Emergency Transfusion

Objectives

To guide military healthcare providers in the delivery of emergency transfusion of blood and blood components for patients with major bleeding and/or haemorrhagic shock in operating environments forward of deployed hospital care.

Scope

Emergency transfusion is defined in Clinical Guidelines for Operations as the emergency administration of blood and blood components to patients with haemorrhagic shock due to bleeding.

This emergency transfusion guideline is intended to support military clinicians managing patients with major bleeding and/or haemorrhagic shock in the forward setting with limited resources. For the deployed military population this is most likely to occur because of injury, although emergency transfusion might also be required for medical causes (such as acute gastrointestinal bleeding).

This guideline does not deal with the technical elements of how to administer a blood transfusion safely or the complications of blood transfusion: these and related guidance, including the Major Haemorrhage guideline for deployed hospital care, can be found in the blood transfusion section of CGOs here.

 

The availability of blood and blood components for emergency transfusion will vary depending on operational context. The following products may be available for use, but not all will be available in all operational situations: 

  • Whole blood (WB), either fresh or cold-stored
  • Blood components, which may include:
    • Packed Red Blood Cells (PRBCs)
    • Fresh Frozen Plasma (FFP) 
    • Dried plasma (eg LyoPlas™)
    • Platelets
    • Fibrinogen concentrate
    • Cryoprecipitate

This guideline relates to emergency transfusion only and therefore describes the use of

whole blood (WB)

packed red blood cells (PRBCs)

plasma (which may be fresh frozen plasma that has been defrosted for use, or dried plasma that has been reconstituted for use)

Audience

This guideline is intended for use by registered healthcare professionals and those holding current non-medical authorisation (NMA) competency, fulfilling a general role in a forward medical location or in an Emergency Department on deployed operations.

Initial Assessment & Management

Emergency transfusion is one component of damage control resuscitation (DCR), and should be undertaken alongside other measures to treat haemorrhagic shock, including: 

  • Systematic MARCH (or <C>ABCDE) approach.
  • Control of major haemorrhage: for example CAT application, dressings, splinting 
  • Early tranexamic acid administration. 
  • Minimal handling to preserve clot stability. 
  • Prevention of hypothermia (warm the patient, warm the blood). 
  • Treatment of pain.
  • Minimising delays to definitive/higher levels of care. 

Indications for Emergency Transfusion

Traumatic or non-traumatic major haemorrhage 

+ 

Signs of reduced organ perfusion 

(HR >110bpm, systolic BP <90mmHg, altered mental state) 

 

 

What to give

If whole blood is available, administer one unit initially, then reassess need for further units depending on response. 

Otherwise aim to administer blood components in a 1:1 ratio (1 unit PRBCs : 1 unit plasma), then reassess.

Plasma alone can be used until whole blood or packed red blood cells are available.

Tranexamic acid should be given promptly to all patients in whom significant haemorrhage is suspected with an initial bolus of 1g IV/IO. (2g if there is a head injury with GCS ≤12).
Hypocalcaemia is associated with trauma and exacerbated by transfusion of blood or blood components: initially administer 10ml of 10% Calcium Chloride to patients who require emergency transfusion. If possible use separate IV/IO access, or otherwise ensure that the line is thoroughly flushed before and after calcium administration to avoid precipitation. 

Calcium dosing - give 10ml of 10% calcium chloride without delay when a need for emergency transfusion is identified. Reassess after two units of whole blood, or after four units of blood components (two PRBC and two plasma). If further transfusion is required then give a further dose of 10ml 10% calcium chloride. As soon as testing available, confirm ionised calcium levels in order to prevent iatrogenic hypercalcaemia.

Women of childbearing potential - Whole blood or PRBCs provided for emergency transfusion will normally be either Group O RhD negative or Group O RhD positive. Women of child-bearing potential should ideally be transfused Group O RhD negative to avoid sensitisation if the patient is themselves RhD negative. However, if only Group O RhD positive is available, transfusion MUST NOT be delayed. The risks associated with delaying transfusion vastly outweigh the risks of sensitisation.

Crystalloid fluid - If blood or blood components are unavailable in any form, then use crystalloid fluid. Although blood and blood components are preferred, inadequate resuscitation is more harmful than crystalloid-based resuscitation. Use 0.9% sodium chloride or Hartmann’s solution. 

 

How much to give

For patients with penetrating or blunt trauma - tolerate hypotension for up to an hour following injury to optimise clot formation and stabilisation:

  • Administer blood products or IV crystalloid to maintain a systolic BP>90mmHg OR a palpable radial pulse.
  • If required to administer IV crystalloid, give in boluses of 250mls to a maximum of 2000mls. 

 

In patients with injury patterns that includes a suspected traumatic brain injury then prioritise the dominant pathology: 

  • If haemorrhagic shock/bleeding is the dominant condition, continue hypotensive resuscitation strategy and target a radial pulse / systolic BP >90mmHg. 
  • If traumatic brain injury is the dominant condition, use a normotensive resuscitation approach to maintain adequate cerebral perfusion, targeting a systolic BP >110mmHg.  

Advanced Assessment & Management

Major Haemorrhage GuidelineFor the management of emergency transfusion in the deployed hospital environment, including resuscitation and blood/blood component use guided by point of care and lab testing, refer to the Major Haemorrhage CGO (link to follow).

Prolonged Casualty Care

If a hypotensive resuscitation approach has been initially used, this should not be continued for more than one hour following injury. After this first hour, further emergency transfusion should aim to normalise haemodynamic status (typically aiming for a systolic BP of >110mmHg).

In the prolonged care environment, patients who have received emergency transfusion should also have treatments that support the other components of damage control resuscitation continued. In particular:

  • Ensure that a thorough MARCH assessment has been completed including mitigation of hypothermia.
  • Administer antibiotics, analgesia and anti-emetics as indicated
  • If bleeding is due to trauma, follow the initial bolus of TXA with an infusion of 1g over 8 hrs
  • Complete a thorough secondary survey to identify and address other sources of blood loss

Patients should continue to be monitored for any deterioration or signs of acute transfusion reactions that may emerge after emergency transfusion has been completed.

 

Fibrinogen Replacement

Fibrinogen concentrate is not within the main scope of this guideline as it will normally only be available in a deployed hospital environment where it should be administered following laboratory testing in accordance with guidance in the major haemorrhage guideline.

However, in limited circumstances fibrinogen replacement may be carried in a forward location where laboratory testing is not available, and may be administered as part of ongoing resuscitation if clinical features of coagulopathy (such as cannula site bleeding) are seen despite balanced blood component resuscitation.

Fibrinogen should only be administered empirically in cases of prolonged resuscitation without access to laboratory testing.

Paediatric Considerations

Children have a smaller total blood volume than adults. Small volume losses in children can therefore be physiologically significant.
Children have smaller stroke volumes than adults so are more reliant on mounting a tachycardia to maintain their cardiac output than adults. Hypotension in children is therefore a sign of acute physiological decompensation and imminent cardiorespiratory arrest.  

 

Normal values for paediatric vital signs differ significantly from adult values: use the paediatric ‘Page per Age’ reference in CGOs (here).  

Suspect major bleeding (>40% volume loss) if clinical parameters are as follows: 

Age 

Heart rate (bpm) 

sBP (mmHg) 

<1 year 

>160 

<70 

1-2 years  

>150 

<80 

3-5 years 

>140 

<80 

6-12 years 

>120 

<90 

>12 years 

>100 

<100 

Any child 

Loss of radial pulse, increased work of breathing/tachypnoea, abnormal mental state. 

 

Hypotensive resuscitation strategies should not be used in children. Aim for normotension irrespective of the time since injury. 

 

What to give: 

Consult page for age guidelines for doses appropriate to age and weight.

In general, give a bolus of 10ml/kg of whole blood, or 5ml/kg packed red blood cells and 5ml/kg of plasma in a 1:1 ratio then reassess and repeat as needed. Aim to restore normal vital signs for the child’s age. 

Give tranexamic acid as a bolus in all patients suspected to have significant haemorrhage due to trauma - use page for age to confirm the paediatric dose which is based on 15mg/kg to a maximum of 1g (30mg/kg to a maximum of 2g if there is a head injury with GCS ≤12).

Give 10% calcium chloride without delay to all patients who require emergency transfusion - use page for age to confirm the paediatric dose which is based on 0.2ml/kg 10% calcium chloride to a maximum of 10ml.

For further doses of calcium, follow the same approach as for adults: reassess either after transfusing two boluses of whole blood or after transfusing both two boluses of PRBC and two of plasma. If further transfusion is indicated then repeat the dose of 10% calcium chloride, and continue this pattern until testing of calcium levels is available. 

If blood or blood components are not available, use crystalloid fluid in bolus doses of 10ml/kg. 

 

Haemorrhagic Shock & Major Haemorrhage

Haemorrhagic shock due to bleeding is the leading preventable cause of death for injured patients, with the majority of these deaths occurring in the pre-hospital setting [8].  These early deaths are driven by an abnormal cycle of physiological outcomes due to bleeding: hypothermia, acute traumatic coagulopathy and metabolic acidosis [3].  

Bleeding sufficient to cause haemorrhagic shock can be internal or external in origin, and the severity of this bleeding can be challenging to recognise early. ‘Major haemorrhage’ will usually be associated with haemorrhagic shock and is defined as bleeding that leads to a heart rate of >110bpm or a systolic BP (sysBP) <90mmHg [10]. A ‘major haemorrhage’ CGO exists to support military medical teams in deployed hospital settings, and this comprehensive guideline should be used when there is improved access to blood and/or blood components and biochemical/haematological tests (e.g. Hb, pH, lactate, coagulation profile), such as the Role 2 (or higher) environment. 

Damage Control Resuscitation

Damage control resuscitation (DCR) is the systematic approach taken to managing bleeding trauma patients. DCR begins in the prehospital phase and continues through damage control surgery (+/- definitive surgery) and the post-operative critical care phase of treatment.  

The goals of DCR are: 

  1. Rapid control of bleeding – including surgery or interventional radiology when required. 
  2. Restoration of circulating blood volume with emergency transfusion of blood and/or blood components. 
  3. Prevention of hypothermia, acute traumatic coagulopathy and metabolic acidosis. 

Hypotensive Resuscitation & Blood Products

There is uncertainty about the most effective volume-replacement strategy in bleeding trauma patients. This uncertainty includes: 

  1. What to give (e.g. exactly what blood components, or what other fluid if blood and/or blood components are unavailable). 
  2. How much to give (e.g. what physiological or biochemical parameters to target). 

Evidence over the last 20 years (which includes evidence from military populations in combat) favours a hypotensive resuscitation strategy using blood components such as Packed Red Blood Cells (PRBCs) and Fresh Frozen Plasma (FFP), given in balanced ratios (e.g. 1 PRBCs : 1 FFP) until definitive bleeding control can be achieved  [3,9].  

Alternatives to PRBCs and FFP include Whole Blood (WB) and dried plasma (e.g. LyoPlas™).  

Hypotensive resuscitation involves targeting a systolic blood pressure high enough to maintain critical organ perfusion (i.e. brain, heart) but low enough not to disrupt the potentially unstable clots critical to early haemostasis. Once definitive control of bleeding has been achieved, hypotensive resuscitation can stop and normalisation of haemodynamic status should be targeted [3].  

Hypotensive resuscitation strategies result in fewer overall blood products being transfused per patient, less volume of intravenous crystalloid being administered, and a lower incidence of acute respiratory distress syndrome and multi-organ failure after injury [9]. These factors are important considerations in military operational contexts where there may be a scarcity of blood/blood components, prolonged timelines to definitive care and limited critical care capacity.

Blood Pressure Thresholds for Emergency Transfusion

Although hypotensive resuscitation is a widely used strategy, there is no consensus on the exact value of the physiological parameters used to define hypotension or to determine the thresholds for treatment with blood/blood components or other IV fluids. A sysBP of >90mmHg or MAP of >60mmHg / presence of a peripheral pulse is thought adequate to ensure cerebral and coronary perfusion [1,2,3,9].  

The aim of emergency transfusion is to treat haemorrhagic shock by maintaining organ perfusion through the restoration of the patient’s circulating volume, as part of damage control resuscitation. Emergency transfusion should be initiated when there is evidence of haemorrhage with signs of impaired organ perfusion (shock), such as:

Signs of shock 

Causes 

Elevated respiratory rate 

Metabolic acidosis 

Elevated heart rate 

↑ ↑ catecholamine release due to ↓ ↓ cardiac filling 

Hypotension (systolic BP <90mmHg) 

↓ ↓ circulating volume 

Altered / abnormal mental state 

↓ ↓ cerebral perfusion 

Decisions regarding starting treatment with blood and/or blood components (or other IV fluids if blood products are not available) should be based an assessment of organ perfusion using sysBP and cerebral perfusion (i.e. normality of mental state). Where this is not possible (e.g. equipment not available or readings being inaccurate/incompatible with the patient’s observed state) then peripheral/central pulses should be used as a surrogate marker, with a central pulse representing a sysBP >60mmHg and a radial pulse a sysBP >90mmHg [1,2]. 

In patients with mixed injury patterns, such as polytrauma with significant head and torso injury, UK guidelines recommend BP targets tailored to the dominant pathology [1,2]:  

  • Hypotensive resuscitation where bleeding is the greatest threat to life (i.e. target a radial pulse / systolic BP >90mmHg) 
  • Normotensive resuscitation where traumatic brain injury is dominant (i.e. target a systolic BP >110mmHg) . 

Last reviewed: 04/03/2026

Next review date: 04/03/2027

Related resources

Blood Transfusion CGOs

References

[1] Joint Royal Colleges Ambulance Liaison Committee and Association of Ambulance Chief Executives (2022) JRCALC Clinical Guidelines 2022. Bridgwater: Class Professional Publishing. Available at: https://icpgweb.co.uk/guidelines/D0370  

[2] National Institute for Health and Care Excellence (NICE) (2016) Major trauma: assessment and initial management. NG39. Available at: https://www.nice.org.uk/guidance/NG39/chapter/Recommendations#management-of-haemorrhage-in-prehospital-and-hospital-settings  (Accessed: day month year). 

[3] Spahn DR, Bouillon B, Cerny V, Duranteau J, Filipescu D, Hunt BJ, Komadina R, Maegele M, Nardi G, Riddez L, Samama CM, Vincent JL, Rossaint R. The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition. Crit Care. 2019 Mar 27;23(1):98. https://doi.org/10.1186/s13054-019-2347-3  

[4] ter Avest, E., Carenzo, L., Lendrum, R.A. et al. Advanced interventions in the pre-hospital resuscitation of patients with non-compressible haemorrhage after penetrating injuries. Crit Care 26, 184 (2022). https://doi.org/10.1186/s13054-022-04052-7  

[5] Pusateri AE, Moore EE, Moore HB, et al. Association of Prehospital Plasma Transfusion With Survival in Trauma Patients With Hemorrhagic Shock When Transport Times Are Longer Than 20 Minutes: A Post Hoc Analysis of the PAMPer and COMBAT Clinical Trials. JAMA Surg. 2020;155(2):e195085.  

[6] Malkin, Michael et al. Effectiveness and safety of whole blood compared to balanced blood components in resuscitation of hemorrhaging trauma patients - A systematic review. Injury. 2021. 52(2); 182 – 188. https://doi.org/10.1016/j.injury.2020.10.095  

[7] Crombie, Nicholas et al. Resuscitation with blood products in patients with trauma-related haemorrhagic shock receiving prehospital care (RePHILL): a multicentre, open-label, randomised, controlled, phase 3 trial. The Lancet Haematology. 2022. 9(4), e250 - e26. https://doi.org/10.1016/S2352-3026(22)00040-0  

[8] Brohi, K., Gruen, R.L. & Holcomb, J.B. Why are bleeding trauma patients still dying?. Intensive Care Med 45, 709–711 (2019). https://doi.org/10.1007/s00134-019-05560-x  

[9] Owattanapanich, N., Chittawatanarat, K., Benyakorn, T. et al. Risks and benefits of hypotensive resuscitation in patients with traumatic hemorrhagic shock: a meta-analysis. Scand J Trauma Resusc Emerg Med 26, 107 (2018). https://doi.org/10.1186/s13049-018-0572-4  

[10] Stanworth SJ, Dowling K, Curry N, Doughty H, Hunt BJ, Fraser L, et al., on behalf of The Transfusion Task Force of the British Society for Haematology. A guideline for the haematological management of major haemorrhage: A British Society for Haematology Guideline. Br J Haematol. 2022; 198: 654–667. https://doi.org/10.1111/bjh.18275  

[11] Soutar R, McSporran W, Tomlinson T, Booth C, Grey S. Guideline on the investigation and management of acute transfusion reactions. Br J Haematol. 2023; 201(5): 832–844. https://doi.org/10.1111/bjh.18789