British journal of anaesthesia
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Editorial Comment
Developments in the safe use of high frequency jet ventilation.
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Eight patients with a history of failed tracheal intubation during pregnancy were investigated by x-ray laryngoscopy after delivery. Partial elevation of the epiglottis with no view of glottic structures was found in five patients who were therefore considered to still present difficulty. ⋯ Relatively few abnormal anatomical indices were seen in these patients and this was in keeping with the level of difficulty encountered. An angular measure of jaw protrusion from a line joining the upper incisors and a point just above and anterior to the vocal cords, to the mid-point on the inner surface of the mandible was useful: the lower angle of this triangle was as important as the angle at the incisors.
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We have studied eight patients with a history of difficult tracheal intubation, using x-ray laryngoscopy and local anaesthesia, a curved Macintosh blade and a standard intubating position. The view obtained was better than recorded previously during general anaesthesia in two patients, and in a third the x-ray showed that positioning the blade tip beneath the epiglottis would have improved vision, suggesting that reproducibility of the assessment may not be consistent. The "ease of intubation" and "complementary" angles may be helpful in the assessment of such patients. ⋯ In the absence of muscle paralysis, removal of the blade caused immediate correction. However, during anaesthesia with neuromuscular block it is suggested that this not only occurs more readily but, may not correct when the blade is removed. Iatrogenic airway obstruction during moderately difficult tracheal intubation may be common and should be anticipated.