Transtracheal high frequency jet ventilation prevents aspiration

Area of Science:

• Anesthesiology
• Respiratory Physiology

Background:

• Aspiration during artificial ventilation poses a significant risk.
• Cuffed endotracheal tubes, while common, have associated complications.
• High frequency jet ventilation (HFJV) presents an alternative method for preventing aspiration.

Purpose of the Study:

• To evaluate the efficacy of high frequency jet ventilation (HFJV) in preventing aspiration.
• To determine the optimal parameters for HFJV to prevent aspiration.

Main Methods:

• Utilized 6 anesthetized dogs with surgically exposed tracheas.
• Introduced a catheter for HFJV and another for intratracheal pressure monitoring.
• Employed direct endoscopic visualization and endoscopic film to assess fluid aspiration and vocal cord dynamics.

Main Results:

• HFJV demonstrated a convincing ability to prevent fluid aspiration into the larynx.
• Efficacy was reduced at frequencies below 60/min or when inspiration constituted less than 33% of the cycle.
• Intratracheal pressures remained slightly above fluid levels, with cords separated and gas bubbling through fluid.

Conclusions:

• HFJV prevents aspiration through a continuous outward laryngeal gas flow, not solely valve mechanisms.
• Optimal prevention occurs at rates above 60/min with expiratory duration ≤ 66%.
• This method is associated with low positive airway pressure and good blood gas exchange.