Body-worn monitor for measuring respiration rate
The invention provides a multi-sensor system that uses an algorithm based on adaptive filtering to monitor a patient's respiratory rate. The system features an impedance pneumography sensor and a motion sensor (e.g., an accelerometer) configured to attach to the patient's torso and measure therefrom a motion signal. The system further comprises a processing system, configured to operably connect to the impedance pneumography sensor and motion sensor, and to determine a respiration rate value by applying filter parameters obtained from the impedance pneumography sensor signals to the motion sensor signals.
1. A system for continuously monitoring a patient's respiration rate comprising:
a combined impedance pneumography, electrocardiography (ECG), and motion sensor unit comprising a housing configured to be mounted on the patient's torso and comprising: an impedance pneumography circuit within the housing configured to generate an impedance pneumography waveform, an ECG circuit within the housing configured to generate an ECG waveform, and an accelerometer within the housing configured to generate a motion waveform;
a photoplethysmography sensor configured to be mounted on a finger of the patient and to generate a photoplethysmography waveform; and
a processing system configured to, on a continuous basis;
(i) receive the impedance pneumography waveform, the ECG waveform, the motion waveform, and the photoplethysmography waveform,
(ii) select using a metric of signal quality one of the received waveforms to provide an initial respiration rate,
(iii) determine the initial respiration rate from the waveform selected in (ii), and
(iv) process one or more of the received waveforms not selected in (ii) using an adaptive filtering algorithm that uses parameters determined from the initial respiration rate to obtain and report the respiration rate for the patient.