Respiration rate monitor
First Claim
1. A system for monitoring the respiration rate of a patient, comprising:
- means for detecting acoustical energy generated by said patient and for producing a first output signal in response thereto, said output signal comprising a component corresponding to breath sounds, a component corresponding to heart sounds and a component corresponding to ambient noise;
means for filtering said first output signal to remove said components corresponding to said heart sounds and ambient noise and for producing a second output signal corresponding only to said breath sounds;
means for producing an AC coupled energy signal corresponding to the breath sound energy level of said second output signal; and
means for identifying significant positive-going zero crossings in said AC coupled energy signal within a band of predetermined width and for correlating said significant zero crossings with the respiration rate of said patient.
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Accused Products
Abstract
A monitoring system for providing an accurate indication of a patient'"'"'s respiration rate. The system is effective in eliminating or significantly reducing the effects of heart sounds and ambient noise. The system comprises means for obtaining a first signal waveform containing components corresponding to the patient'"'"'s breath sounds, as well as components corresponding to heart sounds and ambient noise. The signal is passed through a digital bandpass filter having a passband selected to remove heart sounds and ambient noise to produce a second waveform. From the second waveform the total energy is computed of a portion of the signal within a moving window of predetermined length. The resulting energy envelope signal is smoothed and then high-pass filtered by removing the average DC value of the signal over a predetermined preceding time interval. Respiration is detected by identifying significant, positive-going zero crossings of the resulting signal through a band about zero. The zero-band threshold used to obtain this waveform can be controlled by the operator or pre-set for a particular sensitivity.
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Citations
6 Claims
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1. A system for monitoring the respiration rate of a patient, comprising:
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means for detecting acoustical energy generated by said patient and for producing a first output signal in response thereto, said output signal comprising a component corresponding to breath sounds, a component corresponding to heart sounds and a component corresponding to ambient noise; means for filtering said first output signal to remove said components corresponding to said heart sounds and ambient noise and for producing a second output signal corresponding only to said breath sounds; means for producing an AC coupled energy signal corresponding to the breath sound energy level of said second output signal; and means for identifying significant positive-going zero crossings in said AC coupled energy signal within a band of predetermined width and for correlating said significant zero crossings with the respiration rate of said patient. - View Dependent Claims (2, 3)
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4. A method for determining respiration rate of a patient, comprising the steps of:
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detecting acoustical energy generated by said patient and producing a first output signal in response thereto, said output signal comprising a component corresponding to breath sounds, a component corresponding to heart sounds and a component corresponding to ambient noise; filtering said first output signal to remove said components corresponding to said heart sounds and ambient noise and producing a second output signal corresponding only to said breath sounds; producing an AC coupled energy signal corresponding to the breath sound energy level of said second output signal; and identifying significant positive-going zero crossings in said AC coupled energy signal within a band of predetermined width and correlating said significant zero crossings with the respiration rate of said patient. - View Dependent Claims (5, 6)
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Specification