Abstract
Anaemia affects a significant number of preoperative patients and has independently been associated with increased morbidity and mortality. Identification, assessment, and treatment of preoperative anaemia is now widely accepted as a new standard of care for patients. There remains a lack of conclusive evidence that optimizing the haemoglobin (Hb) preoperatively impacts on the increased risks, but there is increasing evidence normalizing iron stores has a positive impact.
The commonest cause of anaemia in this setting is iron deficiency. It is important to consider and exclude other causes, there are established recommendations for screening investigations. Early identification allows time for Hb optimization. Oral iron replacement is advised first line, however there are often time constraints and tolerability concerns. In some circumstances surgical delay is appropriate. It is important patients understand the rationale behind management and are involved in the decision-making process. Where possible, red cell transfusions are avoided preoperatively given associations with worse surgical outcomes, there may be circumstances however where both transfusions and erythropoiesis stimulating agents are considered.
As evidence and research in this field grows hospitals should develop preoperative anaemia care pathways to ensure appropriate screening investigations are performed and management delivered.
After reading this article, you should be able to:
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recognize the importance of pre-optimization of the anaemic patient
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summarize the recommended investigations for an anaemic patient prior to surgery
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discuss the management options for an anaemic patient pre-operatively
Background
Anaemia affects a significant number of preoperative patients with a reported prevalence of 35–50%. There is a wide differential for preoperative anaemia, with varying severity. The commonest cause is iron deficiency, accounting for 80% of cases. Appropriate investigation and management of pre-operative anaemia can identify patient’s with potentially modifiable and correctable causes such as nutritional deficiencies, facilitating haemoglobin (Hb) optimization prior to surgery. Rectifying anaemia preoperatively is thought to reduce a patients’ operative risk.
Preoperative anaemia has independently been identified as a risk factor for increased morbidity and mortality. It is associated with poor outcomes in patients undergoing major surgery including length of hospital stay, postoperative complications and death. Preoperative anaemia has been linked to an increased need for red cell transfusions, which in themselves are associated with worse patient outcomes. , Red cell transfusions carry risks, including transfusion reactions, transfusion associated circulatory overload and incorrect component transfusions.
Patient blood management (PBM) is the principle of minimizing blood product usage through the optimization of alternative non-transfusion management options when appropriate. PBM is an evidence-based approach, and is associated not only with improved patient outcomes but also improved use of resources, which in the current climate given constant stock level concerns is of significance. The PBM approach is underpinned by three pillars; ‘optimize haematopoiesis’, ‘minimize blood loss and bleeding’ and ‘harness and optimize tolerance of anaemia’.
Identification, assessment and treatment of preoperative anaemia is now widely accepted as a new standard of care for patients. With increasing evidence available, documents such as the International consensus on the management of preoperative anaemia have been compiled with recommendations for best practice. Early identification is paramount to give time for Hb optimization without causing significant delays or interference with elective surgical scheduling. Individual trusts should develop policies to support the management of preoperative anaemia care pathways. There is increasing evidence that intravenous iron reverses iron deficiency and reduces the postoperative re-interventions and admission to intensive care.
Approach to the anaemic patient
The World Health Organization (WHO) defines anaemia as Hb < 130 g/litre for men and Hb < 120 g/litre for females. In the pre-operative setting a threshold of <130 g/litre should be considered irrespective of gender as an indication for further investigation to capture non-anaemic iron deficient females, where often heavy menstrual bleeding drives the iron deficiency. There are suggestions that the severity of anaemia correlates with surgical outcomes. Patients with moderate (109–80 g/litre) to severe (<80 g/litre) anaemia have worse outcomes than those with a mild (129–110 g/litre) anaemia.
The focus in preoperative clinic is on screening for anaemia and identifying patients who would benefit from additional screening investigations based on history, ethnicity and co-morbidities. This is particularly of relevance in patients with known anaemia or with a cancer diagnosis. Preoperative clinics aim to identify patients with potentially corrective anaemia such as iron deficiency prior to planned surgery. Specialist referrals may be required if the cause remains unclear, suggests an underlying haematological diagnosis or additional investigations such as endoscopies are required. Table 1 shows different types of anaemia and possible causes that should be considered.
| Type of anaemia | Possible causes |
|---|---|
| Iron deficiency | Poor dietary intake, malabsorption, bleeding |
| Functional iron deficiency | Infection, inflammation |
| B12 deficiency | Poor dietary intake, malabsorption, autoimmune, medication |
| Folate deficiency | Poor dietary intake, malabsorption, medication |
| Anaemia of chronic disease | Malignancy, autoimmune, infection, renal impairment |
| Haemoglobinopathy | Sickle cell, thalassaemia |
| Aplastic anaemia | Idiopathic, hereditary, infection, medication |
| Haemolytic anaemias | Autoimmune, medication |
| Anaemia secondary to bone marrow dysfunction | Bone marrow infiltration, e.g. leukaemia myeloma Bone marrow dysfunction, e.g. myelodysplasia |
Investigations
All patients planned for major elective surgery should be screened preoperatively with a full blood count (FBC) initially. Given the emphasis on timely investigation to facilitate Hb optimization prior to surgery individual trusts may consider different approaches when developing a preoperative anaemia pathway in an attempt to minimize multiple hospital visits, the associated costs and to reduce delays. , Patients at increased risk of anaemia based on their history/co-morbidities could have point of care Hb testing during preoperative clinic with screening tests sent if subsequently anaemic. There may be merit in reflex testing where additional anaemia screening tests are added if anaemic or trusts may adopt a standard set of anaemia bloods for all patients visiting clinic.
The ‘International consensus statement on the peri-operative management of anaemia and iron deficiency’ recommended the minimum initial screening tests. Table 2 highlights its suggestions with some additional tests that could also be considered. In some cases, following these initial investigations, more specialist testing may be required.
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