Alterations in feline tracheal permeability after mechanical ventilation

Area of Science:

• Respiratory physiology
• Pulmonary medicine
• Critical care medicine

Background:

• Mechanical ventilation is crucial for respiratory support but can induce airway injury.
• Previous studies focused on histopathologic changes, leaving epithelial permeability less explored.

Purpose of the Study:

• To investigate the hypothesis that mechanical ventilation alters tracheal epithelial permeability.
• To evaluate changes in tracheal epithelial permeability using different mechanical ventilation strategies in an animal model.

Main Methods:

• Prospective controlled trial involving 36 adult cats, divided into five groups (control and four mechanical ventilation types).
• Animals were mechanically ventilated for 8 hours, with varying respiratory rates (20-900 breaths/min).
• Tracheal epithelial permeability was assessed using 14C-sucrose, 3H-inulin, and fluorescein isothiocyanate-dextran-20.

Main Results:

• Mechanical ventilation significantly increased tracheal epithelial permeability to all tested molecules.
• Increased permeability showed a progressive pattern, directly correlating with ventilatory frequency.
• The highest ventilatory rates resulted in the most substantial changes in permeability.

Conclusions:

• Mechanical ventilation is associated with increased tracheal epithelial permeability, affecting both small and large nonionic molecules.
• All tested clinical ventilator types induced these permeability changes.
• The degree of permeability alteration is directly related to the ventilatory rate.