The respiration apparatus of von Frey and Gruber was the first device for organ perfusion. A closed-circuit system features a film oxygenator that receives oxygen via a valve and a gas pressure measuring device. A motor-driven syringe and valves facilitate the continuous circulation of warmed blood before it passes through the isolated organ. An air trap is in place to protect the organ from gas embolism. (Adapted from Boettcher et al., 2003 [9]).