This chapter discusses the cell-based model of coagulation, regulation of coagulation, and bleeding disorders. The disorders include congenital disorders and acquired disorders such as thrombocytopenia, disseminated intravascular coagulation (DIC) and microangiopathic haemolytic anaemia. Thrombocytopenia may occur because of impaired production, sequestration, increased consumption, and enhanced degradation. Activated protein C has been shown to reduce mortality in sepsis especially in patients with DIC and multi-organ failure. During the resuscitation of patients who have suffered a major haemorrhage, factors that can contribute to associated coagulopathy are: hypothermia, metabolic acidosis, and consumption of clotting products. Heparin-induced thrombocytopenia (HIT) usually occurs 5-10 days following exposure to heparin. It is a pro-thrombotic disorder and can lead to significant venous and arterial thrombosis. HIT usually resolves following the discontinuation of heparin over a few days. Management includes the prompt removal of all heparin containing medication and the substitution of a direct thrombin inhibitor to control clotting.

The initial assessment of the critically ill patient should begin with a brief, targeted history and an appraisal of the patient's vital signs to identify life threatening abnormalities that merit immediate attention. The goals of resuscitation are usually achieved by the use of supplemental oxygen, fluid or red blood cell transfusion, inotropic support or antibiotics as needed. Physiological Scoring Systems (PSS) developed from the recognition that critically ill patients, and in particular patients who suffered cardiac arrests, often had long periods of deterioration before the crisis or medical emergency occurred. Medical emergency teams (METs) and critical care outreach (CCO) teams aim to provide critical care skills rapidly to critically ill patients. Referrals to the critical care services may happen from any level, but the final decision to admit a patient to a critical care bed should be made by an experienced critical care physician.