Limits of high frequency percutaneous transtracheal jet ventilation using a fluidic logic controlled ventilator

Area of Science:

• Veterinary Medicine
• Respiratory Physiology
• Critical Care

Background:

• High-frequency jet ventilation (HFJV) is an advanced mechanical ventilation technique.
• Understanding the physiological limits of HFJV is crucial for its safe and effective application in veterinary critical care.

Purpose of the Study:

• To determine the maximum effective rate of carbon dioxide (CO2) exchange during HFJV in dogs.
• To assess the circulatory effects and gas exchange efficiency of HFJV at varying respiratory rates.

Main Methods:

• Fifteen dogs were ventilated using a transtracheal catheter with a fluidic logic controlled oxygen jet ventilator at rates up to 600 breaths/min.
• Hemodynamic parameters, intratracheal pressures, electrocardiogram, blood gases, and cardiac output were continuously monitored.
• A control group underwent apnoeic oxygenation followed by HFJV to assess CO2 clearance.

Main Results:

• Normal arterial blood gas levels and effective CO2 exchange were observed up to a respiratory rate of 400 breaths/min with low tidal volumes and intratracheal pressures.
• No adverse circulatory effects were noted at rates up to 400 breaths/min.
• At rates of 500-600 breaths/min, cardiac output decreased due to reduced heart rate and increased peripheral resistance, although cardiac contractility remained unaffected.
• HFJV facilitated the resumption of spontaneous ventilation during weaning.
• In control dogs, HFJV effectively reduced elevated PaCO2 levels as the rate decreased.

Conclusions:

• High-frequency jet ventilation is effective for maintaining normal gas exchange in dogs up to 400 breaths/min.
• Higher rates (500-600 breaths/min) can compromise cardiac output, necessitating careful monitoring.
• HFJV does not impede the weaning process and can be used to normalize CO2 levels.