REPLACE – Seven Steps to Remember During A Massive Blood Transfusion
At first thought, this seems like an obvious answer: give blood! However, the amount of blood that a person receives during a massive blood transfusion can cause a set of complications that needs to be addressed concurrently.
To remember the principles involved with managing a patient requiring a massive blood transfusion, remember the acronym REPLACE:
|L||Low temperature management|
Note: A massive blood transfusion can be defined as follows:
- The transfusion of an adult’s blood volume within 24 hours – this can also be defined as having to administer more than 10 units of packed red blood cells in 24 hours, or the anticipated need to do so.
- The transfusion of half an adult’s blood volume in 4 hours – this can also be defined as the loss of over 150mL of blood per minute. (NBA 2011)
The average blood volume is approximately 70 mL/kg for adults of ideal body weight (Red Cross 2020).
Replacement of Intravascular Volume Loss
Excessive bleeding causes a loss of intravascular volume and circulating haemoglobin, resulting in decreased perfusion of the vital organs. This eventually leads to hypovolaemic shock (Taghavi & Askari 2020).
The general rule of thumb is that intravascular volume should be replaced by what has been lost. In a bleeding patient, we should replace with blood.
A bit of crystalloid filling may be considered in order to dilute the blood and help circulate it around the body, but a 1:1 ratio of blood to crystalloid is no longer advocated due to adverse outcomes such as oedema, compartment syndrome and acute lung injury (NBA 2011).
Attempting to replace the blood that is being lost is futile if the bleeding is not stopped. If the bleeding is external, try to control it by compressing the bleeding site, applying a tourniquet above the bleeding extremity or packing the bleeding wound. If the bleeding is internal, there needs to be an urgent surgical intervention to find the source and control it (ANZCOR 2017).
Adopt the Goldilocks principle here; not too much, not too little…just right! Permissive hypotension of 80-100mmHg systolic is usually recommended until the bleeding has stopped, as adding more force behind the bleed is only going to worsen it (NBA 2011).
Low Body Temperature Management
Hypothermic people have a slower heart rate, decreased myocardial contractility and impaired uptake of oxygen by the cells, leading to worsening shock. It is easier to keep a patient warm than trying to warm them up. Use a blood warmer to administer the blood where possible and remember to put an active warming blanket on the person, aiming for a temperature of more than 35 degrees celsius (NBA 2011).
Each unit of blood contains approximately 15 mmol of hydrogen ions. As the kidneys are only able to eliminate approximately 1 mmol/kg of hydrogen ions a day, acidosis can occur with massive blood transfusions if the kidneys are unable to keep up with the buffering and removal.
Each unit of blood has a base deficit of 20 mmol/L to 40 mmol/L depending on the age of the bag, with a base deficit reducing the ability of the body to buffer a worsening acidosis. The metabolic acidosis will eventually rectify itself once the bleeding has been stopped.
There are various blood products and adjuncts that can be administered to help slow the bleeding, including:
- Fresh Frozen Plasma (FFP) that contains all the coagulation factors in normal concentrations and promotes coagulation of blood along the intrinsic, extrinsic and common pathways – administer 15 mL/kg if the international normalised ratio (INR) is more than 1.5.
- Platelets that help to form a stabilised clot by binding with fibrin fibres – administer one unit if platelets are less than 50,000 mCL.
- Cryoprecipitate that contains mostly fibrinogen, factor 8, factor 13 and von Willebrand factor – administer 3 to 4 grams if the fibrinogen is less than 1.0 g/L.
- Tranexamic acid (TXA), which is an antifibrinolytic that works to counteract the degrading effects that plasmin has on fibrin, thereby preserving stabilised fibrin to participate in the clotting process for longer.
- Protamine, which helps reverse the effects of heparin if the bleeding is thought to be a result of a heparin-induced coagulopathy.
- Vitamin K, which helps to activate factors 2, 7, 9 and 10 if the bleeding is thought to be a result of a warfarin-induced coagulopathy. (NBA 2011; Nickson 2019)
Each unit of blood contains citrate that works to prevent blood clotting by binding to ionised calcium, impeding the clotting cascade significantly. The liver converts citrate to bicarbonate, thereby releasing calcium ions to facilitate the clotting ability of the blood. However, a massive blood transfusion overwhelms this process.
For this reason, calcium needs to be replaced to maintain an ionised calcium level of more than 1.1 mmol/L (NBA 2011).
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