3. Pre-operative optimisation of haemoglobin

Why it is important to manage preoperative anaemia?

Preoperative anaemia is caused by disease, disorder or a nutritional deficit. Even mild preoperative anaemia is independently associated with increased perioperative morbidity and mortality. An underlying disease may negatively affect perioperative outcome, and furthermore preoperative anaemia significantly increases the risk of transfusion and its associated risks. A surgical procedure with a moderate or high blood loss will further aggravate the anaemia and deplete iron stores.

Early screening for preoperative anaemia is necessary to allow time for diagnostic workup and for treatment to raise the haemoglobin concentration and reduce perioperative transfusion. Anaemia should be classified and the underlying cause identified and treated, if possible. Iron deficiency anaemia is the most frequent type, e.g. caused by bleeding, diet or malabsorption. Anaemia of chronic inflammation (disease) is also frequent due to e.g. autoimmune disease or cancer, and is often seen in combination with iron deficiency. Other causes of anaemia are hematologic disease, kidney failure, B-vitamin deficiency and haemolytic conditions, and some of these will be more amenable to treatment than others.

Patients with multiple preoperative risks, such as anaemia in combination with anticoagulant treatment and a major surgical procedure may be at risk for intraoperative organ ischemia and/or massive transfusion and a complicated postoperative period. Patients, in whom anaemia diagnosis reveals severe disease, may have to have their surgery postponed or cancelled. In other cases, performing the surgery quickly may be imperative, and further anaemia management may have to be postponed. Therefore, a complete PBM plan should always include an individual risk assessment. Even though PBM should be tailored to the patient, algorithms for anaemia management prior to specific procedures such as cardiac or orthopaedic surgery is useful. See figure in reference 2.

The key elements are

Anaemia:

definitions according to World Health Organization (WHO) [3].
prevalence depends on the haemoglobin threshold.
According to WHO limits, this increases with age to 10% of the general population above 65 years of age and >20% of above 85 years of age [4, 5].
In the middle-aged population, anaemia is associated with cancer, heart and kidney disease, and with increased long-term mortality [6], even at haemoglobin concentrations well above WHO anaemia definition.

Preoperative anaemia:

is frequent and often previously undiagnosed, and depending on age and comorbidity, it is seen in 5-75% of the patients [7-9].
even mild, it is a marker for disease, and associated with increased perioperative mortality and morbidity [1, 10]
is associated with a 2-6 fold increased risk of perioperative transfusion, and postoperative anaemia [11-14]
should be diagnosed at least 4 weeks ahead of surgery to allow time for correction of haemoglobin [7, 15]

How to treat anaemia

The purpose of anaemia treatment is to raise the haemoglobin concentration before surgery. Treatment should be directed against the cause of the anaemia [7, 15]. In iron deficiency anaemia and in functional iron deficiency, haemoglobin can be raised with iron alone or in combination with erythropoiesis-stimulating agents [2, 16-18]. Iron can be administered orally, which is cheap but takes 2-3 month to work. Between 10-30% of the patients on oral iron have gastrointestinal side effects, which reduces compliance with treatment [19, 20]. Furthermore, inflammation inhibits gastrointestinal absorption and reticulo-endothelial release of iron for erythropoiesis, so tablets may not be useful in anaemia of chronic disease [20, 21]. Intravenous iron is more expensive but may increase haemoglobin levels in 2-4 weeks, depending on the pre-treatment haemoglobin level. Intravenous iron bypasses gastrointestinal absorption and can increase haemoglobin levels in patients with anaemia of chronic disease, even as a sole therapy. Side effects are few and generally mild, but rare cases of anaphylaxis are seen [20, 22], and one meta-analysis found an increase in infection rates with intravenous iron [23].

The BloodSafe elearn from National Blood Authorities has very good appendices with details of iron deficiency anaemia management, including the use of the Ganzoni formula for calculation of the dose.
When dosing iron the expected surgical blood loss should be included in the dose calculation [24].
Postoperative iron deficiency or anaemia optimization may succeed in raising haemoglobin and improve fatigue and/or physical function, but transfusion rate may not be affected because of the late timing of iron treatment in relation to the timing of perioperative transfusion [25].

Complete perioperative PBM should be multidisciplinary and should also include:
- Manage coagulation and haemostasis perioperatively.
- Follow evidence based transfusion guidelines.

Key audit criteria

First you need to clearly define the patient population (e.g. all patients admitted for a certain type of elective surgery).
Secondly, you need to establish if and when haemoglobin is measured (how many days or weeks before surgery). If anaemia is systematically investigated weeks prior to surgery, you can go on to measure the effect of anaemia treatment by checking haemoglobin levels immediately prior to surgery and the effect on perioperative blood transfusion.

Suggested indicators

The percentage of patients who gets an early haemoglobin screen 3-8 weeks before elective surgery (patients with surgery + early haemoglobin / all patients with surgery)
The percentage of anaemic patients at the time of the screen (patients with anaemia / all patients with early haemoglobin)
The percentage of anaemic patients just before surgery (patients with anaemia at surgery / patients with anaemia at early screen)
If preoperative target haemoglobin is reached in treated patients
The percentage of patients exposed to RBC transfusion (patients with surgery + transfusion / all patients with surgery)
Number of RBC units per 1000 surgeries (activity-indexed blood utilization)
Improved or unchanged patient safety (e.g. complications, length of stay, mortality)

Relevant Guidelines

Practical tools to support implementation

Algorithm for detection, assessment and management of preoperative anaemia (Figure 2 in [2]) and similar in [15].
Figure 1 (PBM) in [2] gives a quick overview of pre- intra and postoperative anaemia management and the PBM-context.
The Perioperative module (BloodSafe) will provide guidance on how to make an outline for an individual patient PBM ahead of surgery.