This week we have a nice paper that highlights some of the ongoing thoughts and controversies about the use of calcium in major haemorrhage protocols. Hopefully you’ve already read Iain’s excellent review of the matter here which is well worth a read together with the links at the end of this article. You should probably also read up on the RePHILL trial of blood in major trauma patients which has it’s own controversies and nuances that are asking questions of those organisations using prehospital blood products.
In that review Iain concluded (and I agree) that we should be thinking about the early use of calcium in major trauma. We know that hypocalcaemia is associated with poor outcomes and that blood products are associated with a higher incidence of hypocalcaemia (though do remember this is association and not definitive evidence of causation). At the moment then it seems logical that giving calcium to patients receiving blood products is a sensible thing to do. However, the question of how much calcium, in what form, how often and when remains unresolved.
In our local service the SOP states that 10ml of 10% calcium should be given after every 2 units of blood product to keep the iCa above 1.0 (although we are unable to measure this at the moment). So a decent dose of Calcium, but arguably reactive rather than proactive?
Is this a consensus view though? What are other services doing and should we be doing something different, agreeing a consensus statement or even working to primary research to answer an unanswered question?
This month we have a paper that at least answers the first of these questions. Caroline Leech and Eleri Clarke surveyed UK air ambulance services to determine if, how and when they use calcium in patients receiving blood products. The abstract is below, but as always do please read the full paper and come to your own conclusions.
It’s essentially a survey paper. I’m always a little sceptical about surveys as they tend to have low return raters (so favouring returns from the enthusiastic or disgruntled) or they tell us what people think they do rather than what they actually do. That said, in this case I’m less concerned as the basic ask it to look at intentional protocols for the administration of calcium in patients receiving blood products in prehospital care. That’s the sort of question which is reasonable to ask via a survey methodology like this (but with some concerns about intention vs. reality of practice).
What questions were they asking?
The full questionnaire is available in the supplementary materials, but in essence they looked for who carries blood products, how much is carried, and whether calcium is part of the SOP and if so how is it used?
What did they find?
There are 25 services using prehospital blood products in the UK. There is quite a bit of variability in what is carried ranging from just 4 units Lyoplas or 2 units PRBCs, through to 2 PRBC O neg, 2 PRBC O pos, 4 FFP, 4 LyoPlas, 4 g fibrinogen. That translates into a lot of variability in SOPs about what is given, how it is given and when it is given. In some cases I suspect this is due to practical and pragmatic issues, but such variability will always ask the question of us all as to what is best for our patients?
I love it when we find variability in practice as it either means that there is a learning need (the right answer is out there, but people don’t know it yet) OR there is a research need. In this case I think it’s clearly the latter.
Although I’m an enthusiast for early calcium as that is where the association of mortality seems to be at the moment from the secondary analysis of studies like PAMPER and COMBAT, I’m also mindful from an EBM perspective that association is not causation and there are also potential harms for hypercalcaemia.
It seems that we need more data to make an informed decision here and I’m hopeful that this study, together with observational data from other clinical trials will push us in that direction. I sincerely hope that this and others
As this was a UK study I’d be interested to know what the rest of the world thinks, and does. Please leave a comment or join in our twitter discussions.
Leech C, Clarke E. “Pre-hospital blood products and calcium replacement protocols in UK critical care services: A survey of current practice”: https://www.sciencedirect.com/science/article/pii/S2666520422000820
Iain Beardsell, “Hypocalcaemia, Trauma and Major Transfusion. St Emlyn’s,” in St.Emlyn’s, May 22, 2021, https://www.stemlynsblog.org/hypocalcaemia-trauma-and-major-transfusion-st-emlyns/.
Hypocalcemia in trauma patients: A systematic review: Journal of Trauma and Acute Care Surgery: February 2021 – Volume 90 – Issue 2 – p 396-402 doi: 10.1097/TA.0000000000003027 https://journals.lww.com/jtrauma/Fulltext/2021/02000/Hypocalcemia_in_trauma_patients__A_systematic.26.aspx
Ditzel RM Jr, Anderson JL, Eisenhart WJ, Rankin CJ, DeFeo DR, Oak S, Siegler J. A review of transfusion- and trauma-induced hypocalcemia: Is it time to change the lethal triad to the lethal diamond? J Trauma Acute Care Surg. 2020 Mar;88(3):434-439. doi: 10.1097/TA.0000000000002570. PMID: 31876689.
EMCrit 323 – New Trauma Resus Insights with Prof. Karim Brohi https://emcrit.org/emcrit/trauma-brohi/
Simon Carley, “JC: The metabolic and biochemical characteristics of packed red cell transfusions.,” in St.Emlyn’s, August 23, 2019, https://www.stemlynsblog.org/jc-the-metabolic-and-biochemical-characteristics-of-packed-red-cell-transfusions/.
Zaf Qasim, “Everything old is new again – whole blood in the trauma bay – St Emlyn’s,” in St.Emlyn’s, November 9, 2018, https://www.stemlynsblog.org/whole-blood-in-trauma-st-emlyns/.
Pusateri AE, Moore EE, Moore HB, Le TD, Guyette FX, Chapman MP, Sauaia A, Ghasabyan A, Chandler J, McVaney K, Brown JB, Daley BJ, Miller RS, Harbrecht BG, Claridge JA, Phelan HA, Witham WR, Putnam AT, Sperry JL. Association of Prehospital Plasma Transfusion With Survival in Trauma Patients With Hemorrhagic Shock When Transport Times Are Longer Than 20 Minutes: A Post Hoc Analysis of the PAMPer and COMBAT Clinical Trials. JAMA Surg. 2020 Feb 1;155(2):e195085. doi: 10.1001/jamasurg.2019.5085. Epub 2020 Feb 19. PMID: 31851290; PMCID: PMC6990948.