A modularized respiratory treatment apparatus provides various respiratory pressure treatments. The apparatus may be formed by discrete connectable modules such as a flow generator module, alarm module and/or humidifier module. Each module may include its own external casing or housing to independently retain or enclose the respective components that serve the function of the module. Different modules may be adapted with different components and functionalities and may be readily coupled using standardized gas and electrical connection configurations that have flow and communication paths that extend through the modules. When coupled, operation of the respiratory treatment apparatus may be controlled by detection of different modules, such as the alarm module that generates visual and/or audible alarms based on detected conditions, so as to selectively enable or disable different respiratory treatments. The discrete modules of the medical treatment apparatus may include tamper resistant locking mechanisms to impede unauthorized separation of some modules.