Methods and apparatus for guiding medical care based on sensor data from the gastrointestinal tract are described utilizing an apparatus which can be used with enteral feeding. Generally, the apparatus includes an elongated body having a length configured for insertion into a stomach and at least one pair of electrodes located along the length of the elongated body and positionable for placement within the stomach. A controller in electrical communication with the at least one pair of electrodes is included and the control may also be configured to measure a conductivity or impedance between the pair of electrodes and to determine a gastric residual volume of the stomach based on the measured conductivity or impedance.
