Venous Thromboembolism in Complex Trauma: A Medicolegal Perspective
Thromboembolism occurs when a blood clot, or thrombus, forms in a vein. This happens most commonly in the deep veins of the legs or pelvis, and is known as a deep vein thrombosis (DVT). Once formed, fragments from the thrombus can dislodge and travel in the bloodstream. Often, it will end up in the pulmonary arteries, where it forms a pulmonary embolism (PE). Together, DVT and PE are known as venous thromboembolism (VTE). If the blood supply becomes completely blocked by the thrombus, particularly in the lungs, the condition can be fatal. Even non-fatal VTE can cause significant long-term problems, such as post-thrombotic syndrome and chronic pulmonary hypertension. The relative frequency of VTE and protracted morbidity associated with it mean that costs for managing the condition are high.
Mr Aswinkumar Vasireddy, Consultant Orthopaedic Trauma Surgeon, discusses the incidence of VTE in complex trauma.
Among hospitalised patients, those suffering trauma have the highest risk of developing VTE, and the risk is up to 13 times higher than in non-trauma patients. Patients with traumatic brain injuries are at particular risk, due to the prolonged immobility and systemic hypercoagulability associated with this type of injury. While precise numbers are unavailable, it was estimated that in 2004–5 there were 25,000 deaths due to VTE in the UK. PE is associated with mortality rates ranging from 10% to 50% and is a common cause of death in patients with trauma who survive beyond the first 24 hours.
Despite the serious nature of this condition, VTE is often preventable. However, diagnosisis not always straightforward and many cases are missed. A failure to diagnose VTE is one of the commonest reasons for a case of negligence to be brought. Many cases ultimately identified through ultrasonography are otherwise asymptomatic. Therefore, clinical diagnosis alone is often unreliable. Clinical scoring systems, ultrasound scans and blood test measurement of the enzyme D-dimer are used to confirm diagnosis. It is also recommended practice that all patients should be risk–assessed for VTE on admission to hospital. Following the introduction of this guideline, the proportion of adult patients who are assessed for VTE risk has increased from less than 50% in 2010 to around 96% in 2013. Where a significant risk of VTE is identified, prophylaxis should be initiated as soon as possible and ideally within 14 hours of admission.
There are numerous risk factors for VTE, including a previous history of the condition, pregnancy, surgery, obesity and long periods of immobility, whether due to travel or illness. Age is also important: incidence of VTE appears to peak between the ages of 35–54 years, but is also relatively common in patients aged over 60 years. However, the most important risk factor appears to be time since the trauma occurred. While life-threatening VTE events can occur at any point during the patient’s stay in hospital, the majority occur within the first 30 days and the likelihood tends to decrease over time. However, a significant proportion of VTE events occur months after the initial injury. For this reason, prophylaxis should be extended to cover an appropriate length of time post-trauma. If the patient is discharged from hospital before this, it is important that he or she continues to receive appropriate care. Limitations in mobility must be assessed and the patient provided with information relating to the signs and symptoms of VTE, ways to reduce the risk and what to do if symptoms occur.
Without the use of prophylaxis, up to 50% of trauma patients may experience VTE. Thus, the routine use of any form of prophylaxis is recommended for patients with severe trauma. Prophylaxis may be mechanical, and involve the use of sequential compression devices, and/or administered as a medication. Pharmacologic prophylaxis significantly reduces the risk of both PE and DVT and is recommended for trauma patients. The main drugs used are low-dose unfractionated heparin or low-molecular-weight heparin (LMWH).
Despite the benefits of prophylaxis, some doctors are reluctant to initiate it due to possible complications. In some patients, such as those with lower limb fractures, mechanical methods are contraindicated. The main risk associated with pharmacological intervention is that of increased bleeding. Often, a clinician will be required to balance the risk of bleeding against the risk of VTE. This can be a particular concern in patients with brain injuries who have already experienced intracranial bleeding, in whom prophylaxis is often withheld until a week after admission. However, a study of early vs. late administration of LMWH found that patients receiving the drug within 72 hours of admission had lower rates of VTE events without an increase in the risk of later neurosurgical complications or death.
Analysis of cases involving VTE brought against the NHS between 2007 and 2012 shows that, after an initial increase, the incidence of negligent VTE injury appears to have fallen in recent years. The National Institute of Clinical Excellence has published comprehensive guidelines on VTE risk assessment. While the decrease in VTE cases is almost certainly a reflection of the fact that many more patients now undergo this assessment on admission to hospital, lack of compliance has contributed to both morbidity and mortality. Multimodal education, particularly on the benefits of prophylaxis, should help to improve this situation further.
About Mr Vasireddy
Mr Vasireddy is a full-time fellowship-trained Orthopaedic Trauma Surgeon at King’s College Hospital. He specialises in the management of complex open/closed pelvic, acetabular, upper limb and lower limb fractures and amputations. He is also one of a small group of surgeons, and the only contemporary Orthopaedic Surgeon, in the UK who works as a HEMS (Air Ambulance) Pre-hospital Care Doctor.
His medico legal practice includes those who have sustained high-energy injuries. For more information, click here.
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