This invention discloses a modular system having a base module, a mid-section control module, and a display module for preparing and administering a gas-enriched bodily fluid. An apparatus adapted for connecting with a gas tank is included in the system for gas tank hook-up. Gas-enrichment is achieved by a gas-enriching device which can be in the form of a disposable cartridge. During operation, the gas-enrichment device is placed in an enclosure within the control module. An electronic controller manages the various aspects of the system such as the production of gas-enriched fluid, flow rates, bubble detection, and automatic operation and shut down. The system has a power supply for providing electrical power to the system, and a switching mechanism coupled to the power supply and gas tank for synchronized switching of the power supply and the gas tank between an ON state and an OFF state.