Protective effects of topically applied CO 2 ‐impregnated water

Background/aims: The‘positive effect’of CO 2 ‐impregnated water (mechanical process of producing carbonated therapeutic waters for medical use) on the skin of the hands was reported by 76% of 107 users questioned. The present study intends to evaluate this effect by using bioengeneering methods. Methods: In 20 healthy volunteers, mild to moderate irritation was induced on both hands using a standardised washing procedure. One hand was rinsed with CO 2 ‐impregnated water (carbonic acid) once daily for 1 min, the other with tap water as the control. Baseline values and values 30 min after application were recorded by measuring transepidermal water loss (TEWL), skin humidity (SH), microcirculation of the blood (BF) and skin surface pH. Wilcoxon's signed rank test was used for statistical analysis; P‐values of less than 0.05 were considered to be significant. Results: Baseline TEWL, BF and pH tended to be lower (in some cases significantly lower) in the test regions treated with carbonic acid, whereas baseline SH tended to be higher (in some cases significantly higher). TEWL and pH were significantly lower for the side treated with CO 2 30 min after application, whereas in some cases SH was significantly higher compared with the control side. Visual comparison revealed a lesser degree of irritation for the region treated with CO 2 in comparison with the control side. Conclusions: The results show that the skin physiology parameters of irritated skin are favourably influenced by the topical application of CO 2 ‐impregnated water. Although those test regions treated with carbonic acid did not remain uninfluenced by repeated irritation in clinical comparisons, the irritation was more intensive in the test regions treated with fresh water.