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Abstract
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.
- ICU
- mechanical ventilation
- respiratory physiotherapy
- mechanical insufflation-exsufflation
- mucus displacement
- respiratory mechanics
Footnotes
- Correspondence: Antoni Torres MD PhD, Servei de Pneumologia i Al·lèrgia Respiratòria, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036 Barcelona, Spain. E-mail: atorres{at}clinic.ub.es
See the Original Study on Page 1637
The authors have disclosed no conflicts of interest.
Drs Marti and Martínez-Alejos equally contributed to this work.
Supplementary material related to this paper is available at http://rcjournal.com.
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