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Biomedical subjects

D J Effeney

Publications and source records attributed to D J Effeney.

At least 55 records · Page 3Linked to original sources
PubMed1984

The importance of abdominal wall collateral blood vessels. Planning incisions and obtaining arteriography.

While several patterns of collateral blood flow around aortoiliac obstruction exist, the thoracic to lower-extremity pathway is often unrecognized. The principal blood vessels involved in this network are the internal mammary, superior epigastric, intercostal, inferior epigastric, and external iliac arteries. Two patients with aortoiliac occlusion experienced precipitation of rest pain because of transverse abdominal incisions for nonvascular procedures. Femoral anatomy was demonstrated arteriographically in two other patients by injection of contrast medium into the aortic arch. Patients with lower-extremity peripheral vascular disease may suffer exacerbation of their symptoms if the thoracic to lower-extremity collateral pathway is divided by poorly planned abdominal incisions. Ascending aortic or subclavian angiography is useful in some patients to define femoral arterial anatomy.

Abdominal Muscles↗
PubMed1984

Induction of quinidine metabolism and plasma protein binding by phenobarbital in dogs.

Two porta-caval transposed mongrel dogs were studied for phenobarbital (PB) induction of quinidine disposition after separate quinidine infusions via normal intravenous route and via portal vein. The plasma concentrations of quinidine and of three metabolites measured (3-OH quinidine, quinidine N-oxide, quinidine 10,11-dihydrodiol) were quite similar between i.v. and portal vein infusions, suggesting that the liver extraction ratio for quinidine in dogs is very low. After PB pretreatment plasma quinidine concentrations at the end of a 10 hr infusion increased about twofold while the half-life decreased from a control value of about 16 hr to 6 hr. Plasma concentrations of the three major metabolites measured were also increased following PB treatment. Plasma protein binding for quinidine and two of its three measured metabolites (3-hydroxy quinidine and quinidine N-oxide) were increased after PB treatment. Pharmacokinetic analysis of the data showed a decrease in steady-state volume of distribution (Vdss) of quinidine from an average value of 153 L to 54 L after PB treatment, while the total clearance did not change (6.6 vs. 5.6 L/hr). This decrease in Vdss could be explained by an increase in plasma protein binding of quinidine after PB treatment. The unbound nonrenal clearance of quinidine was induced by PB treatment. The decrease in fraction free in plasma and increase in unbound nonrenal (hence total) clearance resulted in little or no change in total plasma clearance for quinidine. The formation rate constants calculated for two quinidine metabolites, 3-hydroxy quinidine and quinidine N-oxide, were increased after PB treatment, suggesting an induction in these two metabolic pathways. Only quinidine 10,11-dihydrodiol was found in the bile after quinidine infusion, and the biliary clearance of this metabolite was also induced after PB treatment.

Animals↗
PubMed1984

Nonlinear formation of propranolol metabolites in dogs after portacaval transpositions.

The formation of four major metabolites of propranolol by the liver was examined at steady state in three dogs that had undergone surgical portacaval transposition, following which injection of drug into the hindlimb delivers the total dose to the liver. Propranolol was infused directly into the liver via a hindlimb vein at dose rates ranging from 1.01 to 6.3 mg/min. In all dogs the formation of 4-hydroxypropranolol, alpha-naphthoxylactic acid, and propranolol glycol was saturable. Vmax and Km values were determined at steady state by relating the rate of excretion of each metabolite into bile and urine to the blood concentration of propranolol. The formation of propranolol glucuronide was a first order process. The use of a dog with a portacaval transposition has permitted development of a method to estimate, in vivo, the kinetic properties of enzymes responsible for hepatic first-pass metabolism of drugs.

Animals↗
PubMed1984

Iliofemoral venous thrombosis: real-time ultrasound diagnosis, normal criteria, and clinical application.

We determined the response of the common femoral vein to respiratory maneuvers using high resolution real-time ultrasound in 10 normal subjects, and we evaluated this modality in the diagnosis of iliofemoral venous thrombosis in 36 patients. We developed diagnostic criteria for assessment of the venous system and have confirmed them with phlebography or pathologic findings. An increase in venous diameter of 50-200% on performance of the Valsalva maneuver, with a prompt return to the original configuration, was always associated with a normal iliofemoral venous system. Two patterns of occlusion of the femoral venous system were found: an enlarged circular femoral vein that did not increase in size on deep inspiration or performance of the Valsalva maneuver, and difficulty or inability to detect the common femoral vein. A dampened response, i.e., a 10-50% diameter increase on performance of the Valsalva maneuver, was associated with deep vein thrombosis in four of six patients. The false positive rate of 8% was due to gross congestive cardiac failure in one patient. This technique is simple to perform, relatively inexpensive, expeditious, and has proved useful in confirming or denying the presence of iliofemoral venous thrombosis.

Adult↗
PubMed1984

Dose-dependent bioavailability and metabolism of salicylamide in dogs.

The dose-dependent first-pass metabolism and pharmacokinetics of salicylamide (SAM) were studied at four dose levels in six dogs. Four minutes after each oral dose, a tracer dose of [14C]SAM was given i.v. to determine clearance and bioavailability. Over the dosage range studied, 5 to 40 mg/kg, bioavailability increased from 0.24 +/- 0.14 (mean +/- S.D.) to 0.76 +/- 0.20 (P less than .05). Clearance decreased from 3.4 +/- 1.0 to 0.60 +/- 0.11 liters/min (P less than .01) and half-life increased from 5.0 +/- 1.2 to 23.5 +/- 6.1 min (P less than .01). Measurement of SAM clearance to individual metabolites indicated that the sulfoconjugation and not the glucuronidation pathway was responsible for the dose-dependent effects observed. These effects occurred even at doses not expected to have caused significant depletion of body stores of inorganic sulfate; the plasma concentration of inorganic sulfate decreased by only a maximum of 13 and 26% after the 5- and 10-mg/kg SAM doses, respectively. When [14C]SAM was given alone in tracer amounts, clearance values greatly exceeded cardiac output. This suggests that SAM undergoes sulfation in organs other than the liver and intestinal wall.

Animals↗
PubMed1983

Algorithms in the management of cerebrovascular disease.

We present a diagnostic approach to the various clinical presentations of patients with cerebrovascular disease. It involves grouping the patients into five categories: (1) asymptomatic, (2) transient neurologic episodes, (3) unstable neurologic deficits, (4) prolonged neurologic deficits and (5) completed stroke. An algorithm is given for each category and an approach to management is outlined. The algorithms are clinically validated by reviewing the results of 185 reconstructive operations performed on patients with manifestations of cerebrovascular disease who were managed following the algorithms.

Angiography↗
PubMed1983

Aneurysms of the carotid arteries.

Twenty-one patients with 22 carotid aneurysms have been managed between 1960 and 1982. The aneurysms were congenital (3), atherosclerotic (8), false aneurysms after previous carotid operation (10) and mycotic (1). Carotid ligation was performed on four patients, one of whom suffered a stroke and died. Carotid reconstruction was undertaken in 15 patients without operative mortality but with postoperative strokes in two. Autogenous repairs of the carotid are recommended.

Adult↗
PubMed1983

Fibromuscular dysplasia of the carotid artery.

A series of 101 patients with carotid fibromuscular disease have been treated and followed for at least one year. Transient ischaemic attacks and amaurosis fugax were the most common presentation, while 22% of patients had had a completed stroke prior to surgery. Graduated dilatation was the most commonly used surgical method. In 150 operations, there were no deaths and three operative strokes. The operative repair has proven to be very durable and associated with a low incidence of neurologic events.

Adult↗
PubMed1983

Spontaneous dissection of the carotid artery.

Twenty-seven patients with spontaneous dissection have been managed between 1966 and 1982. Most presented with focal neurologic symptoms and 33% had had a completed stroke. Because of early failures of attempted operative repair, expectant management was adopted in 17 patients, none of whom had further neurologic events. The artery had re-expanded to a new normal caliber in 9 of 10 patients evaluated by angiography.

Adolescent↗
PubMed1983

Carotid body tumours.

Twenty-one patients with 22 carotid body tumours have been managed between 1963 and 1982. All presented with a neck mass and, if the tumour was extensive, pain. The diagnosis was made clinically, by ultrasound (2) and by angiography (16) and confirmed by biopsy in 19 patients. Eighteen resections were performed, without mortality but with a stroke rate of 16% and an overall complication rate of 36%. Four patients required reconstruction of the internal carotid artery.

Adolescent↗
PubMed1982

Static and real-time B-mode sonography of arterial occlusions.

Static and real-time sonography can be used to confirm the clinical diagnosis of arterial occlusion. When occluded, both native arteries and grafts showed three sonographically detectable patterns. More often (18/23), the vessel or graft has a normal B-mode appearance but does not pulsate on real-time examination. Less often (4/23), there is no detectable vascular channel. In one instance, using a 10 MHz transducer, the occluding thrombus was demonstrated. Real-time imaging is an important tool in the examination of patients with vascular disease and can distinguish the normal-appearing but occluded artery seen on static examination from the patent, pulsatile one.

Aged↗
PubMed1982

A technique to study hepatic and intestinal drug metabolism separately in the dog.

A model to study hepatic and intestinal drug metabolism in the dog has been evaluated. The model is made by performing a portacaval transposition, cholecystectomy and inserting a Thomas cannula into the duodenum. The result is a healthy animal in which drugs can be infused either in a normal i.v. (forelimb) fashion, directly into the liver (hindlimb) or given orally. Blood can be sampled from a peripheral vein, peripheral artery or hepatic vein. Bile and urine can be collected continuously. Pharmacokinetics can be studied in awake, unmedicated animals. The model can be used to assess oral, i.v. or hepatic infusion of drugs and their hepatic, intestinal or pulmonary metabolism.

Animals↗
PubMed1982

Lack of gastrointestinal metabolism of propranolol in dogs after portacaval transposition.

We studied whether or not propranolol underwent presystemic metabolism in the gastrointestinal wall in five dogs. The dogs were studied before and four weeks after creation of a portacaval transposition. Before surgery, systemic bioavailability of the oral dose was 8 +/- 8% (mean +/- S.D.), whereas after transposition the bioavailability was 102 +/- 9%. The systemic plasma clearance increased from 766 +/- 192 to 976 +/- 280 ml/min. The terminal half life and apparent volume of distribution after transposition were not significantly different from those obtained preoperatively. Our results indicate that there is complete absorption but no metabolism of propranolol by the gastrointestinal wall.

Administration, Oral↗
PubMed1981

The aortofemoral graft: detection and identification of healing complications by ultrasonography.

Although accepted as an accurate method for determining the size of abdominal aortic aneurysms, the value of gray-scale ultrasound in other aspects of peripheral vascular disease is less well defined. Therefore, we studied 87 patients with are aortofemoral grafts using B-scan and real-time scanners to determine the efficacy of these techniques in the detection of healing complications. Sonography delineated the proximal anastomosis in 84%, the iliac graft limbs in 88% to 91%, and the distal anastomosis in all but one instance. Sixty-six abnormalities, most clinically unsuspected, were identified. Of these, anastomotic femoral and aortic false aneurysms were most common. Ultrasound also identified perigraft fluid collections secondary to hematoma, seroma, and infection that were not detected by angiography. Ultrasound is relatively inexpensive, atraumatic, and without radiation hazard. It is recommended as the initial method for evaluating suspected healing complications of arterial grafting and as a means of long-term follow-up of patients with aortofemoral grafts.

Aged↗
PubMed1981

Intraoperative anticoagulation in cardiovascular surgery.

The optimal heparin dose to prevent intraoperative thrombosis or excessive bleeding during the occlusive phase of cardiovascular operations has not been determined. Therefore, we studied the kinetics of heparin effect in 28 patient undergoing peripheral vascular and cardiac operations. The activated clotting time (ACT) was measured in seconds by an electronic clot timer. The maximum ACT after initial heparin administration, the time to reach maximum ACT, and the half-time of heparin effect (t1/2) were determined. The anticoagulant effect of a given dose of heparin varies greatly among patients. No correlation was found between the t1/2 and the dosage of heparin administered. Despite higher doses of heparin administered to cardiac patients, the t1/2 in cardiac and vascular patients was not significantly different. Four patients received the same dose of heparin preoperatively and intraoperatively in an effort to predict the intraoperative effect. The times to maximum effect were the same but t1/2 intraoperatively was longer. These results indicate: (1) maximum heparin effect occurs later than previously believed and is different for cardiac and peripheral vascular patients; (2) the recommendation to give more heparin based on the 5-minute ACT is not valid; (3) individual response to a standard dose of heparin is unpredictable, both in duration and maximum effect; and (4) intraoperative monitoring of the heparin effect is practical and is the only way that any consistent, specific and point of heparin can be achieved.

Aged↗
PubMed1980

Why operate on carotid fibromuscular dysplasia?

Serious antecedent neurologic events occurred in 86 patients operated on for fibromuscular dysplasia (FMD). We applied the following criteria to the assessment of outcome: (1) the lesion should be surgically accessible; (2) the operation should be performed with minimal risk; (3) the operative repair is durable; and (4) benefits of repair are long lasting. Intraluminal dilation fulfills the first criterion: 118 dilations have been performed in 79 patients, with no deaths, three postoperative strokes that recovered completely, and eight single episodes of transient ischemia or amaurosis. The repair was durable, there being one late closure of a dilated artery. There were two subarachnoid hemorrhages, two strokes, and two patients had recurrence of symptoms during the follow-up period. Intraluminal dilation should be offered to patients with symptomatic FMD. A registry of patients with asymptomatic FMD should be established to study its natural history.

Adult↗