The effects of carbon dioxide baths on the skin microcirculation at different times of the day

Application of CO2 baths are a well-known treatment of cardiovascular and occlusive peripheral diseases, because they induce peripheral vasodilation. We investigated the effects of CO2 baths at 4 different times of a day. Left forearms of 10 healthy volunteers were bathed in CO2 rich water (32 degrees C). Skin microcirculation was examined on the left as well as the right forearms by means of a laser Doppler flowmeter. Blood pressure and heart rate were also measured. Tap water baths were administered as a control application. At 7.00 a.m. CO2 baths led to an increase in skin microcirculation, at 11.00 a.m. there was still a slight increase. In the afternoon and evening skin microcirculation was lowered by CO2 baths. The perfusion of the skin decreased at any time of a day through baths in tap water. There were no significant changes in blood pressure and heart rate. Our results show a clear prevalence of peripheral vasodilation in CO2 baths in the morning, and therefore indicate that this time of the day might induce most preferable therapeutic results.