Protection from lung damage by blood filtration during deep hypothermia in puppies.

Ten puppies underwent deep hypothermia with surface cooling and bypass cooling. They were subjected to circulatory arrest for 30 minutes and then were rewarmed by means of bypass. There were 5 control puppies and 5 for which a Swank filter was placed in the arterial perfusion line. All puppies had some degree of lung damage, but it was more severe in those in which perfused blood was not filtered. The damage involved the lung vessels, interstitial tissue, and alveoli. Platelet-fibrin aggregates and margination and sequestration of leukocytes appeared to be important pathological findings. Apparently, the Swank blood filter protects the lung by removing leukocytes and damaged platelets from the circulation.