British journal of anaesthesia
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We report two cases who exhibited a decrease in their bispectral index (BIS) score, associated with syncope during venipuncture in patients with suspected needle phobia. In case 1, the reduction in BIS score occurred during the development of hypotension and bradycardia and may well have been caused by cerebral hypoperfusion. In case 2, the patient lost consciousness with decreasing BIS score before hypotension and bradycardia; this patient's condition could not be completely explained by cerebral hypoperfusion as a result of a vasovagal reflex because the patient's blood pressure and heart rate remained normal during the syncopal episode.
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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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Pulse transit time (rPTT), the interval between ventricular electrical activity and arrival of a peripheral pulse waveform, has been used to detect changes in autonomic tone. The aim of this observational pilot study was to measure changes in rPTT in response to general anaesthesia and noxious stimuli. ⋯ Variation in rPTT reflects autonomic responses to nociceptive stimulation and fluctuations in anaesthetic depth independently of heart rate.