LIQUID VENTILATION IMPROVES PULMONARY-FUNCTION AND CARDIAC-OUTPUT IN A NEONATAL SWINE MODEL OF CARDIOPULMONARY BYPASS

Objective: Neonatal and infant cardiopulmonary bypass results in multi organ system dysfunction, Organ protective strategies have traditional ly been directed at the myocardium and brain while neglecting the some times severe injury to the lungs. We hypothesized that liquid ventilat ion would improve pulmonary function and cardiac output in neonates af ter cardiopulmonary bypass. Methods: Twenty neonatal swine were random ized to receive cardiopulmonary bypass with or without liquid ventilat ion. In the liquid-ventilated group, a single dose of perflubron was a dministered before bypass. The control group was conventionally ventil ated, Each animal was placed on nonpulsatile, hypothermic bypass. Low- flow cardiopulmonary bypass was performed for 60 minutes. The flow rat e was returned to 125 ml/kg per minute, and after warming to 37 degree s C, the animals were removed from bypass. Hemodynamic and ventilatory data were obtained after bypass to assess the effects of liquid venti lation. Results: Without liquid ventilation, cardiopulmonary bypass re sulted in a significant decrease in cardiac output, oxygen delivery, a nd static pulmonary compliance compared with prebypass values. Input p ulmonary resistance and characteristic impedance increased in these co ntrol animals. At 30, 60, and 90 minutes after bypass, the animals rec eiving liquid ventilation showed significantly increased cardiac outpu t and static compliance and significantly decreased input pulmonary re sistance and characteristic impedance compared with control animals no t receiving liquid ventilation. Conclusions: Liquid ventilation improv ed pulmonary function after neonatal cardiopulmonary bypass while incr easing cardiac output. The morbidity associated with cardiopulmonary b ypass may be significantly reduced if the adverse pulmonary sequelae o f bypass can be diminished. Liquid ventilation may become an important technique to protect the lungs from the deleterious effects of cardio pulmonary bypass.