Intragastric pressure and its relevance to protective cricoid force

Cricoid pressure is frequently used to protect the anaesthetised and paralysed patient from passive regurgitation. Although intragastric pressure (Pga) drives regurgitation, its relevance in the setting of protective cricoid force has been largely ignored. We sought to define the likely range of Pga encountered in the population at risk. We studied 100 consecutive patients presenting for surgery requiring mechanical ventilation. We measured respiratory swings in Pga during mechanical ventilation in the paralysed state following rapid sequence induction (n = 24) and routine induction of anaesthesia ( n = 76). Pga (mmHg) in the whole group recorded at end-inspiration (Pga-In) and end-expiration (Pga-Ex) was [ mean (SD)]: Pga-In 6.48 (2.60) mmHg and Pga-Ex 3.23 (2.24) mmHg. We found no correlation between Pga and body mass index ( r(2) = 0.018). These findings have implications for the level of cricoid force required to protect a patient during the induction of anaesthesia.