Ventilator versus manual hyperinflation in adults receiving mechanical ventilation: A systematic review

Ventilator hyperinflation associated with flow bias optimization in the bronchial hygiene of mechanically ventilated patients

BACKGROUND

Ventilation configurations are of great clinical importance for adequate outcomes in mechanically ventilated patients, and they may even be used as specific physical therapy techniques.

OBJECTIVES

To compare the effectiveness of lung hyperinflation through mechanical ventilation (HMV) with HMV plus flow bias optimization regarding respiratory mechanics, hemodynamics, and volume of secretion.

METHODS

Patients mechanically ventilated > 24 h were included in this randomized crossover clinical trial. The following techniques were applied: HMV alone (control group) and HMV plus flow bias optimization (intervention group).

RESULTS

The 20 included patients underwent both techniques, totaling 40 collections. A total of 52 % were women, the mean age was 60.8 (SD, 15.7) years, and the mean mechanical ventilation time was 4.3 (SD, 3.0) days. The main cause of mechanical ventilation was sepsis (44 %). Expiratory flow bias in optimized HMV was higher. than conventional HMV (p < 0.001). The volume of tracheal secretions collected was higher during optimized than conventional HMV. (p = 0.012). Significant differences in peak flow occurred at the beginning of the technique and a there was a significant decrease in respiratory system resistance immediately and 30 min after applying the technique in the intervention group.

CONCLUSIONS

The volume of tracheal secretions collected was higher during optimized HMV, and, HMV with flow bias optimization resulted in lower respiratory system resistance and flow peaks and produced expiratory flow bias.

Ventilator hyperinflation - what settings generate an expiratory flow rate bias?

OBJECTIVES

To determine which mechanical ventilation settings influence the attainment of expiratory flow rate characteristics that may promote secretion mobilisation during ventilator hyperinflation (VHI).

DESIGN

Prospective, single centre study.

SETTING

Intensive care unit, tertiary metropolitan hospital.

PARTICIPANTS

Twenty-four patients receiving mechanical ventilation.

INTERVENTIONS

Patients were recruited to either a low PEEP or high PEEP group (5-9 cmH₂O or 10-15 cmH₂O PEEP respectively). Each group had three hyperinflation protocols applied.

MAIN OUTCOME MEASURES

Peak inspiratory flow rates (PIFR) and peak expiratory flow rates (PEFR) were measured and reported as PIFR/PEFR of less than or equal to 0.9; a PEFR-PIFR greater than or equal to 33 L/min; and PEFR greater than or equal to 40 L/min.

RESULTS

In both the low and high PEEP groups, VHI protocols using volume-controlled ventilation were significantly better at generating expiratory flow rate bias compared to pressure-controlled or Pressure Support ventilation. An expiratory flow rate bias was also achieved when VHI was performed in volume-controlled ventilation with either a peak inspiratory pressure target of 35 cmH₂O or a driving pressure of 20 cmH₂O. Median heart rate and blood pressure values did not change during VHI, but transient reductions in blood pressure were present in six participants (25%).

CONCLUSIONS

VHI performed using volume-controlled ventilation was more effective than pressure-controlled or Pressure Support ventilation to generate an expiratory flow rate bias.

CONTRIBUTION OF THE PAPER

Mechanical ventilator settings can be altered to perform hyperinflation and achieve expiratory flow rate properties that may increase the mobilisation of airway secretions. The results demonstrate that to achieve these properties.