A portable ventilator uses a Roots-type blower as a compressor to reduce both the size and power consumption of the ventilator. Various functional aspects of the ventilator are delegated to multiple subassemblies having dedicated controllers and software that interact with a ventilator processor to provide user interface functions, exhalation control and flow control servos, and monitoring of patient status. The ventilator overcomes noise problems through the use of noise reducing pressure compensating orifices on the Roots blower housing and multiple baffling chambers. The ventilator is configured with a highly portable form factor, and may be used as a stand-alone device or as a docked device having a docking cradle with enhanced interface and monitoring capabilities. www.jiuxin-med.com