Effects of Mechanical Insufflation-Exsufflation With Different Pressure Settings on Respiratory Mucus Displacement During Invasive Ventilation.

BACKGROUND: Mechanical insufflation-exsufflation (MI-E) has been proposed as a potential strategy to generate high expiratory flows and simulate cough in the critically ill. However, efficacy and safety of MI-E during invasive mechanical ventilation are still to be fully elucidated. This study in intubated and mechanically ventilated pigs aimed to evaluate the effects of 8 combinations of insufflation-exsufflation pressures during MI-E on mucus displacement, respiratory flows, as well as respiratory mechanics and hemodynamics. METHODS: Six healthy Landrace-Large White female pigs were orotracheally intubated, anesthetized, and invasively ventilated for up to 72 h. Eight combinations of insufflation-exsufflation pressures (+40/-40, +40/-50, +40/-60, +40/-70, +50/-40, +50/-50, +50/-60, +50/-70 cm H2O) were applied in a randomized order. The MI-E device was set to automatic mode, medium inspiratory flow, and an inspiratory-expiratory time 3 and 2 s, respectively, with a 1-s pause between cycles. We performed 4 series of 5 insufflation-exsufflation cycles for each combination of pressures. Velocity and direction of movement of a mucus simulant containing radio-opaque markers were assessed through sequential lateral fluoroscopic images of the trachea. We also evaluated respiratory flows, respiratory mechanics, and hemodynamics before, during, and after each combination of pressures. RESULTS: In 3 of the animals, experiments were conducted twice; and for the remaining 3, they were conducted once. In comparison to baseline mucus movement (2.85 ± 2.06 mm/min), all insufflation-exsufflation pressure combinations significantly increased mucus velocity (P = .01). Particularly, +40/-70 cm H2O was the most effective combination, increasing mucus movement velocity by up to 4.8-fold (P < .001). Insufflation pressure of +50 cm H2O resulted in higher peak inspiratory flows (P = .004) and inspiratory transpulmonary pressure (P < .001) than +40 cm H2O. CONCLUSIONS: MI-E appeared to be an efficient strategy to improve mucus displacement during invasive ventilation, particularly when set at +40/-70 cm H2O. No safety concerns were identified although a transient significant increase of transpulmonary pressure was observed.

Effects of Mechanical Insufflation-Exsufflation on Sputum Volume in Mechanically Ventilated Critically Ill Subjects.

BACKGROUND: Mechanical insufflation-exsufflation (MI-E) is a noninvasive technique performed to simulate cough and remove sputum from proximal airways. To date, the effects of MI-E on critically ill patients on invasive mechanical ventilation are not fully elucidated. In this randomized crossover trial, we evaluated the efficacy and safety of MI-E combined to expiratory rib cage compressions (ERCC). METHODS: Twenty-six consecutive subjects who were sedated, intubated, and on mechanical ventilation > 48 h were randomized to perform 2 sessions of ERCC with or without additional MI-E before tracheal suctioning in a 24-h period. The primary outcome was sputum volume following each procedure. Secondary end points included effects on respiratory mechanics, hemodynamics, and safety. RESULTS: In comparison to ERCC alone, median (interquartile range) sputum volume cleared was significantly higher during ERCC+MI-E (0.42 [0-1.39] mL vs 2.29 [1-4.67] mL, P < .001). The mean ± SD respiratory compliance improved in both groups immediately after the treatment, with the greater improvement in the ERCC+MI-E group (54.7 ± 24.1 mL/cm H2O vs 73.7 ± 35.8 mL/cm H2O, P < .001). Differences between the groups were not significant (P = .057). Heart rate increased significantly in both groups immediately after each intervention (P < .05). Additionally, a significant increase in oxygenation was observed from baseline to 1 h post-intervention in the ERCC+MI-E group (P < .05). Finally, several transitory hemodynamic variations occurred during both interventions, but these were nonsignificant and were considered clinically irrelevant. CONCLUSIONS: In mechanically ventilated subjects, MI-E combined with ERCC increased the sputum volume cleared without causing clinically important hemodynamic changes or adverse events. (ClinicalTrials.gov registration: NCT03316079.).