A system for measuring respiratory rate from a patient, comprising: an impedance pneumography sensor connected to at least two electrodes, the impedance pneumography sensor comprising a processing circuit configured to process signals from the at least two electrodes to measure an impedance pneumography signal from the patient; a motion sensor connected to the patient and configured to measure at least one motion signal corresponding to motion of a portion of the patient's body to which it is attached; and a processing system configured to: determine a motion parameter from the motion signal; and based on the motion parameter, select one of the following algorithms to process at least one of the motion and impedance pneumography signals to determine the patient's respiratory rate: i) a first algorithm comprising a step for counting breathing-induced pulses in the impedance pneumography signal to determine respiratory rate; ii) a second algorithm comprising collectively processing both the motion signal and impedance pneumography signal to determine a digital filter, and then processing one of the motion signal and impedance pneumography signal with the digital filter to determine respiratory rate, or iii) a third algorithm comprising processing the impedance pneumography signal to determine a frequency-domain impedance pneumography spectrum, processing the motion signal to determine a frequency-domain motion spectrum, collectively processing both the impedance pneumography spectrum and motion spectrum to remove motion components from the impedance pneumography spectrum and then determining respiratory rate. an impedance pneumography sensor connected to at least two electrodes, the impedance pneumography sensor comprising a processing circuit configured to process signals from the at least two electrodes to measure an impedance pneumography signal from the patient; a motion sensor connected to the patient and configured to measure at least one motion signal corresponding to motion of a portion of the patient's body to which it is attached; and a processing system configured to: determine a motion parameter from the motion signal; and based on the motion parameter, select one of the following algorithms to process at least one of the motion and impedance pneumography signals to determine the patient's respiratory rate: i) a first algorithm comprising a step for counting breathing-induced pulses in the impedance pneumography signal to determine respiratory rate; ii) a second algorithm comprising collectively processing both the motion signal and impedance pneumography signal to determine a digital filter, and then processing one of the motion signal and impedance pneumography signal with the digital filter to determine respiratory rate, or iii) a third algorithm comprising processing the impedance pneumography signal to determine a frequency-domain impedance pneumography spectrum, processing the motion signal to determine a frequency-domain motion spectrum, collectively processing both the impedance pneumography spectrum and motion spectrum to remove motion components from the impedance pneumography spectrum and then determining respiratory rate. determine a motion parameter from the motion signal; and based on the motion parameter, select one of the following algorithms to process at least one of the motion and impedance pneumography signals to determine the patient's respiratory rate: i) a first algorithm comprising a step for counting breathing-induced pulses in the impedance pneumography signal to determine respiratory rate; ii) a second algorithm comprising collectively processing both the motion signal and impedance pneumography signal to determine a digital filter, and then processing one of the motion signal and impedance pneumography signal with the digital filter to determine respiratory rate, or iii) a third algorithm comprising processing the impedance pneumography signal to determine a frequency-domain impedance pneumography spectrum, processing the motion signal to determine a frequency-domain motion spectrum, collectively processing both the impedance pneumography spectrum and motion spectrum to remove motion components from the impedance pneumography spectrum and then determining respiratory rate. i) a first algorithm comprising a step for counting breathing-induced pulses in the impedance pneumography signal to determine respiratory rate; ii) a second algorithm comprising collectively processing both the motion signal and impedance pneumography signal to determine a digital filter, and then processing one of the motion signal and impedance pneumography signal with the digital filter to determine respiratory rate, or iii) a third algorithm comprising processing the impedance pneumography signal to determine a frequency-domain impedance pneumography spectrum, processing the motion signal to determine a frequency-domain motion spectrum, collectively processing both the impedance pneumography spectrum and motion spectrum to remove motion components from the impedance pneumography spectrum and then determining respiratory rate.