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

Abstract

Aim: 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. Background: 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. Method: 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. Results: 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), R2 = 0·75]. Significantly less fluid was aspirated when a PEEP of 35 cmH2O was applied when compared with competing techniques. Discussion and conclusions: 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.