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

Area of Science:

• Critical Care Medicine
• Respiratory Therapy
• Mechanical Ventilation

Background:

• Airway secretion mobilization is crucial for patients on mechanical ventilation.
• Ventilator Hyperinflation (VHI) is a technique used to aid secretion clearance.
• Optimizing VHI requires understanding the influence of mechanical ventilator settings.

Purpose of the Study:

• To identify mechanical ventilation settings that enhance expiratory flow rates during VHI.
• To determine settings that promote secretion mobilization.

Main Methods:

• A prospective, single-center study involving 24 mechanically ventilated patients.
• Patients were allocated to low or high Positive End-Expiratory Pressure (PEEP) groups.
• Three VHI protocols were applied, measuring Peak Inspiratory Flow Rates (PIFR) and Peak Expiratory Flow Rates (PEFR).

Main Results:

• Volume-controlled ventilation (VCV) significantly improved expiratory flow rate bias compared to pressure-controlled or Pressure Support ventilation.
• Expiratory flow bias was achieved with VCV using a peak inspiratory pressure target of 35 cmH2O or driving pressure of 20 cmH2O.
• Hemodynamic parameters remained stable, with transient hypotension in 25% of participants.

Conclusions:

• VCV is more effective than other modes for generating expiratory flow bias during VHI.
• Adjusting mechanical ventilator settings, particularly using VCV, can optimize VHI for secretion mobilization.