Activate on the physiology. Transfuse in ratio. Then chase the targets — and stand it down.

• “Use physiological criteria that include the patient's haemodynamic status and their response to immediate volume resuscitation to activate the major haemorrhage protocol.” (NG39 1.5.13)
• “Do not rely on a haemorrhagic risk tool applied at a single time point to determine the need for major haemorrhage protocol activation.” (NG39 1.5.14)

BSH 2022 frames the same idea as a dynamic definition based on “the clinical status of the patients, their physiology and response to resuscitation therapy… e.g., heart rate >110 beats/min and/or systolic blood pressure <90 mm Hg.” And the warning that catches people out: “these physiological changes may be masked in some patient groups, e.g., the elderly or pregnancy” — which is why the numbers alone are not enough.

On activation: take a baseline group-and-screen ideally before the first unit; give emergency group O while waiting. “Group O RhD- and K-negative RBCs should be prioritised for females of childbearing potential (aged <50 years) and in patients whose sex is unknown.” Every patient wears an ID wristband — wrong-blood-in-tube is the commonest emergency-transfusion near miss.

• Restrictive until control: “For patients with active bleeding use a restrictive approach to volume resuscitation until definitive early control of bleeding has been achieved” (NG39 1.5.18). “In hospital settings do not use crystalloids for patients with active bleeding” (1.5.23).
• Red cells: BSH recommends a threshold Hb of 70 g/l and a post-transfusion target range of 70–90 g/l, alongside clinical judgement of severity. “Once bleeding is controlled, there is no indication to restore Hb to physiological levels.”
• Ratio, trauma: NG39 says use 1:1 plasma to red cells in adults (1.5.24). BSH agrees: “plasma should be given early as part of initial resuscitation in major haemorrhage due to trauma, and in a 1:1 (not >1:2 ratio) with RBCs, until results from coagulation monitoring are available.”
• Ratio, general (no lab results yet): “units of FFP be transfused in at least a 1:2 ratio with units of RBCs.” Then guided by tests, “aiming to maintain the PT ratio at <1.5-times mean normal (or equivalent)”.
• Children: NG39 — 1 part plasma to 1 part red cells, volume based on the child's weight (1.5.25). FFP dose is weight-adjusted, 15–20 ml/kg.
• Fixed then guided: “For patients with active bleeding, start with a fixed-ratio protocol for blood components and change to a protocol guided by laboratory coagulation results at the earliest opportunity” (NG39 1.5.27).

Check haemostatic tests “every 30–60 min depending on the severity of the haemorrhage”. Use the Clauss fibrinogen assay, not a PT-derived fibrinogen, which can read falsely high. Viscoelastic assays (ROTEM/TEG) can guide component therapy but are “less sensitive to measuring fibrinolytic activation in trauma and should not be used to withhold the use of TXA.”

This is the single most setting-dependent decision in the protocol.

• Trauma: “Patients with traumatic injury (including mild–moderate TBI) should be given TXA as soon as possible after injury (and no later than 3 h); a suitable regimen includes 1 g bolus dose intravenously over 10 min, followed by a maintenance infusion of 1 g over 8 h should be used.” NG39 adds: not after 3 hours unless there is evidence of hyperfibrinolysis (1.5.5).
• PPH: “an initial dose of TXA (1 g intravenously) is given to women with PPH within 3 h of bleed onset. If bleeding continues after 30 min, or it stopped and restarted within 24 h of the first TXA dose, a second dose of 1 g should be given.”
• Surgery: “all patients having in-patient surgery should receive 1 gram of tranexamic acid prior to skin incision”.
• Gastrointestinal bleeding: “Tranexamic acid is not recommended for patients with acute gastrointestinal bleeding” (grade 1A). The HALT-IT trial found no mortality benefit and a higher risk of venous thromboembolism. This is the trap: the trauma reflex to give TXA is wrong here.

The headline recommendation: “Tranexamic acid is recommended for patients with presentations of major bleeding due to trauma and PPH, but not gastrointestinal bleeding” (grade 1A).

• Reverse only if bleeding. “Rapidly reverse anticoagulation in patients who have major trauma with haemorrhage” (NG39 1.5.6); “do not reverse anticoagulation in patients who do not have active or suspected bleeding” (1.5.12).
• Vitamin K antagonist, adult, bleeding: “use prothrombin complex concentrate immediately” (1.5.8); do not use plasma to reverse a VKA (1.5.9).
• Any other anticoagulant (adult), or any anticoagulant in a child: consult a haematologist immediately (1.5.10–1.5.11). The DOAC agents and the PCC dose are in the reversal module.
• Antiplatelet + intracranial bleed: the PATCH trial found platelet transfusion increased death in spontaneous intracerebral haemorrhage on antiplatelets — do not reflexively transfuse platelets to “cover” an antiplatelet in this setting.
• Not recommended: “The use of desmopressin, rVIIa or aprotinin is not recommended in the management of major haemorrhage unless as part of a clinical trial” (grade 1B).

“Hypothermia, acidosis and hypocalcaemia will further worsen coagulation.” Each is preventable in the resus room:

• Warmth: “Minimise ongoing heat loss in patients with major trauma” (NG39 1.6.1). Transfuse through a blood warmer; the resuscitated, exposed patient is the one who gets cold.
• Calcium: “Calcium levels should be monitored and supplemented as appropriate.” Citrate in transfused blood chelates calcium, so massive transfusion drives ionised calcium down. BSH sets no specific numeric threshold; keep ionised calcium in the normal range per your local protocol, and check it early and often.
• Acidosis: is largely corrected by restoring perfusion — stopping the bleeding and transfusing, not by giving bicarbonate.

“Deactivation of the MHP is also important, as delays in standing down the MHP will lead to blood wastage and prevent resumption of other laboratory services.” Frontline staff should “know when to activate and deactivate the local MHP” (grade 2B).

Stand down explicitly, tell the laboratory, return unused components, and convert the patient's emergency or major-incident identifier back to their routine hospital identifier. The protocol is not finished until it has been switched off.

• It is not your trust's MHP. Pack contents, phone numbers and exact triggers are local and agreed with your transfusion lab — follow those.
• It does not give the PCC or reversal-agent dose. Those are in the reversal module.
• It does not set VHA (ROTEM/TEG) numeric thresholds. BSH points to a separate VHA guideline for those.
• It does not decide the source-control procedure — laparotomy, IR, endoscopy, uterotonics — which is the definitive treatment the protocol buys time for.
• It does not give paediatric volumes. NG39 is weight-based in children; use your paediatric MHP and the paediatric tool.

• NICE NG39. Major trauma: assessment and initial management. Published 17 February 2016. The full Recommendations chapter was parsed; the haemorrhage recommendations used here are in section 1.5, and heat and pain in 1.6–1.7. Recommendations apply to both children (under 16s) and adults (16 or over) unless otherwise specified.
• Stanworth SJ, Dowling K, Curry N, et al.; Transfusion Task Force of the British Society for Haematology. Haematological management of major haemorrhage: a British Society for Haematology Guideline. Br J Haematol 2022;198(4):654–667. The full guideline, including the graded Recommendations, was parsed for this module.

Every quotation on this page is verbatim from the recommendation or guideline named beside it. HALT-IT (Lancet 2020) and PATCH (Lancet 2016) are named as the trials the BSH recommendations rest on.