Follow-up imaging of traumatic vertebral artery dissections is unnecessary in asymptomatic patients.

OBJECTIVE: Routine computed tomography (CT) imaging in trauma patients has led to increased recognition of blunt vertebral artery injuries (BVIs). We sought to determine the prevalence of strokes, injury progression, and need for intervention in patients with BVI. METHODS: Consecutive patients presenting with BVI during 2 years were identified from the institutional trauma registry. Inpatient records, imaging studies, and follow-up data were reviewed in detail from the electronic medical record. RESULTS: There were 76 BVIs identified in 70 patients (64% male; mean age, 47 ± 19 years); bilateral injuries occurred in 6 patients. Five patients who arrived at the hospital intubated had evidence of posterior circulation infarcts on admission CT, whereas one additional patient had evidence of a posterior circulation infarct attributed to complications of late spinal surgery. Four of the five patients with infarcts on admission CT survived to discharge, but only one had residual stroke symptoms. Minor (grade 1 or grade 2) injuries occurred in 25 (36%) patients; severe (grade 3 or grade 4) injuries occurred in 45 (64%). Twelve patients died of associated injuries (eight with severe BVI, four with minor BVI). Stepwise logistic regression analysis selected age (odds ratio, 1.14; confidence interval, 1.04-1.25; P < .001) and intubation on arrival (odds ratio, 450.4; confidence interval, 17.41-1645.51; P < .001) as independent predictors of hospital stroke and death. Of the 58 surviving to discharge, 31 (53%) returned for follow-up CT scans. Six of 10 (60%) patients with minor injuries had resolution or improvement compared with 3 of 21 (14%) with severe injuries (P = .027). One patient (10%) with a minor BVI and two patients (10%) with severe BVI had radiologic progression, but none were clinically significant. During a mean follow-up of 15 ± 13 months, none of the study patients had treatment (surgical or interventional) for BVI, and there were no delayed strokes. Only five patients in this series had vertebral pseudoaneurysms, which limits conclusions about this type of BVI. CONCLUSIONS: These data suggest that BVI-related strokes are present at the time of admission and do not have clinical sequelae. No late strokes occurred in this series, and no surgical or interventional treatments were required even in the presence of radiographic worsening. The relatively few cases of vertebral pseudoaneurysms in this series limit any conclusions about these specific lesions. However, these data indicate that follow-up imaging of nonaneurysmal BVI is not necessary in adults who are found to be asymptomatic on follow-up.

Initial and intermediate-term treatment of the phantom thrombus (primary non-occlusive mural thrombus on normal arteries).

An embolic event originating from thrombus on an otherwise un-diseased or minimally diseased proximal artery (Phantom Thrombus) is a rare but significant clinical challenge. All patients from a single center with an imaging defined luminal thrombus with a focal mural attachment site on an artery were evaluated retrospectively. We excluded all patients with underlying anatomic abnormalities of the vessel at the attachment site. Six patients with a mean age of 62.5 years were identified over a 2.5-year period. All patients had completed treatment for or had a current diagnosis of malignancy and none were on antiplatelets or other anticoagulants. Four thrombi originated in the aorta proximal to the renal arteries and one originated distal. One thrombus was found in the common carotid artery and one was in an arterialized vein graft. Mean follow-up was 22 months. None of the patients underwent removal or exclusion of the embolic source. With systemic anticoagulation, four of the phantom thrombi were resolved on imaging within 8 weeks, one resolved after 72 weeks. One phantom thrombus reoccurred after 6 months on reduced anticoagulant dosing. There was one acute and one death in follow-up (26 months). One patient required a partial foot amputation secondary to tissue necrosis from the initial thromboembolic event. Arterial thrombi forming on otherwise normal vessels are a distinct clinical entity. In patients with a phantom thrombus, a strategy of therapeutic anticoagulation for management of the embolic source seems to be safe and effective over both the short and intermediate-term.

Does Management of True Aneurysms of Peripancreatic Arteries Require Repair of Associated Celiac Artery Stenosis?

BACKGROUND: True aneurysms of the gastroduodenal (GDA) and pancreaticoduodenal (PDA) arteries have been attributed to increased collateral flow due to tandem celiac artery stenosis or occlusion. Although GDA and PDA aneurysm exclusion is recommended because of the high reported risk of rupture, it remains uncertain whether simultaneous celiac artery reconstruction is necessary to preserve end-organ flow. STUDY DESIGN: We conducted a retrospective analysis of consecutive patients admitted from 1996 to 2015 with true aneurysms of the GDA or PDA. RESULTS: Twenty patients with true aneurysms of the PDA (n = 16) or GDA (n = 4) were identified. Mean age was 61.5 years (range 35 to 85 years) and 11 (55%) were women. Nine (45%) presented with rupture, 8 (40%) presented with pain, and 3 (15%) were asymptomatic. All 9 patients who presented with rupture had contained retroperitoneal hematomas, and none experienced rebleeding. Fifteen (75%) patients had an associated celiac artery >60% stenosis or occlusion, and 2 (10%) had both celiac and superior mesenteric artery stenoses. Thirteen (65%) patients underwent successful endovascular coiling, only 1 of which had a prophylactic celiac artery bypass. Three (15%) patients underwent open aneurysm exclusion and celiac bypass, and 4 (20%) others were observed. There were no aneurysm-related deaths in this series, and none of the patients who underwent coiling without celiac revascularization had hepatic ischemia or other mesenteric morbidity develop during a median follow-up of 6 months (maximum 200 months). CONCLUSIONS: Gastroduodenal artery and PDA aneurysms present most commonly with pain or bleeding, and all should be considered for repair, regardless of size. Aneurysm exclusion is safely and effectively achieved with endovascular coiling. Although associated celiac artery stenosis is found in the majority of cases, celiac revascularization might not be necessary.

Aortic arch involvement worsens the prognosis of type B aortic dissections.

OBJECTIVE: Medical management of acute aortic dissections limited to the descending thoracic aorta (AD-desc) is associated with acceptable outcomes. Uncertainty remains about whether acute type B aortic dissections involving the aortic arch (AD-arch) have an increased risk of retrograde extension into the ascending aorta or other dissection-related complications. This study compared outcomes of AD-arch with AD-desc managed medically. METHODS: Consecutive patients admitted from 2005 to 2014 with acute aortic dissections not involving the ascending aorta were retrospectively analyzed. Primary end points included dissection-related death and operative intervention. RESULTS: The study included 99 patients (63% men; mean age, 60 ± 14 years) with acute aortic dissections. Dissections were limited to the aorta distal to the left subclavian artery (AD-desc) in 79 patients (80%), and 20 (20%) had involvement of the left subclavian (n = 16), left common carotid (n = 1), or innominate (n = 3) arteries (AD-arch). Dissections ended proximal to the celiac artery in 30 patients (30%), between the celiac artery and aortic bifurcation in 36 (36%), and distal to the aortic bifurcation in 33 (33%). During medical management, further proximal extension into the arch occurred in two AD-arch patients and one AD-desc patient (P < .05), but proximal dissection into the ascending aorta occurred in only one AD-arch patient with Marfan disease. Compared with patients with AD-desc, those with AD-arch were younger (53 ± 12.5 vs 62 ± 16 years; P < .01) and had more frequent early interventions (40% vs 19%; P = .047), cardiac complications (35% vs 11%; P < .01), and neurologic events (25% vs 6%; P < .01). Seven AD-arch patients (35%) and nine AD-desc patients (11%) died of dissection-related causes (P < .01). Among survivors, late interventions were performed in four of eight AD-arch patients (50%) and in six of 58 AD-desc patients (10%; P = .02). Medical treatment without intervention was successful in four AD-arch patients (20%) and in 52 AD-desc patients (66%; P < .001). Multivariate logistic regression retained arch involvement as the sole predictor of dissection-related death (odds ratio, 4.2; 95% confidence interval, 1.3-13.4) and failure of medical treatment (odds ratio, 7.7; 95% confidence interval, 2.5-29). The distal extent of dissection had no bearing on outcome. CONCLUSIONS: AD-arch dissections are associated with a higher risk of cardiac and neurologic events, need for early intervention, and dissection-related death than AD-desc dissections. Because further proximal dissections into the ascending aorta were rare in this study, medical management appears to be safe as the initial treatment of AD-arch dissections. However, surgeons should be aware of the increased risk of complications and the potential need for urgent interventions in these patients.

Patients with faecal peritonitis admitted to European intensive care units: an epidemiological survey of the GenOSept cohort.

INTRODUCTION: Faecal peritonitis (FP) is a common cause of sepsis and admission to the intensive care unit (ICU). The Genetics of Sepsis and Septic Shock in Europe (GenOSept) project is investigating the influence of genetic variation on the host response and outcomes in a large cohort of patients with sepsis admitted to ICUs across Europe. Here we report an epidemiological survey of the subset of patients with FP. OBJECTIVES: To define the clinical characteristics, outcomes and risk factors for mortality in patients with FP admitted to ICUs across Europe. METHODS: Data was extracted from electronic case report forms. Phenotypic data was recorded using a detailed, quality-assured clinical database. The primary outcome measure was 6-month mortality. Patients were followed for 6 months. Kaplan-Meier analysis was used to determine mortality rates. Cox proportional hazards regression analysis was employed to identify independent risk factors for mortality. RESULTS: Data for 977 FP patients admitted to 102 centres across 16 countries between 29 September 2005 and 5 January 2011 was extracted. The median age was 69.2 years (IQR 58.3-77.1), with a male preponderance (54.3%). The most common causes of FP were perforated diverticular disease (32.1%) and surgical anastomotic breakdown (31.1%). The ICU mortality rate at 28 days was 19.1%, increasing to 31.6% at 6 months. The cause of FP, pre-existing co-morbidities and time from estimated onset of symptoms to surgery did not impact on survival. The strongest independent risk factors associated with an increased rate of death at 6 months included age, higher APACHE II score, acute renal and cardiovascular dysfunction within 1 week of admission to ICU, hypothermia, lower haematocrit and bradycardia on day 1 of ICU stay. CONCLUSIONS: In this large cohort of patients admitted to European ICUs with FP the 6 month mortality was 31.6%. The most consistent predictors of mortality across all time points were increased age, development of acute renal dysfunction during the first week of admission, lower haematocrit and hypothermia on day 1 of ICU admission.

Natural history of grade I-II blunt traumatic aortic injury.

BACKGROUND: Endovascular aortic repair has revolutionized the management of traumatic blunt aortic injury (BAI). However, debate continues about the extent of injury requiring endovascular repair, particularly with regard to minimal aortic injury. Therefore, we conducted a retrospective observational analysis of our experience with these patients. METHODS: We retrospectively reviewed all BAI presenting to an academic level I trauma center over a 10-year period (2000-2010). Images were reviewed by a radiologist and graded according to Society for Vascular Surgery guidelines (grade I-IV). Demographics, injury severity, and outcomes were recorded. RESULTS: We identified 204 patients with BAI of the thoracic or abdominal aorta. Of these, 155 were deemed operative injuries at presentation, had grade III-IV injuries or aortic dissection, and were excluded from this analysis. The remaining 49 patients had 50 grade I-II injuries. We managed 46 grade I injuries (intimal tear or flap, 95%), and four grade II injuries (intramural hematoma, 5%) nonoperatively. Of these, 41 patients had follow-up imaging at a mean of 86 days postinjury and constitute our study cohort. Mean age was 41 years, and mean length of stay was 14 days. The majority (48 of 50, 96%) were thoracic aortic injuries and the remaining two (4%) were abdominal. On follow-up imaging, 23 of 43 (55%) had complete resolution of injury, 17 (40%) had no change in aortic injury, and two (5%) had progression of injury. Of the two patients with progression, one progressed from grade I to grade II and the other progressed from grade I to grade III (pseudoaneurysm). Mean time to progression was 16 days. Neither of the patients with injury progression required operative intervention or died during follow-up. CONCLUSIONS: Injury progression in grade I-II BAI is rare (~5%) and did not cause death in our study cohort. Given that progression to grade III injury is possible, follow-up with repeat aortic imaging is reasonable.

TNF and TNFR polymorphisms in severe sepsis and septic shock: a prospective multicentre study.

Tumour necrosis factor (TNF) is an important pro-inflammatory cytokine produced in sepsis. Studies examining the association of individual TNF single nucleotide polymorphisms with sepsis have produced conflicting results. This study investigated whether common polymorphisms of the TNF locus and the two receptor genes, TNFRSF1A and TNFRSF1B, influence circulating levels of encoded proteins, and whether individual polymorphisms or extended haplotypes of these genes are associated with susceptibility, severity of illness or outcome in adult patients with severe sepsis or septic shock. A total of 213 Caucasian patients were recruited from eight intensive care units (ICU) in the UK and Australia. Plasma levels of TNF (P = 0.02), sTNFRSF1A (P = 0.005) and sTNFRSF1B (P = 0.01) were significantly higher in those who died on ICU compared to those who survived. There was a positive correlation between increasing soluble receptor levels and organ dysfunction (increasing SOFA score) (sTNFRSF1A R = 0.51, P < 0.001; sTNFRSF1B R = 0.53, P < 0.001), and in particular with the degree of renal dysfunction. In this study, there were no significant associations between the selected candidate TNF or TNF receptor polymorphisms, or their haplotypes, and susceptibility to sepsis, illness severity or outcome. The influence of polymorphisms of the TNF locus on susceptibility to, and outcome from sepsis remains uncertain.

Local activation of coagulation and inhibition of fibrinolysis in the lung during ventilator associated pneumonia.

BACKGROUND: Fibrin deposition is a hallmark of pneumonia. To determine the kinetics of alterations in local coagulation and fibrinolysis in relation to ventilator associated pneumonia (VAP), a single centre prospective study of serial changes in pulmonary and systemic thrombin generation and fibrinolytic activity was conducted in patients at risk for VAP. METHODS: Non-directed bronchial lavage (NBL) was performed on alternate days in patients expected to require mechanical ventilation for more than 5 days. A total of 28 patients were studied, nine of whom developed VAP. RESULTS: In patients who developed VAP a significant increase in thrombin generation was observed in the airways, as reflected by a rise in the levels of thrombin-antithrombin complexes in NBL fluid accompanied by increases in soluble tissue factor and factor VIIa concentrations. The diagnosis of VAP was preceded by a decrease in fibrinolytic activity in NBL fluid. Indeed, before VAP was diagnosed clinically, plasminogen activator activity levels in NBL fluid gradually declined, which appeared to be caused by a sharp increase in NBL fluid levels of plasminogen activator inhibitor 1. CONCLUSION: VAP is characterised by a shift in the local haemostatic balance to the procoagulant side, which precedes the clinical diagnosis of VAP.

Outcome for cardiothoracic surgical patients requiring multidisciplinary intensive care.

BACKGROUND AND OBJECTIVE: Patients who require multidisciplinary intensive care after cardiac surgery have a poor prognosis. The aim was to investigate factors in the mortality of this group of patients at 6 months. METHODS: A retrospective analysis was made of the 6-month mortality rate in 301 adults who required admission to a multidisciplinary intensive care unit following cardiac surgery from 1991 to 1997. Mortality was correlated with clinical and patient characteristic variables. RESULTS: The intensive care mortality rate was 34% and at 6 months after patients' discharge from intensive care it was 51%. There were positive correlations with death at 6 months for ventricular failure (odds ratio of death 3.4, P = 0.002), sepsis (odds ratio 3.0, P = 0.004) and age over 80 yr (odds ratio of death 9.2, P = 0.034). Patients who had undergone isolated coronary artery graft surgery (odds ratio of death 0.28, P = 0.036) or thoracic surgery (odds ratio of death 0.22, P = 0.042) had better 6-month outcomes. Patients with respiratory or renal failure in the absence of ventricular failure or sepsis had a 6-month mortality rate of 36%; but the lower mortality rate did not achieve statistical significance. CONCLUSIONS: The 6-month mortality rate of 51% in a group of patients requiring multidisciplinary intensive care after cardiac surgery is consistent with previous studies; mortality was particularly high in extreme old age and in patients referred with sepsis or ventricular failure. Those patients with uncomplicated respiratory or renal failure had a better outcome than the group as a whole.

The pulmonary physician in critical care . 12: Acute severe asthma in the intensive care unit.

Most deaths from acute asthma occur outside hospital, but the at-risk patient may be recognised on the basis of prior ICU admission and asthma medication history. Patients who fail to improve significantly in the emergency department should be admitted to an HDU or ICU for observation, monitoring, and treatment. Hypoxia, dehydration, acidosis, and hypokalaemia render the severe acute asthmatic patient vulnerable to cardiac dysrrhythmia and cardiorespiratory arrest. Mechanical ventilation may be required for a small proportion of patients for whom it may be life saving. Aggressive bronchodilator (continuous nebulised beta agonist) and anti-inflammatory therapy must continue throughout the period of mechanical ventilation. Recognised complications of mechanical ventilation include hypotension, barotrauma, and nosocomial pneumonia. Low ventilator respiratory rates, long expiratory times, and small tidal volumes help to prevent hyperinflation. Volatile anaesthetic agents may produce bronchodilation in patients resistant to beta agonists. Fatalities in acute asthmatics admitted to HDU/ICU are rare.

Indices of nitric oxide synthesis and outcome in critically ill patients.

We measured the concentrations of serum nitrates/nitrites and plasma cyclic guanosine monophosphate as markers of nitric oxide synthesis in patients with or without septic shock for 5 days following admission to intensive care. We found that nitrate/nitrite concentrations, when corrected for the effect of renal failure, were significantly higher in patients with septic shock, both on admission and in the final samples drawn. In a logistic regression analysis, the rate of change of nitrate/nitrite concentration was associated with survival to day 28 (falling in survivors). The concentration of cyclic guanosine monophosphate when corrected for the confounding effects of renal function and platelet count, was only associated with the septic shock group on admission.

Human-computer interactions: can computers improve the way doctors work?

As medicine becomes more complex and the knowledge base expands, the integration of computer systems into clinical practice would appear to be an inescapable necessity rather than an option. The issues of security and reliability have largely been solved by industrial and business applications of computer technology. The larger challenge lies in designing convenient, efficient and acceptable interfaces between the clinician and computer for data input and presentation. In the future, decision making algorithms are likely to assist the clinician in diagnosis and management to a degree that should significantly improve clinical effectiveness.

Laparostomy for severe intra-abdominal infection complicating colorectal disease.

PURPOSE: The aim of this study was to evaluate the use of laparostomy in the management of patients with severe intra-abdominal infection resulting from colorectal disease. METHODS: Seven patients, four with inflammatory bowel disease, two with colorectal carcinoma, and one with diverticular perforation, underwent laparostomy during a six-year period for postoperative, severe, intra-abdominal infection. RESULTS: The median age was 42 years, the mean Acute Physiology and Chronic Health Evaluation II score was 22.7, and the observed mortality was 28.6 percent (2/7 patients). In one patient the laparostomy was closed at 11 days; in all the others the wound was left to heal by granulation and contraction, and two of these later required reconstructive surgery. The median follow-up was three years and seven months. CONCLUSION: Laparostomy is an effective and practical method of managing patients with severe intra-abdominal infection as a result of colorectal disease.

Carotid endarterectomy in patients with significant renal dysfunction.

PURPOSE: Recent reports suggest that carotid endarterectomy (CEA) should not be performed in patients with end-stage renal disease (ESRD) because of an unacceptable rate of perioperative stroke and other morbidity. Because these conclusions were based on a small number of patients, we reviewed the perioperative and long-term outcome of patients with ESRD and chronic renal insufficiency (CRI) who underwent CEA at our institution. METHODS: The 1081 patients who had a CEA between 1990 and 1997 were cross-referenced with those patients in whom renal insufficiency had been diagnosed. These charts were reviewed for patient demographics and perioperative and long-term outcome. Patients undergoing CEA during a 1-year period (1993) served as controls. RESULTS: Fifty-one CEAs were performed in 44 patients with CRI (32 in 27 patients) and ESRD (19 in 17 patients). In the CRI+ESRD group, 66.7% were symptomatic, and 70.7% of the control group were symptomatic. Six operations (11.8%) in the CRI+ESRD group were redo endarterectomies. There were no perioperative strokes in the CRI+ESRD group, but one patient died 29 days postoperatively because of a myocardial infarction, for a combined stroke-mortality rate of 2.0%. The control group had a 2.6% combined stroke-mortality rate. Long-term survival analysis revealed a 4-year survival rate of 12% for patients with ESRD and 54% for patients with CRI, compared with 72% for controls (P <.05). CONCLUSION: CEA can be performed safely in patients with ESRD or CRI, with perioperative stroke and death rates equivalent to that of patients without renal dysfunction. However, the benefit of long-term stroke prevention in the asymptomatic patient with ESRD is in question because of the high 4-year mortality rate of this patient population.

Adhesion formation is reduced after laparoscopic surgery.

BACKGROUND: Adhesion formation after abdominal operations causes significant morbidity. METHODS: Adhesion formation in pigs was compared after placement of prosthetic mesh during celiotomy (group 1), laparoscopy with large incision (group 2), and laparoscopy (group 3). After peritoneum was excised, polypropylene mesh was fixed to the abdominal wall, then to the opposite abdominal wall in the preperitoneal space followed by peritoneal closure. Adhesion area, grade, and vascularity were measured. RESULTS: More adhesions (p < 0.02) covered intraperitoneal mesh (7.57 +/- 1.89 cm2) than covered reperitonealized mesh (2.16 +/- 1.13 cm2), and adhesion grade was significantly greater (p < 0.02). Adhesion areas were significantly greater in groups 1 and 2 than in group 3 (p = 0.001 and 0.03, respectively). Adhesion grade was significantly greater in groups 1 and 2 than in group 3 (p = 0.02 and p = 0.04, respectively). Groups 1 and 2 had more vascular adhesions than group 3 (p < 0.01 and p = 0.02, respectively) CONCLUSIONS: A foreign body within the peritoneum stimulates more numerous and denser adhesions. Tissue trauma distant from the site of adhesions increases their formation. A major advantage of laparoscopic surgery is decreased adhesion formation.

Orally administered heparin for preventing deep venous thrombosis.

BACKGROUND: Sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) is an acetylated amino acid molecule that facilitates the gastrointestinal absorption of heparin. This study was undertaken to evaluate the efficacy of orally administered combination SNAC:heparin in preventing deep venous thrombosis in a standard rat model. METHODS: Forty-four adult male Sprague-Dawley rats were randomly divided into five groups: group I control, group II SNAC, group III oral heparin, group IV combination SNAC:heparin, and group V intravenous heparin. Thirty minutes after drug administration, the internal jugular vein was bathed in a sclerosant mixture for 2 minutes and reexplored at 120 minutes. Activated partial thromboplastin times (aPTT) were measured in 30 rats equally divided into three groups: group I SNAC, group II oral heparin, and group III combination SNAC:heparin. Forty-five minutes posttreatment, blood was obtained for aPTT levels. RESULTS: The incidence of deep venous thrombosis in the control group was 89% (8 of 9) versus 25% (2 of 8) in the combination SNAC:heparin group (p < 0.01). There was also a significant reduction in clot weight among groups. Combination SNAC:heparin significantly increased aPTT levels compared with SNAC or oral heparin alone. CONCLUSION: In a rat model of venous thrombosis, combination of orally administered heparin:SNAC elevated aPTT levels and significantly reduced the formation of deep venous thrombosis.

Duplex-directed vena caval filter placement: report of initial experience.

BACKGROUND: Fluoroscopy, cost, and patient transport contribute to difficulties occasionally associated with the placement of vena caval filters. Follow-up data in the literature document the use of duplex ultrasonography in visualizing the filter and determining caval patency. Filter placement at the bedside or in the vascular laboratory with duplex ultrasonography may simplify this common procedure. We have attempted to define the feasibility of this method. METHODS: Patients referred to the vascular surgery service for vena caval interruption were evaluated for ability to visualize the renal veins and inferior vena cava. Location of renal veins, maximum diameter of the vena cava, and presence or absence of thrombus were documented. If visualization was adequate, placement was performed at the bedside for patients in intensive care or in the vascular laboratory for nonmonitored patients. The initial 10 patients and subsequent patients in whom there was a question of adequate deployment underwent completion abdominal roentgenography. Patient follow-up was difficult. Duplex ultrasonography was used to assess migration, thrombus adherent to the filter, and vena caval patency. Patients in whom filter placement was prophylactic were given anticoagulants at the discretion of the primary physician. Inadequate visualization or vena caval size greater than 28 mm prompted fluoroscopic placement of the vena caval filter, because only Greenfield titanium filters were used in the study. RESULTS: Twenty-nine patients were referred for vena caval interruption. Inadequate visualization occurred in four obese patients, and filters were placed by fluoroscopy. There were no vena caval measurements greater than 24 mm. Twenty-five filters were placed without technical difficulty. One filter tilted into the right renal vein, requiring a suprarenal filter placed by fluoroscopy. Patient retrieval for follow-up has been difficult, but by ultrasonography there has been one vena caval thrombosis and no major filter migration. There have been no reported pulmonary emboli other than the one patient with initial tilt of the filter. CONCLUSIONS: Placement of vena caval filters is feasible with duplex ultrasonography. Visualization is the only limiting condition to placement and occurs rarely. Reducing the need for fluoroscopy, lowering costs, and not needing to transport the critically ill patient support the use of this system. Intravascular ultrasonography in selected patients may eliminate the need for fluoroscopic placement of vena caval filters.