1ST-PASS STUDIES OF ACUTE LUNG INJURY

Mild hydrochloric acid was introduced to a caudal lung section in each of eight dogs to induce injury. Transits of Tc-99m-labeled red blood cells (RBC) and [I-123]iodoantipyrine (IAP) injected intravenously wer e recorded by a scintillation camera. Lungs and blood samples were ana lyzed post-mortem. Peak-to-equilibrium ratios (P/E) of RBC time-activi ty curves were computed to be 3.83 +/- 0.54 for the control lung, 2.58 +/- 0.55 for the injured lung and 2.23 +/- 0.58 for the injured cauda l section. For IAP, the respective results were 3.78 +/- 0.29, 2.02 +/ - 0. 18 and 1.77 +/- 0.17. The decrease of P/E in injured areas was at tributed to reduced blood flow. Using mean transit times of the tracer s, we computed extravascular lung water per unit blood volume to be 0. 35 +/- 0.18 for the control lungs and an increased value of 0.68 +/- 0 .24 for the injured lungs. These results displayed sensitivity to inju ry, but were gross underestimates relative to the corresponding values of 2.04 +/- 0.54 and 4.56 +/- 1.85 in post-mortem analyses.