Abstract
BACKGROUND: In patients on mechanical ventilation, lung hyperinflation is often performed to reverse atelectasis and clear retained mucus. We evaluated the effects of manual hyperinflation and ventilator hyperinflation on mucus clearance, gas exchange, pulmonary mechanics, and hemodynamics.
METHODS: Six mechanically ventilated pigs with severe Pseudomonas aeruginosa pneumonia randomly received either 12 manual hyperinflation breaths over a period of 2 min (through a gradual manual compression of a resuscitation bag within 4 s to achieve 40 cm H2O of airway pressure), or 12 ventilator hyperinflation over 2 min to achieve the same ventilatory end points as in manual hyperinflation. Mucus clearance rate was measured through fluoroscopic tracking of tracheal markers. Prior to each maneuver and 15 min thereafter, we assessed arterial and mixed gas exchange, pulmonary mechanics, and hemodynamics.
RESULTS: Both manual hyperinflation and ventilator hyperinflation significantly decreased inspiratory flow by approximately 16 L/min (P < .001) and increased peak expiratory flow by roughly 44 L/min (P < .001). The median (interquartile range) mucus clearance rate was 1.31 (0.84–2.30) prior to the interventions, and 0.70 (0.00–2.58) and 0.65 (0.45–1.47) during manual hyperinflation and ventilator hyperinflation, respectively (P = .09). Hyperinflations, whether delivered manually or through the ventilator, did not significantly modify pulmonary or hemodynamic parameters.
CONCLUSIONS: In an animal model of severe P. aeruginosa pneumonia, neither manual hyperinflation nor ventilator hyperinflation improved mucus clearance. If confirmed in comprehensive clinical experimentations, these findings should promote reappraisal of indications for both manual hyperinflation and ventilator hyperinflation as a therapeutic technique for mucus clearance and atelectasis reversal.
Footnotes
- Correspondence: Antoni Torres MD PhD, Pulmonary and Critical Care Unit Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2 08036 Barcelona, Spain. E-mail: atorres{at}clinic.ub.es.
Drs Li Bassi and Martí are co-first authors.
The authors have reported relationships with Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Ministerio de Ciencia e Innovación (PS09/01249); Fundació Catalana de Pneumologıa (FUCAP); Sociedad Española de Neumología y Cirugía Torácica (SEPAR); Centro de Investigación Biomedica En Red-Enfermedades Respiratorias (CIBERES).
Dr Li Bassi presented a version of this paper at the 26th ESICM Meeting, held October 5-9, 2013, in Paris, France.
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