Increasing positive end expiratory pressure at extubation reduces subglottic secretion aspiration in a bench-top model

Abstract

To estimate the ability of simulated tracheal suction, adjusting the positive end expiratory pressure (PEEP) settings on the ventilator or compressing a self-inflating bag to minimize aspiration during cuff deflation and extubation in a bench-top model. During intubation, colonized secretions accumulate in the subglottic space above the endotracheal tube (ETT) cuff. Consequently, during cuff deflation and extubation, there is a risk of aspiration of the secretions. This may result in pneumonitis or pneumonia. There are a number of techniques used during cuff deflation and extubation to prevent secretion aspiration. A model trachea was intubated and the proximal end of the ETT was attached to a mechanical ventilator. Ten millilitres of water was placed above the inflated cuff and then nine test protocols were implemented in a random order to simulate tracheal suction, adjusting the PEEP settings on the ventilator or compressing a self-inflating bag. The volume of water 'aspirated' by the model was determined by weighing the apparatus pre- and post-extubation. Statistical analysis was performed using regression analysis and heteroscedastic t tests with a Bonferroni correction. The level of PEEP was negatively correlated with the volume of fluid aspirated [co-efficient -0.24 (99% confidence interval -0.31 to -0.17), R(2) = 0.75]. Significantly less fluid was aspirated when a PEEP of 35 cmH(2)O was applied when compared with competing techniques. This study suggests that applying PEEP during cuff deflation and extubation is protective against aspiration. We conclude that unless there is a contraindication, the application of PEEP should be considered when extubating patients.