Tracheobronchial histopathology associated with high-frequency jet ventilation

Area of Science:

• Veterinary Pathology
• Respiratory Physiology
• Biomedical Engineering

Background:

• Mechanical ventilation is crucial for respiratory support but can cause airway injury.
• Conventional mechanical ventilation (CMV) and high-frequency jet ventilation (HFJV) differ in delivery mechanisms and potential for histopathology.
• Understanding ventilator-induced lung injury (VILI) is critical for optimizing patient outcomes.

Purpose of the Study:

• To compare tracheobronchial histopathology between CMV and HFJV in adult cats.
• To evaluate the impact of two distinct HFJV humidification systems on airway injury.
• To elucidate the differing mechanisms of injury associated with CMV and HFJV.

Main Methods:

• Forty-four adult cats underwent mechanical ventilation with either CMV or HFJV.
• Two HFJV humidification methods were tested: entrained mist alone and direct saline infusion.
• Tracheobronchial tissues were analyzed for histopathological changes, including inflammation, necrosis, and cellular alterations.

Main Results:

• HFJV induced significantly more tracheal damage than CMV, primarily at the endotracheal tube tip, characterized by acute inflammation, erosion, necrosis, and polymorphonuclear leukocyte infiltration.
• The HFJV system using entrained mist alone resulted in greater tracheal damage compared to the direct saline infusion system.
• HFJV increased luminal mucus production across all airway levels.
• CMV led to more significant histopathology in the carina and mainstem bronchi after 16 hours, including cilia loss, goblet cell depletion, and inflammation.

Conclusions:

• HFJV poses a higher risk of tracheal injury compared to CMV in cats.
• The humidification strategy employed with HFJV significantly influences the severity of airway damage.
• Distinct patterns of histopathological injury suggest divergent mechanisms of damage between CMV and HFJV.
• Findings highlight the importance of selecting appropriate ventilator settings and humidification techniques to minimize ventilator-associated airway injury.