A device configured: for insertion into a body cavity of a patient, in particular into an organ (26, 27, 37) of the patient; for insufflation of a gaseous medium to expand the body cavity, wherein the gaseous medium is CO 2; and for generating a therapeutic aerosol within the body cavity, the device comprising: - a first expandable fluid chamber configured to seal a first section of the body cavity; - an aerosol generating device configured to generate a therapeutic aerosol from a substance in a treatment section of the body cavity extending after the first section, the aerosol generating device including a first supply line configured to supply the substance; and - an insufflation device configured to insufflate the gaseous medium into the treatment section of the body cavity, the insufflation device comprising a second supply configured to supply the gaseous medium and means configured to pressurise the gaseous medium; the device being structured such that: after the first fluid chamber has been expanded, whereby the expanded first fluid chamber closely abuts a wall of the body cavity so that the first section of the body cavity is sealed by the expanded first fluid chamber, the first supply line and the second supply line can be passed through the first fluid chamber into the treatment portion of the body cavity, so that the gaseous medium can then be insufflated through the second supply line into the treatment section of the body cavity, and thereafter the therapeutic aerosol can be generated in the treatment section of the body cavity insufflated with the gaseous medium. for insertion into a body cavity of a patient, in particular into an organ (26, 27, 37) of the patient; for insufflation of a gaseous medium to expand the body cavity, wherein the gaseous medium is CO 2; and for generating a therapeutic aerosol within the body cavity, the device comprising: - a first expandable fluid chamber configured to seal a first section of the body cavity; - an aerosol generating device configured to generate a therapeutic aerosol from a substance in a treatment section of the body cavity extending after the first section, the aerosol generating device including a first supply line configured to supply the substance; and - an insufflation device configured to insufflate the gaseous medium into the treatment section of the body cavity, the insufflation device comprising a second supply configured to supply the gaseous medium and means configured to pressurise the gaseous medium; - a first expandable fluid chamber configured to seal a first section of the body cavity; - an aerosol generating device configured to generate a therapeutic aerosol from a substance in a treatment section of the body cavity extending after the first section, the aerosol generating device including a first supply line configured to supply the substance; and - an insufflation device configured to insufflate the gaseous medium into the treatment section of the body cavity, the insufflation device comprising a second supply configured to supply the gaseous medium and means configured to pressurise the gaseous medium; the device being structured such that: after the first fluid chamber has been expanded, whereby the expanded first fluid chamber closely abuts a wall of the body cavity so that the first section of the body cavity is sealed by the expanded first fluid chamber, the first supply line and the second supply line can be passed through the first fluid chamber into the treatment portion of the body cavity, so that the gaseous medium can then be insufflated through the second supply line into the treatment section of the body cavity, and thereafter the therapeutic aerosol can be generated in the treatment section of the body cavity insufflated with the gaseous medium.