Risk assessment and prophylaxis of venous thromboembolism in acutely and/or critically ill patients.

Both undetected and clinically evident venous thrombosis and venous thromboembolism (VTE) can seriously impact the prognosis of acutely and/or critically ill patients. Pulmonary embolism (PE) is harder to diagnose in the acutely and/or critically ill, many of whom also have developed respiratory failure for other reasons. Deep vein thrombosis (DVT) of the upper and lower extremities can subsequently complicate insertion of central venous catheters, leading to PE, sepsis and septic shock. Recovery from the original critical illness (e.g. weaning from mechanical ventilation) can be adversely affected by these complications. There are recent data suggesting that, for prophylaxis, low-molecular-weight heparin (LMWH) is more effective than unfractionated heparin (UFH) in critically ill trauma patients, and that high-dose LMWH is more effective than placebo or low-dose LMWH in seriously ill medical patients. In both populations, LMWH appeared safe. While LMWH appears superior to UFH in acute stroke patients to prevent venographically-proven lower-extremity DVT, whether it provides a superior long-term outcome after acute stroke is uncertain. One study found that a high dosage of the LMWH dalteparin was more effective than placebo in preventing left ventricular thrombi after acute myocardial infarction, but there was a significant safety cost. Current questions surrounding prophylaxis of VTE and the use of LMWH in acutely and/or critically ill patients include whether monitoring levels and dosage adjustment in some of these patients would improve outcome, and whether the diagnosis of VTE can be improved so that treatment can be instituted when prophylaxis has failed. Copyright 2001 S. Karger AG, Basel