 Risk-benefit Assessment: The risks of the study include the risks of performing a muscle biopsy, discomfort associated with the placement of the feeding tube, emotional problems associated with prolonged hospitalization in the GCRC and risks associated with venipuncture. There are no direct benefits to the subjects as a result of their participation in this study. However, if we demonstrate that the higher arterial pH is better at preservation of nutritional status, it may have the potential of decreasing the prevalence andor severity of protein-energy malnutrition in patients undergoing automated peritoneal dialysis. 