[Gaseous oxygen for protection and conditioning of organs during ischemia]

During organ ischemia, oxygen (O2) is the first "substrate", which is depleted. However, during ischemic storage in hypothermia (0-4 degrees C), a sufficient oxygenation is attainable by means of gaseous O2. The results of organ preservation were (mostly) better than those obtained with other methods at the respective times. O2 can be supplied via organ surfaces: Applying high O2-pressures (3040-15,200 hPa), ileum and lungs or hearts had some functions after 48 and 72 h storage, respectively; life-supporting functions regained kidneys and pancreas after 48 and 22 h storage, respectively. At normobaric conditions, intestine supplied with O2 via its lumen had during ischemic storage an aerobic metabolism and a better post-ischemic function. Using the "two-layer-method" (TLM), pancreas was stored for 96 h and after 90 min anaerobic warm ischemia (aWI) for 48 h with life-supporting functions after transplantation (Tx). Ischemic organs can be persufflated normobarically with gaseous O2 via their vessels. Hearts, skeletal muscles and kidneys in normothermia or frogs' spinal cords-remained viable for many hours. In hypothermia, kidneys damaged by 30 or 60 min aWI could be preserved for 48 and 24 h, respectively, with life-supporting functions after Tx. Hearts subjected to several hours of aerobic ischemia performed post-ischemically better. Livers aerobically stored for 48 h, or for 24 or 4 h after 30 or 60 min aWI, respectively, exhibited greatly improved post-ischemic functions. After 60 min aWI and 2 h persufflation for reconditioning, livers could be stored for another 22 h period of anaerobic ischemia. With normobaric O2-persufflation or TLM during ischemia, energy supply in form of ATP and its demand-meeting utilisation during hypothermia are apparently guaranteed, so that even longer periods of ischemia for Tx-related measures can be overcome. Not only the maintenance of cell and organ integrity or of cellular functions, but also the repair of damaged structures and functions have become possible with less expenditures and risks than with perfusion. The composition of the solutions for preservation or reconditioning of the ischemic organs is pivotal.