Low-molecular-weight heparin
Low molecular weight heparin (LMWH) is a class of anticoagulant medication.
These drugs are used for treating Deep-Vein Thrombosis, pulmonary embolism when it is located in the veins, or heart attacks and strokes when located in the arteries.
LMWHs, consist of only short chains of polysaccharide. LMWHs are defined as heparin salts having an average molecular weight of less than 8000 Da and for which at least 60% of all chains have a molecular weight less than 8000 Da. These are obtained by various methods of fractionation or depolymerization of polymeric heparin.
Heparin derived from natural sources, mainly porcine intestine or bovine lung, can be administered therapeutically to prevent thrombosis. However, the effects of natural, or unfractionated heparin are more unpredictable than LMWH.
For emergencies: can be reversed with protamine Non-emergencies: Longer times are needed in renal failure. A factor Xa level can be used to check anticoagulation status, but this usually must be sent out, making it unsuitable for acute management.
LMWH prophylaxis in pediatric TBI appears to be more effective than UH in preventing VTE. Large, multicenter prospective studies are warranted to confirm the superiority of LMWH over UH in pediatric patients with TBI. Moreover, outcomes of VTE prophylaxis in the very young remain understudied; therefore, dedicated studies to evaluate this population are needed.
Evidence suggests that it reduces cerebral edema and improves neurological recovery following stroke and traumatic brain injury (TBI), through blunting of cerebral leukocyte (LEU) recruitment. It remains unknown if unfractionated heparin (UFH) similarly affects brain inflammation and neurological recovery post TBI.
Prophylaxis was associated with decreased risk of pulmonary embolism and Deep-Vein Thrombosis, but no increase in risk of late neurosurgical intervention or death. Early prophylaxis may be safe and should be the goal for each patient in the context of appropriate risk stratification 1).
Unfractionated heparin (UFH) after TBI reduces LEU recruitment, microvascular permeability and brain edema to injured brain. Lower UFH doses concurrently improve neurological recovery while higher UFH may worsen functional recovery. Further study is needed to determine if this is due to increased bleeding from injured brain with higher UFH doses 2).
Low-dose heparin pretreatment may decrease the development of post-SAH early brain injury (EBI) 3).