Comparison Between Different Ventilator Hyperinflation Maneuvers

The hyperinflation ventilator was performed in different modalities and ventilatory adjustments, with total pressure of 40cmH2O. The inspiratory volume, inspiratory time, mean airway pressure, inspiratory and expiratory flow, and bias flow were evaluated.

PURPOSE: To compare different ways of applying ventilator hyperinflation. METHODS: A randomized crossover clinical trial was performed with 30 patients (66.5 ± 17.3 years) with hypersecretion. The ventilator hyperinflation was performed in five ventilatory modalities for five minutes, with an interval of 2 hours, the order being determined by randomization: controlled ventilation at volume (VCV) with constant flow of 20 (VCV20) Lpm and 40 Lpm (VCV40), controlled ventilation pressure ventilation (PCV), controlled pressure ventilation associated with inspiratory time adjustment (PCV + Tins) and support pressure ventilation (PSV). In VCV mode, the volume was increased every 50mL, until reaching a maximum pressure of 40cmH2O. In the pressure controlled modes, the inspiratory pressure was increased every 5 cmH2O until the total pressure reached 40 cmH2O. The inspiratory time was adjusted so that the inspiratory flow reached the baseline. The following variables were evaluated: tidal volume, inspiratory time (Tins), mean airway pressure (Pmean), peak inspiratory flow (PIFR) and expiratory flow (PEFR), PIFR / PEFR and Bias Flow (PEFR-PIFR).

In order to perform both interventions, the patients were placed in dorsal decubitus with a head elevated at 45 ° and submitted to closed tracheal aspiration, according to the recommendations of the American Association for Respiratory Care. In addition, the bacteriological filter was changed, the cuff pressure was increased and the presence of leaks in the mechanical fan circuits was verified. All patients underwent five hyperinflation maneuvers, the order being determined by randomization. Controlled volume ventilation (VCV) at a constant flow rate of 20 Lpm (VCV-20) and 40 Lpm (VCV-40), controlled pressure ventilation (VCV-40) was performed for 2 minutes at 10 minute intervals. PCV), pressure-controlled ventilation associated with inspiratory time adjustment (PCV + Tins) and pressure-supported ventilation (PSV). PEEP and FiO2 were maintained throughout the study.

Volume-controlled ventilation mode under constant flow of 20 Lpm. The inspired volume was progressively increased until the maximum pressure reached 40cmH2O.

Volume controlled ventilation mode under constant flow of 40 Lpm. The inspired volume was progressively increased until the maximum pressure reached 40cmH2O.

Pressure controlled ventilation mode, inspiratory time of 1 second. The inspiratory pressure was increased every 5 cmH2O, until reaching the maximum pressure of 40 cmH2O.

Pressure controlled ventilation mode and inspiratory pressure was increased every 5cmH2O, until the maximum pressure of 40 cmH2O was reached. The inspiratory time was gradually increased until the inspiratory flow reached the baseline. Concomitantly, the respiratory rate was decreased to allow the expiratory flow also to reach the baseline, to avoid self-PEEP.

Pressure support ventilation mode, with progressive increases of 5 cmH2O at inspiratory pressure, until reaching Pmax of 40 cmH2O. The expiratory sensitivity was adjusted by 25% for all patients.

controlled volume ventilation mode under constant flow of 20 Lpm. The inspired volume was progressively increased until the Pmax reached 40cmH2O.

volume controlled ventilation mode under constant flow of 40 Lpm. The inspired volume was progressively increased until the Pmax reached 40cmH2O.

controlled ventilation mode, 1 second inspiratory time. The inspiratory pressure was increased every 5 cmH2O, until reaching the maximum pressure of 40 cmH2O.

controlled ventilation and inspiratory pressure was increased every 5 cmH2O until the maximum pressure was 40 cmH2O. The inspiratory time was gradually increased until the inspiratory flow reached the baseline. Concomitantly, the respiratory rate was decreased to allow the expiratory flow also to reach the baseline, to avoid self-PEEP.

ventilatory mode with pressure support, with progressive increases of 5 cmH2O at inspiratory pressure, until reaching Pmax of 40 cmH2O. The expiratory sensitivity was adjusted by 25% for all patients.

Inspiratory volume reached in each mode of ventilator hyperinflation, under a maximum pressure of 40cmH2O

inspiratory time necessary for the inspiratory flow to reach the baseline or according to the settings of each modality

Inclusion Criteria: Pulmonary infection Mechanically ventilated for more than 96 hours through pressure-assisted ventilation (PSV) or pressure-controlled ventilation (PCV) Static compliance between 30 and 70 mL/cmH2O PEEP between 5 and 8 cmH2O. Exclusion Criteria: Hemodynamic instability Non-drained pleural effusion or pneumothorax Intracranial hypertension Bronchospasm Adult respiratory distress syndrome (ARDS) Decompensated congestive heart failure