Morphologic and physiologic correlates of increased extravascular lung water

Area of Science:

• Pulmonary Medicine
• Critical Care Medicine
• Medical Imaging

Background:

• Extravascular lung water (EVLW) is a key indicator of pulmonary edema.
• The thermal-green dye indicator dilution method is validated for gravimetric EVLW measurement.
• Limited data exists correlating in vivo EVLW with postmortem morphologic and physiological parameters.

Purpose of the Study:

• To correlate in vivo EVLW measurements with postmortem lung morphologic findings.
• To assess the relationship between in vivo EVLW and pulmonary physiologic parameters.
• To validate the thermal-green dye method across a spectrum of pulmonary edema.

Main Methods:

• Hydrostatic edema induced in 12 swine using a left atrial Foley balloon.
• In vivo EVLW, blood gases, and expired gases measured periodically.
• Postmortem lung morphometrics included perivascular cuff width, septal width, and alveolar flooding.

Main Results:

• Perivascular cuff width to vessel diameter ratio correlated linearly with EVLW (r2=0.76).
• Alveolar flooding increased linearly with EVLW after doubling from normal.
• Increased shunt fraction correlated linearly with EVLW (r2=0.76).

Conclusions:

• In vivo EVLW measurements closely align with conventional morphologic and physiologic assessments.
• The thermal-green dye method effectively detects pulmonary edema from mild to severe.
• This technique provides a sensitive measure of extravascular lung water in vivo.