Key Points
- To determine the effects of lung volume, left atrial pressure, and blood flow rate on pulmonary capillary transit time in an isolated lung model.
- Assessed subpleural microcirculation transit times in isolated perfused rabbit lungs using fluorescence video microscopy and arterial-to-venular dye dilution curves.
- Evaluated transit time across three blood flow levels (~80, ~40, and ~20 ml·min⁻¹·kg⁻¹) under varying airway pressures (5 to 15 cmH2O) and left atrial pressures (0 to 22 cmH2O, spanning West zones 2 and 3).
- Capillary transit time was successfully quantified in real time by calculating the difference between mean transit times of arteriolar and venular dye dilution peaks.
- Systematic changes in transpulmonary pressure, left atrial pressure, and perfusion rates directly altered microvascular transit times across distinct physiological lung zones.
Structured PICO
PPopulationIsolated perfused rabbit lungs
IInterventionVariations in lung volume (airway pressure 5 to 15 cmH2O), left atrial pressure (0 to 22 cmH2O), and blood flow (20 to 80 ml.min-1.kg-1)
CComparatorDifferent levels of airway pressure, left atrial pressure, and blood flow
OOutcomeCapillary transit time (difference between mean time values of arteriolar and venular dye dilution curves)surrogate
This preclinical study describes a method to measure the effects of lung inflation, left atrial pressure, and blood flow on pulmonary capillary transit time in isolated rabbit lungs.