Small increases in extravascular lung water are accurately detected by transpulmonary thermodilution

Detection of small (10-20%) increases in lung water may be relevant to detect incipient pulmonary edema but no clinically usable method has demonstrated this capability to date.

In six pigs weighing 28 to 35 kg, we performed 18 determinations of extravascular lung water (EVLW; transpulmonary thermodilution method) before and immediately after the intratracheal introduction of 50 mL of saline solution. Six determinations were performed in normal lung and 12 in edematous lung.

In normal lung, the mean of EVLW increased from 245 +/- 18 mL to 288 +/- 19 mL (p < 0.001) after the intratracheal introduction of 50 mL of saline solution; therefore, 43 of the 50 mL (84%) were detected (range, 37-48 mL). In edematous lung, the EVLW increased from 491 +/- 106 mL to 530 +/- 108 mL after the introduction of 50 mL of saline solution; therefore, 39 of the 50 mL (77%) were detected (range, 15-67 mL).

The transpulmonary thermodilution technique accurately detects small increases in extravascular lung water and may permit accurate diagnosis of incipient pulmonary edema.