Definition

Loss of one blood volume (5 L in an adult) within a 24 hr period, or 50% blood volume within 3 hours or a rate of loss of 150 ml per minute.

Most frequent cause of death is inadequate replacement of circulating volume and red cells.

Principles of management

Most blood banks have a clear-cut policy about managing transfusion in massive-bleeding patients.

TREAT SHOCK (SEE CHAPTER ON SHOCK)

Insert large bore peripheral cannulae.

Give crystalloid or colloid to achieve an acceptable systolic blood pressure and prevent tissue hypoxia.

Send blood samples for crossmatch, FBC, coagulation screen and renal function.

When blood is required immediately it may be necessary to issue Group O, Rh D negative un-crossmatched red cells if the patient's blood group is unknown.

ABO group-specific red cells should be given at the earliest possible opportunity. (ABO and Rh D grouping can be performed within five minutes.)

Intraoperative blood salvage may be of great value in reducing requirements for allogeneic blood.

MAINTAIN HAEMOSTASIS

Packed red cells do not contain coagulation factors or platelets, but the platelet count rarely falls below 50 × 109/l unless 1.5 blood volumes have been transfused.

Use platelet concentrates to maintain platelet count > 50 × 109/l.

Use FFP to maintain PT ratio < 1.5 times the control value.

Use cryoprecipitate to maintain fibrinogen concentration at > 1.0 g/dl.

HOMEOSTASIS

Coagulation factors work best at physiological pH and temperature.

Beware of metabolic disturbances such as hypocalcaemia, hyperkalaemia and acidosis.

When a fast rate of transfusion is required (>50 ml/kg per hour), a blood warmer should be used.