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Biomedical subjects

B Kay

Publications and source records attributed to B Kay.

At least 55 records · Page 3Linked to original sources
PubMed1985

A qualitative dynamic analysis of reiterant speech production: phase portraits, kinematics, and dynamic modeling.

The departure point of the present paper is our effort to characterize and understand the spatiotemporal structure of articulatory patterns in speech. To do so, we removed segmental variation as much as possible while retaining the spoken act's stress and prosodic structure. Subjects produced two sentences from the "rainbow passage" using reiterant speech in which normal syllables were replaced by /ba/ or /ma/. This task was performed at two self-selected rates, conversational and fast. Infrared LEDs were placed on the jaw and lips and monitored using a modified SELSPOT optical tracking system. As expected, when pauses marking major syntactic boundaries were removed, a high degree of rhythmicity within rate was observed, characterized by well-defined periodicities and small coefficients of variation. When articulatory gestures were examined geometrically on the phase plane, the trajectories revealed a scaling relation between a gesture's peak velocity and displacement. Further quantitative analysis of articulator movement as a function of stress and speaking rate was indicative of a language-modulated dynamical system with linear stiffness and equilibrium (or rest) position as key control parameters. Preliminary modeling was consonant with this dynamical perspective which, importantly, does not require that time per se be a controlled variable.

Female↗
PubMed1985

Neuromuscular block: atracurium and vecuronium compared and combined.

The neuromuscular blocking action of atracurium and vecuronium acting separately and in combination have been compared using the evoked EMG of the adductor pollicis muscle. Dose response curves have been drawn for the drugs given separately and found to be nonparallel (P less than 0.05). Atracurium was calculated to be 5.25 and 4.1 times less potent than vecuronium, ED50 and ED95 respectively. The effect on neuromuscular transmission of a combined medication using equipotent doses of atracurium and vecuronium, determined from the dose response plots, was found to be greater than would be expected by addition of their separate actions. The combination of small doses resulted in significant neuromuscular blockade.

Anesthesia, General↗
PubMed1985

Induction of anaesthesia with propofol ('Diprivan') or thiopentone and interactions with suxamethonium, atracurium and vecuronium.

A randomized study involving 60 healthy patients was performed to examine the induction characteristics and the possible interactions between propofol 2.5 mg/kg or thiopentone 4 mg/kg and three neuromuscular blocking agents, suxamethonium, atracurium and vecuronium. The time of onset to maximum blockade, the degree of blockade and the duration of blockade were measured using the electromyogram. The response to each muscle relaxant was not significantly different after induction of anaesthesia by propofol or thiopentone. A decrease in arterial blood pressure which occurred after both induction agents was greater after propofol than after thiopentone P less than 0.05. There was no significant difference in the increase in heart rate which occurred after the injection of either propofol or thiopentone.

Adult↗
PubMed1985

Propofol ('Diprivan') for outpatient cystoscopy. Efficacy and recovery compared with althesin and methohexitone.

In two non-concurrent investigations, propofol was compared with methohexitone and with Althesin as an intravenous anaesthetic for cystoscopy in outpatients. In the comparison between propofol and methohexitone the 60 patients also received alfentanil in similar dosage; in comparison with Althesin (43 patients) the Cremophor formulation of propofol was used. During induction of anaesthesia propofol caused fewer excitatory effects than either methohexitone or Althesin, and less pain than methohexitone. There was no difference in the incidence of apnoea caused by propofol 1.5 mg/kg and Althesin 0.05 ml/kg, or propofol 2 mg/kg and methohexitone 1.5 mg/kg. Induction of anaesthesia by propofol was faster than that by Althesin. The use of alfentanil 7 micrograms/kg at induction of anaesthesia apparently increases the incidence of apnoea seen at that time and during maintenance of anaesthesia, but an overall dose of approximately 1 mg reduces the mean dose of propofol required from 0.459 mg/kg/min to 0.192 mg/kg/min and improves the quality of anaesthesia. During maintenance of anaesthesia propofol produced less myoclonia and movement than Althesin, and fewer hiccups than methohexitone, but the mean minimum systolic arterial pressure observed in the propofol group was less than that seen in the methohexitone group. Immediate recovery of consciousness was faster and better after propofol than methohexitone, and fewer complications were seen after propofol than Althesin. Recovery of coordination and perception, tested by the digit substitution test, was faster after propofol than methohexitone. Exact comparisons of recovery of ocular tone (Maddox Wing test) between the anaesthetics were not possible as both Althesin and methohexitone rendered some patients incapable of taking the tests in the early post-operative period. In response to a take-home questionnaire, patients stated that they were drowsy for a shorter time, and ate earlier after propofol than after methohexitone. No patient who received propofol vomited or was nauseated and all would wish to receive the same anaesthesia again. The studies suggest that propofol is preferable to both Althesin and methohexitone for intravenous anaesthesia for cystoscopy in outpatients.

Adult↗
PubMed1985

Propofol in emulsion form: induction characteristics and venous sequelae.

Propofol in a 1% emulsion was used to induce anaesthesia in 20 female patients premedicated with diazepam (10 mg). A dose of 2.5 mg kg-1 produced a rapid loss of consciousness and only minor excitatory effects. Discomfort during the injection was not severe. Cardiovascular changes included a fall in blood pressure similar to that which occurs with other induction agents, and a decrease in pulse rate. Apnoea occurred after each induction and in some patients (13) was prolonged (greater than 60 s). There were no venous sequelae, and patient acceptance was high. Propofol given in an emulsion to induce anaesthesia merits further study.

Adult↗
PubMed1985

Parenteral meptazinol--international clinical experience.

Meptazinol is an opioid partial agonist with a potency at a dose of 100 mg similar to that of pethidine, but with a faster onset and shorter duration of action. It is a suitable analgesic for use in the treatment of postoperative, chronic and cancer pain, where its low dependence liability and few prescribing controls are advantageous. Meptazinol has been shown to be effective in the treatment of obstetric pain where it was preferred to pethidine because of its rapid elimination from the neonate. In normal use meptazinol appears to be free from respiratory or cardiovascular depressant actions.

Azepines↗
PubMed1984

Measurement of the rates of nitrous oxide uptake and nitrogen excretion in man.

Using a completely closed anaesthetic circuit, nitrous oxide uptake and nitrogen excretion were measured simultaneously in patients undergoing nitrous oxide in oxygen anaesthesia for abdominal surgery. The results have been compared with standard models of uptake and excretion. Mean nitrous oxide uptake was measured and did not exceed 400 ml min-1 (normalized to 70-kg man) and was not less than 60 ml min-1 at 100 min after the start of nitrous oxide in oxygen anaesthesia. Nitrogen excretion did not exceed 100 ml min-1 and was measurable (8 ml min-1) at 100 min. The persistence of nitrogen excretion contrasts with other published data obtained with intact volunteers and this suggests that exposure at surgery of abdominal tissues, including fat, affects substantially the rates of excretion and uptake after 70 min.

Abdomen↗
PubMed1984

Nalbuphine and Althesin anaesthesia. A controlled double-blind comparison for cystoscopy.

In a double-blind, randomized study of 52 unpremedicated outpatients undergoing cytoscopy, either nalbuphine 20 mg or saline 2 ml was given intravenously immediately before induction of anaesthesia with Althesin 0.05 ml/kg. Increments of Althesin 0.5 ml were used to maintain anaesthesia. The patients received nalbuphine required less Althesin than those who received saline (p less than 0.001) for a similar duration of surgery, and there was less movement during anaesthesia (p less than 0.001). During surgery hyperventilation was observed in the patients who received saline; those who received nalbuphine had lower respiratory rates and higher peak expired CO2 levels (p less than 0.001), and also a smaller increase in pulse rate (p less than 0.05). Recovery after surgery was faster in the patients who received nalbuphine than those who did not (p less than 0.05) and both patients (p less and anaesthetists (p less than 0.001) graded Althesin anaesthesia as better after nalbuphine than after saline. Intravenous nalbuphine 20 mg improved Althesin anaesthesia for cystoscopy without apparent disadvantages.

Adjuvants, Anesthesia↗
PubMed1984

Reducing the haemodynamic responses to laryngoscopy and intubation. A comparison of alfentanil with fentanyl.

The effects of alfentanil and fentanyl on controlling the haemodynamic responses to laryngoscopy and intubation have been compared. Five groups of ten patients were studied. Induction was with thiopentone 4 mg/kg. Thirty seconds later group 1 received 1 ml/20 kg saline, group 2 received 15 micrograms/kg alfentanil, group 3 received 30 micrograms/kg alfentanil and group 4 received 5 micrograms/kg fentanyl one minute before induction. Suxamethonium was given 60 seconds after induction and intubation of the trachea was performed 150 seconds after the start of induction. Heart rate and mean arterial pressure were recorded every minute throughout and compared with pre-induction control values. Control patients (group 1) showed significant increases associated with tracheal intubation in all haemodynamic variables. No increases were noted in groups receiving 30 micrograms/kg alfentanil or 5 micrograms/kg fentanyl. The heart rate, but not blood pressure, increased with intubation after 15 micrograms/kg alfentanil. The mean time to movement in 50% of the control patients was 7 minutes. In those given 15 and 30 micrograms/kg alfentanil it was 11 and 12 minutes respectively. In those given 5 micrograms/kg fentanyl it was greater than 15 minutes. Alfentanil is shown to reduce the cardiovascular responses to laryngoscopy and intubation and the effect appears to have a shorter duration than that of fentanyl.

Adjuvants, Anesthesia↗
PubMed1984

The analgesic effect of a low dose of alfentanil.

The effect of a single small dose of alfentanil (6 micrograms/kg) on postoperative pain was compared with saline using a double blind study. Pain was assessed using a linear analogue scale and shown to decrease at 2, 5 and 10 minutes after injection of alfentanil (p less than 0.01). The PE'CO2 was increased at 2 and 15 minutes (p less than 0.05) and 5 and 10 minutes (p less than 0.01) after injection of alfentanil. There were no changes in pain or PE'CO2 in the control group throughout the study. Intravenous alfentanil given to patients in pain provides quick effective analgesia for a short period of time, but respiratory depression may occur.

Alfentanil↗
PubMed1984

Electromyography in anaesthesia. A comparison between two methods.

Two instruments measuring evoked compound muscle action potentials (EMG) produced by train of four stimulation of the ulnar nerve were compared. The neuromuscular transmission section of a Datex Anaesthesia and Brain Monitor (ABM), which utilises an integration technique to measure the EMG, and the Medelec MS6 , by which amplitude of the EMG was recorded and measured were attached to the same electrodes placed over adductor pollicis. Eight patients scheduled for surgery requiring non-depolarising neuromuscular blockade were studied. The changes in neuromuscular transmission measured by the two methods correlated well, with no statistically significant difference in results. The ABM provides a simple and accurate automatic measurement of evoked EMG for use in the study of neuromuscular transmission.

Action Potentials↗
PubMed1984

Premedication by controlled-release morphine.

In a double-blind investigation the effect of oral controlled-release morphine (MST 30 mg) on pre-operative anxiety was assessed in 50 patients undergoing cholecystectomy. The effects on anaesthetic requirements and recovery, and postoperative pain were also studied. The patients who received morphine treatment were more sedated than those who received the placebo; however there was no significant difference in the anxiety scores for both groups of patients. During anaesthesia there were no significant differences between the groups, although the group of patients who received morphine required less anaesthetic supplement, and appeared to recover more slowly than the placebo group. One hour postoperatively, the morphine group had significantly less pain and were more sedated than the placebo group; the time to the administration of a postoperative analgesic was also significantly longer in the morphine group than the placebo group.

Administration, Oral↗
PubMed1984

The anesthesia and brain monitor (ABM). Concept and performance.

Three integral components of the ABM, the frontalis electromyogram (EMG), the processed unipolar electroencephalogram (EEG) and the neuromuscular transmission monitor (NMT) were compared with standard research methods, and their clinical utility indicated. The EMG was compared with the method of Dundee et al (2) for measuring the induction dose of thiopentone; the EEG was compared with the SLE Galileo E8-b and the NMT was compared with the Medelec MS6. In each case correlation of results was extremely high, and the ABM offered some advantages over the standard research methods. We conclude that each of the integral units of the ABM is simple to apply and interpret, yet as accurate as standard apparatus used for research. In addition the ABM offers excellent display and recording facilities and alarm systems.

Adjuvants, Anesthesia↗
PubMed1984

Etomidate and alfentanil infusion for major surgery.

An intravenous infusion of etomidate 125 mg together with alfentanil 5 mg diluted to 50 ml was used to induce and maintain anesthesia in 20 patients undergoing major surgery. A dose of etomidate 0.2 mg/kg, and alfentanil 8 micrograms/kg was used to induce anesthesia, which was initially maintained by one tenth of that dose given each minute by syringe pump. Subsequent dosage was regulated in response to cardiovascular, EEG and EMG changes, with infusion stopped a mean 7.3 min. before the end of surgery. Alcuronium provided muscle relaxation. The technique was clinically successful, with effective anesthesia and rapid recovery. Good monitoring is important for optimal control of intravenous anesthesia. In this series the Datex ABM was used.

Adjuvants, Anesthesia↗
PubMed1984

Measurement of oxygen uptake: a method for use during nitrous oxide in oxygen anaesthesia.

A new method for oxygen uptake (VO2) measurement based on a constant volume closed circuit is discussed. The accuracy of the method tested in the laboratory was demonstrated to be +/- 1.8% and estimated to be +/- 2.01% in clinical use during abdominal surgery. The 0-90% rise time of the measurement to step changes in VO2 was found to be 42 s, for a change of 15 ml min-1 with a lag time of less than 30 s.

Anesthesia↗
PubMed1983

Change in the work of breathing imposed by five anaesthetic breathing systems.

Measurements of pressure and flow in five anaesthetic breathing systems were studied with various fresh gas flows (FGF) using volunteers, and mechanically simulated breathing. Pressure measurements were made at the patient connection and in the neck of the reservoir bag. A pneumotachograph was used to measure flow in the patient connection. The change in the work of breathing imposed by the circuit was derived from the pressure-volume graph and apportioned to stages of the breathing cycle. All the systems studied increased the work of breathing. Expiratory work was always increased more than inspiratory work. The additional work imposed on expiration and the total extra work imposed on breathing were further increased at FGF greater than the minimum clinical requirement.

Anesthesia, Inhalation↗