• Marcia S Volpe, Juliane M Naves, Gabriel G Ribeiro, Gualberto Ruas, and Amato Marcelo B P MBP Pulmonary Division, Cardio-Pulmonary Department, Heart Institute (Incor), Hospital Das Clínicas da FMUSP, University of Sao Paulo, São Paulo, Brazil.
• Department of Human Movement Sciences, Federal University of São Paulo, Santos, São Paulo, Brazil. marciasvolpe@gmail.com.
• Respir Care. 2018 Oct 1; 63 (10): 1214-1222.

BackgroundStandard mechanical insufflation-exsufflation (MI-E) therapy is applied with fast insufflation-exsufflation pressures to achieve high peak expiratory flows (PEF) and assist airway clearance. No attention is given to the resultant high peak inspiratory flows (PIF), although it may impair secretion removal. It has been proposed that an expiratory flow bias (ie, PEF higher than PIF) might be the key determinant for mucus clearance instead of the PEF alone. We examined the effects of 2 MI-E maneuvers, standard versus optimized, with fast and slow insufflation, respectively, along with different MI-E pressure settings on secretion displacement in 3 lung-impedance scenarios that simulated a patient on mechanical ventilation.MethodsThe MI-E device was connected to a lung model that simulated a patient on mechanical ventilation. Known quantities of mucus simulant were injected into the system and exposed to various MI-E ventilation conditions. Mucus movement was examined with image-analysis software.ResultsThe optimized MI-E maneuver resulted in a much lower PIF (37.5 L/min [interquartile range, 24.9-47.9 L/min] vs 101.8 L/min [interquartile range, 89.1-115.7 L/min], P < .001). Consequently, the expiratory flow bias, expressed by PEF:PIF and the PEF-PIF difference, was much higher in the optimized maneuver. The higher expiratory flow bias in the optimized maneuver displaced the mucus outward, with a difference of 2.6 cm compared with the standard maneuver. Multivariate analysis revealed that the type of maneuver (optimized vs standard), PEF-PIF difference and MI-E pressure gradient were significantly correlated with mucus displacement (r2 = 0.817, P < .001), whereas the PEF was not. PEF:PIF and the PEF-PIF difference were lower in the obstructive lung scenario when compared with the restrictive and normal lung scenarios.ConclusionsThe optimized MI-E maneuver, applied with slow insufflation, resulted in a higher expiratory flow bias, which made the therapy more effective at moving mucus outward, compared with the standard MI-E maneuver, typically applied with fast insufflation.Copyright © 2018 by Daedalus Enterprises.

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