National guidelines (i.e. Sign Guidelines, Nice Guidelines refer to VTE prevention in relation to short term immobility, however there is no specific guideline to dictate duration of treatment in patients with long term immobility.
In the general population there are many people in the community or residential care settings with restricted mobility, for whom VTE risk does not appear to be increased.
It is neither safe nor practical to continue VTE prophylaxis on a long term basis but there are no defined criteria for discontinuation.
General principles to consider:
- Anticoagulation is associated with a bleeding risk, especially if the patient is prone to falls.
- Side-effects from anticoagulants are otherwise infrequent other than for easy bruising especially at injection sites.
- In the absence of acute medical illness immobility is the only major risk factor for VTE. Therefore, restoration of mobility should be associated with cessation of treatment. Restoration of mobility refers to restoration of consistent and regular walking over any distance either supported or unsupported (as opposed to walking only in the physiotherapy gym).
- For patients in whom mobility is not restored, the risk of VTE returns toward normal between 3 months and 1 year post brain injury. The reasons for this are unclear but speculated theories include:
- Spasticity to may prevent venous pooling (but risk also seems to normalise in those who have flaccid paresis).
- Reduction in blood flow in paralysed lower limbs leads to reduction in blood vessel capacity requirement, resulting in reduction in venous diameters and reduced potential for pooling.
- Balancing risks against benefits, anticoagulation is generally discontinued at a period of 3 to 4 months post injury, BUT renewal should be considered if risk factor profile changes (e.g. if the patient develops sepsis sufficient to require IV fluids or antibiotic).
Choice of Preventative Treatment
In all situations you should consult or be familiar with the admitting trauma team or intensive care team’s policies, your employer’s VTE management guidelines and/or relevant national guidelines.
Chemical prophylaxis using Low Molecular Weight Heparin (LMWH) or unfractionated Heparin (UF) depending on medical risk profile is typically recommended.
Mechanical preventive strategies such as elasticated compression stockings or intermittent pneumatic compression may also be considered but:
- Evidence for benefit in post-acute settings in neurological patients is unproven.
- They are associated with poor tolerance or local pressure effects.
