The MHP is appropriately triggered when a patient is massively bleeding, requiring red blood cells (RBCs) AND other components, such as plasma and platelets. Do NOT call an MHP if you only need unmatched RBCs.

• Definitions of massive hemorrhage (such as 10 units/24 hours or 6 units in 4 hours) often not useful for managing patients, as hopefully one wouldn’t wait 24 hours before saying an MHP is appropriate!
• All centres must have an objective trigger, as clinical gestalt alone has poor sensitivity and specificity (~65%)

• MHP predictor scores have been published and usually include combinations of clinical parameters, laboratory results, and ultrasound findings as variables
  • Scores that use all 3 categories are the most predictive; however, laboratory results are not immediately available and may delay activation. Trauma Associated Severe Hemorrhage (TASH) and Traumatic Bleeding Severity Score (TBSS) are the most useful scores from this group
  • If ultrasound and a competent operator are available, ABC score can be used for trauma patients and performs moderately well
  • To trigger, must have ≥2 of the following:
    • • Penetrating mechanism
      • Systolic blood pressure (SBP) ≤90 mmHg, heart rate (HR) ≥120 bpm
      • Positive Focused Assessment by Sonography in Trauma (FAST) ultrasound
  • If not, use Shock Index (HR/SBP generally >1); it is easy to use and performs moderately well
  • Alternatively, the Critical Administration Threshold (≥3 units of RBCs within 1 hour) is also a useful trigger
  • Future considerations:
    • Biomarkers
    • Computer decision support tools
    • Iterative assessments
    • Physiological measurements
• Triggering process
  • Ideally, MHP should be a code and triggered with a single phone call to a hospital switchboard and then the message disseminated by switchboard to all relevant team members
  • Ideally, MHP should be an overhead code to ensure that all team members are alerted simultaneously
  • Alternatively, MHP may be triggered through computerized physician order entry (CPOE) followed by a phone alert/overhead page to relevant parties
  • Many centres also trigger via a verbal/telephone order to transfusion medicine

References:

1. Callum JL, Yeh CH, Petrosoniak A, et al. A Regional Massive Hemorrhage Protocol Developed Through a Modified Delphi Technique. CMAJ Open. 2019;7(3):e546-561.
2. Pommerening MJ, Goodman MD, Holcomb JB, et al. Clinical Gestalt and the Prediction of Massive Transfusion After Trauma. Injury. 2015;46(5):807-813.
3. Shih AW, Al Khan S, Wang AY, et al. Systematic Reviews of Scores and Predictors to Trigger Activation of Massive Transfusion Protocols. J Trauma Acute Care Surg. 2019;87(3):717-729.