Addition of Sodium Bicarbonate to Irrigation Solution May Assist in Dissolution of Uric Acid Fragments During Ureteroscopy

Abstract

Introduction: We hypothesized that adding sodium bicarbonate (bicarb) to normal saline (NS) irrigation during ureteroscopy (URS) in patients with uric acid (UA) nephrolithiasis may assist in dissolving small stone fragments produced during laser lithotripsy. In vitro testing was performed to determine if dissolution of UA fragments could be accomplished within one hour. Materials and Methods: 100% UA renal calculi were fragmented, filtered, and separated by size. Fragment sizes were <0.5mm and 0.5-1mm. Similar amounts of stone material were agitated in solution at room temperature. Four solutions were tested (NS, NS+1 ampule bicarb/liter, NS+2, NS+3). Both groups were filtered to remove solutions after fixed periods. Filtered specimens were dried and weighed. Fragment dissolution rates were calculated as percent removed per hour. Additional testing was performed to determine if increasing the temperature of solution affected dissolution rates. Results: For fragments <0.5mm, adding 2 or 3 bicarb ampules/liter NS produced a dissolution rate averaging 91±29% per hour. This rate averaged 226% faster than NS alone. With fragments 0.5-1mm, addition of 2 or 3 bicarb ampules/liter NS yielded a dissolution rate averaging 22±7% per hour which was nearly 5 times higher than NS alone. There was a trend for an increase in mean dissolution rate with higher temperature but this increase was not significant (P=0.30). Conclusions: The addition of bicarbonate to normal saline more than doubles the dissolution rate of UA stone fragments and fragments less than 0.5 mm can be completely dissolved within one hour. Addition of bicarb to NS irrigation is a simple and inexpensive approach that may assist in the dissolution of UA fragments produced during ureteroscopic laser lithotripsy. Further studies are needed to determine whether a clinical benefit exists.

Kidney Stone Prevention

“…However, the CUA recommends using allopurinol only in patients with calcium stones and hyperuricemia to prevent the stone recurrence but does not recommend its use in those with normouricemia [ 11 ]. Finally, the aforementioned drugs are also applicable for prevention of uric acid stone [ 142 , 163 , 164 ]. However, their adverse effects should be periodically checked.…”

Baseline urine pH is related to effective urine alkalization by short-term alkaline water supplementation: data from a self-controlled study in healthy Chinese volunteers following a systematic review and meta-analysis of literature

“…Use of sodium bicarbonate is a common option for urine alkalization in patients with UA calculi, but not justified for regular use in normal individuals as a prevention, considerably due to gastrointestinal disturbance. On the other hand, a dietary approach could be more acceptable for this purpose (8,(10)(11)(12)(13). Based on the acid-ash hypothesis, oral use of alkaline water has been attempted to provide more alkaline ions after metabolism.…”