The present invention provides a blood parameter sensing system that may include a sensor, a blood access system, a flow controller and a monitor system. The blood access system may include a blood draw member having an internal configuration adapted to avoid clotting without the use of anticoagulants and under a range of flow profiles, including small volume blood draws. The flow controller may be configured to adapt to a range of access devices by using feedback from the sensor and monitor to customize flow profiles. The monitor system is configured to reduce parameter measurement error by modeling sensitivity change during system startup or reconnect.
