Hypofibrinogenaemia and hypocalcaemia in adult trauma patients receiving pre-hospital packed red blood cell transfusions: Potential for supplementary pre-hospital therapeutic interventions

Comparison between point-of-care international normalised ratio, COAST, TICCS and truncated FibAT scores to rule in clinically significant hypofibrinogenaemia in the prehospital setting

BACKGROUND

Hypofibrinogenaemia on ED arrival and in the prehospital setting has been associated with both increased mortality and increased blood transfusions. The timely administration of fibrinogen-rich products on arrival to hospital is difficult to achieve and there is no clinical benefit with early, in-hospital empirical fibrinogen supplementation.

METHODS

This was a prospective study of a convenience sample of adult trauma patients who had blood drawn in the prehospital setting prior to the administration of tranexamic acid. A point-of-care international normalised ratio (PoCINR) was performed at the time of blood draw, and Coagulopathy of Severe Trauma (COAST) score, Trauma Induced Coagulopathy Clinical Score (TICCS) and truncated Fibrinogen on Admission in Trauma (FibAT) score were calculated. Hypofibrinogenaemia was defined as a FibTEM A5<10 or a fibrinogen level ≤1.5 g/L with a clinically important specificity defined as 85%.

RESULTS

A total of 152 patients were included in the primary analysis. The cohort was predominately male (82.9%) with a median age of 35 years (IQR 26-51). The median Injury Severity Score was 17 (IQR 10-25.5) with 18.4% sustaining penetrating trauma and 24.3% receiving prehospital blood transfusions. The area under the receiver operating characteristic curve for hypofibrinogenaemia was PoCINR: 0.63 (95% CI 0.53 to 0.73), FibAT: 0.57 (95% CI 0.47 to 0.67), COAST: 0.47 (95% CI 0.37 to 0.58) and TICCS: 0.50 (95% CI 0.40 to 0.61). A cut-off PoCINR value of ≥1.2, FibAT score ≥4, COAST≥4 and TICCS≥12 all yielded ≥85% specificity in detecting hypofibrinogenaemia.

CONCLUSIONS

PoCINR and a truncated FibAT are potential tools for the prehospital detection of hypofibrinogenaemia. Future work should examine the feasibility of PoC devices to test for hypofibrinogenaemia in the prehospital setting and if the use of PoC devices and/or clinical risk stratification tools would result in more rapid fibrinogen replacement.

Hypocalcaemia upon arrival (HUA) in trauma patients who did and did not receive prehospital blood products: a systematic review and meta-analysis

PURPOSE

Hypocalcaemia upon arrival (HUA) to hospital is associated with morbidity and mortality in the trauma patient. It has been hypothesised that there is an increased incidence of HUA in patients receiving prehospital transfusion as a result of citrated blood products. This research aimed to determine if there was a difference in arrival ionised calcium (iCa) levels in trauma patients who did and did not receive prehospital transfusion.

METHODS

We conducted a systematic review and meta-analysis of patients with an Injury Severity Score (ISS) > / = 15 and an iCa measured on hospital arrival. We then derived mean iCa levels and attempted to compare between-group variables across multiple study cohorts.

RESULTS

Nine studies reported iCa on arrival to ED, with a mean of 1.08 mmol/L (95% CI 1.02-1.13; I2 = 99%; 2087 patients). Subgroup analysis of patients who did not receive prehospital transfusion had a mean iCa of 1.07 mmol/L (95% CI 1.01-1.14; I2 = 99%, 1661 patients). Transfused patients in the 3 comparative studies had a slightly lower iCa on arrival compared to those who did not receive transfusion (mean difference - 0.03 mmol/L, 95% CI - 0.04 to - 0.03, I2 = 0%, p = 0.001, 561 patients).

CONCLUSION

HUA is common amongst trauma patients irrespective of transfusion. Transfused patients had a slightly lower initial iCa than those without transfusion, though the clinical impact of this remains to be clarified. These findings question the paradigm of citrate-induced hypocalcaemia alone in trauma. There is a need for consensus for the definition of hypocalcaemia to provide a basis for future research into the role of calcium supplementation in trauma.