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Biomedical subjects

R B Smith

Publications and source records attributed to R B Smith.

At least 271 records · Page 15Linked to original sources
PubMed1983

Reduced clearance of triazolam in old age: relation to antipyrine oxidizing capacity.

Thirty-three healthy male and female volunteers aged 21 to 87 years received a single 0.5 mg oral dose of triazolam. Plasma triazolam concentrations were measured in multiple samples drawn during 24 h after the dose. Mean triazolam elimination half-life was not significantly different between young and elderly men (3.0 vs 4.6 h), nor between young and elderly women (2.7 vs 3.2 h). However, apparent oral clearance of triazolam was significantly reduced in elderly as compared to young groups of both sexes, leading to higher peak plasma concentrations and increased total area under the curve. Values of half-life and clearance of antipyrine, a low-extraction hepatically oxidized compound, were poorly correlated with those of triazolam (r = 0.34 and 0.44, respectively), suggesting different mechanisms controlling age-related changes in clearance of these two hepatically oxidized drugs.

Adult↗
PubMed1983

Effects of hypo-, normo-, and hypercarbia in dogs with acute cardiac tamponade.

The hemodynamic effects of changes in PaCO2 during intermittent positive pressure ventilation (IPPV) were studied in nine dogs with acute cardiac tamponade. During steady state light thiopental anesthesia, measurements were performed during hypocarbia (24.0 +/- 2.6), normocarbia (40.4 +/- 2.4), and hypercarbia (56.8 +/- 3.1 mm Hg; mean +/- SD). The study was carried out at a standardized level of cardiac tamponade that gave a 60% reduction in cardiac output (CO) at normocarbia. Changes in airway pressure were avoided by adding CO2 to the inspiratory gas to obtain the desired PaCO2. Hypercarbia increased pericardial pressure 2-4 mm Hg and significantly decreased CO. During hypocarbia CO increased as pericardial pressure decreased 3-6 mm Hg. These findings are the reverse of changes seen when tamponade is not present. The changes in pericardial pressure most likely influence myocardial tone and cardiac volume and, thus, CO. The results suggest that patients with cardiac tamponade requiring general anesthesia should not breathe spontaneously if there is any danger of respiratory depression and hypercarbia.

Acute Disease↗
PubMed1983

The results of pantalar reduction in the management of congenital talipes equinovarus.

One hundred and twenty-five patients with 194 feet affected by congenital talipes equinovarus were treated by the senior author during the period 1959 to 1980. Of these, 70 patients presented either at birth or in the early neonatal period, and 55 were seen later, having been referred from other centres. Seventy-five patients were subsequently reviewed by two of us; the remaining 50 were assessed from records and research files. Patients seen within four weeks of birth were termed "early", the remainder "late". Of the early group of 70 patients, 44 (with 68 affected feet) were reviewed and 26 (with 41 affected feet) were assessed from records. Excellent or good results were achieved in 94 per cent of feet treated conservatively and in 82 per cent of feet which required pantalar release. Of the 55 late referrals 32 patients (with 55 affected feet) were reviewed and 23 (with 30 affected feet) were assessed from records. Satisfactory results were slightly less frequent, but were achieved in 75 per cent of cases. There was no statistical correlation between early soft-tissue release and a good final outcome, but there was a positive statistical correlation between good clinical results and a high talocalcaneal index. Osseous correction (a laterally based wedge tarsectomy or a triple arthrodesis) was necessary at a later date in four feet (four per cent) of those who presented early and in 13 feet (15 per cent) of late referrals.

Adolescent↗
PubMed1983

Aneurysms of the internal iliac artery.

Twenty-one patients with aneurysms of the internal iliac artery were identified over a 14-year period. Group A included those patients who had aneurysms associated with aortoiliac artery aneurysms and group B were those who had isolated internal iliac aneurysms. The natural course of these aneurysms is one of progressive expansion and rupture. A pulsatile pelvic mass, often associated with compression symptoms of the neurologic, gastrointestinal, genitourinary, and peripheral venous structures, is often present. Aortography, computerized tomographic scanning, and abdominal ultrasonography are the most useful diagnostic procedures. Proximal ligation and endoaneurysmorrhaphy make up the most appropriate surgical treatment. A case report is presented of a patient who underwent successful elective embolization as an alternative method of management.

Accidents, Traffic↗
PubMed1983

Dysplasia and the effects of soft tissue release in congenital talipes equinovarus.

The anatomic abnormalities and the effects of serial release of soft tissue are described in seven stillborn fetal clubfeet. The essential anatomic abnormality is a dislocation of the talocalcaneonavicular joint, with dysplastic changes in the talus and less severe changes in the adjacent bones. By gradually releasing the structures contributing to the tether, the amount of correction of deformity was equated to three current types of surgical procedures: posterior release, posteromedial release, and a combined full subtalar, midtarsal, and posteromedial release. In severe deformities, only by using the third most extensive procedure is the navicular fully reduced onto the talar head, and the calcaneous rotated laterally and posteriorly with the cuboid to open the "scissors" of the hindfoot. The talonavicular joint, the calcaneocuboid and subtalar joints, and the lateral calcaneofibular ligament must be released to achieve this end. This experimental technique encompasses the release of many structures. With varying severity of deformity, a less extensive dissection may often be sufficient to achieve correction.

Clubfoot↗
PubMed1983

Reoperative abdominal arterial surgery--a ten-year experience.

The safety and durability of elective reconstructive procedures of the abdominal aorta and its major branches are universally accepted; however, late complications continue to threaten limbs and lives of a minority of patients. The strategy of managing such revascularization failures has received inadequate attention. Between February 1971 and July 1981, 76 patients underwent 83 remedial, transabdominal revascularization procedures because of failed reconstructions. Group I consisted of 34 patients with occlusive complications (0% remedial operative mortality rate); group II, 21 patients with prosthetic sepsis including graft-enteric fistula (14% operative mortality); group III, 11 patients with aneurysmal degeneration (36% operative mortality); and group IV, 10 patients with visceral ischemia (0% operative mortality). The remedial operative mortality rate for the combined groups was 7.9%. Limb preservation was the rule in group I (91%); however, 29% of limbs at risk in group II ultimately required major amputation (15% early, 14% late). All patients in group II without an established graft-enteric fistula were saved; however, three of ten with active hemorrhage died of the sequelae of hypovolemic shock. Progressive arteriosclerotic morbidity and massive intraoperative bleeding accounted for the high mortality rate in group III. Favorable results were obtained in reoperation for recurrent visceral ischemia (renal ischemia in five, mesenteric ischemia in five). On the basis of this experience, an aggressive surgical approach seems justified. First, complete bifemoral revascularization performed at the time of original operation should reduce the need for reoperation. Second, elective, transabdominal remedial arterial surgery can be done with acceptable morbidity and mortality rates. Third, graft-enteric erosions and periprosthetic sepsis must be treated aggressively to avoid life-threatening sepsis and hemorrhage. Finally, anatomic revascularization can be performed successfully after a suitable period following removal of an infected retroperitoneal prosthesis.

Adult↗
PubMed1982

Isolated perfused rabbit lung as a model for intravascular and intrabronchial administration of bronchodilator drugs I:Isoproterenol.

The absorption, uptake, and metabolism of isoproterenol was studied following intravascular, intrabronchial, and aerosol administration of the drug to the isolated perfused rabbit lung. Capacity-limited metabolism of isoproterenol was observed following the addition of five doses, ranging from 10(-7) to 10(-5) moles, directly into the circulation of the lung system. A physiologically based perfusion model was developed to describe the disposition of the drug and metabolite in the isolated lung preparation. This model was also used to analyze data collected following intrabronchial and aerosol administration of isoproterenol.

Aerosols↗
PubMed1982

Interaction of lower esophageal sphincter pressure and length of sphincter in the abdomen as determinants of gastroesophageal competence.

This study defines the components of distal esophageal sphincter function which predict gastroesophageal competence and examines the mechanisms by which three antireflux procedures restore competence to the cardia. In a prospective study, the reflux status of 391 patients was determined by 24 hour pH monitoring. Distal esophageal sphincter pressure and length of sphincter exposed to the positive pressure environment of the abdomen was measured by esophageal infusion manometry. Similar pre- and postoperative studies were performed in 45 patients who were randomized to three equal groups for the Hill, Belsey and Nissen antireflux procedures. Two hundred sixty-seven (68 percent) of the 391 patients had a positive 24 hour pH test. Competence of the cardia was related to pressure in the distal esophageal sphincter, to the length of sphincter in the abdomen and to an interaction between both (all p less than 0.05). Thus, competence of the cardia requires an adequate pressure and length of sphincter in the abdomen. In determining competence, the pressure and length effects are not additive, but have an interacting relationship. Sphincter pressure and abdominal length are independently corrected by surgery. Restoration of competence requires increases in both. The gastric fundic wrap best augments distal esophageal sphincter pressure by application of normal functioning smooth muscle to the lower esophagus. Sphincter dynamics are normal after a wrap as the gastric fundus and distal esophageal sphincter share the functions of synchronous contractions and simultaneous relaxation on deglutition.

Esophagogastric Junction↗
PubMed1982

Ten years portal hypertensive surgery at Emory. Results and new perspectives.

Five hundred four Shunt procedures have been done at Emory University Hospitals between 1971 and 1981 to decompress bleeding esophageal varices. This paper reviews how far the experiences of a prospective randomized study (55 patients) of distal splenorenal shunts against total shunts is supported by the nonrandomized experience (449 patients), and outlines our current methods of management dictated by this experience. The overall operative mortality for 348 selective shunts is 4.1% and for 156 nonselective shunts, 14.1%. The five-year survival following Selective shunt is 59%, and following nonselective shunt is 49%: more than half the selective shunt patients are alive, in contrast to the median survival of 44.5 months for patients having nonselective shunts. Following Selective shunt, the survival in nonalcoholic patients is significantly better than the median survival of alcoholic patients of 57 months. Encephalopathy, reported at three years after surgery in the randomized patients was significantly (p < 0.001) lower after selective shunt (12%) compared to nonselective shunt (52%): in the same population at seven years, all patients with patent nonselective shunts have clinical or subclinical encephalopathy, but only 30% of the selective shunt patients have subclinical encephalopathy. Shunt patency, immediately after surgery, is 93% following selective shunt, with only two documented late thromboses: nine of nine patients, at a mean of seven years, retain patency in the randomized study. Shunt occlusion increases with time after interposition nonselective shunts: seven of 13 are occluded at a mean follow-up of seven years in the randomized study. Portal venous perfusion is retained in 93% of patients seven to ten days after selective shunt, but in no patient with a patent nonselective shunt. Late portal perfusion is maintained in nine of the eleven patients in the randomized group studied at a mean of seven years after selective shunt. Restoration of portal perfusion has led to clearing of encephalopathy and improvement in hepatic function in six patients. The following conclusions are made: (1) selective shunts can be done with low operative mortality, and long-term patency with excellent control of bleeding; (2) hepatic portal venous perfusion has been maintained after selective shunt for ten years, and this is vital for preventing encephalopathy and maintaining hepatic function; (3) long-term survival after selective shunt is better than any reported series for nonselective shunt; and (4) selective shunts are the operative procedure of choice for variceal decompression and nonselective shunts should rarely be performed for elective decompression.

Analysis of Variance↗
PubMed1982

Concomitant carotid and coronary artery reconstruction.

Data are presented on 68 patients who underwent concomitant carotid endarterectomy (CE) and coronary artery bypass surgery (CAB) at Emory University Hospital from January 1974 to February 1981. This group is then compared with a randomly selected, matched population without known carotid disease who underwent CAB alone. Asymptomatic bruit was the reason for investigation in 40 patients (59%); another 23 patients (34%) experienced transient cerebral ischemic attacks (TIAs); and five patients (7%) had TIA and prior stroke. Carotid stenoses (>75% luminal narrowing) were demonstrated as follows: isolated left, 24 patients; isolated right, 27 patients; and bilateral lesions, 16 patients. One patient had innominate artery stenosis. Associated total occlusion of one or both vertebral arteries was demonstrated in six patients. Ninety-seven per cent of patients had disabling angina pectoris prior to operation; the angina was unstable in 57%, 15% had congestive heart failure, and 54% had had at least one prior myocardial infarction (MI). Single-vessel coronary disease was present in 12.5% of patients, double in 37.5%, triple in 41.1%, and left main stenosis in 9%; 43% of patients had abnormal ventricular contractility. CE was performed on 67 patients (36 left and 31 right); aortocarotid bypass was performed on one. The CE procedures were performed immediately prior to the sternotomy for CAB under the same anesthesia. CAB consisted of single bypass in eight patients (11.8%); double in 16 patients (23.5%); triple in 22 patients (32.4%); and quadruple or more in 22 patients (32.4%) (mean = 2.9 grafts per patient). There was no hospital mortality. Perioperative MI occurred in 2.0% and stroke with residual deficit in 1.3%. Cumulative survival is 98.5% at two years. Sixty-three patients (92%) reported improvement or elimination of anginal symptoms after operation. Rehospitalization for stroke was necessary in 3.7% patients. Postoperative activity levels are; self-care only, 3.9%; normal daily activity only, 17.6%; moderate exercise capability, 45%; and vigorous exercise capability, 33%. Comparison was made with a group of 84 randomly selected patients who underwent CAB alone during the same time interval. Data revealed no significant difference between the groups regarding sex, angina subset, ventricular function, coronary anatomy, vessels grafted, perioperative stroke or MI, mortality, or postoperative activity capability. Older age (59.8 vs. 55.6, p < 0.01) and less complete coronary revascularization possible (66 vs. 84%, p < 0.05) in the CECAB group were the only significant differences. Carotid stenosis co-existing in patients requiring CAB should be concomitantly corrected with the same risk and results expected from CAB alone.

Aged↗
PubMed1982

High frequency ventilation in dogs with open chests.

This study evaluated and compared the physiological responses to high frequency percutaneous transtracheal ventilation in dogs before and after median sternotomy thoracotomy. Standard intermittent positive pressure ventilation (IPPV) was established before and after high frequency rates (100 and 300 breath/min) with the chest closed and then after thoracotomy. Gas exchange as judged by arterial and mixed venous blood gases, and cardiac performance as judged by pulmonary capillary wedge pressure, pulmonary and systemic arterial pressures, vascular resistances, and cardiac index all remained clinically acceptable. Physiologically, ventilation in the open chest condition was adequate but was associated with a slight decrease in PaCO2 and a decrease in PaO2. Peak and mean airway pressures were similar for IPPV and high frequency modes of ventilation.

Animals↗
PubMed1982

Confirming evidence of an effective treatment for brain dysfunction in alcoholic patients.

In earlier studies we found that cranial electrotherapy stimulation (CES) was associated with significant improvement in several areas of brain dysfunction commonly found in alcoholic persons. In this study we compared the effects of CES among treatment and control groups on each of the six subscales of the Revised Beta Examination (Lindner, R. M., and Curvitz, M. Revised Beta Examination, Psychological Corp., New York, 1957) and found CES related to significant improvement on the two subscales which are below the norms in alcoholic patients and which have been correlated with other measures of brain dysfunction. It is concluded that CES can be an important therapeutic strategy in reducing to weeks the time required for recovery of several reversible brain dysfunctions in alcoholic persons which usually require months or years of abstinence.

Adult↗
PubMed1982

Aortovenous fistulas due to ruptured infrarenal aortic aneurysms: experience with six cases.

A review of patients undergoing aortic aneurysmectomy between 1970 and 1979 at the Emory University Hospital and the Atlanta Veterans Administration Medical Center disclosed six patients with aortovenous fistulas. Four fistulas were aorta to vena cava; one, aorta to left renal vein; and one, aorta to left iliac vein. Four of the arteriovenous fistulas were identified preoperatively. In another patient the symptoms and signs were masked by concomitant retroperitoneal rupture of the aneurysm. The final patient was asymptomatic preoperatively, but had an occluded fistula discovered at operation when laminated thrombus was removed from the wall of the aneurysm. One patient died while being prepared for operation; five were operated upon and survived. Successful management of this problem is contingent upon preoperative recognition, careful manipulation of the aneurysm with endoaneurysmal closure of the fistula, and judicious perioperative fluid management.

Aged↗