In vitro effect of hyperbaric oxygen on the chemolysis of infective stones

In order to extend the feasibility of hyperbaric oxygen therapy in the urological field, the present study aimed to investigate the dissolution activity of human infective stones in UROCITRA solution under hyperbaric oxygen condition.

The dissolution activity of 7 struvite and 11 mixed struvite and carbonate apatite stones in UROCITRA solution were studied under 2.5 atmosphere (atm) hyperbaric oxygen (HBO) status in a Sigma I N-124 monoplace chamber. Another 7 struvite and 10 mixed struvite and carbonate apatite stones were also studied under normal condition. Chemolysis was performed in a drip device with a 150-ml/hour continuous flow rate.

Under 2.5 atm HBO status, the PO2 of UROCITRA solution was 365 +/- 44 mmHg, which was significantly higher than that of tap water (113 +/- 62 mmHg) and UROCITRA solution (125 +/- 12 mmHg) under normobaric condition (p < 0.001). The decreases in the stone weight of struvite under normobaric condition were 31 +/- 8.8% after 2 h and 48 +/- 15% after 4 h of treatment. The HBO-enriched UROCITRA solution did not increase the dissolution activity as reflected by comparable decreases in the dried stone weight (31.2 +/- 14.6% and 54 +/- 19% at the 2nd and 4th post-treatment hours, respectively, p > 0.05). Similarly, there was no significant difference in the percent stone weight decrease of the mixed struvite and carbonate apatite stones under either HBO or normobaric condition. The dissolution responsiveness of struvite was significantly greater than that of the mixed struvite and carbonate apatite stones.

The chemolysis of struvite in UROCITRA solution is significantly greater than that of the mixed struvite and carbonate apatite stones. However, the UROCITRA solution enriched with HBO does not enhance the dissolution of infective stones.