Traumatic resuscitation is evolving – and reasonably so – to an aggressive, early-intervention strategy. The current evidence seems to suggest patients benefit from early, whole blood volume replacement in the setting of hemorrhage.
But, in order to aggressively intervene early, it’s necessary to predict such need equally early in the initial trauma assessment process. Therefore, a variety of prediction decision-instruments have been derived, such as this one from Japan. These authors looked retrospectively at 119 severely injured trauma patients, developed odds ratios for massive transfusion via logistic regression, and then created a scoring system with a cut-off predicting massive transfusion. They then subsequently validated this score on another retrospective cohort of 113 patients from the same institution. Their score contains, essentially, the expected elements – age, lactic acid level, systolic blood pressure, FAST exam findings, and pelvic fracture type – and a score of 15 or higher was 97.4% sensitive and 96.2% specific for massive transfusion.
However, what this rule predicts is not the population that needs massive transfusion – but, because both steps were performed retrospectively, it simply describes the consistency in the authors’ general practice at this single institution. At the authors’ institution, the patients that looked like the ones described by the rule – elderly, hypotensive, positive FAST, etc. – are the ones that received massive transfusion. Therefore, when they look back to derive a decision instrument – they’ll find it simply reflects their general practice. Subsequently, to validate the instrument – again, if their practices haven’t changed, the decision rule will simply accurately reflect the continued practice pattern from which it was derived. The authors do not mention whether they had a formal early massive transfusion protocol or practice in place, but, if so, this would further skew the decision instrument to reflect the guidelines guiding practice, rather than actual patient need. Finally, for one last hit to external generalizability, a “massive transfusion” was defined as 10 units of PRBCs – which, in Japan, are about 1/3rd the volume of those in the United States.
Despite its reportedly excellent performance, this rule cannot be relied upon until prospective, external study validates its use.
“Predicting the need for massive transfusion in trauma patients: The Traumatic Bleeding Severity Score”
http://www.ncbi.nlm.nih.gov/pubmed/24747455