British journal of anaesthesia
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Case Reports
Intracranial placement of a nasotracheal tube after transnasal trans-sphenoidal surgery.
Intracranial misplacement of a tracheal tube during attempted nasotracheal intubation is a rare, usually lethal complication. Such incidents are associated with fractures of the face and base of the skull. We report inadvertent intracranial placement of a nasotracheal tube in a patient who had 2 weeks previously undergone transnasal trans-sphenoidal surgery for a pituitary tumour. One should be aware that transnasal trans-sphenoidal surgery leaves a bony defect in the skull, which is susceptible to perforation by nasally introduced tubes.
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Physostigmine, a centrally acting anticholinesterase, antagonizes the hypnotic effect of propofol, as shown by the return of consciousness (response to commands) or wakefulness (spontaneous eye-opening without response to commands) and by recovery of auditory evoked potentials (40 Hz auditory steady-state response (ASSR)) and the bispectral index (BIS). We measured the effects of physostigmine on the hypnotic effect of inhaled volatile anaesthetics, using sevoflurane as the representative agent. ⋯ Physostigmine can antagonize, at least partially, the hypnotic effect of sevoflurane and changes in arousal after physostigmine are shown by ASSR measurements. However, the antagonism is not as clear or reliable as with propofol.
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Isoflurane and propofol reduce the recordability of compound muscle action potentials (CMAP) following single transcranial magnetic stimulation of the motor cortex (sTCMS). Repetition of the magnetic stimulus (repetitive transcranial magnetic stimulation, rTCMS) might allow the inhibition caused by anaesthesia with isoflurane or propofol to be overcome. ⋯ In most patients, rTCMS can overcome suppression of CMAP during propofol/nitrous oxide anaesthesia, but not during isoflurane anaesthesia. A train of four magnetic stimuli at a frequency of 333 Hz is most effective in evoking potentials from the upper and lower limb muscles. The authors conclude that rTCMS can be used for evaluation of the descending motor pathways during anaesthesia.