Lung water content measurement system and calibration method

A system for monitoring lung water content of a patient, the system comprising:

• at least two microwave sensors;
• and
• a processor configured to perform a method comprising
• transmitting one or more microwave signals into the thorax of a patient using one or more of the microwave sensors;
• receiving one or more of the microwave signals using one or more of the microwave sensors, the one or more received microwave signals each comprising at least one frequency component having a magnitude and a phase;
• analyzing the phase of one or more received microwave signals to monitor changes in the lung water content;
• and
• analyzing the magnitude of one or more received microwave signals to determine whether the lung water content is increasing or decreasing.

A system for monitoring a physiological characteristic of a patient, the system comprising:

• more than two microwave sensors;
• and
• a processor configured to perform a method comprising
• measuring microwave scattering parameters from the microwave sensors, the microwave scattering parameters comprising at least microwave transmission coefficients respectively corresponding to a selected first microwave sensor and at least a second microwave sensor and a third microwave sensor;
• analyzing the measured microwave transmission coefficients to determine the physiological characteristic.

A system for monitoring lung water content of a patient, the system comprising:

• at least two microwave sensors;
• and
• a processor configured to perform a method comprising
• transmitting one or more microwave signals into the thorax of a patient using one or more of the microwave sensors;
• receiving a first waveform corresponding to a first pair of the microwave sensors;
• analyzing at least one characteristic of the first waveform to determine a physiological characteristic.