Strategies to avoid intra-operative blood transfusion

Abstract

Transfusion of donor blood is sometimes unavoidable during the surgical episode. However, it is associated with increased morbidity and mortality, whilst interventions that reduce the need for donor transfusions have a positive impact on outcome. The principles underpinning reducing the need for transfusion are collectively known as ‘patient blood management’ which incorporates three pillars: anaemia management, limitation of blood loss and restrictive transfusion triggers. When used in combination, these principles appear the most effective way to limit the impact of surgical blood loss and reduce allogenic blood transfusions.

Learning objectives

After reading this article, you should be able to:

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describe the three pillars of patient blood management
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list ways to optimize a patient pre-operatively to reduce the need for transfusion
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outline how point of care testing can assist in peri-operative blood product usage
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understand the principles, indications and contra-indications to intra-operative cell salvage
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employ evidence based, restrictive blood transfusions

The risks surrounding blood transfusions were thrown into the public spotlight recently, following the publication of the infected blood inquiry. The report attributes over 3000 deaths to infected blood or blood products. Primarily due to HIV and hepatitis C infections between 1970 and 1998. Although the report emphasizes that receiving a blood transfusion today is significantly safer than in the 1970s, it highlights that there are always inherent risks, some of which may, as yet be unknown.

The known risks of allogenic (donor) blood transfusion are multiple, with specific reactions such as transfusion-related lung injury, allergic reactions and febrile haemolytic or non-haemolytic reactions well documented throughout the literature. Transfusion-associated circulatory overload (TACO) is another serious complication of blood transfusions which must be considered.

A national patient safety alert was issued in April 2024 to highlight the risk of TACO as one of the most common causes of transfusion related death in the UK. It should be considered in any patient experiencing worsening respiratory function or pulmonary oedema within 12 hours of a blood transfusion. Serious Hazards of Transfusions (SHOT) have developed a risk assessment tool which should be used prior to transfusion to identify those at highest risk and enable steps to be taken to mitigate this.

Longer-term implications of blood transfusion are also of concern, with a recent meta-analysis confirming an increase in short and long term mortality in patients who received a peri-operative blood transfusion. By considering all the risks detailed above we can see the importance of reducing the use of allogenic blood transfusions where possible. Patient blood management (PBM) protocols use a multidisciplinary approach to address this.

The principles of PBM are divided into three key areas known as ‘pillars’ ( Table 1 ) and focus on points throughout the peri-operative journey where optimization can occur to reduce the need for transfusions. In 2021 the World Health Organization (WHO) highlighted the impact PBM can have by publishing a policy brief calling for organisations around the world to adopt PBM strategies to improve patient care on both an individual and organizational basis.

Table 1

Three pillars of patient blood management

1)

Diagnosis and management of pre-operative anaemia:
Reducing the likelihood of a haemoglobin level that would require transfusion.

2)

Minimizing intra-operative blood loss:
By optimizing surgical and anaesthetic techniques, avoiding and treating coagulopathy .

3)

Appropriate use of a restrictive transfusion policy:
Including optimizing a patient’s physiological reserve to tolerate anaemia.

Althoff et al. reviewed data from, mostly observational, studies where the three pillars of PBM were used. The meta-analysis showed reductions in donor transfusion, reduced length of hospital stays and reduced rates of reported complications. A more recent meta-analysis, by Roman and colleagues, of randomized trials also confirmed reduced transfusion rates with PBM principles. This review failed to show any other outcome benefits but there is concern the original studies used in this analysis were underpowered to identify other clinical benefits.

During pre-operative planning, it is important to ensure that patients are made aware of the possibility of requiring a blood transfusion and its risks. There is also an obligation to inform the patient of the alternative therapy options such as those we will discuss throughout this article.

Pillar 1: pre-operative anaemia management

WHO defines anaemia as a haemoglobin (hb) <130 g/litre in men and <120 g/litre in non-pregnant women, although there have been calls to use an hb target of 130 g/litre in both sexes for peri-operative management. Pre-operative anaemia is associated with increased rates of peri-operative morbidity and should therefore be a key focus in the peri-operative planning period.

Investigations

All patients undergoing surgery where blood loss is likely to be >500 ml, as well as those with a complex medical history undergoing more minor surgery, should have a full blood count (FBC) performed as early as possible in their Peri-operative journey. If anaemia is identified the following investigations are recommended as standard:

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C-reactive protein
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Renal function
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Serum ferritin
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Transferrin saturations
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B12 and folate

If relevant consider:

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Liver function tests
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Tests for coeliac disease, if malabsorption is a possibility
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Haemoglobinopathy screen if there is clinical suspicion.

Once the nature of the anaemia has been defined ( Table 2 ) it is important to consider the root cause, with a third of iron deficient patients being found to have a significant underlying pathology. The question of delaying surgery to investigate and treat the anaemia further must be discussed with the patient and the decision made on an individual risk benefit analysis.

Table 2

Blood results indicating nature of anaemia

Ferritin level (micrograms/litre)	Transferrin saturations	Likely diagnosis
<30	<20%	Iron deficiency
30–100	<20%	Functional iron deficiency ^a
>100	>20%	Not iron deficient consider B12/folate levels or refer to haematology

a Functional iron deficiency = sufficient total body iron stores but unavailable in the circulation for erythropoiesis. This is often related to chronic inflammation or chronic disease.

Iron deficiency

If iron deficiency is identified, iron replacement is indicated and may be best achieved with IV iron when considering timing of surgery and tolerance of oral iron therapy. The PREVENTT trial is the first randomized control trial (RCT) to test whether a single dose of iron, if given pre-operatively, affects surgical outcome. The trial demonstrated an increase in hb and reduced hospital readmission in the treatment group but found no difference in transfusion rates or mortality. It is important to note that this trial did not stipulate that anaemia was caused by iron deficiency and therefore may be underpowered. A smaller RCT of non-anaemic patients undergoing cardiac surgery did show a reduction in rate of transfusions with pre-operative IV iron. More research is required in this area to further elucidate the role of IV iron in the peri-operative setting.

There is growing recognition of the importance of identifying and treating patients with iron deficiency without anaemia (IDWA). There is some evidence that iron replacement in patients with IDWA can reduce blood transfusion rates in cardiac surgery. There is also evidence that treating iron deficiency with or without anaemia can improve quality of life and functional status of patients with heart failure. The IRONMAN trial showed improved health-related quality of life at 4 months following IV iron, but failed to find statistical significance for its primary endpoint of cardiovascular deaths and hospital admissions for heart failure. These results were similar to those found in the AFFIRM-AHF trial. However, a recent meta-analysis pooling seven studies did find a statistically significant decrease in hospital admissions for heart failure when iron deficient patients were given IV iron.

Pillar 2: minimizing blood loss

The strategies to reduce intra-operative blood loss can be broadly divided into pre-operative, intra-operative and post-operative considerations as depicted in Table 3 .

Table 3

Summary of measures to minimize blood loss

Pre-operative	Intra-operative	Post-operative
Identify and correct pre-operative coagulopathy	Meticulous surgical technique	Strict monitoring and treatment of post-operative blood loss
Consider autologous blood donation if appropriate	Optimize anaesthetic technique	Optimize physiology to reduce coagulopathy
	Antifibrinolytic therapy	Minimize blood loss from iatrogenic causes
	Monitor and maintain normal coagulation	Gastrointestinal ulcer prophylaxis
	Blood cell salvage