Significance of renal function in changes in acid-base metabolism after orthotopic bladder replacement: colon neobladder compared with ileal neobladder.

BACKGROUND: The objective of this study was to determine whether renal function influences the acid-base metabolism in patients undergoing orthotopic bladder replacement using intestinal segment.

METHODS: Acid-base balance, serum electrolytes and renal function were studied in 30 patients with colon neobladder and 18 patients with ileal neobladder. Mean follow up was 51 months. Effects of renal function on acid-base metabolism in both types of bladder replacement were compared. Therapeutic efficacy of the sodium bicarbonate administration was also evaluated in cases with hyperchloremic acidosis.

RESULTS: No significant differences were observed in any of the variables examined between the colon and ileal neobladder groups, except for potassium concentration. Although metabolic acidosis was detected using the Siggard-Anderson acid-base nomogram in eight (26.7%) and seven (38.9%) patients in the colon and ileal neobladder groups, respectively, this difference was not significant. In both the colon and ileal neobladder groups, the serum creatinine concentrations in patients diagnosed with metabolic acidosis were significantly higher than in those diagnosed with a normal metabolic status. Furthermore, as a result of severe metabolic acidosis, three (10.0%) and three (16.7%) patients in the colon and ileal neobladder groups, respectively, were administered sodium bicarbonate and their metabolic status was fully normalized.

CONCLUSIONS: Despite there being no statistical difference, patients with ileal neobladder may more easily develop metabolic acidosis compared with those with colon neobladder. In addition, a close association between the serum creatinine level and the degree of metabolic acidosis was observed in both groups. However, even if severe metabolic acidosis occurs, it is relatively easy to correct using sodium bicarbonate. These findings suggest that it might be safe to use a colon segment for orthotopic bladder reconstruction in patients with higher serum creatinine levels, despite no significant difference in acid-base metabolism and detection rates of metabolic acidosis between the colon and ileal neobladder groups.