Cricoid pressure: which hand?

We studied 20 anaesthetic assistants applying simulated cricoid pressure with the left or right hand in random order. Simulated cricoid pressure was continued for up to 5 min with one hand and then, after resting, with the other hand. Applied pressure was measured at intervals and the subjects were blind to the results. Nineteen assistants were right-handed and all routinely applied cricoid pressure with their right hand. Mean (SD) force applied during simulated 'awake' cricoid pressure was 13.8 (5.7) N with either left or right hand, and during 'anaesthetised' cricoid pressure it was initially 25.1 (8.2) N and 24.7 (8.8) N with left or right hand, respectively. Mean force was maintained above 20 N and below 30 N throughout the study period with either hand. Force applied with the left hand was significantly lower than with the right hand but the difference was clinically insignificant (0.4 N). Inadequate or excessive force was more frequently associated with use of the left hand (p < 0.0001). Cricoid pressure was released before 5 min in three cases, two left-handed and one right-handed. Our results demonstrate that anaesthetic assistants apply a lower force than is classically taught and are able to maintain the force with either hand for a sustained period. Application with the left hand is justified where clinically indicated but may have a lower margin for error than when applied with the right hand.