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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↗
PubMed1979

The measurement of occlusion pressure during anaesthesia. A comparison of the depression of respiratory drive by methohexitone and etomidate.

Occlusion pressure (Po max) was used to indicate the depression of respiratory drive following rapid administration of methohexitone 0.5 mg/kg and etomidate 0.067 mg/kg to fourteen patients under stable light anaesthesia. Methohexitone produced considerably more respiratory depression than etomidate, the difference probably being clinically significant. Po max is the maximum sub-atmospheric pressure generated in the trachea when inspiration is prevented by occlusion of the airway, at functional residual capacity. The factors concerning the use of this simple, non-invasive technique during anaesthesia are discussed, and suggestions made for producing consistent, useful, measurements.

Adult↗
PubMed1979

Comparative study of cardiovascular, neurological and metabolic side effects of 8 narcotics in dogs. Pethidine, piritramide, morphine, phenoperidine, fentanyl, R 39 209, sufentanil, R 34 995. III. Comparative study of the acute metabolic toxicity of the narcotics used in high and massive doses in curarised and mechanically ventilated dogs.

The I.V. administration in dogs of high and massive doses of narcotics produced an acute rise in CO2 consumption, a rise of plasma catecholamines and other slight biochemical and metabolic perturbances. A general trend towards metabolic acidosis and hypermetabolism was noticed but important differences appeared according the drugs and doses chosen. The safety margin for metabolic toxicity (ratio between IV doses producing severe metabolic side-effects and doses necessary for deep surgical analgesia) were calculated for each narcotic and found as follows: 1 for pethidine, 3.3 for piritramide, 13 for morphine and phenoperidine, 12.5 for R 39 209, 60 for fentanyl, 800 for sufentanil and 4 000 for R 34 995. Drug associations may decrease or increase the metabolic safety margin of the narcotics. Beneficial associations with morphinomimetics are found with droperidol, etomidate and flunitrazepam.

Acidosis↗
PubMed1979

Comparative study of cardiovascular, neurological and metabolic side effects of 8 narcotics in dogs. Pethidine, piritramide, morphine, phenoperidine, fentanyl, R 39 209, sufentanil, R 34 995. II. Comparative study on the epileptoid activity of the narcotics used in high and massive doses in curarised and mechanically ventilated dogs.

The experimental design, described in part I, was again used here. The electrocortical activity was registered with an EEG amplifier using a bipolar derivation of needle electrodes fixed in the scalp of a dog in the fronto-occipital position. In this situation the convlusion threshold for the 8 substances is as follows: pethidine 20 mg.kg-1 I.V., piritramide 30, morphine 180, phenoperidine 4, R 39 209 5, fentanyl 4, sufentanil 4 and R 34 995 10 mg.kg-1 I.V. Comparing the I.V. doses producing severe convulsions with the doses necessary for deep surgical analgesia a safety margin of neurological toxicity was calculated. This was for pethidine 2.2, for piritramide 6.6, for phenoperidine 16, for R 39 209 62.5, for morphine 72, for fentanyl 160, for sufentanil 1 000 and for R 34 995 10 000. It is concluded that for pure narcotics there exists an inverse relationship between analgesic potency and neurological toxicity which is always accompanied by a hyperactivity of the automatic nervous system. Factors modifying the convulsive level of the narcotics are still under investigation. In the meanwhile it can be stated that the association of a strong narcotic with flunitrazepam, droperidol or etomidate will increase the convulsion threshold of the morphinomimetics.

Acidosis↗
PubMed1978

A double-blind comparison of morphine and buprenorphine in the prevention of pain after operation.

A double-blind, between-patient comparison has been made of the effects of morphine 10 mg i.v. and buprenorphine 0.3 mg i.v. on the prevention of pain after operation. The drugs were given by the anaesthetist at the end of the operation, and the onset and severity of pain were assessed by a trained nurse. Both drugs caused a significant delay in the appearance of severe pain when compared with the control group, but with buprenorphine the mean delay of 10.5 h was more than twice that of morphine. The only side-effect to occur more frequently after administration of the analgesics was drowsiness, the incidence being greater after buprenorphine than after morphine.

Adult↗
PubMed1978

Monitoring ventilation during anesthesia.

In patients under anesthesia, ventilation is often monitored less adequately than circulation. A simple method, neglected in adults, is the use of a precordial or oesophageal stethoscope. Respiratory volumes may be measured directly, or inferred from flowrates or pressure changes. A rough measurement of inspired volumes may be made using a nonrebreathing valve, and controlling fresh gas input to maintain a constant underfilled reservoir bag. Spirometry of expired volumes is difficult and requires sophisticated apparatus. Respiratory volumes are easily inferred from flowrates using the Wright or Dräger respirometers. Flowrates may also be inferred from pressure changes, which are easy to record, as in the pneumotachorgraph. Accurate measurements require attention to many details, such as linearity of the transducer response over the flowrates measured. Calibration should be with the anesthetic gases used, at controlled temperature and humidity. Positive pressure ventilation peaks give a high flow artefact, and electronic drift requires regular recalibration. Electrical impedance changes may also be used to infer and record respiratory volumes, with reasonable accuracy if individual calibration is carried out. Anesthesia offers excellent opportunities to measure compliance and resistance, but itself changes these values, so that relation to normal values or changes due to pathology is difficult. Occlusion pressure is also readily measured during anesthesia, as an indication of respiratory drive, but rigid control of all other factors affecting respiratory muscle tensions is necessary.

Airway Resistance↗
PubMed1977

Duration of action of analgesic supplements to anesthesia. A double-blind comparison between morphine, fentanyl and sulfentanil.

In a double-blind trial, in a total of 45 patients, sulfentanil was compared with fentanyl and morphine in equipotent doses, as a narcotic supplement to anesthesia. Initially, morphine was shown to have a significantly longer duration of effect than fentanyl and sulfentanil, which for the first 3 doses had similar durations of action to each other. Later doses of fentanyl, however, had an extended effect, presumably because of cumulation. This was not seen with sulfentanil.

Adjuvants, Anesthesia↗
PubMed1977

A clinical comparison of tilidine hydrochloride and pentazocine, given orally for the treatment of postoperative pain.

A controlled, double-blind study involving 250 women was carried out ot assess the efficacy of oral tilidine 25, 50 and 100 mg in treating postepisiotomy pain, and to offer a comparison with oral pentazocine 50 mg. All the analgesics produced significant pain relief. At peak effect tilidine 50 mg produced very similar results to pentazocine 50 mg with tilidine 25 mg producing less, and tilidine 100 mg more pain relief. These results were not, however, statistically significant. In these postdelivery ambulant patients pentazocine 50 mg and tilidine 100 mg produced at 25% incidence of side-effects, mainly dizziness and drowsiness, but tilidine 25 mg produced significant analgesia with virtually no side-effects.

Administration, Oral↗
PubMed1977

I.C.I. 35868 - The effect of a change of formulation on the incidence of pain after intravenous injection.

I.C.I. 35868 is a promising new intravenous induction agent, but intravenous injection of the initial 2% formulation frequently caused pain. The solvent vehicle of the 2% formulation, which contained Cremophor E.L. and ethanol, was therefore investigated to see if this could be the cause of the pain. Twenty volunteers received both 5 ml isotonic saline and 5 ml solvent vehicle intravenously. The injection of saline never caused pain, but the solvent caused mild or moderate pain in 9 patients. I.C.I. 35868 was therefore reformulated in a 1% solution, excluding ethanol from the solvent. When intravenous injection of I.C.I. 35868 1% was compared to methohexitone 1% in 24 patients, both agents caused pain. Four out of 12 patients reveiving I.C.I. 35868 1% felt pain, with a total pain "score" of 6, but 6 out of 12 patients who received methohexitone 1%, felt pain, with a total pain "score" of 12. In no instance was intravenous injection followed by persistant pain, or evidence of thrombosis or phlebitis.

Anesthesia, Intravenous↗