**5.4 Machine perfusion**

Machine perfusion is a novel technique aimed to increased use of suboptimal grafts and consequently to enlarge donor pool. Large animal experiments have

revealed the superiority of machine preservation. The possibility of perfusing highrisk livers consistently for 24 hours has been shown. During that period little evidence of deterioration of the functional and histologic characteristics of the livers were noted. It has been claimed that perfusion may overcome the time limitations related with utilization of high risk livers. Another advantage of normothermic machine perfusion is measuring the functional parameters which give an idea about the viability of the organ [33] and this feature of machine perfusion is also valid for heart. The clinician may predict the risk of primary graft dysfunction. Repair and conditioning of thoracic organs are at experimental level for the time being. It has been reported that machine perfusion may also act as an immunoregulatory agent for lung [34]. Hypothermic and normothermic machine perfusion and controlled oxygenated rewarming keep kidney grafts functionally and metabolically active during preservation. Ex-vivo kidney perfusion has found clinical practice and on the other hand, preclinical results reveal that prolonged warm perfusion appears superior than a brief end-ischemic reconditioning as far as renal function and injury is concerned [35].
