- Calcium plays a significant role in coagulation, platelet adhesion and contractility of myocardial and smooth muscle cells. It is required by clotting factors II, VII, IX and X aswell as protein C & protein S for activation at the damaged endothelium.
- Severe ionised hypocalcemia is defined as Ionised calcium < 0.9 mmol/L and is assosciated with increased mortality in critically ill adults, whereas levels < 0.8 mmmol/L is assosciated with adverse cardiac effects.
- PRBC, FFP & platelet contains approx 3g of citrate anticoagulant per unit as preservative. This is usually insignificant as 3g is metabolised by liver in 5 minutes. But in hypovolemic shock the combination of rapidly infused blood products and decreased hepatic clerance due to hypoperfusion and hypothermia may impair clearance of citrate.
Recent Evidence
- Ginacarcelli et al (J Surg Res..2016) did retrospective analysis of 156 trauma patients who received massive transfusion and found 111 (71%) patients had iCa <0.9mmmol/L (Severe hypocalcemia). Patients in the iCa < 0.9 mmmol/l had received more blood products . They also found that mortality was higher in patients with severe hypocalcemia.
- Potestio et al (cureus. 2022) did a retrospective study on 52 trauma patients requiring massive transfusion and found that incidence of hypocalcemia was 85 - 97%. They also found that 97% of their patients developed hypocalcemia during first six hours. Nadir occured after median of eight units of blood products were given.
Recommendation
- ATLS 10th Edition donot recommend routine administration of calcium . Calcium supplementation should be guided by level of ionised calcium.
- Joint Trauma System ( US Defense Health Agency - 2019 updates recommends use of 1gm calcium (30 ml of calcium gluconate ) immediately after first blood transfusion and then again after 4 units.
Conclusion
- Hypocalcemia is found to be common during massive transfusion. But there is lack of clear guidelines on dose and timing of calcium administration. Hence it advisable to monitor calcium at routine intervals and provide supplement based on the values.
Reference
- https://doi.org/10.1016/j.jss.2015.12.036
- Doi: 10.7759/cureus.22093
