Topical application of CO2 increases skin blood flow.

The topical application of carbon dioxide water to the rat hindpaw produced a concentration-dependent increase of skin blood flow as measured by a laser Doppler flowmeter. About a 100% increase of skin blood flow occurred in response to CO2 when the bath temperature was at 23 degrees C or 34 degrees C, but there was no significant effect of CO2 at 41 degrees C. Carbon dioxide exposure also produced about the same increase of skin blood flow in the acutely or chronically denervated paw as in the control. These findings give experimental support for the clinical use of CO2 bathing in the treatment of disturbances of skin circulation as well as skin ulcers and wounds.