Anaesthesia
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Randomized Controlled Trial Clinical Trial
The effect of clonidine on sevoflurane requirements for anaesthesia and hypnosis.
We evaluated the effects of clonidine given orally on sevoflurane requirements for anaesthesia and hypnosis. Patients received either clonidine (5 micrograms.kg-1) by mouth (n = 21) 90 min before surgery or no premedication (n = 21) by random allocation. MAC was calculated using repeated tetanic nerve stimulation with end-tidal sevoflurane concentration increased or decreased by 0.3 vol.% depending on the previous response. ⋯ The mean (SD) MAC in the clonidine-treated patients was 1.53 (0.20)% compared with 1.83 (0.15)% in the control group (p < 0.001). Similarly, MAC awake was reduced in the clonidine group (0.50 (0.08)% compared with 0.60 (0.07)% in the control group) (p < 0.001). We conclude that clonidine 5 micrograms.kg-1 orally administered pre-operatively reduces sevoflurane requirements for anaesthesia and hypnosis.
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Randomized Controlled Trial Clinical Trial
The effects of single-handed and bimanual cricoid pressure on the view at laryngoscopy.
The effects of two different methods of cricoid pressure on laryngoscopic view were studied in 94 healthy women presenting for routine gynaecological surgery. Laryngoscopy was performed with either single-handed or bimanual cricoid pressure; after grading of the view obtained, the other method was used and second grading performed. Laryngoscopic view was better with the bimanual than with the single-handed technique (p = 0.016). ⋯ Age, weight, Mallampatti score and thyromental distance did not differ between patients in these three groups. Bimanual cricoid pressure should be the initial technique of choice during rapid sequence induction but, in a minority of cases, switching to a single-handed technique may improve the laryngoscopic view. The technique of cricoid pressure which produces the best laryngoscopic view in an individual patient cannot be predicted from the physical features studied.
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Clinical Trial
A new combined spinal-epidural apparatus: measurement of the distance to the epidural and subarachnoid spaces.
A new combined spinal-epidural anaesthesia apparatus with a 27G lockable spinal needle was used in 151 patients. Two groups could be created, based on whether dural perforation was felt or not (group 1: with dural click; group 2: no dural click). Measurements of the epidural space depth and of the protrusion of the spinal needle from the epidural needle (tip-to-tip distance) were made. ⋯ Four patients felt paraesthesia during placement of the spinal needle and, in another four patients, aspiration was necessary to detect cerebrospinal fluid. Two patients needed epidural top-ups due to insufficient level of anaesthesia. The lockable spinal needle provides safe and stable conditions during injection and a high rate of success in reaching the subarachnoid space.
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Guidelines for cardiac anaesthesia could reduce irrational variation in practice and so improve cardiac surgical outcome. In October 1994, a postal survey was undertaken to determine the views and attitudes of consultant cardiac anaesthetists in the United Kingdom towards guidelines. ⋯ Responses to other parts of the questionnaire showed that those against guidelines for cardiac anaesthesia were less positive towards their advantages and more negative to their disadvantages compared with those in their favour. The majority of cardiac anaesthetists, although believing them to be valuable in medicine, do not want guidelines for cardiac anaesthesia because they are concerned that guidelines would be inflexible and would neither reduce variation in, nor improve the quality of, cardiac anaesthesia.
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Case Reports
Near-infrared spectroscopy changes during hypothermic circulatory arrest with retrograde cerebral perfusion.
We report on the changes in cerebral near-infrared spectroscopy during grafting of a thoraco-abdominal aneurysm. A 58-year-old man presented with a complex dissecting aortic aneurysm. Repair of the aneurysm was performed under hypothermic circulatory arrest with retrograde cerebral perfusion. ⋯ When retrograde cerebral perfusion was commenced the signals representing total haemoglobin, oxygenated haemoglobin and cytochrome aa3 were all restored to near baseline values. Deoxygenated haemoglobin, however, remained elevated. These changes support the hypothesis that some cerebral perfusion occurs during retrograde cerebral perfusion.