A system for providing respiratory therapy to a patient comprising: a nebulizer comprising a mesh operable to aerosolize a medicament; a cylindrical mixing chamber having an inlet port, an outlet port, an aerosol port in fluid communication with the nebulizer, and a drainage port, the inlet port configured to receive a flow of breathing gas from a source of breathing gas, the outlet port having a first end and a second end, the second end external to the mixing chamber and configured to interfit with a delivery tube for delivery of the flow of breathing gas to the patient, the mixing chamber configured to receive a flow of aerosol from the nebulizer via the aerosol port, entrain aerosol into the flow of breathing gas, and deliver the breathing gas entrained with aerosol to the outlet port, the mixing chamber having a diameter that is larger than a diameter of the inlet port and a diameter of the aerosol port, and characterised in that the system further comprises: an impacting cap in fluid communication with the mixing chamber, the impacting cap having a sloped inner surface (210, 220) and forming a settling volume with the mixing chamber, the mixing chamber configured to receive the aerosol in the settling volume and cause a first portion of the aerosol to coalesce into droplets in or on any of the settling volume, the inner wall of the mixing chamber, and the sloped inner surface of the impacting cap, the inner wall of the mixing chamber and the sloped inner surface of the impacting cap being configured to direct rain-out resulting from the droplets toward the drainage port; and a recirculation tube adapted to return the rain-out to the nebulizer. a nebulizer comprising a mesh operable to aerosolize a medicament; a cylindrical mixing chamber having an inlet port, an outlet port, an aerosol port in fluid communication with the nebulizer, and a drainage port, the inlet port configured to receive a flow of breathing gas from a source of breathing gas, the outlet port having a first end and a second end, the second end external to the inlet port configured to receive a flow of breathing gas from a source of breathing gas, the outlet port having a first end and a second end, the second end external to the mixing chamber and configured to interfit with a delivery tube for delivery of the flow of breathing gas to the patient, the mixing chamber configured to receive a flow of aerosol from the nebulizer via the aerosol port, entrain aerosol into the flow of breathing gas, and deliver the breathing gas entrained with aerosol to the outlet port, the mixing chamber having a diameter that is larger than a diameter of the inlet port and a diameter of the aerosol port, the mixing chamber configured to receive a flow of aerosol from the nebulizer via the aerosol port, entrain aerosol into the flow of breathing gas, and deliver the breathing gas entrained with aerosol to the outlet port, the mixing chamber having a diameter that is larger than a diameter of the inlet port and a diameter of the aerosol port, and characterised in that the system further comprises: an impacting cap in fluid communication with the mixing chamber, the impacting cap having a sloped inner surface (210, 220) and forming a settling volume with the mixing chamber, the mixing chamber configured to receive the aerosol in the settling volume and cause a first portion of the aerosol to coalesce into droplets in or on any of the settling volume, the inner wall of the mixing chamber, and the sloped inner surface of the impacting cap, the inner wall of the mixing chamber and the sloped inner surface of the impacting cap being configured to direct rain-out resulting from the droplets toward the drainage port; and an impacting cap in fluid communication with the mixing chamber, the impacting cap having a sloped inner surface (210, 220) and forming a settling volume with the mixing chamber, the mixing chamber configured to receive the aerosol in the settling volume and cause a first portion of the aerosol to coalesce into droplets in or on any of the settling volume, the inner wall of the mixing chamber, and the sloped inner surface of the impacting cap, the inner wall of the mixing chamber and the sloped inner surface of the impacting cap being configured to direct rain-out resulting from the droplets toward the drainage port; and a recirculation tube adapted to return the rain-out to the nebulizer.