Packed Red Blood Cells (PRBC)

Red blood cells are necessary for their oxygen-carrying capacity, and contribute to improved haemostasis through rheological effect leading to axial flow, and thus margination of platelets and plasma.

• O RhD Negative

• O RhD Positive

Fresh Frozen Plasma (FFP)

Fresh-frozen plasma (FFP) contains all of the clotting factors, fibrinogen plasma proteins, electrolytes, and physiological anticoagulants (protein C, protein S, antithrombin, tissue factor pathway inhibitor). It is prepared from the supernatant liquid obtained by centrifugation of one donation of leucocyte-depleted whole blood.

General Principles

The following principles should be incorporated into local Standard Operating Procedures:

• Emergency blood products are a precious and limited resource.

• Ensure all efforts to preserve blood volume are maximised before and during emergency blood transfusion.

• All blood components should be administered through a warmer.

• Blood components should be administered in a 1:1 ratio of FFP:PRBC.

• Calcium chloride should be co-administered early.

• Once removed from the controlled storage container blood components should be transfused within 4 hours.

• Every effort must be made to minimise wastage of blood components

Indications for Prehospital Transfusion

Transfusion should only be used when the benefits outweigh the risks and there are no appropriate alternatives. Transfusion decisions should be based on clinical assessment underpinned by evidence-based clinical guidance.

Administration of blood components is indicated in patients suffering life-threatening haemorrhagic shock as suggested by:

• Major Trauma patients meeting both the following criteria:

  • Mechanism of Injury consistent with major haemorrhage

  • Clinical signs of life-threatening haemorrhagic shock or low

• Non-trauma patients meeting the following criteria:

  • Evidence of major bleeding due to non-traumatic cause (e.g acute gastro-intestinal bleeding ruptured aortic aneurysm, major obstetric bleeding)

  • Clinical signs of life-threatening haemorrhagic shock or low output state due to haemorrhage

Clinical signs of life-threatening haemorrhagic shock - The 'Hateful 8'

The 'Hateful 8' criteria were developed by London Air Ambulance as a tool to help their clinicians identify patients with a life-threatening failure in perfusion (shock) due to haemorrhage and guide prehospital transfusion and/or REBOA. In the presence of significant external bleeding or a mechanism of injury consistent with major haemorrhage, the presence of a combination of the following features is felt to increase the likelihood of life-threatening haemorrhagic shock:

1. Pale

2. Clammy

3. Air Hunger

4. Venous Collapse

5. Low BP

6. Low/Falling ETCO2

7. Altered LOC

8. Fast or Slow Pulse

The 'Hateful 8' tool is based on the principle that no single factor can accurately predict the need for pre- hospital blood transfusion and over-reliance on systolic blood pressure and/or heart rate in isolation will result in unnecessary transfusion and wastage. By actively seeking the often-subtle corollary signs of impaired tissue perfusion, the criterion aims to better identify those patients with life threatening perfusion failure that could benefit from immediate transfusion of blood components.

Cardiac Arrest due to Haemorrhage - Low Output State in Trauma (LOST)

Patients in profound haemorrhagic shock may present with an absent central pulse but clinical evidence of residual cardiac output (e.g. ETCO2, cardiac contractility on echo, pulsatile invasive pressure trace).

Bleeding Mimics

Although haemorrhage is the commonest cause of shock in the context of major trauma, there are several other clinical conditions that are easily attributed to haemorrhagic shock and are referred to as bleeding mimics.

• Prodromal Activity - Prodromal events such as excessive exertion, illicit substances, fear, and severe anxiety can precipitate a profound sympathomimetic response to traumatic injuries, mimicking haemodynamic compromise.

• Vagal Reflexes - Incisional trauma, breach of pleural and peritoneal membranes, and blood irritation of thoracic and abdominal cavities can precipitate a profound vagal response.

• Hyperacute Head Injury - Traumatic brain injury and concussive forces to the brainstem can result in cardiovascular compromise (neurocardiac syndrome) that can mimic hypovolaemia.

• Obstructive Shock - Tension Pneumothorax and Cardiac Tamponade should be actively excluded within the primary assessment.

• Cardiogenic Shock - Likely common and multifactorial. Can be caused by direct blunt trauma to the heart, or indirectly as a consequence of hyperacute head injury, systemic acidosis, hypothermia and cytokine mediated damage.

• Neurogenic Shock - Neurogenic shock occurs when there is damage to the spinal cord above the level of T10 with subsequent loss of sympathetic outflow leading to unopposed peripheral vasodilatation. Seek other signs of cord injury.

• Medical - Medical conditions may coexist in trauma patients e.g. Acute coronary syndrome, Aortic aneurysm, etc.

• Iatrogenic - Administration of anaesthetic drugs and institution of positive pressure ventilation can result in haemodynamic deterioration.

Bleeding mimics can occur in isolation but may also occur concurrently with one another and haemorrhagic shock, making prehospital diagnosis and resuscitation extremely challenging.

Useful aids to ruling out bleeding mimics include:

• Thinking about bleeding mimics.

• Observing the temporal changes in physiology.

• Response to initial fluid challenge e.g. 250ml (5ml/kg) 0.9% Saline.

• Response to analgesic/anxiolytic agent e.g. fentanyl or ketamine.

Adults with Compressible/Controlled haemorrhage

Patients with signs of life-threatening haemorrhagic shock and controlled (non-active) bleeding should be managed with a non-restrictive approach to volume resuscitation.

• Titrate volume resuscitation to achieve normal physiology - palpable radial pulse and SBP 100-120mmHg.

• Blood should usually be the fluid of first choice, but 0.9% saline may be considered if the patient is felt to be at a low risk of further bleeding or coagulopathy.

Transfusion Procedure

Enhanced Care Services delivering prehospital blood components must have a Standard Operating Procedure that outlines the procedure for consent, administration, and documentation of blood component administration within their service. This should include but not be limited to:

• The process for patient consent (where applicable).

• The process for warming blood components.

• The process for checking blood components.

• The process for administering blood components to adult and paediatric patients.

• Post-transfusion procedure - return of unused products/resupply.

• A procedural checklist.

• Transfusion documentation.

• The procedure for reporting of adverse events.