Pulsed Dose Oxygen Delivery During Mechanical Ventilation: Impact on Oxygenation

Area of Science:

• Mechanical Ventilation
• Respiratory Physiology
• Biomedical Engineering

Background:

• Adequate oxygenation is critical in mechanical ventilation, especially for battlefield casualties where oxygen is a limited resource.
• Portable oxygen concentrators offer a continuous oxygen supply powered by electricity, addressing resource limitations.
• Previous research indicated that pulsed-dose oxygen delivery from concentrators can enhance ventilator oxygenation.

Purpose of the Study:

• To evaluate a ventilator system integrated with a portable oxygen concentrator using closed-loop control for oxygen delivery.
• To assess the system's efficacy in maintaining target oxygen saturation in a porcine model with induced lung injury.

Main Methods:

• A portable ventilator and oxygen concentrator were interconnected with a USB cable for closed-loop control based on SpO2.
• Lung injury was induced in pigs via saline lavage, creating a model of severe acute respiratory distress syndrome.
• The system autonomously adjusted oxygen bolus size to maintain a target SpO2 of 94%, with PEEP manually adjusted.

Main Results:

• Optimal oxygen bolus injection timing was determined to be 300 ms before ventilator breath delivery.
• The system successfully maintained target SpO2 (94-98%) in pigs with severe lung injury within 2 hours.
• The SpO2 to SaO2 difference remained within 4%, validating the system's accuracy.

Conclusions:

• The integrated ventilator/concentrator system effectively managed oxygenation in a porcine model with severe lung injury.
• Oxygen bolus injection synchronized with ventilator breaths and optimized PEEP maximized oxygen delivery.
• This system presents a viable solution for oxygenation support where high-pressure oxygen is unavailable but electricity is accessible.