The present invention is an inflation system utilizing an inflation device and an adaptor therefor. The inflation device includes a cylindrical housing which receives a pressurized cartridge of gas, a head unit, and a nozzle. The head unit of the device includes structure for creating and delivering a metered bolus of gas per each actuation of the device. The device audibly indicates to the user when a single bolus of gas has been successfully delivered to an inflatable bladder. In another aspect of the invention, an elastomeric inflation port which serves as an adaptor for connecting the inflation device of the invention to an inflatable bladder is provided. The inflation port of the invention may also function as a fluid release mechanism to vent fluid from the bladder.