Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 568

The diagnosis of DIC is made in the presence of a predisposing cause, the clinical manifestations of systemic bleeding and multiorgan dysfunction, and appropriate laboratory investigations (Table 23.2). The haemoglobin is usually reduced owing to intravascular red cell fragmentation, resulting in a microangiopathic haemolytic anaemia (MAHA), and there is profound thrombocytopenia. Coagulation times are abnormal, with a prolongation of the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT) and depletion of fibrinogen, all due to consumption. In addition, there is evidence of fibrinolytic activation and fibrin degradation with elevations of serum FDPs or plasma D‐dimers. As well as these rapid and readily available tests, recent studies have shown that waveform analysis of the coagulation profile on automated machines can have both diagnostic and prognostic significance, and laboratory abnormalities can be included in a validated scoring system for DIC. In addition to consumption of the coagulation factors and prolongation of the clotting times, levels of natural anticoagulant pathway proteins – antithrombin, protein C, and protein S – are also significantly reduced, contributing to microvascular thrombosis.⁷

Table 23.2 Laboratory diagnosis of DIC.

Test	Result
APTT	Prolonged >10 seconds beyond normal
PT	Prolonged > 5 seconds beyond normal
TT	Prolonged > 10 seconds beyond normal
Fibrinogen	Low, usually <1 g l−1
Platelets	Low, usually <50 × 109 l−1
D‐dimer	Raised > 1000 ng/ml

As DIC is a dynamic condition, it is preferable to perform the simple clotting tests frequently, both before and after clinical interventions, to judge their efficacy and the need for further blood product replacement therapy or interventions. The role of thromboelastography (TEG) in monitoring DIC has progressed in recent years, with the use of whole blood and near‐patient testing, particularly in operating theatres, able to direct the appropriate component to replace when bleeding is excessive.