This may be classified as the loss of one blood volume in 24 hours.
Physiological effects of acute haemorrhage
Reduced blood volume results in reduced venous return and cardiac output. Arterial blood pressure falls, with activation of the baroreceptor reflex. Sympathetic activity is increased. Tachycardia ensues and peripheral vasoconstriction to the skin, viscera and kidneys occurs to restore blood pressure.
Increased vasopressin causes vasoconstriction, sodium and water retention and thirst. The stress response results in increased catecholamine and corticosteroid secretion.
Assessment of loss
This is frequently underestimated and survival depends on early and accurate assessment and effective management.
<25% loss: Tachycardia is often (but not always) one of the first signs; blood pressure may be normal. Pulse pressure is often narrow. Capillary refill will be at upper end of normal. Respiratory rate will be increased.
25-40% loss: Tachycardia, hypotension, prolonged capillary refill, tachypnoea, oliguria and altered mental state.
>40% loss: the patient will be shocked. Bradycardia, hypotension, prolonged capillary refill, abnormal respiratory rate, anuria and possibly coma. These effects are thought to be vagally mediated, due to cardiac afferent C-fibre discharge caused by ventricular distortion and underfilling.
Apply local pressure over bleeding points/pressure points, adopt supine position and raise the patient’s feet.
Establish minimum two large bore IV access.
Resuscitate with warm fluids (colloid/crystalloid/blood).
Liaise with haematologist as clinical picture evolves.
Colloid maintains intravascular expansion longer than crystalloid and saline is more effective than dextrose.
In emergency, use O negative, then type-specific blood and cross-matched blood when available.
Blood products should be guided by coagulation test results.
Central venous pressure monitoring may be possible after an improvement in the circulating volume, and, together with urine output measurement, is useful for monitoring volume replacement.
Fresh frozen plasma should be given to maintain prothrombin time and activated partial thromboplastin time <1.5 x control.
Cryoprecipitate should be given if fibrinogen levels fall (1 pack/10 kg body weight).
Platelets are crucial and there may be a significant delay before they are available (transferred from blood centre).
i] Bradycardia in acute haemorrhage.
I Thomas, J Dixon.
BMJ 2004; 328(7437): 451-3.
ii] Fluids for resuscitation.
Br J Anaesth 1991; 67(2): 185-93.
Methods of reducing blood loss
Use of a tourniquet
Local infiltration with vasopressor drugs, e.g. epinephrine
The cell saver returns warmed blood with normal levels of 2,3 diphosphoglycerate to the patient. Its use is contraindicated in septic patients, patients with blood which contains intestinal contaminants and in patients with malignant disease.
[i] Economic analysis of an intraoperative cell salvage service.
Szpisjak DF, Potter PS, Capehart BP.
Anesth Analg 2004; 98(1): 201-5.