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INTRODUCTION
Because of the increasing reliance on renal transplantation as the treatment of choice for most patients with end-stage renal disease and the resultant shortage of donor organs, improved methods of organ procurement and organ preservation are more important than ever. Improving organ preservation would increase the number of viable organs available for transplantation and, in theory, improve post-transplant organ function.
Patients spend an average of three to five years on the waiting list for a kidney transplant. According to the U.S. Government Accountability Office Report of 2007, Medicare's cost of maintaining a kidney transplant recipient is approximately $8,550 per year, a fraction of the cost of dialysis, which is $50,938 annually [1]. Both the pre-transplant waiting time and expense would be reduced if there were more organs available. One strategy to achieve this is to improve methods of organ storage.
Organs recovered from deceased donors for transplantation are inevitably damaged by the ischemia after cessation of cardiac and respiratory function. Before - and after - declaration of brain death, an organ donor may experience a variable period of hemodynamic instability, hypotension and tissue hypoxia. Following organ procurement, organs immediately begin to suffer from hypoxia, with resultant cell swelling, decreased cellular ATP and mitochondrial energy stores, along with degradation of cell membranes and increased expression of immunologically active cell membrane proteins (i.e., MHC, adhesion molecules, P-Selectin, cytokines).
To complicate matters further, there is the issue of ischemic reperfusion injury (IRI) once an organ is transplanted and blood supply restored. The two periods of ischemia, cold storage and warm ischemia reperfusion, are distinct in the type of cellular and ischemic damage the organ is subjected to. Methods used to improve organ storage and viability before and during transplantation must take the different mechanisms of ischemic stress into account. The history of hyperbaric oxygen therapy has mostly involved its application during cold storage, but as more is learned about the effects of hyperbaric oxygen at the cellular and molecular level, application during cold and warm ischemia may be both feasible and beneficial.
Hyperbaric oxygen therapy (HBO^sub 2^T) involves the breathing/administration of pure oxygen while in a sealed chamber that has been pressurized at one and one-half to three times the normal atmospheric pressure. In the early...