Inspiratory oscillatory flow with a portable ventilator: a bench study.

Area of Science:

• Critical Care Medicine
• Respiratory Therapy
• Biomedical Engineering

Background:

• Oscillatory flow was observed during transport ventilation of critically ill patients using the Dräger Oxylog 3000.
• This phenomenon occurred in pediatric patients and adults with severe airway obstruction under pressure-regulated or pressure-controlled modes.

Purpose of the Study:

• To investigate the previously undescribed oscillatory flow phenomenon during ventilation with the Dräger Oxylog 3000.
• To identify conditions and patient factors contributing to this oscillatory flow.

Main Methods:

• A bench study utilized Dräger Oxylog 3000 and Evita-4 NeoFlow ventilators connected to a lung simulator.
• Data on airway pressure and flow were collected using a Datex-S5 Monitor and analyzed with S5-Collect software.
• 258 combinations of patient factors and ventilator settings were tested to determine occurrence thresholds.

Main Results:

• High resistance ventilation with the Oxylog 3000 induced oscillatory flow, leading to jerky inspirations and higher-than-set peak airway pressures.
• Reducing inspiratory flow velocity eliminated the oscillation but decreased tidal volumes.

Conclusions:

• Oscillatory flow during Dräger Oxylog 3000 ventilation poses potential risks, particularly in patients with high airway resistance.
• This includes pediatric patients with small endotracheal tubes (<6 mm ID) and adults with obstructive lung diseases.