British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
A novel method of deriving the effect compartment equilibrium rate constant for propofol.
Calculation of the effect compartment concentration (Ce) in non-steady-state conditions requires the equilibrium rate constant, keo. Most studies of propofol derive the keo using EEG measurements. This study investigated an alternative method. Starting from a predicted concentration-time profile, a keo value was included so that the predicted Ce at a specific pharmacodynamic end-point was the same when using three different methods of injection. ⋯ The effect compartment equilibrium rate constant and concentration at loss of the eyelash reflex can be derived without the use of electronic central nervous system monitors.
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Randomized Controlled Trial Clinical Trial
Cardiovascular changes after the three stages of nasotracheal intubation.
Nasotracheal intubation typically comprises three distinct stages: (i) nasopharyngeal intubation; (ii) direct laryngoscopy to identify the vocal cords; and (iii) the passage of the tracheal tube into the trachea. The aim of this study was to identify and compare the cardiovascular responses associated with each of these stages. ⋯ Nasopharyngeal intubation causes a significant pressor response. Stimulation of the larynx and trachea by the passage of the tracheal tube, but not direct laryngoscopy, causes a significant increase in this response.
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This study was undertaken to investigate why the superficial cervical plexus block for carotid endarterectomy is so effective. Initial consideration would suggest that a superficial injection would be unlikely to block all terminal fibres of relevant nerves. One possibility is that the local anaesthetic crosses the deep cervical fascia and blocks the cervical nerves at their roots. ⋯ The superficial cervical space communicates with the deep cervical space and this may explain the efficacy of the superficial block. The method of communication remains unknown. Our findings also indicate that the suitable site of injection for the superficial cervical plexus block is below the investing fascia of the neck, and not just subcutaneous.
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Aortic atheromatous disease is known to be associated with an increased risk of perioperative stroke in the setting of cardiac surgery. In this study, we sought to determine the relationship between cerebral microemboli and aortic atheroma burden in patients undergoing cardiac surgery. ⋯ We demonstrate a positive relationship between TCD-detected cerebral emboli and the atheromatous burden of the ascending aorta and aortic arch. Previously demonstrated associations between TCD-detectable cerebral emboli and adverse cerebral outcome may be related to the presence of significant aortic atheromatous disease.