Biomedical subjects
Publications and source records attributed to R S Vaughan.
A patient with a tracheostomy and an iatrogenic tracheo-oesophageal fistula presented for diagnostic bronchoscopy and right upper lobectomy. The anaesthetic management is discussed with reference to the options available and, in particular, the use of a Brompton Pallister single lumen endobronchial tube.
We have studied 22 patients to examine whether or not cricoid pressure affects ventilation of the lungs via the laryngeal mask and its correct positioning. In a randomized, crossover design, the laryngeal mask was inserted with or without cricoid pressure applied with a standardized force of 30 N using a cricoid yoke. A standardized pillow (6 cm in height) was placed under the patient's occiput, but the neck was not supported. Ventilation of the lungs via the laryngeal mask was adequate in all patients when no cricoid pressure was applied, but in only three of 22 patients when cricoid pressure was applied (P << 0.001; 95% confidence interval (CI) 0.72-1.0). The mask was positioned correctly in 18 patients when no pressure was applied, and in none after application of cricoid pressure (P << 0.001; 95% CI 0.66-0.98). We had planned to study, in an additional 20 patients, the effect of cricoid pressure without a pillow under the occiput; placement of the mask, however, was difficult even when cricoid pressure was not applied and there was a high incidence of bleeding from the oropharynx. We thus abandoned that part of the study after eight patients. In those eight patients, the success rate of ventilation via the laryngeal mask was lower when cricoid pressure was applied. We conclude that when sufficient force was applied, cricoid pressure, regardless of the method of application, did impede placement of the laryngeal mask.
We have studied the effects of phonation and posture on the Mallampati classification of view of the pharyngeal structures. Differences between observers were allowed for by the experimental design and log-linear modelling. Sixty-four patients were assessed on the ward, sitting upright, with and without phonation, by each of two observers. Another 64 patients were assessed without phonation, but both upright and supine, again by both observers. Phonation (the patient saying "Ah") produced a marked, systematic improvement of view; moving to the supine posture produced a small, systematic, non-significant worsening of the view. Differences between observers were non-systematic but substantial. About 25% of patients phonated spontaneously. It is recommended that anaesthetists make their own assessments of Mallampati classification, with the patient in either of the postures but always either with or without phonation, and thereby gradually "calibrate" their assessments against the degree of difficulty encountered in intubation.
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The effect of allowing patients unlimited access to oral water in the time up until 2 h pre-operatively was the subject of a randomised, blind, controlled trial. No effect was seen on gastric volume or pH, or on plasma osmolality, and allowing water pre-operatively was associated with a reduction in anxiety in the anaesthetic room.
OBJECTIVE: To determine the influence of general or regional anaesthesia on long term mental function in elderly patients. DESIGN: Prospective study of patients randomly allocated to receive general or regional anaesthesia. SETTING: The patients' homes and a large teaching hospital in Cardiff. SUBJECTS: 146 Patients aged 60 and over scheduled for elective hip or knee replacement. MAIN OUTCOME MEASURES: Scores achieved in tests of cognitive function and functional competence. RESULTS: 72 Patients were allocated to receive general anaesthesia and 74 regional anaesthesia. Anaesthetic technique did not influence the duration of the operation, time to mobilisation postoperatively, requirements for analgesia after the operation, or duration of stay in hospital. Three months after the operation there was an improvement in the score for the recognition component (76 ms, 95% confidence interval 9 to 144) and the response component (82 ms, 5 to 158) of the choice reaction time in the group receiving general anaesthesia compared with the group receiving regional anaesthesia. This was the only significant difference between the two groups in the assessments of cognitive and functional competence. Eleven patients receiving regional anaesthesia and 12 receiving general anaesthesia reported that their memory and concentration were worse than before the operation, but this was not confirmed by testing. CONCLUSION: Cognitive and functional competence in elderly patients was not detectably impaired after either general or regional anaesthesia when attention was paid to the known perioperative influences on mental function.
Topical anesthesia of the respiratory tract for fibreoptic bronchoscopy was compared, in a single-blind study, inhaled from a simple and inexpensive jet nebuliser, administered by cricothyroid injection or by a 'spray-as-you-go technique'. Each technique was supplemented by spraying lignocaine through the fibrescope and intravenous fentanyl-droperidol sedation. Inhaled nebulisation was successfully used for 96% (46 of 48) of patients, was safe, effective and acceptable to the patient and bronchoscopist. The cricothyroid injection method produced better conditions than nebulisation in patients who had diagnostic bronchoscopy. The nebuliser technique is as satisfactory as the spraying technique in patients for diagnostic bronchial lavage in whom bleeding from a cricothyroid puncture is unacceptable. Patients who used the nebuliser were more satisfied. This technique may also be a useful method for 'awake' intubation.
A pregnant woman with Gorlin's syndrome presented for the removal of malignant ovarian tumours. The main problem encountered by the anaesthetists was an unexpected increase in arterial blood pressure. This was most probably associated with surgical manipulation of the ovaries with an increase in prorenin/renin production.
Thirty healthy patients, who were to undergo surgery which required tracheal intubation, were given an intravenous injection of enalaprilat (either 0.5 mg, 1 mg, 2 mg or 4 mg; six patients for each dose) or normal saline 17 minutes before induction of anaesthesia with thiopentone 3-5 mg/kg, and suxamethonium 1.5 mg/kg. Postural manoeuvres were performed 5 minutes before and 6, 11 and 16 minutes after enalaprilat or saline. Complete inhibition of angiotensin converting enzyme occurred with all doses of enalaprilat, which allowed the four different treatment groups to be considered as one large treated group. The mean arterial pressure was almost unchanged during the postural manoeuvres; the heart rate increased, mostly similarly (by approximately 10%) in both groups. Mean arterial pressure in the recumbent position decreased over the 17 minutes before induction in the enalaprilat group, and increased slightly in the control group (treated mean, -5.0%; controls mean, 1.8%; difference, -6.8%; 95% confidence intervals of difference, -2.3 to -11.3%, p less than 0.01). This difference was again seen after induction (treated, -8.0%; controls, 7.7%; confidence intervals of difference, -0.6 to -31%) and for a 5-minute period shortly after tracheal intubation. The increases in mean arterial pressure produced by intubation itself were similar in both groups (treated, + 36%; controls, + 35%; 95% confidence intervals of difference, -16% to + 18%). Changes in heart rate after induction were also similar in both groups. It is concluded that intravenous enalaprilat acted as a hypotensive agent with a sparing effect on autonomic reflexes, both before and after induction of anaesthesia.
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A case of postoperative coma associated with diabetes insipidus and hypothermia is presented. Some recommendations are offered for the future management of similar cases.
This is a comparative study of two methods to relieve postoperative thoracotomy pain. Continuous thoracic epidural infusion of fentanyl produced superior analgesia when compared with cryo-analgesia of the relevant thoracic nerves. Linear analogue pain scores were consistently lower in the epidural group reaching significance (p less than 0.05) at 32 and 40 hours after operation. All 36 patients in the cryo-analgesia group required additional analgesia, while 12 out of the 32 patients in the epidural group did not. This difference was significant at p less than 0.001. Respiratory and cardiovascular measurements were similar in both groups and the only side effect attributable to the epidural fentanyl was itching but this was not a problem.
Temazepam 0.5, 1.0 and 1.5 mg kg-1 in an elixir formulation (Euhypnos Elixir), was compared with trimeprazine tartrate 3 mg kg-1 in a syrup (Vallergan Forte Syrup), as premedication in 220 children (ASA grade I) undergoing tonsillectomy and associated procedures. Each patient was randomly allocated to one of the four treatments. The administration was blind to the observers in theatre, recovery room and postoperative ward, who assessed each patient according to a total of 14 criteria. A modelling technique allowed account to be taken of the effects of concomitant variables (e.g. age and duration of anaesthesia) where appropriate. No statistically significant difference was found between the efficacy of the treatments. The only statistically significant differences were that temazepam was associated with more ectopic beats under anaesthesia (P = 0.03 or 0.002, depending on the test applied), more postoperative vomiting (P = 0.04) and more postoperative restlessness (P less than 0.0001).
Red rubber and polyvinyl chloride bronchial double lumen tubes were compared. Polyvinyl chloride tubes are easier to pass quicker to position and cause less damage to the mucosa of the respiratory tract than the red rubber equivalents.
An intravenous regional sympathetic block was produced in the upper limb using a Bier's technique and guanethidine. The dilatation produced allowed accurate delineation of the vasculature at angiography which could be reproduced after further injections of contrast medium. It is further suggested that this technique may be used immediately before tissue grafting as it may prevent vasoconstriction at any anastomotic sites.