Department of Electronics and Instrumentation Technology

RVCE

A Seminar on

RESPIRATORY RATE MONITOR

By:

Goverdhan. R

1st sem, M.Tech

RVCE

Under the Guidance of

of

Dr. B.G Sudharshan

Associate Professor,

Dept. of IT, R.V.C.E 03-12-2014BMSPI, Dept. of E & IT 1

Contents

Introduction

Importance of monitoring respiratory rate

Various method of measuring respiratory rate

Respiratory rate measurement using Piezoelectric Sensor (PZO)

Respiratory rate measurement from Laser Doppler Vibrometer(LDVi)

Respiration rate measurement system using Pyroelectric Sensor

Impedance pneumography method

Capnometry

Respiratory rate measurement using PPG signal

Conclusion

References03-12-2014BMSPI, Dept. of E & IT 2

Introduction

Respiration rate is an important vital sign. It is, the number ofbreaths taken within a set amount of time.

Tachypnea /Bradypnea / Apnoea, is a sensitive indicator ofphysiologic distress that requires immediate clinical intervention.

Figure 1. Normal breathing rate [1]03-12-2014BMSPI, Dept. of E & IT 3

Importance of monitoring respiratory rate[2]

Tachyapnoea are an important predictor of cardiac arrest.(25-27breaths/minute)

Mortality is high in Tachypnea persons.

Figure 2: Causes of death (SOURCE: Sudden Cardiac Arrest Foundation)

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Various method of measuring respiratory rate

Respiratory rate measurement using Piezoelectric Sensor (PZO).

Respiratory rate measurement from Laser Doppler Vibrometer (LDVi).

Respiration rate measurement System Using Pyroelectric Sensor.

Impedance pneumography method.

Capnometry.

Respiratory rate measurement using PPG signal.

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• Piezoelectric sensors have been used to detect breathing effects,

utilizing the piezoelectric property.

• It directly measures the electric potential changes produced when the

piezoelectric ceramic is impacted by respiratory airflow.

• piezoelectric film sensor made of aluminum nitride (AlN) material has

good sensitivity.

Respiratory Rate measurement using Piezoelectric Sensor (PZO)[3]

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Respiratory Rate using Piezoelectric Sensor (PZO)[3](contd…)

Figure 3. Respiration belt Sleep Sense 1387-kit.(Courtesy: www.biosemi.com) Figure 4. Piezoelectric output, periodogram

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Measurement of Respiratory Rate from Laser

Doppler Vibrometer (LDVi)[4]

LDVi is a fully no-contact measurement method for monitoring of the respiration rate.

This method is operated at a distance of 3m, on different point of the patient thoracic and abdominal area.

Laser Doppler vibrometers can effectively detect vibration within two hundred meters with a sensitivity on the order of 1 (mm/s)/V.

The laser sensor works with a He–Ne laser source.

No special safety precautions are required since laser power is less than 1 mW.

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Measurement of Respiratory Rate from Laser

Doppler Vibrometer (LDVi)[4] (contd…)

Figure 6: Polytec OFV-505, an advanced laser Vibrometer head, output signal.

Figure 5:Velocity signal measured on the chest area03-12-2014BMSPI, Dept. of E & IT 9

Measurement of Respiration Rate in Preterm Infants by Laser Doppler Vibrometry[5]

Figure 8: scheme and procedure.Figure 7: Setup of measurement. 03-12-2014BMSPI, Dept. of E & IT

10

Respiration Rate Measurement System UsingPyroelectric Transducer[6]

A polyvinylidene fluoride (PVDF) has faster response time than

those of traditional thermal devices.

A PVDF film has both piezoelectric and pyroelectric properties.

The difference of temperature can be best sensed by using

PVDF placed in front of the nostrils by means of a suitable

holding device.

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Respiration Rate Monitoring Gauze Mask

System Using Pyroelectric Transducer[6]

Figure 9: Experiment setup Figure 10:Waveform derived from belt system and experiment setup

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Impedance Pneumography Method[7]

The objective of this technique is to measure changes in theelectrical impedance of the person’s thorax caused by respirationor breathing.

In both of these methods, a high-frequency ac current is injectedinto the tissue through the drive electrodes.

This potential difference is related to the resistivity of the tissuebetween the voltage-sensing or receive electrodes.

The equivalent resistance is defined as the ratio of the voltagedifference between the two receive electrodes and the currentthat flows through the tissue.

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Impedance Pneumography Method[7]

Figure 11: (A) Two Terminal measurement (B) Four Terminal Measurement (C) Simulator output

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Capnography

The measurement is based on the absorption

property of infrared rays by certain gases (like

CO2, CO, and NO2).

When infrared rays are passed through the

expired air containing a certain amount of CO2,

some of the radiations are absorbed by it.

The detector changes the loss in heating effect of

the rays into an electrical signal.

Figure 12: Normal Capnogram

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Respiratory rate measurement using PPG signal[8]

Photoplethysmography(PPG) is themeasurement of blood volumetricchanges with each heartbeat.

The PPG pulse obtained by the opticalsensor is used for various cardiovascularparameter measurement.

Frequency domain analysis of PPG signalshows a two peaks first around 0.25 to0.35Hz and second at around 1 to 1.5Hz.

Figure 13: Frequency spectrum of the PPG signal

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Respiratory rate measurement using PPG signal[8]

Figure 14: System block diagram Figure 15: PPG of subject

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Conclusion

Several techniques have been developed for themeasurement.

The choice of a particular method depends upon theease of application of the transducer and their acceptanceby the subject under test.

Respiratory rate monitor using PVDF is cost-effective.

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References

[1] Cretikos M, Bellomo R, Hillman K, Chen J, Finfer S, Flabouris A, “Respiratory Rate: theneglected vital sign,” The Medical Journal of Australia Dec 2007.

[2] Ian Smith, John Mackay, Nahla Fahrid, Don Krucheck, “Respiratory rate measurement: acomparison of methods,” British Journal of Healthcare Assistants, vol 05 No 01, January2011.

[3] Bryson Padasdao, Olga Boric-Lubecke, “Respiratory Rate Detection Using a WearableElectromagnetic Generator ,“ International Conference of the IEEE EMBS Boston,Massachusetts USA, August 30 - September 3, 2011.

[4] Zhigang Zhu, Ning Xiang, “Detecting Voice, Heart Beats and Respiration by a Laser DopplerVibrometer,” Online.

[5] Lorenzo Scalise, Ilaria Ercoli, Paolo Marchionni, Enrico Primo Tomasini, Measurement ofRespiration Rate in Preterm Infants by Laser Doppler Vibrometry,”IEEE,2011

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References

[6] Y. P. Huang, M. S. Young and K. N. Huang, “Respiratory Rate Monitoring Gauze Mask System Based on a Pyroelectric Transducer,” IEEE, pp 1648-1649, 2008.

[7] Amit K. Gupta, “Respiration Rate Measurement Based on Impedance Pneumography,” Application Report, Texas Instruments, 2011.

[8] Nivedita Daimiwal, M. Sundhararajan and Revati Shriram, “Respiratory Rate, Heart Rate and Continuous Measurement of BP Using PPG,” International Conference on Communication and Signal Processing, IEEE, pp 999-1002 April 2014.

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