Fluids and blood products in trauma Acute Care Day Scenario based teaching

Importance The two leading causes of death in trauma are neurological injury and blood loss There is much current research into optimum fluid therapies in trauma There are some differences to major haemorrhage from other sites

Reasons for debate – competing priorities Maintain perfusion Maintain coagulation Good tissue perfusion is dependent upon a good cardiac output Cardiac output is augmented by high filling pressures – need blood volume A decent blood pressure is needed to overcome tissue resistance Solution: give lots of fluids and blood High BP can dislodge forming clots, leading to continued clotting factor consumption IV fluids and red-cells dilute clotting factors Fluids can cool a patient – clotting factors work less well Solution: don’t give any fluid or blood!

What’s the solution? Some middle ground is needed. What is worse – hypoperfusion or coagulopathy?

How bad is hypo-perfusion Hypo-perfusion leading to tissue ischaemia can impair the function of all organs Tissues may start to respire anaerobically, producing lactic acid. Acidosis adversely affects enzymatic action – including the clotting cascade However, the effects of short periods of relative hypo-perfusion are usually fairly rapidly correctable

How bad is coagulopathy? Trauma patients can have multiple sites of blood loss that are not immediately controllable – ie. may need surgery or interventional radiology to cease bleeding. If coagulopathy develops, bleeding is exacerbated. This then worsens any hypoperfusion  anaerobic respiration and acidosis. You need to play “catch-up” – transfusing blood products which can cool the patient

The Lethal Triad Coagulopathy Acidosis Cold

What’s the solution then? A degree of hypo-perfusion is tolerated in the acute setting, until haemorrhage control has been achieved. In practice, this means a conscious patient with a palpable radial pulse and a systolic blood pressure of at least 80mmHg If these criteria are not met, 250ml boluses of fluids (eg. Hartmanns) can be given to boost blood pressure Coagulopathy should be aggressively avoided.

When should you start giving blood? No set rule – but in general you should try and use as little crystalloid as possible – certainly give blood if approaching 1 litre of crystalloids Crystalloid versus colloid debate: currently raging, but there appears to be minimal if any benefit in giving colloids If a trauma patient needs volume replacement, try to make as much of it blood as possible.

What blood products are there? Fresh Frozen Plasma Whole Blood Cryoprecipitate Platelets

Red blood cells Three options: O negative. Available immediately in A&E or blood bank. Group specific. Takes about 15 minutes from receipt of sample in lab. Fully cross-matched. Takes about 40 minutes from receipt of sample in lab.

Red blood cells Oxygen carrying component, so most important aspect of blood. However, the bags contain no clotting factors or platelets. These factors must also be replaced.

Fresh Frozen Plasma This contains all clotting factors Not usually administered until the patient has received at least 4 units of red cells

Platelets and cryoprecipitate Cryoprecipitate – contains a few clotting factors, but main component is fibrinogen These each contain multiple units within one bag. Bags of these are not usually given until about 8 units of red cells have been transfused Liaise with haematology regarding ongoing blood product management.

Is this going to change?? Evidence from the military supports a more liberal usage of FFP, platelets and cryoprecipitate. Suggest using 1 unit of FFP with every 1 or 2 units of red cells. This is not current practice in UK hospitals….but things may change!

Clotting augmentation Fibrinolysis is the process of clot lysis Tranexamic acid is an anti-fibrinolytic: it inhibits clot breakdown It is cheap and very safe Good evidence that administering this to bleeding trauma patients reduces their mortality. Give this with your first unit of blood.

Clotting optimisation The clotting cascade is a series of enzymes They work best at normal body temperature and pH Critically important to maintain these – warm all blood products, keep patient covered. Clotting factors also need calcium – levels can drop in major haemorrhage, so top up if necessary

What happens once bleeding has stopped? Definitive control of bleeding is usually surgical. Once achieved, priority shifts from coagulation maintenance to perfusion maintenance Aim for higher blood pressure, be more liberal with administration of blood products. May also give some IV fluids.

Summary Blood and fluid therapy in trauma is not straight-forward Perfusion can be relatively sacrificed to maintain coagulation Try to minimise use of crystalloids or colloids – especially if large blood loss is anticipated Avoid development of the lethal triad: cold, acidosis and coagulopathy