Tolerance of cricoid pressure by conscious volunteers.
It is recommended that a cricoid pressure (force) of 40 N should be applied to prevent regurgitation. The tolerance of incremental levels of cricoid pressure was assessed in 22 conscious volunteers. Each level of cricoid pressure was applied for 20 s using a cricoid yoke. Only 14 volunteers could tolerate 40 N of cricoid forte for 20 s; all 22 volunteers could tolerate 25 N for that time but 19 of them found it uncomfortable and 1 wanted to retch. Nine subjects complained of breathing difficulties at cricoid forces of 35 N or above; 2 had complete airway obstruction. A, cricoid force of over 20 N is likely to be poorly tolerated by the awake patient. It is recommended that a force of 20 N should be maintained before loss of consciousness and the full force of 40 N be reserved for the onset of general anaesthesia; the assistant can practise these levels on a set of weighing scales.
Vanner
R G
RG
Department of Anaesthetics, St Thomas' Hospital, London, UK.