The effect of cricoid pressure and neck support on the view at laryngoscopy.

Abstract

Fifty female patients were studied to compare the view of the larynx at direct laryngoscopy under general anaesthesia with and without cricoid pressure applied. We also compared the view using the standard technique of cricoid pressure with that using cricoid pressure in an upward and backward direction and further investigated whether these views were improved with a firm foam rubber neck support. The order in which the types of cricoid pressure were applied was randomised and also blinded with a drape over the neck. Cricoid pressure was simulated on weighing scales after each case and a mean force of 3.2 kg was applied. The majority of views at laryngoscopy (95%) were grade 1, with too few grade 2 and 3 views for statistical comparison. Both types of cricoid pressure applied without neck support were more likely to give a better view than no cricoid pressure (p < 0.01) and cricoid pressure in an upward and backward direction was more likely to give a better view at laryngoscopy than the standard technique (p < 0.01). Neck support during the standard technique of cricoid pressure did not improve the view of the larynx at laryngoscopy. Cricoid pressure is likely to improve the view at laryngoscopy which may be further improved by applying it in an upward and backward direction.