Intraoperative intraarterial urokinase in early postoperative stroke following carotid endarterectomy: a useful adjunct.

The purpose of this study was to determine the efficacy of intraoperative intraarterial urokinase (UK) in patients who suffered an acute stroke immediately following carotid endarterectomy (CEA). From January 1995 to March 1998, 823 carotid endarterectomies were performed. The subsequent results showed that intraarterial UK in the setting of early post-CEA neurologic events appears to be safe and may be a useful adjunct to re-exploration in improving neurologic outcomes.

New duplex ultrasound scan criteria for managing symptomatic 50% or greater carotid stenosis.

PURPOSE: The North American Symptomatic Carotid Endarterectomy Trial (NASCET) showed that selected patients benefited from surgery when their carotid artery was 50% or more stenosed. This study assessed the accuracy of color-flow duplex ultrasound scanning (DUS) parameters to detect 50% or greater carotid artery stenosis and to determine the situations in which carotid endarterectomy (CEA) without angiography could be justified. METHODS: From March 1, 1995, to December 1, 1995, all patients considered for CEA were studied with DUS and carotid angiography. Results of the two tests were blindly compared. DUS measurements of internal carotid artery (ICA) peak systolic velocity (PSV), end diastolic velocity, and ratio of the ICA to common carotid artery PSV (ICA/CCA) were subjected to receiver operator characteristic curve analysis to determine the most accurate criterion predicting 50% or greater angiographic stenosis. The criterion for identifying patients for CEA without angiography was selected from criteria with a high positive predictive value (PPV) and sensitivity. RESULTS: A total of 188 carotid bifurcations were available for comparison. A PSV (ICA/CCA) of 2 or higher was the most accurate criterion for detection of 50% or greater stenosis, with an accuracy rate of 93% (sensitivity, 96%; specificity, 89%; PPV, 92%). A PSV (ICA/CCA) of 3.6 or higher was the best criterion for identifying candidates for CEA who had not undergone earlier angiography, with PPV, sensitivity, specificity, and accuracy rates of 98%, 77%, 98%, and 86%, respectively. CONCLUSION: These redefined criteria detect the NASCET-defined threshold level of 50% or greater ICA stenosis, above which CEA results in stroke reduction. A management algorithm based on these criteria should help to minimize both angiography and unnecessary intervention.

Vascular trauma associated with fractures and dislocations.

Vascular trauma occurs relatively infrequently in association with general orthopedic trauma but may be seen more often in injuries involving joint dislocations and areas in which vascular structures are tethered at the fracture site. The mechanisms of vascular trauma are identified, and the general principles in managing these injuries, including the operative approach to the injury itself and the options in repairing both arterial and venous injuries, are discussed. The role of fasciotomy and primary amputation are also reviewed. Several specific injuries, including pelvic fracture, knee dislocation, shoulder and upper limb injuries, complex tibial fractures, and iatrogenic injuries, are examined from diagnostic and management perspectives. Despite an ongoing evolution in the diagnosis and management of these often challenging injuries, the essential requirements for a good clinical outcome remain early recognition of the dysvascular limb and rapid institution of therapy.

Determination of the route of medium-chain and long-chain fatty acid absorption by direct measurement in the rat.

BACKGROUND: Medium-chain triglycerides are used for the treatment of malabsorptive states. We measured directly the absorption of medium- and long-chain fatty acids via the mesenteric lymphatics and portal vein in normal animals. These results may be useful in guiding therapy for short-bowel syndrome. METHODS: Under anesthesia, male Lewis rats (n = 6) underwent placement of jugular and portal venous lines, mesenteric lymphatic duct cannula, and a duodenal tube. After recovery, a 0.3% lauric acid (C12:0) and 0.37% palmitic acid (C16:0) solution solublized with 3.25 mmol/L lecithin and 23.75 mmol/L taurocholic acid in phosphate-buffered saline was infused at a rate of 3 mL/h via the duodenal tube. After stabilization of lymphatic flow (6 hours), a pulse of radiolabeled lauric and palmitic acid was given via the duodenal tube; absorption was measured by collection of lymphatic fluid and sampling of the portal and jugular venous blood for 4 hours. RESULTS: The amount of acid recovered in the lymphatics was 51% +/- 6% (mean +/- SD) for lauric and 59% +/- 6% for palmitic. For both fatty acids, < 1% in total was recovered from the portal vein during the 4-hour postbolus period; thereafter, levels in the blood were constant and very low. At necropsy, the majority of the remaining label was found in the intestine. CONCLUSIONS: These results show no evidence for the preferential absorption of medium-chain fatty acids directly via the portal vein in this model. We suggest that further studies be done to measure directly portal vein absorption of the medium-chain fatty acids.

Fat absorption after small intestinal transplantation in the rat.

BACKGROUND: Intestinal transplantation is now used for patients with severe malabsorption, however, little data exists quantifying the ability of the graft to absorb fat. This study tested the hypothesis that intestinal transplantation would not affect the lymphatic or venous uptake of fatty acids. METHODS: A syngeneic rat model of intestinal transplantation (SIT) with caval drainage of the graft was used. Control animals underwent intestinal division and reanastomosis (n=15 in each group). The animals were followed for 6 weeks, and fat absorption in vivo was quantified. The animals were anesthetized, sampling catheters were placed in the jugular and superior mesenteric veins and in the mesenteric lymphatic duct, and a feeding tube was passed into the duodenum. Animals were allowed to recover, and a steady-state duodenal infusion of lauric (C12:0) and palmitic (C16:0) fatty acid emulsion was begun. A radiolabeled pulse of lauric (C12:0) and palmitic (C16:0) fatty acid was then given, and the subsequent appearance in the lymphatic and venous systems was quantified. RESULTS: In vivo absorption of dietary fat was preserved, but after transplantation the mesenteric lymphatic flow and cumulative lymphatic appearance of both labels was significantly reduced (flow reduced from 4.8+/-1.1 in controls to 1.0+/-0.29 ml/hr in transplant animals, whereas lauric acid absorption was 33+/-11.4% in controls vs. 7.5+/-2.5% in transplant animals). There was a modest increase in the jugular venous appearance of the fatty acids (2.0+/-1.1% in transplant animals vs. 0.75+/-0.55% in controls for lauric acid; P<0.05 for all comparisons). Absorption of lauric and palmitic acids was very similar, and there was no preferential absorption detected in the portal venous system. Dye studies demonstrated lymphatic recannulization around the vascular anastomosis, into the retroperitoneum. CONCLUSIONS: These results suggest that in this model of SIT, fat absorption via the mesenteric duct is reduced, but that compensatory collaterals form into the retroperitoneal lymphatics. There was no evidence of any significant increase in portal venous uptake of fatty acids after SIT, nor of preferential absorption of medium-chain fatty acids. These results may have implications for patients after SIT.