Richard J. Fowl

Protection against postischemic spinal cord injury using a new 21-aminosteroid

Ischemic spinal cord injury following repair of the thoracoabdominal aorta is an unpredictable and devastating complication. Recently, a new class of agents has been developed, the 21-aminosteroids, which have been demonstrated to reduce ischemic neurologic injury in several animal models. We performed this study to determine if the 21-aminosteroid U-74006F exerted a protective effect in a rabbit model of spinal cord ischemia. Nineteen New Zealand rabbits were anesthetized and then subjected to 25 min of temporary infrarenal aortic occlusion. Nine rabbits were given 3.0 mg/kg U-74006F iv 10 min prior to clamping the aorta, followed by 0.75 mg/kg every hour for 6 hr beginning 1 hr after the clamp was removed. Ten rabbits received equivalent doses of an aqueous buffered vehicle. The rabbits were neurologically graded upon awakening and then daily using the following scale: grade 0 = complete paralysis, grade 1 = partial deficit, grade 2 = normal. In the U-74006F-treated group, five animals were normal, one had a partial deficit, and three were paraplegic. In the vehicle group, only one animal was normal and nine were paraplegic. The difference between the mean neurologic grading scores of the two groups was statistically significant (P = 0.013). It is believed that U-74006F acts at the cell membrane level during reperfusion by inhibiting lipid peroxidation and lipid hydrolysis. Our data suggest that this agent may significantly reduce the incidence of postischemic spinal cord injury following temporary aortic occlusion.

Surveillance venous scans for deep venous thrombosis in multiple trauma patients

The high reported incidence of deep venous thrombosis (DVT) in trauma patients has prompted surveillance venous duplex scanning of the lower extremities. We report our retrospective experience with 183 multiple trauma patients who were admitted to the surgical intensive care unit and underwent 261 surveillance venous scans. There were 122 men and 61 women whose average age was 38 years. All patients were treated prophylactically with either extremity pneumatic compression or subcutaneous heparin to prevent DVT. Most (87%) patients suffered blunt trauma and had either head (3%), spinal (3%), intra-abdominal (9%), or lower extremity (17%) injuries or a combination of injuries (68%). Almost two thirds of the patients had no symptoms suggestive of possible DVT. Of the 261 venous scans performed, 239 (92%) were normal, 16 (6%) were positive for proximal lower extremity DVT, and six (2%) showed thrombus limited to the calf veins. Patients with symptoms of lower extremity DVT were significantly more likely to have proximal DVT compared to those without symptoms (15% vs. 5%,p <0.05).Patients with spinal injuries also had a higher incidence of proximal DVT (18% vs. 6%,p <0.05).At current hospital charges, the cost to identify each proximal DVT was

Contralateral duplex scanning for deep venous thrombosis is unnecessary in patients with symptoms

6688. If surveillance duplex scans were performed on all trauma patients in the surgical intensive care unit, the national annual expense would be

Mycotic aneurysm of the tibioperoneal trunk: Case report and review of the literature

300,000,000. Routine DVT surveillance is expensive and should be reserved for symptomatic patients or those with spinal injuries.

Temporary closure of the abdominal wall by use of silicone rubber sheets after operative repair of ruptured abdominal aortic aneurysms

PURPOSE Bilateral lower extremity venous duplex scanning for acute deep venous thrombosis (DVT) has been advocated because of the high incidence of occult contralateral leg involvement. We investigated the clinical necessity of such a policy. METHODS The results from 2996 venous duplex studies performed during the past 2 years were retrospectively reviewed. A total of 1694 of these scans were performed on patients with symptoms, of whom 248 (15%) were found to have an acute DVT. Symptoms were limited to one side in 198 patients, whereas bilateral complaints were noted in 50 patients. RESULTS Among the patients with symptoms of acute DVT, 72 (29%) had bilateral involvement. Bilaterality was more likely in patients with bilateral symptoms than in those with only unilateral symptoms (56% vs 22%; p < 0.005). Of the patients with unilateral symptoms and bilateral DVT, all of them had either acute (80%) or acute and chronic (20%) thrombosis in the symptomatic leg. The contralateral asymptomatic limb had fewer acute and more chronic DVT (41% and 55%, respectively). No patient from the entire group admitted with symptoms had an acute DVT in the asymptomatic limb without a concomitant acute DVT in the symptomatic leg. Unilateral scanning would decrease the examination time by 21% and potentially increase total reimbursement for symptomatic venous scans by 9% compared with routine bilateral duplex scanning. CONCLUSIONS Although bilateral involvement is frequent in patients with symptoms of acute DVT, treatment in these patients is not altered by this finding. We conclude that contralateral venous scanning in patients with unilateral symptoms is not clinically indicated and that unilateral scanning would result in improved cost-efficiency for vascular laboratories.

The limitations of impedance plethysmography in the diagnosis of acute deep venous thrombosis

Peripheral mycotic aneurysms can occur when septic emboli lodge in either the lumen or the vasa vasorum of a peripheral vessel. Such aneurysms have become rare after the widespread use of aggressive antibiotic treatment for bacterial endocarditis. We report the case of a large mycotic aneurysm of the tibioperoneal trunk 18 months after an episode of Streptococcus viridans bacterial endocarditis. Treatment included complete resection of the aneurysmal sac with restoration of circulation to the posterior tibial artery with a reversed saphenous vein graft. To our knowledge, this is the first case of a mycotic aneurysm of the tibioperoneal trunk reported in the English literature. It also represents the first case in which a mycotic aneurysm of an infrapopliteal vessel was managed successfully with restoration of circulation.

Inappropriate use of venous duplex scans: An analysis of indications and results☆☆☆★★★

Management of patients after operative repair of abdominal aortic aneurysms can be further complicated if primary closure of the abdominal wall cannot be technically accomplished or is associated with profound increases in intraabdominal and peak inspiratory pressures. We recently treated five patients with ruptured abdominal aortic aneurysms and one patient with a ruptured thoracoabdominal aneurysm whose abdominal incisions had to be closed with a Dacron reinforced, silicone sheet. All patients were hemodynamically unstable either at admission to the hospital or became so during operation. Four patients required the insertion of a silicone rubber sheet at the primary operation because of massive retroperitoneal hematoma or edema of the bowel wall or both. Incisions in two patients were closed primarily, but the patients required reexploration and secondary closure with silicone rubber sheets because of the development of marked increases in peak inspiratory pressures, intraabdominal pressures, and decreased urinary output. Four of the six patients subsequently underwent successful removal of the silicone rubber sheets with delayed primary closure of the abdominal wall, and two others died before removal. The patient with the ruptured thoracoabdominal aneurysm died on postoperative day 20 because of pulmonary sepsis but had a healed abdominal incision. The three surviving patients have been discharged. A silicone rubber sheet may be necessary for closure of the abdominal wall after repair of ruptured abdominal aortic aneurysm in patients where primary abdominal wall closure is impossible or where it results in compromise in respiratory or renal function.

Preferential Use of ePTFE For Above-Knee Femoropopliteal Bypass Grafts

We reviewed our experience with impedance plethysmography (IPG) and duplex scanning in the diagnosis of acute deep venous thrombosis (DVT) to determine their respective accuracy and current role in our noninvasive vascular laboratory. During a recent 22-month period 1776 patients were evaluated in our laboratory for DVT. Sixty patients (64 limbs) underwent ascending venography within 48 hours of testing (49 limbs were evaluated by all three modalities). With the venograms used as the reference standard, B-mode scanning correctly identified the presence of acute thrombus in 24 of 27 limbs (88.8%) and the absence of thrombus in 31 of 34 limbs (91.2%), for an overall accuracy of 90.6%. IPG alone was less sensitive (75%) and less specific (44.8%), with an overall accuracy of only 57.1%. Twenty-eight IPGs were performed on patients with negative venous scans. Two positive IPGs were the result of chronic venous occlusion and two others detected clinically significant isolated iliac vein thrombi, but 13 patients had false positive IPGs. One false negative IPG occurred. The difference in the sensitivity of scan alone vs scan plus IPG was not significant (chi 2 = 0.045; difference not significant), but the decrease in specificity was chi 2 = 17.3; p less than 0.001). The rarity of isolated iliac vein thrombosis and the high false positive rate for IPG do not justify its continued use if B-mode venous scanning is available. Although positive scan results may be used confidently to institute therapy without the need for venography, in high-risk patients with a strong clinical suspicion of proximal DVT despite a negative scan venography should be obtained before withholding anticoagulation.

Complications of Anomalous Origin of the Right Subclavian Artery: Case Report and Review of the Literature

PURPOSE The increasing demand for venous duplex scans despite the relative rarity of detecting acute deep venous thrombosis (DVT) prompted us to review our experience with this diagnostic method. METHODS We retrospectively analyzed the results and indications of 2993 lower extremity venous duplex scans performed between July 1, 1992, and June 30, 1994, at our institution. The indication for the study and the results were prospectively recorded in a computerized data bank. The indications for these studies were leg pain (34%), leg swelling (24%), surveillance for DVT in a patient at high risk (23%), searching for a source of pulmonary embolism (14%), follow-up of previously diagnosed DVT (3%), and other indications (i.e., varicose veins, venous ulcer, 2%). RESULTS Overall, 74.1% of all scans were completely normal, and only 13.1% detected acute proximal (popliteal vein or higher) DVT. Scans performed for surveillance (87.3% normal) or source of pulmonary embolism (79.6% normal) were significantly more likely to be normal than when performed for any other indication (p < 0.01). When leg edema or calf tenderness was present, the incidence of acute DVT was significantly greater for all indications (p < 0.0001). CONCLUSIONS The high percentage of normal venous scans implies that this diagnostic method is being inappropriately used. In the current climate of cost containment our data suggest that indications for venous duplex scans must be better defined and that improved education for referring physicians is needed.

Natural History of Claudicants with Critical Hemodynamic Indices

We have used polytetrafluoroethylene preferentially for bypasses to the above-knee popliteal artery since 1979. Since this approach has recently been challenged, we reviewed our experience with 138 grafts in 128 patients. The majority (74%) of patients were male with a mean age of 63.2 years. Risk factors included: smoking (85%), hypertension (55%), diabetes mellitus (45%), and coronary artery disease (41%). The indications for operation were disabling claudication (18%), rest pain (42%), gangrene/tissue loss (33%), and miscellaneous (7%). Perioperative (30 day) mortality was 3% and morbidity (excluding amputation or graft failure) was 5%. Patients were followed for up to eight years with a mean follow-up of 22.1 months. Grafts which remained patent, but did not prevent major amputation, were classified as “failed”. Primary patency was 75% at one year and 54% at five years. Limb salvage was 88% at one year and 70% at five years. Risk factors, indication for operation and arteriographic runoff had no statistically significant impact on short- or long-term patency. However, bypass grafts to isolated popliteal segments had a significantly (p=0.025) increased perioperative failure rate compared to all other grafts. Our data support the continued use of polytetrafluoroethylene for above-knee femoropopliteal bypass except perhaps in patients who require grafting to an isolated popliteal segment where higher early failure rates were seen.