Anaesthesia
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Almost 30,000 cardiopulmonary bypass operations are performed in the UK every year, consuming a considerable portion of the UK blood supply. Each year, in cardiac surgery, 90% of blood products are used by only 10% of patients, and over the past 25 years, much innovation and research has gone into improving peri-operative diagnosis and therapy for these patients. Visco-elastic tests performed at the bedside, with modifications to allow direct quantification of fibrinogen levels, are probably the biggest advancement. ⋯ Factor concentrates, however, carry significant risks, particularly unnecessary donor exposures, potential selective over-correction of partial deficiencies and the possibility that the postoperative risk of venous thromboembolism is increased; as yet there are no data on risk-benefit analysis. There are a number of promising drugs used in topical haemostasis, but the requirement to apply these before major bleeding is manifest limits their use considerably. Hyperfibrinolysis is less important than in the past due to the wide spread adoption of antifibrinolytic agents and close intra-operative monitoring of heparin effect.
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It is estimated that up to 1% of the general population has a congenital bleeding disorder. With this level of disease burden, it is more likely than not that any practising surgeon or anaesthetist will, at one time or another, have occasion to manage one such patient. Congenital haemophilia, both A and B, von Willebrand's disease, and inherited qualitative platelet defects, constitute the bulk of these disorders, with the rest distributed between much rarer conditions. ⋯ Of equal importance, at least in developed countries, has been the ease of access to highly purified, safe and effective haemostatic products. The key to successful surgical management of the patient with a bleeding disorder is a multidisciplinary approach involving not only surgeons, anaesthetists and haematologists, but also laboratory scientists, specialist physiotherapists and haemophilia nurses. With careful planning, most surgical and invasive procedures can be carried out safely in persons with haemophilia and other bleeding disorders.
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Over the last 10 years, the management of major haemorrhage in trauma patients has changed radically. This is mainly due to the recognition that many patients who are bleeding when they come in to the emergency department have an established coagulopathy before the haemodilution effects of fluid resuscitation. This has led to the use of new terminology: acute traumatic coagulopathy, acute coagulopathy of trauma shock or trauma-induced coagulopathy. ⋯ While there is as yet no universally accepted assay or definition, many experts use prolongation of the prothrombin time to indicate that there is, indeed, a coagulopathy. Hypoxia, acidosis and hypothermia and hormonal, immunological and cytokine production, alongside consumption and blood loss, and the dilutional effects of resuscitation may occur to varying extents depending on the type of tissue damaged, the type and extent of injury, predisposing to, or amplifying, activation of coagulation, platelets, fibrinolysis. These are discussed in detail within the article.
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The pathophysiology of bleeding, regardless of cause, is complex and ill understood. For traumatic or sudden unexpected haemorrhage, the use of transfusion packs with red cells, fresh frozen plasma, cryoprecipitate and platelets being given in ratios of between 1:1 and 1:3 seems reasonable. ⋯ There is increasing evidence for the efficacy and safety of fibrinogen concentrates as a single agent. The combination of fibrinogen and prothrombin complex concentrates could be powerful and has the possibility to the management of bleeding and improve outcome in patients but, as yet, remains unproven.