Bedside insertion of vena cava filters in the intensive care unit using intravascular ultrasound to locate renal veins.
BACKGROUND
Historically, contrast venography has been used to determine renal vein location and assist with vena cava filter placement. This technique, however, exposes the patient to nephrotoxic contrast and radiation. For trauma patients in the intensive care unit (ICU), inferior vena cava filters should ideally be placed without contrast at the bedside to avoid nephrotoxic agents, radiation, and transport of a critically injured patient to the operating room or x-ray department. Previously, the authors have shown that intravascular ultrasound is a safe and accurate method for locating renal veins and assisting with vena cava filter placement. The purpose of this study was to evaluate bedside vena cava filter placement prospectively using only intravascular ultrasound for imaging.


METHODS
Between August 2000 and July 2003, 29 patients met trauma service criteria for prophylactic or therapeutic placement of a vena cava filter. The 7 females and 22 males had a mean age of 51.3 years (range, 20-92 years), a mean height of 177 cm (range, 160-218.4 cm), a mean weight of 101.9 kg (range, 59.1-186.4 kg), and a body mass index of 33 (range, 14.7-56.1). Fifteen patients (55.5%) had a body mass index exceeding 30. The mean Injury Severity Score was 25.4 (range, 12-45). Intravascular ultrasound was the sole imaging method, and no contrast or fluoroscopy was used. All procedures were performed in the ICU by trauma surgeons. Data collection was prospective and included demographics, injuries, vena caval anatomy, length of procedure, complications, and follow-up radiographic confirmation of appropriate deployment.


RESULTS
The location of the renal veins and vena cava diameter was imaged in all the patients. Three patients were noted to have accessory renal veins, and no patient had thrombus in the vena cava. The inferior vena cava diameter was less than 28 mm in all the patients, thus allowing standard filters to be deployed. Filter deployment was successful for all the patients. Of the 29 patients, 27 had abdominal computed tomography (CT) during their hospital stay. When the location of the renal veins identified by CT was compared with the level of the filter on abdominal x-ray, the filter tip was found to be at or below the level of the most caudal renal vein in 26 of the 27 patients (96.3%). In one patient, the filter tip was purposely placed 2 to 3 cm above an accessory caudal renal vein, but below the main right and left renal veins. The mean procedure time was 37.7 minutes (range, 12-86 minutes). No complications were associated with filter placement.


CONCLUSIONS
Intravascular ultrasound is a safe and effective imaging method that may be used for the bedside placement of vena cava filters in the ICU. This technique avoids the use of nephrotoxic intravenous contrast and eliminates the risk of transporting a critically injured patient to the operating room or x-ray department.
Mercer University School of Medicine Department of Surgery, Macon, Georgia, USA. ashley.dennis@mccg.org
Dennis W
DW
Ashley
T Clark
TC
Gamblin
Beth L
BL
McCampbell
Debra M
DM
Kitchens
Martin L
ML
Dalton
Maurice M
MM
Solis
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003422:Critical Care / Q000379:methods; D005260:Female; D005845:Georgia; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D011655:Pulmonary Embolism / Q000517:prevention & control*; D012082:Renal Veins / Q000000981:diagnostic imaging*; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional / Q000379:methods*; D016306:Vena Cava Filters; D014947:Wounds and Injuries / Q000628:therapy*