Anaesthesia
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Randomized Controlled Trial
A randomised comparison of InnoScope and Macintosh laryngoscope in simulated difficult tracheal intubation in manikins.
We conducted a crossover randomised study to evaluate the performance of a novel optical stylet, the InnoScope, for tracheal intubation in simulated normal and difficult airways. Twenty-five anaesthetists attempted tracheal intubation on a SimMan 3G simulator using the InnoScope first followed by the Macintosh laryngoscope or vice versa. Three airway scenarios were tested: (1) normal airway; (2) difficult airway with swollen pharynx; and (3) limited neck movement. ⋯ Using the InnoScope, tracheal intubation during the first attempt was only successful in 48% of cases with difficult airway. In this scenario, the median (interquartile range [range]) duration of tracheal intubation was significantly longer with [corrected] InnoScope compared with the Macintosh laryngoscope, (70 (19-120 [15-120)] s vs 30 [21-58 (15-120)] s, [corrected] p = 0.01. We conclude that an improved laryngeal view with the use of the InnoScope did not translate into better conditions for tracheal intubation.
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Allergic reactions to amide local anaesthetic agents are rare. We report the case of a 74-year-old man who suffered anaphylaxis, presenting with cardiovascular collapse, immediately after receiving regional anaesthesia on two separate occasions, the first involving the use of levobupivacaine and the second using ropivacaine. Skin testing revealed positive reactions to both levobupivacaine and ropivacaine, and negative reactions to articaine and lidocaine. Severe allergic reactions can be caused by the amide local anaesthetic drugs, levobupivacaine and ropivacaine.
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Previous volunteer studies of an effect-site controlled, patient-maintained sedation system using propofol have demonstrated a risk of over-sedation. We have incorporated a reaction-time monitor into the handset of the patient-maintained sedation system to add an individualised patient-feedback mechanism. This study assessed if such reaction-time feedback modification would reduce the risk of over-sedation in 20 healthy volunteers deliberately attempting to over-administer themselves propofol. ⋯ The mean (SD) lowest S(p) O(2) was 97 (1.7) % when breathing room air and no volunteer required supplementary oxygen. The mean (SD) maximum effect-site propofol concentration reached was 1.7 (0.4) μg.ml(-1). The present system was found to be safer than its predecessors, allowing conscious sedation, but preventing over-sedation.
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Increasing the calculated plasma concentration of propofol has been shown to increase choice reaction time and visual and auditory response times. We studied the relationship of reaction to a vibrating handset as the effect-site target-controlled propofol concentration was incrementally increased in 20 patients during sedation, before induction of general anaesthesia. ⋯ The loss of response to verbal contact occurred at a propofol effect-site concentration of 2.4 (0.5) μg.ml(-1). Reaction time may be of use clinically to warn of impending loss of verbal contact.