Being your best self before surgery
Five things to know about ... Preoperative anemia in major elective surgery.
Clarissa P. Skorupski MD, Matthew C. Cheung MD SM, Yulia Lin MD
Cite as: CMAJ 2023 April 17;195:E551. doi: 10.1503/cmaj.221635
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1. The prevalence of preoperative anemia is high
An estimated 23%–45% of patients undergoing major surgery have anemia, with the most common causes being iron deficiency anemia and anemia of inflammation or chronic disease. ¹,²
2. Preoperative anemia leads to adverse outcomes
Regardless of its severity, preoperative anemia is an independent risk factor for postoperative death, major morbidity, increased length of hospital stay and transfusion.¹,³ In patients undergoing cardiac surgery, a 10 g/L decrease in preoperative hemoglobin levels increased mortality odds by 16% (95% confidence interval 10%–22%).²
3. A preoperative hemoglobin of 130 g/L or higher should be targeted for both sexes
Females have lower circulating blood volumes and greater proportional operative blood loss than males. (4) Females with a hemoglobin of 120 g/L were shown to be twice as likely as males with a hemoglobin of 130 g/L to receive postoperative blood transfusions.⁴ When treating preoperative anemia, targeting the same hemoglobin level in both sexes minimizes the risk of unfavourable outcomes and transfusions.⁴
4. Patients undergoing major elective surgery, with expected blood loss of more than 500 mL, should be screened for anemia 6–8 weeks before their operation
Clinicians should order a complete blood count and ferritin levels, as iron deficiency anemia (ferritin < 30 ng/mL) is the most common cause.¹,⁴ When underlying inflammation is present, ferritin is less sensitive, and iron deficiency anemia can be diagnosed with a ferritin of 30–100 ng/mL and a transferrin saturation of less than 20%.¹,⁴ Patients with iron deficiency anemia should be investigated for an underlying cause (e.g., gastrointestinal blood loss, menorrhagia, malabsorption).
5. Preoperative iron deficiency anemia should be treated with iron supplementation
Patients with iron deficiency anemia at least 8 weeks from surgery should be treated with oral supplementation at equivalent doses of 40–60 mg elemental iron daily or 80–100 mg every other day.¹,⁴ If patients are within 8 weeks of surgery, or if they are unable to tolerate oral supplementation, they should receive intravenous iron.¹
For patients with refractory or other forms of anemia, erythropoiesis-stimulating agents can be considered along with a specialist referral.¹,⁵
References
1. Greenberg JA, Zwiep TM, Sadek J, et al. Clinical practice guideline: evidence, recommendations and algorithm for the preoperative optimization of anemia, hyperglycemia and smoking. Can J Surg 2021;64:E491-509.
2. Klein AA, Collier TJ, Brar MS, et al.; Association of Cardio-thoracic Anaesthetists (ACTA). The incidence and importance of anaemia in patients undergoing cardiac surgery in the UK: the first Association of Cardiothoracic Anaesthetists national audit. Anaesthesia 2016;71:627-35.
3. Mueller MM, Van Remoortel H, Meybohm P, et al.; ICC PBM Frankfurt 2018 Group. Patient blood management: recommendations from the 2018 Frankfurt Consensus Conference. JAMA 2019;321:983-97.
4. Muñoz M, Acheson AG, Auerbach M, et al. International consensus statement on the peri-operative management of anaemia and iron deficiency. Anaesthesia 2017;72:233-47.
5. Kei T, Mistry N, Curley G, et al. Efficacy and safety of erythro-poietin and iron therapy to reduce red blood cell transfusion in surgical patients: a systematic review and meta-analysis. Can J Anaesth 2019;66:716-31.References
Competing interests: Yulia Lin has received research funding from Canadian Blood Services and Octapharma and is a consultant with Choosing Wisely Canada. No other competing interests were declared.
This article has been peer reviewed.
Affiliations: Department of Medicine (Skorupski), University of Toronto; Odette Cancer Centre (Cheung), Sunnybrook Health Sciences Centre; ICES Central (Cheung); Precision Diagnostics and Therapeutics Program (Lin), Sunnybrook Health Sciences Centre; Department of Laboratory Medicine and Pathobiology (Lin), University of Toronto, Toronto, Ont.
Content licence: This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY-NC-ND 4.0) licence, which permits use, distribution and reproduction in any medium, provided that the original publication is properly cited, the use is noncommercial (i.e., research or educational use) and no modifications or adaptations are made. See: https://creativecommons.org/licenses/by-nc-nd/4.0/
Correspondence to: Clarissa Skorupski, clarissa.skorupski@medportal.ca