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Biomedical subjects

R G Sheiman

Publications and source records attributed to R G Sheiman.

28 records · Page 2Linked to original sources
PubMed1995

Bilateral lower extremity US in the patient with unilateral symptoms of deep venous thrombosis: assessment of need.

PURPOSE: To assess the need for bilateral ultrasound (US) evaluation for lower extremity deep venous thrombosis (DVT) regardless of predisposing factors in patients with unilateral symptoms. MATERIALS AND METHODS: Two hundred six patients with unilateral lower extremity symptoms suggestive of DVT were evaluated prospectively for predisposing factors and symptoms. Bilateral examinations were performed in all patients, and the prevalences of US-diagnosed DVT in symptomatic and in asymptomatic extremities were determined. RESULTS: Thirty-seven of the 206 patients had DVT in the symptomatic extremity. Twenty-five of these 37 patients had predisposing factors. No DVT was found in any asymptomatic extremity. Because compression US has a sensitivity and a specificity of greater than 90% for the diagnosis of DVT, these results were statistically significant (P < .001). CONCLUSION: Regardless of predisposing factors, US screening for DVT in the lower extremities should be limited to the symptomatic extremity in patients with unilateral symptoms. This would decrease scanning time and cost without a decline in the DVT detection rate.

Adolescent↗
PubMed1995

Bilateral lower extremity US in the patient with bilateral symptoms of deep venous thrombosis: assessment of need.

PURPOSE: To assess the frequency of lower extremity deep venous thrombosis (DVT) detected with ultrasound (US) in patients with bilateral symptoms suggestive of DVT. MATERIALS AND METHODS: Fifty patients with bilateral lower extremity symptoms suggestive of DVT were examined prospectively for predisposing factors and type of symptoms. Charts were reviewed for previous lower extremity disease or chronic illness that could explain the patient's symptoms. The frequency of DVT diagnosed with US in this patient group was determined. RESULTS: No DVT was identified in the patients with bilateral symptoms suggestive of DVT. Retrospective review demonstrated that 34 (68%) of the patients had a preexisting condition (cardiac disease, venous insufficiency, chronic swelling, cellulitis or thrombophlebitis, peripheral arterial disease). Because compression US has a greater than 90% sensitivity and specificity for the diagnosis of DVT, these results were statistically significant (P < .001). CONCLUSION: The likelihood of DVT in patients with bilateral lower extremity symptoms is extremely low. Alternative causes should be carefully explored before lower extremity US is considered.

Aged↗
PubMed1995

Interventional radiology and cross sectional imaging in venous access.

The role of radiology and the interventional radiologist in the care of patients requiring long term venous access is expanding. This role includes multimodality imaging for anatomic evaluation, guided catheter placement or repositioning, and diagnosis and treatment of catheter occlusion or related venous thrombosis. Interventional procedures have been developed for relief of venous obstruction, repositioning of catheters, and placement of unconventional access devices.

Catheterization↗
PubMed1993

Combined effects of urokinase and heparin on PTT values during thrombolytic therapy.

The local infusion of urokinase may be complicated by hemorrhage. Except for maintaining fibrinogen levels above 100 mg/dL, no other criteria exist for titrating the dose of urokinase to avoid hemorrhagic complications. A retrospective examination of the fibrinolytic and coagulation states was performed on 11 patients receiving local high-dose urokinase (240,000 U/hr) and heparin for thrombolysis of acute occlusions to identify parameters other than fibrinogen levels that may correlate with bleeding complications. Five patients experienced bleeding complications, 3 of whom had partial thromboplastin time (PTT) values greater than 150 seconds. None of the five patients having hemorrhagic complications had fibrinogen levels below 100 mg/dL at any time. Urokinase began to enhance the effect of heparin on PTT values as a result of reducing fibrinogen levels. In 10 of 11 patients this effect caused PTT values to at least double when compared with heparin alone. This substantial rise in PTT occurred only after fibrinogen levels approached 200 mg/dL in 8 of 11 patients. Although the number of patients is small, these data suggest that when heparin is used during thrombolysis, closer PTT monitoring should be carried out as fibrinogen levels begin to decline, especially when they approach 200 mg/dL, to avoid excessive PTT elevations and subsequent bleeding.

Aged↗
PubMed1992

Traumatic aortic tear: screening with chest CT.

Dynamic chest computed tomography (CT) was performed in 326 patients who had undergone abdominal CT for blunt trauma to evaluate the role of chest CT in screening for thoracic aortic injury. Evidence of mediastinal bleeding constituted an abnormal CT examination. The results were correlated with those from aortography in 131 patients. The chest radiographs were abnormal in 127 patients (39%). Of those 127 patients, chest CT scans were abnormal in 39 patients; an aortic tear was present in eight of those patients (21%). The remaining 88 patients had normal CT scans and no aortic injury. Of the 199 patients with normal radiographs, 15 had abnormal CT scans and 184 had normal CT scans and no aortic injury. There were no false-negative CT scans; 79% of patients with normal CT scans had false-positive chest radiographs. With CT there was a significant improvement over plain radiography in specificity, accuracy, and predictive value of positive results. If chest CT were used as an adjunct to chest radiography in the screening for traumatic aortic tear, the need for aortography would decrease by 56%. Chest CT can safely help discriminate candidates for aortography, is cost-effective, and, in hemodynamically stable patients, should be incorporated in the screening for traumatic aortic tear.

Aorta, Thoracic↗
PubMedDate not supplied

Percutaneous radiofrequency tissue ablation: optimization of pulsed-radiofrequency technique to increase coagulation necrosis.

PURPOSE: To develop a computerized algorithm for pulsed, high-current percutaneous radiofrequency (RF) ablation, which maximally increases the extent of induced coagulation necrosis. MATERIALS AND METHODS: An automated, programmable algorithm for pulsed-RF deposition was designed to permit high-current deposition by periodically reducing current for 5-30 seconds during RF application. Two strategies for pulsed-RF deposition were evaluated: (i) constant peak current (900-1,800 mA) of variable duration and (ii) variable peak current (1,200-2,000 mA) for a specified minimum duration. The extent of induced coagulation was compared to results obtained with continuous (lower current) RF application. Trials were performed in ex vivo calf liver (n = 115) and in vivo porcine liver (n = 30) and muscle (n = 18) with use of 2-4-cm tip, internally cooled electrodes. RESULTS: For 3-cm electrodes in ex vivo liver, applying pulsed-RF with constant peak current for 12 minutes produced 3.5 cm +/- 0.2 of necrosis. Greater necrosis was produced with use of the variable current strategy, in which 4.5 cm +/- 0.2 of coagulation was achieved with use of an initial current > or =1,500 mA (minimum peak-RF duration of 10 sec, with 15 sec of reduced current to 100 mA between peaks; P < .01). This variable peak current algorithm also produced 3.7 cm +/- 0.6 of necrosis in in vivo liver, and 6.5 cm +/- 0.9 in in vivo muscle. Without pulsing, a maximum of 750 mA, 1,100 mA, and 1,500 mA could be applied in ex vivo liver, in vivo liver, and in vivo muscle, respectively, which resulted in 2.9 cm +/- 0.2, 2.4 cm +/- 0.2, and 5.1 cm +/- 0.4 of coagulation (P < .05, all comparisons). CONCLUSIONS: A variable peak current algorithm for pulsed-RF deposition can increase coagulation necrosis diameter over other ablation strategies. This innovation may ultimately enable the percutaneous treatment of larger tumors.

Animals↗
PubMedDate not supplied

Delayed intravenous contrast medium washout from the small bowel in patients with pancreatic carcinoma and splanchnic venous invasion.

PURPOSE: Our goal was to determine whether splanchnic venous invasion by pancreatic carcinoma causes any detectable delay in contrast medium clearance from the small bowel, reflected in alterations in small bowel (SBe), portal vein (PVe), or hepatic (He) enhancement on contrast-enhanced spiral CT. METHOD: The values of SBe, PVe, and He were determined from axial images obtained during performance of an abdominal spiral CT in 20 patients with pancreatic adenocarcinoma. SBe/PVe and SBe/He, felt to reflect intravenous contrast agent washout from the small bowel wall, were also calculated. Nine patients had splanchnic venous invasion (Group 1), and 11 were free of splanchnic venous involvement (Group 2) as determined by surgery or angiography. Similar measurements and ratios were performed in 10 patients with normal spiral CT scans to serve as controls (Group 3). RESULTS: A significant increase in SBe (p < 0.05), SBe/PVe (p < 0.01), and SBe/He (p < 0.05) and decrease in PVe (p < 0.01) were found in patients with invasion when compared with those without invasion and controls, while these parameters were similar in the last two groups. Individual SBe/PVe ratios in Group 1 were consistently elevated when compared with even the highest individual values in Groups 2 and 3. CONCLUSION: A detectable increase in SBe and decrease in PVe exist when comparing patients with and without splanchnic venous invasion by pancreatic adenocarcinoma. This is possibly the result of splanchnic congestion causing a delay in contrast medium washout from the small bowel wall. The SBe/PVe ratio, felt to be an indicator of contrast agent washout, may be used as an aid during spiral CT for pancreatic adenocarcinoma to determine the status of the splanchnic vasculature in equivocal cases.

Adenocarcinoma↗