Total inspiratory work with modern demand valve devices compared to continuous flow CPAP

Area of Science:

• Mechanical Ventilation
• Respiratory Mechanics
• Pulmonary Engineering

Background:

• Continuous positive airway pressure (CPAP) devices are widely used in respiratory support.
• Assessing the inspiratory work of breathing (WOB) is crucial for patient comfort and ventilator management.
• Demand valve CPAP systems may influence WOB differently compared to conventional systems.

Purpose of the Study:

• To evaluate the inspiratory work of breathing for six commercial demand valve CPAP devices.
• To compare the WOB of these devices against a conventional high-flow CPAP system.
• To investigate the impact of trigger sensitivity and pressure support on WOB.

Main Methods:

• An electromechanical lung model was used to simulate breathing.
• Planimetry of pressure/volume loops assessed inspiratory work for 500 ml breaths.
• Calibrated changes in lung compliance and airway resistance were implemented.

Main Results:

• All tested CPAP devices required slightly more inspiratory work than the continuous flow system.
• Engström ERICA and Servo B devices showed the highest increase in WOB (up to 22%).
• Decreased lung compliance and endotracheal tube diameter significantly increased WOB; pressure support reduced it.

Conclusions:

• Demand valve CPAP devices impose a slightly higher inspiratory work load compared to continuous flow systems.
• Lung mechanics (compliance, resistance) are major determinants of total inspiratory work.
• Inspiratory pressure support can effectively reduce the work of breathing across various CPAP devices.