Peak Expiratory Flow During Mechanical Insufflation-Exsufflation: Endotracheal Tube Versus Face Mask

Abstract

Background: Mechanical insufflation-exsufflation (MI-E) applied through the endotracheal tube (ETT) can effectively eliminate airway secretions in intubated patients. However, the effect of the interface (ETT vs face mask) on expiratory air flow generated by MI-E has not been investigated. This study aimed to investigate the effect of the ETT on peak expiratory flow (PEF) along with other associated factors that could influence PEF generated by MI-E.

Methods: Intubated participants received 2 sessions of MI-E via ETT therapy per d for 2 consecutive days. One MI-E session consisted of 5 sets of either constant (+40/-40 cm H₂O) or incremental (+30/-30 to +50/-50 cm H₂O) pressure applications. Following extubation, MI-E sessions were repeated using face mask. Expiratory air flow during MI-E therapy was continuously measured, and every PEF during each application was analyzed using linear mixed-effect and generalized linear mixed models.

Results: A total of 12 participants (9 [75.0%] men; mean [SD] age, 74.0 [10.2] y) completed all MI-E sessions with both ETT and face mask interfaces. The PEF generated during MI-E treatment was influenced by the interface (ETT vs face mask), pressure gradient, and number of session repetitions. Adjusted mean PEF values for MI-E via ETT and face mask at +40/-40 cm H₂O were -2.521 and -3.114 L/s, respectively, and -2.956 and -3.364 L/s at +50/-50 cm H₂O, respectively. At a pressure gradient of +40/-40 cm H₂O, only 172 of 528 MI-E trials via ETT (32.6%) achieved a PEF faster than -2.7 L/s, whereas 304 of 343 MI-E trials via face mask (88.6%) exceeded PEF < -2.7 L/s.

Conclusions: MI-E via ETT generated slower PEF than via face mask, suggesting that a higher-pressure protocol should be prescribed for intubated patients. An insufflation-exsufflation pressure up to +50/-50 cm H₂O could be considered to produce a PEF faster than 2.7 L/s, and the applications were safe and feasible for subjects on invasive mechanical ventilation.

Keywords: cough assist; endotracheal tube; expiratory flow; mechanical insufflation-exsufflation; mechanical ventilation; respiratory therapy.