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Biomedical subjects

A S Rice

Publications and source records attributed to A S Rice.

33 records · Page 2Linked to original sources
PubMed1993

The electrophysiological consequences of electrode impalement of peripheral nerves in the rat.

Peripheral nerve fascicles are deliberately impaled during microneurography experiments. We have assessed conduction block under these circumstances. First we recorded compound action potentials (CAP) in the sural nerve following stimulation of the sciatic nerve. The insertion of injection and microneurography electrodes between stimulation and recording sites produced a 20% decrease in the size of the CAP, which was maintained for the 10 min duration of impalement. After withdrawal, the conduction block partially resolved. In other experiments, single-unit action potentials were recorded from L4 and L5 dorsal roots following peripheral nerve stimulation. Microneurography electrodes inserted into the sciatic nerve produced conduction block in 50% of these axons. When axons were blocked, anodal stimulation through the tungsten electrode became more effective than cathodal stimulation. These results suggest that a temporary conduction block occurs in a significant number of myelinated fibers near the site of an inserted electrode.

Action Potentials↗
PubMed1992

Metabolic acidosis and fatal myocardial failure after propofol infusion in children: five case reports.

OBJECTIVE: To examine the possible contribution of sedation with propofol in the deaths of children who were intubated and required intensive care. DESIGN: Case note review. SETTING: Three intensive care units. SUBJECTS: Five children with upper respiratory tract infections aged between 4 weeks and 6 years. RESULTS: Four patients had laryngotracheo-bronchitis and one had bronchiolitis. All were sedated with propofol. The clinical course in all five cases was remarkably similar: an increasing metabolic acidosis was associated with brady-arrhythmia and progressive myocardial failure, which did not respond to resuscitative measures. All children developed lipaemic serum after starting propofol. These features are not usually associated with respiratory tract infections. No evidence was found of viral myocarditis, which was considered as a possible cause of death. CONCLUSION: Although the exact cause of death in these children could not be defined, propofol may have been a contributing factor.

Acidosis↗
PubMed1992

Peripheral nerve injury caused by injection needles used in regional anaesthesia: influence of bevel configuration, studied in a rat model.

We have studied the immediate and long term (up to 28 days) effects of short and long bevelled needle impalement of the rat sciatic nerve. Three techniques were used to assess neural trauma and its consequences: stained longitudinal nerve sections were assessed by light microscopy and scored for injury; the extravasation of Evan's Blue dye, after antidromic electrical nerve stimulation, was used as a test of unmyelinated fibre function; the flexion withdrawal times from a noxious stimulus were measured. The results of all three experiments suggested that, should a nerve fascicle become accidentally impaled during regional anaesthesia, the lesions induced by short bevelled needles are more severe, more frequent and take longer to repair than those induced by long bevelled needles. Nerve injury induced by short bevelled needles was associated with persisting signs of injury 28 days after the injury. These results suggest that the current practice of using short bevelled needles to prevent nerve injury complicating regional anaesthesia be reassessed.

Anesthesia, Conduction↗
PubMed1991

Plasma concentrations of bupivacaine after supraclavicular brachial plexus blockade in patients with chronic renal failure.

The plasma concentrations of bupivacaine and the latency and duration of anaesthesia after supraclavicular block with 30 ml of 0.5% bupivacaine were measured in 10 patients with chronic renal failure and in 10 patients with normal renal function. No significant difference was found between the two groups in respect of pharmacokinetic parameters, or in block latency or duration.

Adult↗
PubMed1991

A double-blind study of the speed of onset of analgesia following intramuscular administration of ketorolac tromethamine in comparison to intramuscular morphine and placebo.

A double-blind, randomised, parallel group, placebo-controlled study was performed in 85 patients to compare the speed of onset of analgesia following the intramuscular administration of a single dose of 30 mg of ketorolac tromethamine, 10 mg of morphine or placebo. A new, sensitive, method was used to measure the latency of analgesia. The onset of analgesia was defined by the time taken for the pain intensity score to reach a specified percentage of the baseline value. Twenty-five percent of patients achieving a 50% reduction in baseline pain intensity score appears to be the most appropriate parameter to assess the speed of onset of analgesia of ketorolac and morphine in the postoperative setting. Paired comparison demonstrated that ketorolac had a significantly faster onset of analgesia (p = 0.03) when compared to placebo, whilst comparison of morphine to placebo analgesic latency (p = 0.06) just failed to reach significance. There was no significant difference between the analgesic onset time of ketorolac and morphine (p = 0.73). Intramuscular ketorolac and intramuscular morphine have comparable analgesic onset times in the postoperative pain context. However, the sensitive method of measuring onset of analgesia described, highlights the slow onset of analgesia when analgesics of known efficacy are given by the intramuscular route in the postoperative period. More attention should be given to the speed of onset of analgesia in future assessments of analgesics.

Adult↗
PubMed1987

Comparison of trichloroethylene and enflurane as adjuncts to nitrous oxide and relaxant anaesthesia.

Forty women who underwent gynaecological surgery were randomly allocated to receive trichloroethylene, enflurane, or enflurane plus fentanyl as adjuncts to nitrous oxide/relaxant anaesthesia with controlled ventilation. No serious cardiac dysrhythmias were seen in any group. Each patient was observed postoperatively for 4 hours by a nurse blind to the technique used, and questioned at 24 hours by a similarly blinded anaesthetist. Recovery after trichloroethylene was not significantly prolonged although postoperative analgesia by visual analogue was better, opiate analgesia was required less frequently and there was less nausea and vomiting than in either of the enflurane groups. We argue for the continued use of trichloroethylene by this technique, because it costs one hundred times less than enflurane and because of the potential morbidity of the postoperative opiate dosage required after enflurane.

Adjuvants, Anesthesia↗
PubMed1986

Lithium compliance in alcoholic males: a six month followup study.

One hundred alcoholic patients were followed at monthly outpatient clinics for 6 months. Half were assigned low to moderate doses of lithium carbonate and half to chlordiazepoxide (10 mg tid) (active placebo). Drinking behavior and medication compliance were monitored at monthly clinics. After 6 months 52% of the lithium and 44% of the chlordiazepoxide patients were medication compliant. Of the 48% remaining in the lithium group, 14% did not return for a single visit while 14% came only once. Twenty percent came to clinic regularly; however they had never taken the medication as assigned. Of the 56% non-compliant chlordiazepoxide patients, 16% did not attend a single clinic; 24% came only once or twice and the remaining 16% attended clinics regularly although they were never medication-compliant. Drinking days and the percentage of patients reporting abstinence for one or more months were determined for medication compliant patients and for patients who attended clinic regularly but who did not take medication. Data were analyzed by Kruskal-Wallis one way analysis of variance tests. While lithium and chlordiazepoxide compliant patients tended to report fewer mean drinking days per month (4.6 and 4.8 respectively) than the non-medication group (6.9) these differences were not significant; however, compared to 44% in the non-medication group, 60% of the lithium patients and 58% of the chlordiazepoxide patients reported having significantly more months of abstinence (p less than .05). These results do not show that lithium is differentially efficacious in reducing alcohol consumption.

Adult↗
PubMed1982

Prevalence of additional psychiatric syndromes among male alcoholics.

The prevalence of psychiatric syndromes among 565 male alcoholic VA inpatients was examined using the structured Psychiatric Diagnostic Interview (PDI). Almost two-thirds fulfilled criteria for one or more additional psychiatric syndromes. Subjects positive only for alcoholism reported a significantly later onset of problem drinking and fewer first-degree relatives who abused alcohol than those positive for one or more additional syndromes. The most frequent additional syndromes were affective disorders and antisocial personality. The possible significance of subtyping alcoholics by the presence or absence of coexisting psychiatric syndromes is discussed.

Alcoholism↗
PubMedDate not supplied

Ketorolac penetration into the cerebrospinal fluid of humans.

STUDY OBJECTIVE: To determine the cerebrospinal fluid (CSF): total plasma concentration ratio of ketorolac tromethamine following a single intramuscular (IM) dose. DESIGN: Open, single-dose, IM-administration study. SETTING: General operating theaters of a medical school hospital. PATIENTS: 29 ASA physical status I and II patients scheduled to undergo elective surgery with spinal anesthesia. INTERVENTIONS: Patients were premedicated with ketorolac 90 mg IM formulated as 3 ml of a 3% solution. Between 1 and 4 1/2 hours later, an intravenous infusion of 500 ml of compound sodium lactate was begun. Lumbar puncture was then performed, and 2 ml of CSF was collected prior to administration of the spinal anesthetic. In addition, a 5 ml sample of venous blood was taken within 5 minutes of the CSF sample. MEASUREMENTS AND MAIN RESULTS: Simultaneous plasma and CSF concentrations of ketorolac were measured between 62 and 277 minutes following IM administration in 29 patients undergoing spinal anesthesia. The CSF concentrations were on the order of 1,000 times less than the total plasma concentrations; free concentrations of ketorolac in plasma were estimated to be about 10 times more than those in CSF. There appeared to be no constant time factor relating the appearance of ketorolac in the CSF to its plasma concentration following IM administration. CONCLUSION: Although the sensitivity of central prostaglandin synthetase systems to inhibition is unknown, it is unlikely from this pharmacokinetic data that there is a major central mechanism of analgesia for ketorolac.

Adult↗