A heat and moisture exchange unit for use with a patient breathing circuit. The unit includes a housing, an MDI port assembly and a heat and moisturizing medium. The housing forms a patient-side port, a ventilator-side port, and a containment region between the patient-side port and the ventilator-side port. The MDI port assembly includes a frame projecting into the containment region and configured to receive a portion of a metered dose dispenser. The frame terminates at an outlet end, forming a flow passage. The heat and moisturizing medium is maintained within the containment region so as to define a medium face most proximate the outlet end of the MDI port assembly. The unit is characterized by the absence of a body between the outlet end and the medium face.
