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Biomedical subjects

R B Smith

Publications and source records attributed to R B Smith.

576 records · Page 32Linked to original sources
PubMedDate not supplied

The influence of obesity on the pharmacokinetics of oral alprazolam and triazolam.

12 obese patients, pair-matched with 12 normal subjects, received a single 1 mg oral dose of alprazolam. Nine similar subject pairs received a single 0.5 mg oral dose of triazolam. Oral volume of distribution (Vd) was much greater in obese than control subjects for alprazolam (mean 114 vs 73L, p less than 0.001), but there was no difference between the 2 groups for triazolam (117 vs 116L). Apparent oral clearance (not corrected for body weight) of alprazolam was lower, although not significantly so, in obesity (66 vs 88 ml/min), but for triazolam it was much lower in the obese (340 vs 531 ml/min, p less than 0.005). Elimination half-life, which is dependent on both Vd and clearance, was prolonged in obesity for alprazolam (22 vs 11h, p less than 0.001) due to the increase in Vd, and also for triazolam (4.1 vs 2.6 h, p less than 0.025) because of the decreased clearance. Plasma protein binding was unchanged in obese compared with control subjects for both alprazolam and triazolam. During long term administration alprazolam should therefore take longer to reach steady-state concentrations in obese patients but the final levels achieved should be no different than for patients of normal bodyweight, provided dosage is adjusted for ideal rather than total bodyweight. In contrast, triazolam has impaired clearance in obesity. However, if given once-daily it still would not accumulate with long term dosing due to its short half-life relative to the interval between doses.

Administration, Oral↗
PubMedDate not supplied

The use of cranial electrotherapy stimulation in the treatment of closed-head-injured patients.

This double-blind study sought to discover if cranial electrotherapy stimulation (CES), which is a known treatment of depression, anxiety and insomnia in non-head-injured patients, could be an effective, drug-free treatment of stress-related symptoms in the closed-head-injured (CHI) patient. In this study 10 CHI patients treated for 45 min daily, 4 days a week for 3 weeks, responded significantly on all negative mood factors of the Profile Of Mood States, while five sham-treated and six placebo controls did not. While the majority of the patients were known seizure cases, no patient suffered a seizure during CES therapy. No placebo effects were found, nor were any negative effects from CES treatment seen.

Adult↗
PubMedDate not supplied

Intermittent-flow expiratory ventilation (IFEV): delivery technique and principles of action--a preliminary communication.

The ventilator support utilized in acute respiratory failure can exacerbate an underlying lung injury. Various ventilation techniques have been introduced to prevent such damage by limiting tidal volume and inflation pressure, ensuring uniform expansion of the lung, and stabilizing lung volume during expiration. Acceptance of such methods has been limited. Intermittent-flow expiratory ventilation (IFEV) is the latest development in limited-excursion pulmonary ventilation. The method involves the delivery of fresh gas to the respiratory tree during expiration, thereby flushing out the anatomic deadspace and ensuring that the gas initially delivered to the alveolus with the succeeding inspiration is able to participate in gas exchange. By eliminating end-tidal gas in the conducting air passages, series deadspace is functionally reduced, permitting lowering of tidal volume and airway pressures without a corresponding reduction in CO2 removal. This effect may benefit patients who have acute lung injury by permitting ventilator settings with lower tidal volumes and peak airway pressures. The technique of IFEV delivery, a successful clinical application, and possible ways to improve IFEV efficiency are discussed.

Adult↗
PubMedDate not supplied

Descending thoracic aortofemoral-femoral bypass: a remedial alternative for the failed aortobifemoral bypass.

The patient with densely scarred retroperitoneum, multiple previous celiotomies, failed remedial retroperitoneal aortobifemoral graft or multiple extra-anatomic graft failures presenting with limb-threatening ischemia taxes the ingenuity of the most experienced vascular surgeon. Lower extremity revascularization, in these situations, is dependent upon achieving adequate femoral arterial inflow. One remedial alternative method to achieve this goal is the descending thoracic aortofemoral-femoral bypass (DTAF-F). The authors' experience with three recent patients requiring DTAF-F is described, and literature of similar alternative techniques is reviewed.

Aorta, Abdominal↗
PubMedDate not supplied

Pancuronium rapid induction sequence.

Succinylcholine is traditionally used as the muscle relaxant of choice for rapid induction sequence intubation. There are, however, many absolute and relative contraindications for the use of succinylcholine necessitating the need for an alternative muscle relaxant. This study was undertaken to evaluate the effectiveness of pancuronium bromide for muscle relaxation in the rapid induction sequence in comparison to succinylcholine. A double-blind study was undertaken in 90 patients divided into two groups: One group was intubated at 60 seconds and the other at 90 seconds. Each group was divided into four subgroups by random selection and received of the following regimens: (a) succinylcholine, 1.5 mg/kg preceded by 3 mg of d-tubocurarine; (b) pancuronium bromide, 0.1 mg/kg; (c) pancuronium bromide, 0.125 mg/kg; and (d) pancuronium bromide, 0.15 mg/kg as relaxants in rapid sequence intubation. A rapid sequence intubation was performed with each intubation by a staff member or experienced house officer. Pre- and postinduction blood pressure and heart rate were taken. Postinduction blood gases were taken. The times to completion of intubation were recorded. Cord position, ease of intubation and overall relaxation were evaluated. The results indicate that in experienced hands pancuronium bromide in a dose of 0.1-0.15 mg/kg is as an effective muscle relaxant for rapid induction sequence intubation as is succinylcholine. It is an acceptable alternative when succinylcholine is contraindicated. Intubating conditions are best 90 seconds after the administration of pancuronium bromide.

Adolescent↗
PubMedDate not supplied

Is there a place for external grafting of arterial aneurysms in selected patients?

External grafting of aortic and iliac artery aneurysms has been accomplished in 33 highly selected poor risk patients over a period of eight years. This experience demonstrated that external grafting of aneurysms is a technically demanding operative procedure which is accompanied by significant early and late morbidity. The technique does effectively reduce the occurrence rate of late rupture of aneurysms, however, at least for the period of observation of this study. Thus, while external grafting certainly is not generally applicable, the procedure may be used to advantage in highly selected situations, possibly including: 1. Long segment aneurysms of the thoracic or thoraco-abdominal aorta. 2. Aneurysms involving the renal arteries in poor risk patients. 3. As reinforcement for dilated arterial segments adjacent to sites of vascular anastomosis.

Adult↗
PubMedDate not supplied

Single- and multiple-dose pharmacokinetics of oral alprazolam in healthy smoking and nonsmoking men.

The effect of tobacco smoking on alprazolam pharmacokinetics is investigated. Ten healthy men (five smokers and five nonsmokers) between 19 and 42 years old received a single oral 1-mg alprazolam dose followed 48 hours later by alprazolam 0.5 mg every eight hours for six days. Multiple serum samples were collected following the initial dose and after the last 0.5-mg dose and analyzed by gas-liquid chromatography for alprazolam. Pharmacokinetic values were calculated, and mean data from the smoking and nonsmoking groups were compared. Mean plasma alprazolam concentrations during the single-dose phase were comparable between groups. During the multiple-dose phase, mean plasma concentrations were 15-30% lower in the smokers. Total body clearance of alprazolam was 24% greater and the apparent volume of distribution was 17% less in smokers. The elimination half-life was 49% greater in nonsmokers. These differences were not significant. Changes were not observed in elimination half-life or clearance after alprazolam cessation. Steady-state pharmacokinetic values during the multiple-dose phase correlated with values observed following the single dose. Although not significantly different, alprazolam elimination was more rapid in smokers than in nonsmokers.

Adult↗
PubMedDate not supplied

cis-Diamminedichloroplatinum(II) alone and in combination in the treatment of testicular and other malignancies.

A total of 124 patients with malignancy were treated with cis-diamminedichloroplatinum(II) (CDDP) alone (58 patients, 121 courses) or in combination with other drugs (66 patients, 176 courses). Toxic effects of single-agent therapy were primarily nausea and vomiting; mild renal hematopoietic, and auditory toxic effects occasionally occurred. Positive responses were seen in ovarian and testicular tumors. Rare responses were also seen in melanoma and bladder carcinoma. CDDP combined with vinblastine and bleomycin resulted in a 39% complete response rate in testicular germ cell tumors. All complete responders and ten patients treated in an adjuvant fashion remain alive and disease-free. Failures to achieve a complete response were associated with bulky extrapulmonary disease, pulmonary disease greater than 2.5 cm in diameter, and past failure to respond to vinblastine and bleomycin. CDDP combination regimens for acute leukemia and for melanoma were of little value. Combination chemotherapy for head and neck cancer showed activity, including a complete response in one of two patients with nasopharyngeal lymphoepithelioma.

Cisplatin↗