From the Guidelines
The most adverse effect that can occur after massive blood transfusion of cold blood is hypocalcemia and alkalosis due to citrate chelating of serum calcium (option A). When large volumes of cold blood are rapidly transfused, the citrate preservative in stored blood binds to calcium in the recipient's bloodstream, leading to a decrease in ionised calcium concentration, which is essential for the formation and stabilisation of fibrin polymerisation sites and many platelet-related functions 1. This chelation of calcium can lead to symptomatic hypocalcemia, which may manifest as cardiac arrhythmias, hypotension, muscle cramps, and tetany. Additionally, the metabolism of citrate by the liver produces bicarbonate, which can cause metabolic alkalosis. Some key points to consider include:
- The normal range of ionised calcium (Ca2+) is 1.1–1.3 mmol/L and is pH-dependent, with a 0.1 unit increase in pH decreasing ionised calcium concentration by approximately 0.05 mmol/L 1.
- Ionised calcium levels are easily monitored, as they are included as a standard part of a blood gas analysis by the majority of blood gas analysers available on the market 1.
- Transfusion-induced hypocalcaemia, with ionised Ca2+ levels below 0.9 mmol/L or serum total corrected calcium levels of 7.5 mg/dL or lower, should be corrected promptly, as ionised Ca2+ levels below 0.8 mmol/L are associated with cardiac dysrhythmias 1. While febrile non-hemolytic reactions and hemolytic reactions can occur with blood transfusions, they are not specifically related to the temperature of the blood or the volume transfused, making them less directly associated with massive cold blood transfusions compared to the citrate-related hypocalcemia and alkalosis. The preferred agent to correct hypocalcaemia is calcium chloride, which may also be preferable to calcium gluconate in the setting of abnormal liver function, where decreased citrate metabolism results in the slower release of ionised calcium 1.
From the FDA Drug Label
The safety of Calcium Gluconate Injection for long term use has not been established. Calcium Gluconate Injection is a form of calcium indicated for pediatric and adult patients for the treatment of acute symptomatic hypocalcemia. The most common adverse events with Calcium Gluconate Injection are local soft tissue inflammation and necrosis, calcinosis cutis and calcification that are related to extravasation.
The most adverse effect that can occur after massive blood transfusion of cold blood is Hypocalcaemia due to citrate chelating of serum calcium, as calcium gluconate is used to treat acute symptomatic hypocalcemia 2.
- Key points:
- Hypocalcaemia is a condition where the blood calcium levels are low.
- Citrate, a preservative in blood products, can chelate calcium, leading to hypocalcaemia.
- Calcium gluconate is used to treat hypocalcaemia.
- Massive blood transfusion of cold blood can lead to hypocalcaemia due to citrate chelation of serum calcium.
From the Research
Adverse Effects of Massive Blood Transfusion
The most adverse effect that can occur after massive blood transfusion of cold blood is:
Causes of Hypocalcaemia and Alkalosis
Hypocalcaemia and alkalosis can occur due to:
- Citrate toxicity, which can lead to electrolyte abnormalities, including hypocalcemia 3
- The citrate preservative in blood products, which binds to the patient's endogenous calcium, rendering it inactive 4
Comparison with Other Options
Other options, such as:
- Febrile non-haemolytic reaction, are possible complications of blood transfusion, but are not directly related to the use of cold blood 5
- Haemolytic reaction, is a possible complication of blood transfusion, but is not the most adverse effect associated with massive blood transfusion of cold blood 5, 6
Importance of Monitoring and Education
Monitoring and education are crucial in preventing and managing hypocalcemia and alkalosis, as: