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Monday, September 11, 2017

Evaluation of a Device Combining an Inferior Vena Cava Filter and a Central Venous Catheter for Preventing Pulmonary Embolism Among Critically Ill Trauma Patients


Critically ill trauma patients have elevated risk for pulmonary embolism (PE) due to a combination of immobility, depletion of anti-coagulation factors, and contraindications to anticoagulation (AC) in the setting of hemorrhage. In this population, PE is one of the leading causes of death in patients surviving >1 day. Tapson et al. conducted a prospective multicenter single-arm clinical trial to evaluate the efficacy and safety of a new device, the Angel Catheter (Bio2 Medical) which combines an inferior vena cava filter (IVC) with a central venous catheter. This device received 510(k) clearance from the Food and Drug Administration for use as a short term IVC filter and central venous catheter on 7/28/2016. The filter component is made of nitinol, closed cell in geometry, contains no wall anchoring hooks, and is permanently attached to the 9-F triple-lumen central venous catheter. The enrolled study patients had contraindications to pharmacologic venothromboembolism prophylaxis without or with confirmed lower extremity deep venous thrombosis (DVT) or PE. Between February 2015 and December 2015, 163 intensive care unit patients underwent placement of the Angel catheter, of whom 18/163 (11%) had confirmed proximal lower extremity deep venous thrombosis (DVT) at baseline. For the large majority of patients, device insertion was performed bedside in the ICU, with abdominal radiography to confirm post-deployment filter position between L1-L2 and L4-L5 interspaces. The primary endpoint was freedom from clinically significant pulmonary embolism (PE) 72 hours after device removal or discharge and was achieved in 100% of patients. The Angel catheters were removed in 143 (88%) patients, with the large majority of removals occurring once prophylactic anticoagulation was safely initiated, at a mean of 5.5 hospital days. Notably, 12 (8%) catheters which were removed inadvertently by the patient. Cavograms were performed in 129 patients prior to device removal, of which 31 (24%) showed thrombus in the filter component, including 14 (8.6%) with large clot burden (>25% volume of filter basket) and 17 (10%) with low clot burden (<25% volume of filter basket). These patients with thrombus subsequently underwent anticoagulation therapy and/or placement of a conventional IVC filter. Major bleeding occurred in 5 (3%) of all patients receiving the Angel catheter, and catheter related thrombosis occurred in 20 (12%) cases.


Venothromboembolism (VTE) is known to be a major contributor of morbidity and mortality in critically ill trauma patients. Multicenter prospective randomized controlled trials for IVC filters have not included this patient population, but nonrandomized studies have shown decreased rates of PE and PE-related fatalities in patients who receive filters. Although conventional IVC filters may be placed in these patients, studies have demonstrated that the majority of filters are placed late in the ICU course, and therefore the patients may not be adequately protected from PE in their early hospitalization, when they may have contraindications to pharmacologic prophylaxis (reflected in the mean time to initiation of AC of 5.5 days in this study). IVC filters placed in the trauma setting have also been associated with low retrieval rates. The Angel catheter theoretically circumvents both of these pitfalls as a device that may be easily deployed and removed at bedside in the ICU. The results of this study and the European Angel Catheter Registry suggest that this device is both effective for PE prevention and acceptable safety profile in critically ill patients, and may be an exciting addition to the VTE prevention armamentarium in this patient population. As a single arm clinical trial, this study does not offer any comparison to placebo or conventional IVC filter placement, and provides relatively short duration of clinical follow-up, so additional evidence will be needed to elucidate optimal utilization of this device. Because no pre-placement cavography is performed and cross-sectional imaging may not be available in all patients, one could anticipate scenarios in which the Angel catheter could be malpositioned from variant caval or renal vein anatomy and provide suboptimal caval filtration. The relatively high rate of inadvertent catheter dislodgement reported in this study also raises concerns for potential associated morbidity if a filter is pulled out of a vessel without being adequately collapsed in patients not on pharmacology thromboprophylaxis. Despite these limitations, this study provides an important preliminary evaluation of the Angel catheter, which may one day assume a pivotal role in early PE prevention in critically ill patients.

Click here for abstract

Tapson VF, Hazelton JP, Myers J, et al. Evaluation of a Device Combining an Inferior Vena Cava Filter and a Central Venous Catheter for Preventing Pulmonary Embolism Among Critically Ill Trauma Patients. J Vasc Interv Radiol. 2017;28(9):1248-54.

Post Authors:
Jeffrey Forris Beecham Chick, MD, MPH, DABR
Assistant Professor of Vascular and Interventional Radiology
Vice Quality Assurance and Safety Officer
Venous Health Program Faculty
University of Michigan Health System
Michigan Medicine

James X. Chen, MD
Fellow in Interventional Radiology
Hospital of the University of Pennsylvania

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