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Pre-Operative Anaemia (BSH 2024)

 

Intro

 

Pre-op anaemia is common and is a risk factor for complications and death from surgery

  • Mild anaemia (Hb >100) increase morbidity risk by 30% (?the anaemia itself or ?reflection of co-morbidity)

  • Prevalence of pre-op anaemia varies between 35-50% in studies

  • 80% of anaemic pre-op patients are iron deficient

Pre-op anaemia increases healthcare costs and risk of needing blood transfusion

  • Transfused patients have greater morbidity and mortality

DoH and National Blood Transfusion Committee recommend pre-op screening for anaemia

  • Three reasons for this

    • Identify previously undiagnosed disease, e.g. cancer

    • Reduce need for transfusion, conserving stocks

    • Reducing patient exposure to risks of blood transfusion

Because of the above —> Pre-op anaemia is a PBM issue. 

Timing of Assessment

The earlier the better —> increase available time to correct anaemia. 

Options include:

  • GP at time of referral

  • During the diagnostic pathway (e.g. abnormal endoscopy)

  • Surgical Clinic

  • Pre-Op Assessment Clinic.

 

Diagnosis of Anaemia

 

Definition of anaemia in a pre-op setting:

  • Hb <130g/l (male+female) should be used as threshold to screen for correctable causes

Ferritin Cut-Offs:

  • <15 = Absolute iron deficiency

  • <30 = Suggested as a sensitive+specific threshold of iron deficiency that will respond to treatment

  • 30-100 and Tsat <20% = Possible iron deficiency in presence of inflammation

  • <70 = WHO suggested threshold for iron deficiency in presence of inflammation (Raised CRP)

Non-iron related anaemias

  • B12/Folate. CKD, Haemoglobinopathies, Multimorbidity/Frailty

  • If no cause apparent after considering the above, advice should be sought from haematology

 

Investigatory Algorithm

 

Principle

Commissioners should develop integrated pathways for referral and investigation of anaemic pre-op patients. Funding should be agreed between primary and secondary care, with attention to avoiding disrupting surgical pathways.

  • E.g. reflex testing to identify the cause of anaemia may reduce delays and minimise patient visits.

Investigation of Iron Deficiency

  • Up to 15% of unexplained IDA —> malignancy

  • Approx 1% of Ferritin <15 in non-anaemic men and menopausal women —> malignancy

  • —> This is basis of recommendation of endoscopy in response to unexplained iron deficiency 

Management

 

General Considerations

  • Cause and severity of anaemia

  • Anticipated peri-op blood loss

  • Time available between diagnosis and surgery

  • Whether surgery may be safely postponed.

Oral Iron

  • First line choice

  • Cheap, safe and widely available

  • Slow – at best Hb rise of 10g/l per week, and need to continue for further 3 months

  • Absorption impaired by tannins, PPIs, chronic inflammation, renal failure

Parenteral Iron

  • For use where oral iron is ineffective, intolerable or there is insufficient time in surgical pathway for oral Rx.

  • Must be given in facilities with resus equipment – though SAEs <1 in 200,000

  • PREVENTT 2020 - approx 500 patients. 1g ferrinject vs placebo for pre-op anaemia of any cause prior to major abdo surgery. Given median of 15 days prior to surgery. No difference found in any of the primary outcomes or pre-specified subgroups. Surprising finding. ?Given too close to surgery ?peri-op inflammation preventing effective utilisation of the iron ?Heterogenous patient group.

  • Re-analysis of PREVENTT found a greater response in haemoglobin for patients with absolute iron deficiency (ferritin <30) vs those with functional iron deficiency

 

Other considerations

B12/Folate correction

  • Replace as needed

Erythropoiesis-stimulating agents (ESA)

  • Recombinant variants of erythropoietin

  • Expensive, DVT side effects

  • If used, ensure patient iron replete to maximise ESA efficacy

  • Not recommended for pre-op anaemia unless:

    • For another licensed indications, e.g. renal failure

    • Patients who decline transfusion therapy

    • Patients with complex red cell antibodies

Short-term therapy

  • Very short therapy with IV Iron +/- ESA +/- B12&Folate in the week prior to surgery

  • Shown to reduce transfusion requirement

  • But did trial not report on safety or adverse outcomes

Pre-op Transfusion

  • Not recommended

  • If used, reserve for patients with urgency of surgery that cannot wait for other anaemia management and use restrictive transfusion thresholds (Hb 70g/l)