More than 90,000 patients await kidney transplant, according to the U.S. Organ Procurement and Transplantation Network. Approximately 16,000 transplants occur every year, but 35,000 patients are added to the list annually.
Because of this growing list of patients with end-stage renal disease who need new kidneys, transplant surgeons are seeking innovative ways to increase the donor pool. Recently, a number of transplant surgeons began utilizing younger and smaller kidney donors by transplanting their organs en bloc into single recipients. Common reported complications of using smaller kidneys include increased graft thrombosis and hyperfiltration injury. However, in their report on outcomes utilizing kidneys transplanted from donors weighing less than 15 kg (even some less than 10 kg), Sharma and coworkers reported 5-year graft survival at 92%, statistically no different than standard deceased or living donor kidney transplants.
While the majority of organ donations come from living related donors or altruistic donations by brain dead patients and their families, donation after cardiac death (DCD) is becoming more commonplace. Most cases of DCD involve adult donors. However, Hanley and colleagues examined a population that is rarely, if ever, identified as potential DCD donors. By retrospectively reviewing discharges from their neonatal intensive care unit over a 10-year period, the authors identified 159 infants weighing over 1.8 kg who died after withdrawal of life-sustaining support. There were no brain deaths during the 10-year period studied. The authors chose 1.8 kg as their cutoff for potential donor weight because this was the weight of the smallest documented donor in successful DCD kidney transplants. Utilizing regional rates of DCD consents, the authors then determined that 1.7 to 4 paired kidneys could have been transplanted each year at their institution. Extrapolating these figures using national data, they determined that 487 to 1,145 paired donor kidneys could become available each year.
There are a number of problems with this work. First, the weight cutoff used is significantly lower than the weights that have been used in the literature. In the work of Sharma et al, the group weighing <10 kg had a mean weight of 8.3 +/- 1.8 kg. Other investigators have reported transplanting kidneys from donors as little as 4 kg, though utilizing these smaller sizes raises the concern for thrombosis, insufficient aortic cuff, and short ureters. Another concern about this work is the use of extrapolated consent rates. Because this practice has not been established, the actual consent rate is unknowable.
The importance of this article lies in the premise that, although DCD of en bloc kidneys in very small children or infants is technically challenging, the potential for good outcomes in many recipients makes this practice worthy of consideration.
This Concise Critical Appraisal is authored by SCCM member Daniel E. Sloniewsky, MD. Each installment highlights journal articles most relevant to the critical care practitioner. Dr. Sloniewsky is an associate professor in the Department of Pediatrics at the Stony Brook Long Island Children’s Hospital in Stony Brook, NY, where he is board certified in pediatrics and pediatric critical care. He completed his fellowship training at Children’s Memorial Hospital and Northwestern University in Chicago. His major interests are acute pediatric pulmonary disease, transfusion medicine and ethics. He is also actively involved in resident education, Pediatric Advanced Life Support and Pediatric Fundamental Critical Care Support instruction.