Renal transplantation in the older end stage renal disease patient.

Transplant physicians in the United States continue to face an interesting problem when offering kidney transplantation as a form of renal replacement therapy to older end-stage renal disease (ESRD) patients. The limited life-expectancy of these patients and an ever-present shortage of cadaveric organs makes kidney transplantation in this population a potentially controversial issue. Early results suggested poor outcomes for cadaveric renal transplantation in middle-aged or elderly ESRD patients. Improved patient selection, changes in immunosuppression regimens, and living-related transplantation have increased the success of transplantation in these patients. Efforts to define older patients at risk for cardiovascular disease and to account for their altered immune function may further improve outcomes. However, if older ESRD patients are to be rightfully included in the patient population eligible for transplantation, then the organ shortage will inevitably worsen. A potentially intriguing solution to this problem is to expand the donor pool by including older donors. Despite data suggesting that recipients of older grafts may have shorter graft survival; older donors could readily serve as a source of kidneys for older recipients who do not require 20+ year graft survival based upon their projected lifespan. Ultimately, age alone should not serve as a contraindication to renal transplantation. In patients over the age of 60, 1-year patient and graft survival rates approach 85% and 75%, respectively. However, careful assessment of "biologic" age and comorbid illnesses should be considered when offering renal transplantation to older patients.

Clearance of branched chain amino acids by peritoneal dialysis in maple syrup urine disease.

Thirty-eight hours of peritoneal dialysis (PD) was used in an 8-day-old, 3.35 kg boy with maple syrup urine disease (MSUD) to enhance the removal of branched chain amino acids (BCAA). PD clearances for leucine, isoleucine, and valine were 3 ml/min/1.73 m2, compared to urinary clearances of 0.16 ml/min/1.73 m2 (0.4 ml/min/1.73 m2 for isoleucine). The augmented clearance was reflected by a faster rate of fall in the plasma leucine level during dialysis (38 microM/hr) than before or immediately after dialysis (10 microM/hr). The biochemical improvement was accompanied by neurologic improvement in the baby. Once the leucine level fell to below 1500 mu + M, the unaugmented rate of fall for leucine (21 microM/hr) was similar to that augmented by PD. Our experience demonstrates that PD is useful for enhancing clearance of BCAA at leucine levels greater than 1500 microM and that it speeds neurologic recovery.

Intraoperative hemodialysis during cardiopulmonary bypass in chronic renal failure.

This report describes the features and the course of a patient on maintenance hemodialysis in whom infective endocarditis of the aortic valve ensued. The subsequent development of intractable congestive heart failure necessitated aortic valve replacement. Use of intraoperative hemodialysis, facilitating the intraoperative and postoperative management of the patient, is described. Following valve replacement the patient did well with no evidence of congestive heart failure.

Effect of uremia on nutritionally-induced variations in protein metabolism.

The effect of uremia on nutritionally-induced variations in protein metabolism was studied in growing rats with chronic, moderate uremia. Plasma and muscle protein synthetic activities and related values were measured from incorporation rates of 14C-leucine infused over a six-hour period. Synthetic activities were compared in the postabsorptive (2 to 14 hr after feeding) and in the fasting (18 to 24 hr after feeding) states. Differences between uremic and control rats were seen in fasting: plasma and intracellular leucine declined in control rats as fasting developed; they rose in uremic rats. In fasting uremic rats, a smaller percent of leucine efflux from extracellular fluid was used for protein synthesis. In a second study, muscle protein synthesis (Sm) and net urea nitrogen production (UNPr) were compared between control and uremic rats which were a) food-deprived but given carbohydrate for 36 hr, and b) fasted for 36 hr. Fasting, as contrasted with carbohydrate feeding, was associated with depressed muscle protein synthesis and increased UNPr in both control and uremic rats; the changes were greater in uremic rats. We conclude that food deprivation for more than 14 hr incurred greater catabolic responses of body protein in moderately uremic rats. The effect was mediated in part by greater suppression of muscle protein synthesis. In contrast, moderate uremia had little discernible effect upon protein metabolism in the postabsorptive state or food deprived state when gluconeogenesis was suppressed with glucose administration.