similarities do not eliminate the potential for bias, it doesn’t seem to have an obvious impact on the outcomes. Also, we acknowledge these heterogeneities has a potential for statistical bias, but we believe it reflects the real-world scenario where subtle differences in individual practice exist within a given centre and may have an impact on patient outcomes.

Conclusion

Implementing a structured blood conservation protocol in adult patients undergoing open heart surgery significantly reduces the need for blood transfusion. It also has a promising impact on patient recovery after surgery and significant positive cost implications.

Footnotes

Authors’ note

Presentation - This manuscript has been presented at IACTSCON 2023 held in Coimbatore, Tamil Nadu, India on 17.02.2023.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethical statement

ORCID iD

Vivek Bagaria

Appendix

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