A medical apparatus is provided. The medical apparatus includes a water source for supplying water to a mixer, a gas source for supplying gas to a gas reservoir, a gas output for flowing gas from the gas reservoir to the mixer to mix with water to form a first mixture, a line for carrying the first mixture, Venturi tubes on the line, medication units for containing liquid medication and communicating with the Venturi tubes respectively, a mixing device being downstream of the Venturi tubes to atomize the liquid medication and the first mixture to form a final mixture, a control panel, and an outlet for exiting the final mixture. Infected skin areas of a patient can be washed aseptically by the medical apparatus.