ABC Score for Massive Transfusion Calculator

How does this ABC score for massive transfusion calculator work?

This is a health tool evaluating the need for blood transfusion in the ER setting and not only. It helps clinicians evaluate some simple bedside data about the patient and say whether a blood intervention is likely or not.

This ABC score for massive transfusion calculator is based on the original study by Nunez and collaborators, aiming to see the connection between the presence of the following 4 criteria, non laboratory and the necessity of initiating transfusion protocols on trauma patients:

■ Penetrating mechanism of injury – this is the factor showing that the trauma patient is more likely to be needing blood through the protocol.

■ Positive focused assessment sonography for trauma (FAST examination) – this is an effective assessment in blunt trauma, a rapid bedside examination that screens for pericardial effusion or hemoperitoneum.

■ Arrival systolic blood pressure of 90 mmHg or less – hypotension caused by loss of blood is another positive criteria in ABC.

■ Arrival heart rate of 120 bpm or above – increased heart rate trying to compensate the blood depletion.

Every health care institution has customized transfusion protocols but most commonly they contain plasma, platelets and packed red blood cells.

Complications can appear due to the clinicians waiting too long before initiating the protocols and although massive transfusions only occur in 3 to 5% of trauma cases, when this happens and the intervention is not rapid, morbidity and mortality rates increase significantly.

ABC score interpretation

The presence of each of the above four criteria weighs 1 point from the overall 4 points attainable. Therefore the scores range from 0 to 4.

Scores below 2 are unlikely to require massive transfusion (10 units or more of PRBCs) with the probability growing towards 100% chances of transfusion in cases scoring 4 in ABC.

The sensitivity and specificity ranges are 75% to 90%, respectively 67% to 88% at multiple trauma centers.

Massive transfusion protocol and guidelines

It is known that the management of acute coagulopathy of trauma through MT protocols with balanced ratios of blood products and coagulation factors improves chances of survival and recovery. But one of the main issues encountered by specialists, one that the ABC score tries to combate, is that of knowing when the exsanguination present is lethal.

MT is defined as the transfusion of 10 units or more of pRBC in the first 24 hours after admission as a response to massive and uncontrollable hemorrhage. Another definition uses the measure of 5 units of pRBC over 3 hours. This is a kind of treatment aiming to restore the normal blood volume and recalibrate the blood composition to the health limits to restore homeostasis, oxygen carrying and oncotic pressure.

The protocol involves the sequence of components, administering the proper replacement, sampling the procedure, making blood bank arrangements and monitoring the process and the components.

What it also needs to be noted is that MTs are associated with several hemostatic and metabolic complications and the difficulty only starts with finding the right type of donated blood, followed by exacerbated difficulties due to the blood volume replacement.

Some of the other factors to take into account include thrombocytopenia, coagulation factor depletion, hyperkalaemia or acid base disturbances.

References

1) Nunez TC, Voskresensky IV, Dossett LA, Shinall R, Dutton WD, Cotton BA. (2009) Early prediction of massive transfusion in trauma: simple as ABC (assessment of blood consumption)? J Trauma; 66(2):346-52.

2) Cotton BA, Dossett LA, Haut ER, Shafi S, Nunez TC, Au BK, Zaydfudim V, Johnston M, Arbogast P, Young PP. (2010) Multicenter validation of a simplified score to predict massive transfusion in trauma. J Trauma; 69 Suppl 1:S33-9.