A respiratory gas analyzer device (10), such as a capnograph device, is disclosed. A gas measurement component (28), such as a carbon dioxide measurement component in the case of a capnograph, is configured to measure at least one respired gas component (e.g. carbon dioxide). A pump (20) is connected to draw respired gas through the gas measurement component. A pressure gauge (30) is connected to measure pressure in an airflow pathway including the gas measurement component and the pump. An electronic pump controller (40) is programmed to start the pump in response to pressure measured by the pressure gauge satisfying a pump turn on criterion.
