Quantification of lung water by transpulmonary thermodilution in normal and edematous lung

To analyze the accuracy of the transpulmonary thermodilution method in the determination of extravascular lung water (EVLW).

Acute lung injury was produced in eight adolescent pigs weighing 28 to 35 kg by bronchoalveolar lung lavage. EVLW was measured by transpulmonary thermodilution method before and after the intratracheal introduction of 250 or 500 mL of saline solution in different lung injury conditions. No corrections for anatomic dead space were made.

When 250 mL was introduced, 195 +/- 17 mL was detected in normal (uninjured) lungs versus 74 +/- 57 mL in edematous (injured) lungs (P <.05). When 500 mL was introduced, 343 +/- 67 mL was detected in normal lungs versus 160 +/- 51 mL in edematous lungs (P <.001). Considering all determinations together, there was a very high negative correlation between the baseline EVLW and the percentage of EVLW detected (r = -0.92, P <.001).

The transpulmonary thermodilution method is very accurate to detect changes in EVLW in normal lungs. In edematous lung, this method may underestimate the EVLW.