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D L Dawson

Publications and source records attributed to D L Dawson.

33 records · Page 2Linked to original sources
PubMed1993

The role of duplex scanning and arteriography before carotid endarterectomy: a prospective study.

PURPOSE: This study examines the current role of diagnostic tests done before carotid endarterectomy and the need for routine arteriography. METHODS: We prospectively studied vascular surgeons' decision-making over a 29-month period during which 111 carotid arteries in 103 patients were considered for endarterectomy. For each case the surgeon's management plan was recorded after clinical evaluation and review of the duplex scan findings, but before arteriography. This plan was later compared with the patient's ultimate clinical management. RESULTS: Of 111 total cases in this period, 17 were excluded from analysis because arteriography was not done or it was performed before the surgeon's evaluation. Carotid duplex scans were diagnostic in 87 (93%) of the remaining 94 cases. The carotid lesion was incompletely assessed by duplex scanning in seven patients because the disease was not limited to the distal common or proximal internal carotid artery (n = 4); anatomic or pathologic features of the carotid artery interfered with imaging or accurate Doppler assessment (n = 1); or an internal carotid artery occlusion could not be distinguished from a high-grade stenosis (n = 2). When a technically adequate duplex scan showed significant disease of the carotid bifurcation, arteriography contributed information that affected clinical management in only a single case (1%). This patient had a middle cerebral artery occlusion distal to a high-grade carotid bifurcation stenosis. CONCLUSIONS: Clinical assessment and duplex scanning were sufficient for the preoperative evaluation of 93% of the candidates for carotid endarterectomy. Clinical circumstances or atypical duplex scan findings can be used to identify the minority of patients for whom arteriography is necessary. On the basis of this experience, we have developed practical guidelines for the selective use of arteriography before carotid endarterectomy.

Adult↗
PubMed1992

Use of skin staplers in experimental gastrointestinal injuries.

Undocumented reports exist concerning use of skin staplers to close small perforations of the gut. This study examined use of this device in experimental gastrointestinal injuries in dogs. In 18 anesthetized mongrel dogs, matching uniform perforations were made with a sterile leather punch; one perforation of each pair was closed with 3-0 silk and the other with a skin stapler. A total of 80 stomach, 238 small intestine, and 140 colon perforations were created. Hole sizes progressed from 1.9 to 5.0 mm. Unrepaired intestinal wounds leaked and were lethal. No leaks were identified in wounds closed with either sutures or staples provided that closure was complete. Speed of staple closure was faster than that of suture closure (1.2 vs. 16.0 seconds), but ease of closure was similar. It is concluded that skin staplers are safe for repair of small wounds, created under ideal conditions, in canine gastrointestinal tracts. Similar injuries in traumatized humans deserve study, but existing skin staplers may be ineffective for human intestine since gut wall thickness in humans is less than that in dogs.

Animals↗
PubMed1991

Injuries to the portal triad.

We reviewed the management and clinical course of 21 patients with extrahepatic injuries to the portal triad seen over the past 11 years at a Level I trauma center. These represented only 0.21% of patients with multiple trauma admitted during this time. Portal triad injury was never specifically diagnosed preoperatively. Extrahepatic bile duct injury occurred in 4 patients, portal vein injury in 14, and hepatic artery injury in 7; 3 patients had combined injuries. Eleven patients (52%) died, all due to uncontrolled hemorrhage from either an injured portal vein or associated intra-abdominal injuries. Management of the bile duct injuries included drainage alone, bile duct ligation, and Roux-Y hepaticojejunostomy. Survivors of portal vein injury were managed with lateral venorrhaphy. Ligation of the hepatic artery appeared to be optimal for injuries incurred by this vessel. Complications necessitating reoperation or percutaneous drainage procedures were encountered in 8 of 10 surviving patients (80%). Injuries to the portal triad are uncommon, difficult to diagnose, and technically challenging. Mortality is most directly related to uncontrolled intraabdominal hemorrhage, and salvage requires rapid control of bleeding as the first treatment priority.

Adolescent↗
PubMed1991

Role of arteriography in the preoperative evaluation of carotid artery disease.

This retrospective study was undertaken to determine the role of arteriography in the treatment of patients being considered for carotid endarterectomy. The results of preoperative classification of disease severity by duplex ultrasound and arteriography were compared, and the impact of arteriography on patient management was ascertained. We reviewed the records of 83 patients who had carotid surgery planned on the basis of their clinical history and duplex scan results and who then underwent arteriography. Duplex scan results agreed with the classification of stenosis by arteriography in 87% of evaluated sides and were within one category in 98%. In 87% of the cases reviewed, the clinical presentation and duplex scan findings were sufficient for appropriate patient management. In the instances that arteriography was useful (13%), the need for arteriography was evident when the duplex scan (1) was technically inadequate or equivocal; (2) showed an unusual distribution of disease, atypical anatomy, or a recurrent lesion; or (3) demonstrated an internal carotid artery with diameter-reducing stenosis of less than 50% in a patient with hemispheric neurologic symptoms despite antiplatelet therapy.

Adult↗
PubMed1991

Hepatic duct disruption from blunt abdominal trauma: case report and literature review.

A laceration-avulsion injury of the hepatic duct from blunt trauma is described. Operative findings rather than preoperative studies led to the correct diagnosis. A combination of suture repair, left hepatic duct ligation, and hepaticojejunostomy were used to primarily manage this complex injury. Postoperative hepatobiliary scintigraphy and clinical follow-up over 1 year demonstrate satisfactory biliary drainage. Principles of the management of hepatic duct injury are reviewed.

Abdominal Injuries↗
PubMed1989

Technical considerations in distal pancreatectomy with splenic preservation.

Splenic preservation may be attempted when distal pancreatectomy is performed for nonmalignant disease. The splenic artery and vein can be preserved with meticulous control of the multiple small, thin-walled branches that tether these vessels to the pancreas, allowing splenic salvage. Mobilization of the spleen into the operative field, ligation of the short gastric vessels and splenectomy are not performed. Thus, the operative procedure may be accomplished in carefully selected patients with little increase in operative time or blood loss over conventional distal pancreatectomy with splenectomy.

Humans↗
PubMed1986

Distal pancreatectomy with splenic preservation: the anatomic basis for a meticulous operation.

A case of distal pancreatectomy with splenic preservation is presented. In ten cadaver dissections of distal pancreas, an average of 22.1 tributaries of the splenic vein and 7.6 branches of the splenic artery were demonstrated. Anatomic considerations for splenic salvage during distal pancreatectomy are reviewed. Knowledge of the smaller pancreatic branches of the splenic vasculature is important in this surgical repair.

Adult↗
PubMed1986

Venous segmentation of the human spleen. A corrosion cast study.

Partial splenectomy is possible because of vascular segmentation of this organ. Although interest has focused upon arterial supply, this study shows similar venous segmentation. Emerging splenic veins in excess of 1.7 mm at the hilum of ten unembalmed spleens were injected with different colors of modified Batson's compound, and corrosion casts were made. In four additional spleens, alternate veins and arteries were injected. Ten spleens had two primary segments (lobes); four had three lobes. Half of these lobes were further subdivided into two segments. Lobes and segments extended through the full thickness of the spleen. Relatively avascular interlobar planes were always approximately perpendicular to the longitudinal axis of the spleen, whereas intersegmental planes were more variable. Both interlobar and intersegmental planes frequently corresponded to marginal notches. When arteries and veins were both injected, similar segmentation was noted. Venous drainage did not overlap arterial segments, indicating that veins are intrasegmental. These results indicate that the surgical unit of the spleen can be based upon surgically accessible vessels at the hilum of the spleen. Identification of segmental vessels could permit salvage of a larger amount of splenic tissue than would be possible if only lobar vessels were identified.

Adult↗
PubMed1985

Preoperative intraincisional cefamandole reduces wound infection and postoperative inpatient stay in upper abdominal surgery.

The use of preoperative intraincisional (POII) single dose antibiotic prophylaxis has the advantage of providing extremely high concentrations of antibiotic along all layers of the wound, whilst achieving adequate systemic concentrations throughout the operation. In a single blind controlled trial, 250 patients undergoing upper abdominal surgery were randomised to receive POII cefamandole (2g) or to act as control. There was one wound infection in the POII group compared with 18 in the control group (P less than 0.001). Hospital stay was reduced by an average of one day (P less than 0.02) in the antibiotic treated group.

Abdomen↗
PubMed1984

The fate of the left kidney after division of its vein.

The effect of dividing the left renal vein was studied in Sprague-Dawley rats. Immediately after the left renal vein is divided near the renal hilum, the left kidney becomes markedly edematous and dusky. Twenty-four hours later, the kidney remains edematous and boggy. In contrast, the edema that immediately follows division of the left renal vein adjacent to the inferior vena cava is much less dramatic and virtually resolves within 24 hours. When the left renal vein was divided near the hilum simultaneously with right nephrectomy, all animals died within 48 hours. When the vein was divided adjacent to the vena cava with simultaneous nephrectomy, all animals survived. The effect of dividing the renal vein on perfusion of the left kidney was studied in Sprague-Dawley rats using intra-arterial injection of copper pigment. Division of the left renal vein reduced perfusion of that kidney to 68.9 per cent of control levels. This reduction was demonstrated to be totally reversible within 10 days.

Animals↗
PubMed1980

Functional interpretations of the radiographic anatomy of the femora of Myotis lucifugus, Pipistrellus subflavus, and Blarina brevicauda.

Radiographs of right femora from 29 shrews (Blarina brevicauda) and 51 bats (27 Myotis lucifugus, 14 Pipistrellus subflavus) were analyzed to determine if bone in these small mammals conformed to Bassett's ('68) revision of Wolff's Law. Five external and four cortical dimensions were made on enlargements of radiographs of each femur. Comparative descriptions of the spongiosa are given. External dimensions appear to be determined genetically, and, in bats, are closely related to functional demands. Shrew femora retain a primitive mammalian morphology. No apparent relationship exists between animal weight and mid-diaphyseal cortical thickness. Although differences in cortical thickness in bats suggest a possible relation between bone and pressure, no relationship is apparent in shrews; further, the comparative magnitude of these dimensions is similar in all three species, indicating genetic control mechanisms. Computation of maximal loading suggest that loading is so slight, that the inherent strength of bone tissue is adequate to resist mechanical deformation. However, there is evidence or cortical bone response to physiological demands. Inspection of the spongiosa also fails to provide evidence of conformity to Wolff's Law. Instead, the trabeculae appear to be related to pysiologic factors, animal age, and inherited disposition patterns. Thus, there is no evidence that bone in these diminutive mammals responds to mechanical forces, and the applicability of Wolff's Law is not indicated. It is hypothesized that, as the mechanical forces are so minimal, intrinsic tissue strength is sufficient to resist mechanical deformation, and femoral anatomy in these species is dictated by genetic and inherent physiologic conditions.

Animals↗
PubMedDate not supplied

The role of infrapopliteal MR angiography in patients undergoing optimal contrast angiography for chronic limb-threatening ischemia.

PURPOSE: To determine the benefit of infrapopliteal magnetic resonance angiography (MRA) in patients with chronic limb-threatening ischemia who have undergone optimal contrast angiography (CA). PATIENTS AND METHODS: Thirty-four patients (37 limbs) with limb-threatening chronic lower extremity ischemia underwent MRA and CA of the symptomatic extremity. Selective, vasodilator-enhanced digital subtraction angiography of the infrapopliteal vessels was possible for 34 limbs. Two vascular surgeons retrospectively formulated treatment plans based on CA. They then formulated treatment plans based on CA and MRA together. RESULTS: CA clearly visualized 495 of 888 vascular segments as patent, while MRA clearly visualized 412 of 888 segments. Treatment plans differed for at least one of two surgeons in eight limbs, but MRA would possibly have improved clinical outcome in only one. The amount of inflow disease did not appear to influence segment visualization or treatment planning. In eight of 11 limbs that eventually required below- or above-knee amputation, CA clearly visualized more vascular segments than MRA. One patient developed renal insufficiency after CA. CONCLUSION: Most patients undergoing optimal CA for chronic limb-threatening ischemia will not benefit from the addition of MRA. However, MRA should be considered when CA is suboptimal and when it is necessary to conserve contrast material.

Adult↗