High-resolution maps of regional ventilation utilizing inhaled fluorescent microspheres

Area of Science:

• Pulmonary Physiology
• Medical Imaging

Background:

• Accurate mapping of regional lung ventilation is crucial for understanding respiratory diseases.
• Current methods for assessing ventilation distribution have limitations in resolution and accuracy.

Purpose of the Study:

• To develop and validate a novel method for high-resolution mapping of regional lung ventilation.
• To investigate the relationship between regional ventilation and perfusion in mechanically ventilated pigs.

Main Methods:

• Inhaled fluorescent microspheres (FMS) of 1.0-micron diameter were used to map regional ventilation.
• Intravenous radioactive microspheres (15.0-micron) were administered to assess regional perfusion.
• Lung tissue was sectioned, and fluorescence and radioactivity were quantified to create spatial maps.

Main Results:

• High correlation (0.98-0.99) was observed between simultaneously administered inhaled FMS, validating the ventilation mapping technique.
• Mean coefficients of variation for ventilation (47.9%) and perfusion (46.2%) were similar.
• No significant gravitational gradient for ventilation or perfusion was found in prone animals.
• Regional perfusion was the strongest predictor of regional ventilation magnitude (r = 0.77).

Conclusions:

• Inhaled fluorescent microspheres provide a reliable method for high-resolution regional ventilation mapping.
• Regional ventilation and perfusion are closely linked, with perfusion being a key determinant of ventilation.
• Prone positioning in mechanically ventilated pigs minimizes gravitational effects on ventilation and perfusion distribution.