Haemorrhage
In acute blood loss, the need for transfusion is dependent on the estimated percentage loss of the circulatory blood volume and the patient’s ability to compensate for the quantity of blood lost. Blood volume can be estimated as approximately 70 mL/kg for adults, 80 mL/kg in children and 100 mL/kg in neonates.
The British Committee for Standards in Haematology provides the following guidelines for the need for transfusion in response to acute blood loss based on estimation of lost circulating volume(19).
- 15% loss of blood volume (750 mL in an adult): no need for transfusion unless blood loss is superimposed on pre-existing anaemia or when the patient is unable to compensate for this quantity of blood loss because of severe cardiac or respiratory disease.
- 15 – 30% loss of blood volume (750 to 1500 mL in an adult): need to transfuse crystalloids or synthetic colloids. The need for red cells is unlikely unless the patient has a pre-existing anaemia, reduced cardiopulmonary reserve or if blood loss continues.
- 30 – 40% loss of blood volume (1500 to 2000 mL in an adult): rapid volume replacement is required with crystalloids and synthetic colloids, and red cell transfusion will probably be required.
- 40% loss of blood volume (greater than 2000 mL in an adult): rapid volume replacement including red cell transfusion is required.
If bleeding continues after attempted surgical haemostasis and when the coagulation tests are abnormal or the platelet count reduced, then platelets, fresh frozen plasma, or cryoprecipitate or a combination of these products may also be required.
Clinical trials in humans have not demonstrated that albumin solutions or other colloids are superior to crystalloid in resuscitation, but much larger quantities of crystalloid are required. The use of synthetic colloids such as dextrans and hydroxyethyl starch should be limited to 1.5 litres per 24 hours in adults.
Avoid saline in patients for whom sodium overload is a special risk. Care should be taken with Albumex 4 for the same reason in these patients. Specialist advice is recommended for the ongoing management.
Massive transfusion in the emergency setting
Massive transfusion can be defined as replacement of the patient’s entire blood volume within 24 hours(20) or more than 20 units of red cells transfused within 24 hours. It is important to recognise that death is more likely to be due to irreversible shock than to anaemia and reduction in oxygen carrying capacity. Examples of massive transfusion in this setting include severe trauma and ruptured aortic aneurysm.
Treatment begins with fluid resuscitation. Further management is detailed in the table below.
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| Fluid Resuscitation (Crystalloid/Colloid) | Give adequate volume resuscitation to initially stabilise the patient. |
Red Cells
| Where possible pretransfusion compatibility should be performed. Depending on the clinical situation, uncrossmatched group O and preferably Rh(D) negative red cells can be used (especially for females of child bearing age). If group O Rh(D) negative red cells are in short supply, it is safe to provide O Rh(D) positive red cells to male patients and postmenopausal females in this setting.
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| Fresh Frozen Plasma | The amount given should be based on the combination of clinical criteria and frequently determined laboratory values. If PT and/or APTT is > 1.5x upper limit of normal FFP should be considered. Factors against solely relying on transfusion algorithms include the deleterious effect that hypothermia, tissue injury and acidosis has on the patient's ability to clot and the delay between taking the sample and results. Where the patient’s blood group is unknown, give group AB FFP (or A if AB is not available)(7). |
| Cryoprecipitate | FFP should supply enough fibrinogen to correct any deficiency. However if the fibrinogen concentration is lower than 1.0 g/L, cryoprecipitate may be indicated. Where the patient’s blood group is unknown, give AB cryoprecipitate (or A if AB is not available). |
| Platelets | Thrombocytopenia can occur reasonably quickly and usually results from dilution, but may be due to increased consumption. The literature suggests that there is so much patient-to-patient variability in platelet count in this situation, irrespective of transfusion volume, that there is no clear justification for the prophylactic transfusion of platelets to the massively transfused patient in order to prevent microvascular bleeding. The amount given should be based on the combination of clinical criteria and frequently determined laboratory values. Platelets may be appropriate when the platelet count is < 50 x 10^9 /L (< 100 x 10^9 /L in the presence of diffuse microvascular bleeding). |
| Recombinant Factor VIIa | This product appears to be effective and safe in the management of uncontrolled surgical and traumatic haemorrhage in patients not known to have inherited coagulopathy.(Please note that this product is not supplied by ARCBS.) |
For rapidly exsanguinating patients, a formula based transfusion protocol may have some merit, such as 2-4 units of FFP and one adult dose of platelets for every 10 red cell units transfused. However it is important to regularly monitor the laboratory response.
Major complications of massive transfusion include:
- Citrate toxicity
- Acid-base abnormalities
- Hypothermia
- Hyperkalaemia and hypocalcaemia.
Massive transfusion in elective surgery
Identification of patients at high risk of bleeding requires the development of a proactive, specific management plan to control and where possible, to minimise allogeneic blood component therapy. An integrated approach to blood management should be ensured and needs to involve the surgeon, anaesthetist, haematologist and blood bank scientist. Techniques to be considered include:
- Surgical techniques
- Anaesthetic techniques
- Autologous blood techniques
- Use of specialised products such as recombinant factor VIIa.
The combination of perioperative acute normovolaemic haemodilution with the perioperative preparation of plasma, platelet concentrates +/- platelet fibrin gel and the use of intraoperative blood salvage techniques may yield significant advantages in the elective surgical setting with massive transfusion.
References
(7) ANZSBT. Guidelines for pretransfusion testing. (4th edn.) Sydney: Australian and New Zealand Society of Blood Transfusion Inc, 2002.
(19) Guidelines for transfusion for massive blood loss. A publication of the British Society for heamatology 1988; 10: 265-273.
(20) Stainsby D (2000) Management of massive blood loss: a template guideline. Br J Anaesth 85: 487-489.