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Biomedical subjects

D L Steed

Publications and source records attributed to D L Steed.

At least 55 records · Page 3Linked to original sources
PubMed1991

On the inheritance of abdominal aortic aneurysm.

To determine the mode of inheritance of abdominal aortic aneurysm, data on first-degree relatives of 91 probands were collected. Results of segregation analysis performed on these data are reported. Many models, including nongenetic and genetic models, were compared using likelihood methods. The nongenetic model was rejected; statistically significant evidence in favor of a genetic model was found. Among the many genetic models compared, the most parsimonious genetic model was that susceptibility to abdominal aortic aneurysm is determined by a recessive gene at an autosomal diallelic major locus. A multifactorial component in addition to the major locus does not increase the likelihood of the data significantly.

Adult↗
PubMed1990

A model of persistent partial hindlimb ischemia in the rabbit.

An animal model of resting limb ischemia in the rabbit was developed and studied. Anesthetized rabbits underwent unilateral common iliac artery (CIA) division, allowing comparisons between an experimental (ischemic) and the contralateral control limb in the same animal. The time course and severity of the ischemic insult were measured by quantitating muscle blood flow in seven muscle groups using 57Co-radiolabeled microspheres, limb femoral arteriovenous oxygen differences (AVDO2), and limb arterial pressure. Nine of 20 animals had objective evidence of functional limb impairment judged by abnormal resting posture and/or abnormal gait. Muscle blood flow in the experimental limbs became significantly less than blood flows of corresponding contralateral muscle groups (P less than 0.05) when measured at 1 week after CIA division. By 17 days, mean muscle blood flow had returned to within 82.5% of that of the control limb. AVDO2 increased from 4.8 +/- 0.99 to 8.13 +/- 2.26 ml O2/dl blood following CIA division and remained persistently greater than the control limb value until Day 31. Limb arterial pressure decreased markedly after CIA division and remained significantly depressed beyond 6 weeks when the study was terminated. The reasons for the differential time courses of these parameters of blood flow are discussed. Common iliac artery division in the rabbit appears to produce persistent, partial ischemia at least 17 days in duration, allowing in-depth study of the effects of persistent limb ischemia on muscle cell function in the laboratory setting, as well as permitting the assessment of various therapeutic manipulations for the treatment of prolonged muscle ischemia.

Animals↗
PubMed1990

Clinical observations on the effect of carotid artery occlusion on cerebral blood flow mapped by xenon computed tomography and its correlation with carotid artery back pressure.

Xenon computed tomographic cerebral blood flow mapping was correlated with internal carotid artery stump pressures and clinical neurologic assessment during temporary internal carotid artery occlusion. One hundred fourteen patients with skull base tumors or intracranial aneurysms potentially requiring carotid resection or ligation underwent angiography, xenon CT cerebral blood flow mapping, and internal carotid artery blood pressure monitoring. The internal carotid artery was then temporarily occluded with a balloon catheter, stump pressure was measured through the catheter, and the xenon CT cerebral blood flow mapping was repeated. Adequate xenon CT cerebral blood flow was defined as greater than 30 cc/100 gm/min. All patients had normal xenon CT cerebral blood flow before internal carotid artery occlusion. During internal carotid artery occlusion, xenon CT cerebral blood flow was found to be normal (group I, 40 patients), globally reduced but still within the normal range (group II, 50 patients), or low in the distribution of the ipsilateral middle cerebral artery (group III, 13 patients). With balloon occlusion, an immediate neurologic deficit developed in 11 patients (9%) requiring deflation of the balloon preceding xenon CT cerebral blood flow measurement (group IV). In group I internal carotid artery blood pressure was 128 mm Hg. (range 85 to 171 mm Hg) with stump pressure 86 mm Hg (range 46 to 125 mm Hg). In group II internal carotid artery blood pressure was 130 mm Hg. (range 78 to 199 mm Hg), with stump pressure 86 mm Hg (range 31 to 150 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Inflammatory aneurysms of the abdominal aorta.

Inflammatory aneurysms of the abdominal aorta (IAAAs) have distinctive clinical and physical characteristics that separate them from typical atherosclerotic aneurysms. They were identified in 19 (7.2%) of 265 patients undergoing abdominal aortic aneurysm repair. Symptoms were present in 12 (63%) of 19, with one patient presenting with rupture, and multiple symptoms were present in six (32%). Intraoperatively, all aneurysms exhibited dense periaortic inflammation. Adjacent structures most frequently involved were the duodenum in 15 (79%) of 19 patients, the left renal vein in six (32%) of 19, and the ureter in five (26%) of 19. Seventeen (94%) of the 18 patients who underwent elective aneurysm resection survived. The involvement of retroperitoneal structures varied in number and severity, demonstrating that a wide spectrum of inflammation is present in IAAAs, making diagnosis and definition difficult.

Aged↗
PubMed1988

Chronic contained rupture of an abdominal aortic aneurysm presenting as a lower extremity neuropathy.

Rupture of an abdominal aortic aneurysm often presents with a pulsatile abdominal mass, abdominal pain, and hypotension. Recent clinical reports describe patients with less apparent clinical signs and symptoms who were found later in their evaluation to have a contained rupture of an abdominal aortic aneurysm. Even more unusual is a chronic contained rupture of an abdominal aortic aneurysm. Our patient had a chronic contained rupture of an abdominal aortic aneurysm that presented with erosion into the lumbar vertebral bodies and subsequent lumbar neuropathy. CT scan confirmed the contained rupture of the aortic aneurysm and the patient underwent successful repair of his aortic aneurysm. Our report discusses the significance of atypical presentations of abdominal aortic aneurysm rupture and the importance of prompt diagnosis and definitive repair.

Aged↗
PubMed1988

Upper gastrointestinal endoscopy after cardiac transplantation.

Three hundred four patients have undergone cardiac transplantation at the University of Pittsburgh since 1980. Twenty patients have required 27 upper gastrointestinal (GI) endoscopic procedures. After heart transplantation the primary indications for endoscopy were epigastric pain (six patients with gastritis, one with multiple shallow gastric ulcers, and one with normal test results), mild upper GI bleeding (four patients with esophagitis, two with gastritis, and two with multiple shallow gastric ulcers), dysphagia and odynophagia (two patients with esophagitis), persistent nausea and vomiting (one with normal test results), lower GI bleeding (one with normal test results), and routine follow-up (one with normal test results). After heart-lung transplantation the primary indications for the endoscopy were massive upper GI bleeding (three patients with actively bleeding duodenal ulcers), dysphagia and odynophagia (one patient with esophagitis), mild upper GI bleeding (one patient with gastritis), and routine follow-up (one patient with normal test results). No complications resulted from endoscopy. The procedures were performed in the GI suite without cardiac monitoring. Prophylactic antibiotics were not routinely administered. No patient had a fungal infection of the upper GI tract--a finding attributed to the prophylactic use of nystatin in all patients. Opportunistic viral infections were identified histologically in six patients, including two patients with actively bleeding duodenal ulcers. The possibility of opportunistic viral infections in this immunosuppressed group required aggressive diagnostic techniques, including endoscopy and biopsy, which can be safely performed after cardiac transplantation.

Adult↗
PubMed1988

Transcutaneous oxygen measurements in lower extremity ischemia: effects of position, oxygen inhalation, and arterial reconstruction.

Transcutaneous oxygen tension (TcPO2) measurement has been successfully applied to the diagnosis and monitoring of patients with peripheral arterial insufficiency. This study was performed to assess the effects of changes in limb position, oxygen inhalation, and arterial reconstruction on TcPO2 values in patients with peripheral vascular disease. In addition, a TcPO2 index (foot TcPO2/chest TcPO2) was compared with the Doppler-derived ankle-to-brachial index (ABI) to determine which was the more effective monitor of the response to revascularization. Foot TcPO2 values of 22 patients with claudication or rest pain were measured before and after vascular reconstruction. TcPO2 increased after revascularization in both groups regardless of limb position or oxygen (O2) administration. The dependent position and O2 inhalation had an additive effect on TcPO2. Preoperative TcPO2 values in patients with rest pain showed the greatest response to the dependent position, increasing from 14 mm Hg to 33 mm Hg at room air and from 21 mm Hg to 53 mm Hg with O2 inhalation. TcPO2 in both patient groups was remarkably enhanced by O2 administration after revascularization. Postoperative supine TcPO2 values measured at room air increased from 50 mm Hg to 124 mm Hg (148%) in patients with claudication and from 40 mm Hg to 109 mm Hg (173%) in patients with rest pain after O2 inhalation. Comparison of the TcPO2 index with the ABI showed that absolute and normalized TcPO2 values are equally effective in monitoring peripheral arterial insufficiency. This study suggests that placing the limb in the dependent position and administering O2 may augment TcPO2 to levels where symptoms may resolve. The response of TcPO2 to O2 inhalation may be an indicator that reflects the response to revascularization.

Arterial Occlusive Diseases↗
PubMed1987

Surgery on the hemophiliac patient. Special considerations.

Optimum care of patients with hemophilia requires cooperation among the hematologist, the surgeon, nurses, and blood bank personnel. Relatively normal hemostasis can be achieved and maintained in factor-deficient individuals in the perioperative period. Surgical procedures in patients with hemophilia can be accomplished safely with careful monitoring of coagulation factor levels and appropriate replacement therapy.

Factor VIII↗
PubMed1987

Relief of nonhemispheric symptoms in low flow states by anterior circulation revascularization: a physiologic approach.

Operative intervention remains controversial for patients with transient nonhemispheric symptoms with occlusive disease of both the anterior and posterior cerebral circulations. In addition to the standard evaluation of these patients, we have used stable xenon-enhanced computed tomographic mapping of cerebral blood flow (Xe/CT CBF). This relatively new and potentially widely available CBF methodology, by measuring approximately 30,000 CBF values within each of three CT levels, provides a readily interpretable means of evaluating extremes of hemodynamic compromise within any or all vascular territories. In the past 30 months, Xe/CT CBF studies in 300 patients with occlusive vascular disease have identified nine patients with global low flow and nonhemispheric symptoms (vertigo, lightheadedness, and/or blurred vision). Blood pressures determined by ocular pneumoplethysmography of Gee were markedly abnormal with reduced ocular/brachial ratios. Each patient had a combination of both segmental carotid and vertebrobasilar occlusive disease. Each patient had a flow-augmenting procedure performed on the anterior circulation in an attempt to improve global flow: carotid endarterectomy (two patients), subclavian-external carotid bypass (one patient), and superficial temporal artery-middle cerebral artery bypass (six patients). In each case disabling transient symptoms were relieved. There were no operative deaths, but one stroke occurred, probably as a result of a brief period of postoperative hypotension. Postoperative Xe/CT CBF studies show a long-term improved global CBF in all patients.

Brain↗
PubMed1987

Noninfectious complications of long-term central venous catheters: radiologic evaluation and management.

During a 5-year period, 416 long-term double-lumen central venous catheters were inserted into 288 patients. In these patients, 106 catheter venograms and nine upper extremity venograms were performed. All studies were reviewed retrospectively to determine the nature and prevalence of noninfectious catheter-related complications, to evaluate the efficacy and safety of streptokinase therapy, and to determine if catheter venography should be performed before streptokinase therapy is started. Noninfectious complications occurred in 66 (23%) patients. Complications that resulted in catheter malfunction included deposition of fibrin around the catheter tip (formation of a fibrin sheath) in 44 (57%) instances, a constricting suture in six, abutment of the catheter tip against the venous wall in eight, catheter leak in two, and migration of the catheter completely out of the vein in three. Venous thrombosis developed in 11 patients. Treatment with low doses of streptokinase successfully relieved catheter obstruction due to a fibrin sheath in 27 (87%) of 31 instances. No bleeding complications occurred. Five patients had malpositioned catheters in the azygous, axillary, or internal jugular veins. By use of a deflector wire or snare inserted via the femoral vein, all five were relocated successfully into the superior vena cava. Recognition of noninfectious complications associated with use of long-term catheters is important for institution of appropriate therapy, which in many instances obviates removal of the catheter. Formation of a fibrin sheath in only 57% of cases of catheter malfunction provides an argument for performing catheter venography before streptokinase therapy is started. Low-dose streptokinase therapy for long-term central venous catheters occluded by a fibrin sheath is safe and efficacious.

Catheters, Indwelling↗
PubMed1987

Limb sparing operations for sarcomas of the extremities involving critical arterial circulation.

Seven patients underwent resection of a sarcoma of the extremity requiring excision of a vital artery and revascularization. These included osteosarcoma of the pubis, osteosarcoma of the distal femur, undifferentiated sarcoma of the thigh, liposarcoma of the thigh, liposarcoma of the popliteal space, chondrosarcoma of the proximal tibia and rhabdomyosarcoma of the thumb. Preoperative evaluation included computed tomographic scan, magnetic resonance imaging and angiography. Operation involved excision of the iliac artery in one instance, femoral artery in three, popliteal artery in two instances and radial artery in one. Wide local resection including revascularization was undertaken when the tumor could be resected with the artery but separated from the nerve and it was a low grade malignant disease or the patient refused amputation for a high grade malignant disease. In five patients, the tumor margins were adequate. One patient with an osteosarcoma of the pubis with distant disease had a palliative resection and one patient had positive margins but refused amputation. Coverage of the soft tissue and vascular grafts was achieved using a distant pedicle flap in two patients. Amputation was avoided and each patient remained ambulatory. Five patients remained free of disease with patent grafts at six months to six years of follow-up study. One patient died of late myocardial infarction and one who underwent palliative resection died eight months later of metastatic disease. Involvement of the major arterial circulation does not preclude adequate resection of sarcomas of the extremity with limb salvage.

Adult↗
PubMed1986

Repositioning catheters in surgically drained abscesses.

Primary percutaneous drainage of intraabdominal abscesses under local anesthesia is an accepted method of treatment, with low morbidity and mortality. This technique was extended to patients with recurrent or secondary abscesses after initial primary surgical drainage. Four patients had abscesses drained operatively but were reevaluated several weeks later for recurrent fever. Sinography demonstrated an inadequately drained abscess cavity. Under fluoroscopic control and using local anesthesia, new drains were inserted and repositioned to provide better drainage. Resolution of the abscess cavity was documented radiographically, with improvement in the patients' clinical status.

Abdomen↗
PubMed1986

TcPO2 values in limb ischemia: effects of blood flow and arterial oxygen tension.

Transcutaneous oxygen tension (TcPO2) is determined by blood flow and arterial oxygen tension (PaO2) and has been advocated as a measurement of tissue perfusion in peripheral vascular disease. The purpose of this study was to define the relationship between regional blood flow, PaO2, and TcPO2. TcPO2 sensors were placed on the skin of the anterior tibial regions of the hind limbs of 15 dogs. After occluding collateral blood flow, an external flow probe was placed around the femoral artery and an adjustable clamp was used to produce graded ischemia. Progressive reductions in blood flow were correlated with TcPO2 values at inspired oxygen concentrations (FiO2) of 0.21, 0.50, and 1.00. TcPO2 measured at room air decreased nonlinearly in relation to flow with a marked drop occurring below 20% of baseline flow. TcPO2 measured at increased FiO2 was dependent primarily on PaO2 at flow rates greater than 50% of baseline. With reduction in flow below 25% of baseline, TcPO2 was dependent solely on flow and was not augmented by increases in PaO2. The data suggest that TcPO2 can accurately reflect changes in blood flow to an extremity when flow is severely restricted.

Animals↗
PubMed1986

General surgery in adult hemophiliacs.

From 1976 to 1984, 23 operations were performed on 22 patients with hemophilia (18 patients with factor VIII and four with factor IX deficiency). Elective procedures included resection of abdominal aortic aneurysm, liver transplantation, vagotomy/pyloroplasty, insertion of Mousseau-Barbin tube, colectomy, cholecystectomy, inguinal herniorrhaphy (four patients), colonoscopy/polypectomy, mediastinoscopy, arteriovenous fistula for dialysis, anal fistulectomy, and miscellaneous skin and soft-tissue procedures (five patients). Emergency operations were appendectomy (two patients), repair of bleeding liver biopsy site, and repair of an incarcerated inguinal hernia. There were two deaths (9%) within 30 days of operation, neither directly caused by the coagulopathy. Four patients had bleeding after surgery, which was treated with additional cryoprecipitate or factor concentrate. There were no nonhemorrhagic complications. Before operation, appropriate replacement therapy with factor VIII concentrate, cryoprecipitate, or fresh-frozen plasma was provided. Coagulation factor levels were measured before operation and monitored daily after operation. Generally, factor levels were raised to at least 1.0 U/ml and maintained at greater than 0.5 U/ml for 7 to 14 days after operation. However, when patients were treated with fresh-frozen plasma, plasma exchange was performed and factor levels of approximately 0.35 U/ml were achieved before surgery. We conclude that operations in patients with hemophilia can be accomplished safely with careful monitoring of coagulation factor levels and appropriate replacement therapy.

Adolescent↗
PubMed1986

Cerebral blood flow measured by xenon-enhanced computed tomography as a guide to management of patients with cerebrovascular disease.

CT scanning performed before and sequentially during the inhalation of stable xenon (32%), coupled with end-tidal xenon measurements, has made possible the routine construction of regional cerebral blood flow (rCBF) maps with resolution that approximates that of the CT scanner. The capability of obtaining quantitative flow maps with direct anatomic correlation is now available with a commercial package of hardware and software adapted to the General Electric 9800 scanner. The ability to distinguish between normal and reduced rCBF in specific vascular territories has proved useful in the management of cerebrovascular disease. Specific clinical dilemmas that have been addressed with rCBF information from xenon-enhanced CT scanning include the following: In the patient with asymptomatic occlusive disease, is normal rCBF preserved? Is there adequate collateral flow? Are cerebrovascular symptoms a result of emboli or chronic regional low flow? In the patient with complex multivessel occlusive disease, which revascularization procedure is indicated first? Did operation improve rCBF? Should a further procedure be added? May a diffusely diseased but patent artery, which is the source of emboli, be sacrificed safely without compromising rCBF? On the basis of experience with 155 patients, the management and understanding of cerebrovascular disease has been aided substantially by the incorporation of rCBF mapping by xenon-enhanced CT scan in the evaluation of these patients.

Aged↗
PubMed1986

Streptokinase in the treatment of subclavian vein thrombosis.

During the past 2 years, streptokinase has been used to treat subclavian or axillary vein thrombosis in seven patients of whom two were considered "effort" thromboses and five resulted from use of a central venous catheter. All patients had venography performed before treatment to document the thrombosis, and venography was repeated after streptokinase therapy to determine the status of clot dissolution. Streptokinase was given either systemically or in a lowered dose locally, with low-dose therapy chosen whenever a catheter could be threaded up to the clot through an antecubital vein. Although all seven patients had resolution of their clinical symptoms, only one had complete dissolution of the thrombus. The failure of streptokinase to completely dissolve the thrombus suggests that, although apparent clinical improvement can be achieved after streptokinase infusion, treatment of the underlying cause, whenever possible, may be necessary if complete resolution of the thrombus is to occur.

Adult↗
PubMed1986

Recognition and treatment of arterial insufficiency from cafergot.

Cafergot is a combination of ergotamine tartrate and caffeine and may cause symptoms of peripheral vascular insufficiency. Iatrogenic ergotism should be suspected in any patient exhibiting ischemic symptoms while receiving this medication. Progression to fulminant necrosis and gangrene can occur. Two cases are presented and the management reviewed. This effect of ergotamine tartrate and caffeine may be an idiosyncratic hypersensitivity reaction with therapeutic doses or may result from excessive medication. Iatrogenic ergotism occurs most often in women in their mid-thirties with migraine syndrome. By alpha-adrenergic agonism, as well as by possible interactions with prostaglandins, calcium, and serotonin, ergotamine causes vasoconstriction of both arteries and veins. The angiographic pattern of spasm, collateral formation, and intravascular thrombi is typical. Treatment of ergotism depends on the severity of the symptoms and the possibility of gangrene. Discontinuation of ergotamine, cigarette smoking, and caffeine may be all that is necessary in most patients. Nitroprusside is the drug of choice in the treatment of acute vascular insufficiency from ergotism, but in a less urgent situation, prazosin has also been effective. Intra-arterial balloon dilatation has also been helpful. Other forms of therapy have been supportive and the results inconsistent. Cafergot should be used with extreme caution in patients with renal or hepatic failure, peripheral vascular disease, or pregnancy. Relative contraindications include hypertension, ischemic heart disease, and Raynaud's phenomenon.

Adult↗