Canadian Anaesthetists' Society journal
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Comparative Study
Porcine malignant hyperthermia--failure of dantrolene dose response to diagnose susceptibility (halothane effect).
Dantrolene, a skeletal muscle relaxant, has been proven prophylactic and therapeutic for malignant hyperthermia (MH) in swine. This study examined the feasibility of using a dantrolene dose response as measured by indirectly evoked foretoe twitch depression as a means to safely discriminate MH susceptibility in swine. The effect of halothane on the dantrolene response was quantified. ⋯ Under halothane, the MHS animals had significantly augmented dantrolene response compared to MHR pigs, but three MHS animals had developed the MH syndrome prior to receiving dantrolene. We conclude that dantrolene muscle relaxant dose response cannot be used as a diagnostic test for MHS in swine. Halothane augments dantrolene twitch depression in MHS swine.
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Comparative Study
Experimental evaluation of local anaesthetic solutions using rat infraorbital nerve block.
The analgesic effectiveness of various local anaesthetic solutions was measured in the distribution of the infraorbital nerve of the rat. Using Sprague-Dawley rats sedated with phenobarbitone 25 mg/kg intraperitoneally and a simple stereotactic technique, 0.2 ml of solution was deposited at the infraorbital notch. The onset and duration of analgesia were ascertained by timing the unilateral absence of aversive response to pinching the upper lip, tested at intervals of five minutes. ⋯ Solutions were tested on sets of eight animals weighing 500--600 g. The average duration (minutes +/- S. D.) of analgesia produced by the respective injectates was as follows: Lidocaine 0.5% -42+/-12 Lidocaine 1.0% -47+/-10 Mepivacaine 0.5% -58+/-13 Mepivacaine 1.0% -78+/-23 Procaine 0.5% -0+/-0 Procaine 1.0% -34+/-10 Procaine 1.5% -46+/-13 2-Chloroprocaine 1.5% -38+/-9 Bupivacaine 0.5% -100+/-40 Etidocaine 1.0% -59+/-25 Tetracaine 0.2% -0+/-0 Tetracaine 0.3% -0+/-0 Comparison with other animal models used to evaluate conduction block indicates that this technique affords an improved, standardized and reliable experimental guide to the clinical analgesic properties of local anaesthetic agents.
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Medical students should learn certain facts and comprehension of these facts during an elective month spent in a Department of Anaesthesia. This enables them to make the most of the tutorial situation in which they work with clinical anaesthetists. ⋯ They were associated with an improvement in student performance and were acceptable to students and instructors. However, computer based instruction should only be used to improve certain learning situations and should not be employed as an alternative to interaction with physicians and patients.