[Histopathological studies of goats after prolonged ECLA with a heparin-bonded artificial lung]

A pathological study was performed on the effects of prolonged extracorporeal lung assist (ECLA) with a heparin-bonded artificial lung and circuit in goats. A veno-venous ECLA was carried out in 15 goats for 5 to 10 days. Ten of them (Group I) were subjected to heparin-bonded devices and the other 5 (Group II) were subjected to the usual devices as control. The activated clotting time during ECLA was maintained at 130 seconds in Group I vs 200 seconds in Group II. The dose of heparin used in Group I was a half of that in Group II. Thrombi were found only in the lungs and the right side of the heart. The incidence of thrombi formation was low, and it was not significantly different between the two groups. Thrombotic embolism could not be found in any of the vital organs. Except for congestion, histological examination in these groups failed to reveal any remarkable changes. Electron microscopic study showed that heparin-bonded ECLA could maintain the normal alveolar structure. Compared with a usual system, ECLA with a heparin-bonded bypass exerted no significantly different effects on the thrombi formation and tissue histology, in spite of less systemic heparin administration for a prolonged period.