EFFECT OF TPA ON REGIONAL LUNG PERFUSION IN UNILOBAR CANINE PULMONARYTHROMBOEMBOLISM

We investigated effects of tissue-type plasminogen activator (tPA) on regional pulmonary arterial hemodynamics in pulmonary thromboembolism (PTE) in a canine model of unilobar PTE. Ten beagle dogs were divided into two groups-tPA (n = 5) and control group (n = 5). In each dog an artificial blood circuit (ABC) consisting of a silicone tube and a can nulation-type electromagnetic blood flowmeter probe was placed at the left lower pulmonary artery. A unilobar PTE was induced by placing aut ologous clots into a metallic coil inside the ABC. The CO2 sampling tu bes were positioned at the orifice of the left lower bronchus and the trachea, and the end-expiratory CO2 partial pressure (PETCO2) was meas ured. In the tPA group, blood flow at the left lower pulmonary artery (LL-flow) was improved to near baseline within approximately 30 min of receiving tPA, and PETCO2 at the left lower bronchus (LL-PETCO2) incr eased in direct correlation with. LL-flow. The hemodynamic improvement after tPA therapy correlated with the partial pressure of the regiona l pulmonary expiratory CO2. Moreover, it was suggested that changes in physiologic conditions in PIE were not determined by clot quantity al one.