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Point of care ultrasound screening for deep vein thrombosis in critically ill COVID-19 patients, an observational study
Point of care ultrasound screening for deep vein thrombosis in critically ill COVID-19 patients, an observational study
REVIEWED BY | Matt Adams ASA SIG: Vascular
REFERENCE | Authors: Sarah Galien, Michael Hulström, Miklós Lipcsey, Karl Stattin, Robert Frithiof, Jacob Rosén Journal: Thrombosis Journal Open Access: Yes
WHY THE STUDY WAS PERFORMED
Deep vein thrombosis (DVT) and the potentially lethal sequelae of pulmonary embolism (PE) are very real threats to those who are critically ill with COVID-19. The hallmark symptom of DVT – unilateral lower limb swelling – can often be hard to distinguish in the bedridden patient due to general states of stasis. As a result of this, referrals for evaluation of suspected DVT are often based on risk assessment scores and D-dimer tests, the efficacy of which have been and still are under debate. Duplex ultrasound is the preferred method in assessing for DVT; however, its sensitivity and specificity rely on the extensive training of skilled healthcare professionals who are not always available to perform this exam. This problem has only been compounded by the COVID-19 pandemic due to the potential for operator exposure and in-hospital contamination. This study explored the viability of screening for lower limb DVT in critically ill COVID-19 patients led by ICU medical residents performing an abbreviated study.
HOW THE STUDY WAS PERFORMED
Bilateral lower limb screening for DVT was performed on 56 eligible patients between April–July 2020. All subjects were ≥ 18 years old, had respiratory failure and tested positive for COVID-19. All DVT studies were performed by ICU medical residents recruited to a DVT screening program. They all received a 25-minute online video tutorial followed by a ‘hands-on’ session supervised by a physician verified in echocardiography but with limited experience in DVT studies. All scans consisted of either a two-compression (common femoral and popliteal veins) or extended compression protocol (includes superficial veins). Patients who had pathological findings on screening were referred for formal duplex DVT study.
WHAT THE STUDY FOUND
Seven ICU residents were recruited, of whom 2 had limited experience (10–20 scans), with the others having no experience at all. A median of 4 scans were performed per person at median day 3 after admission via 2-point compression (61%) and extended compression (39%) techniques. Four (7.1%) patients were positive for DVT on screening, 3 (5.4%) of which were confirmed by a formal DVT duplex examination. Two of the DVTs were localised in the popliteal vein. None of the 52 patients with a negative DVT screening result were diagnosed with DVT during follow-up.
RELEVANCE TO CLINICAL PRACTICE
As the authors of this article state, the small sample size and single-centre nature of this study make it hard to generalise its results across the board, especially when an incidence of DVT in critically ill COVID-19 patients has been reported at 10–23% elsewhere in the literature. What is relevant to the clinical practice of sonographers is the DVT screening itself. It is common knowledge that sonographers, particularly within the vascular subspecialty, are in short supply so it is understandable that a specialised sonographer can’t be assigned to an ICU unit to perform a DVT screening service. If this expertise is locally available, however, then perhaps the training of willing junior ICU doctors should be via sonographers and not by senior doctors who are proficient in an unrelated field of ultrasound and have only dabbled in lower limb studies. This could be a window of opportunity for professional ultrasound bodies like the ASA to devise a DVT screening curriculum for ICU personnel so that this essential diagnostic tool is performed with the highest degree of sensitivity and specificity.
