An exemplary suction catheter adaptor includes an adaptor body (200) having a passageway between a proximal end (202) and a distal end (204) of the adaptor body. The proximal end of the adaptor body receives an instrument (10) and, when coupled with an airway adaptor (400) having a valve (460) within a passageway between a proximal end (402) and a distal end (404) of the airway adaptor, the distal end of the adaptor body deflects the valve to permit the instrument to be advanced or retracted through the valve. A seal (208) within the passageway of the adaptor body is biased to engage the valve during advancement of an instrument toward the valve, and the seal is disengaged when the instrument is retracted away from the valve. The valve, when not engaged, occludes the passageway between a proximal end and a distal end of the airway adaptor.
