An electrical impedance based neonatal respiration monitor for pneumonia detection Shahnaj Parvin, Ahamad Imtiaz Khan, Kamrul Hussain, M Abdul Kadir and K Siddique-e Rabbani Department of Biomedical Physics & Technology, Dhaka University, Dhaka, Bangladesh. Email: [email protected] Second WHO Global Forum on Medical Devices 22-24 November 2013, Geneva, Switzerland Poster No. H.06 Abstract No: 169823 Abstract There is no good detection technique for pneumonia as yet, particularly for neonates and babies in low resource countries where qualified doctors are not available. X-ray, normally used in conjunction with other symptoms, is not available either. Respiration rate in conjunction with other symptoms can give a diagnosis, and electronic equipment interface is needed for a telemedicine system, but a baby cries on connecting diagnostic equipment, which changes the respiration rate jeopardising the measurement. We developed an electrical impedance based technique using an innovative palm-worn electrode probe mounted on a flexible rubber pad and covered by a cotton sheet, to be worn by the mother or a nurse, using a Velcro strap. Necessary electronic circuitry, computer interface and software were also developed. As the mother touches the baby’s thorax using this palm-worn electrode pad the impedance variation of lungs with respiration is displayed and recorded in a computer. Later, using signal processing techniques the respiration rate is obtained from acquired data. Pulsating blood flow also creates changes in the data and heart beat rates may also be extracted from the same measurement. Four electrode impedance measurement technique was employed where current is passed through two electrodes and the potential is measured between the other two. Measurement on a 2 year child and a 2 month old baby were successful – they did not cry! Introduction Looking for a cue: Major symptoms of Pneumonia • Unusually rapid breathing (in some cases, this is the only symptom) • Increased body temperature (fever) • Severe chest indrawing • Cough Pneumonia kills 1.2m every year 1 (<5yrs age) Mostly in low resource countries In rural areas X-ray not available Doctors not available Correct diagnosis difficult Over or Under medication NEED TO LOOK FOR ALTERNATIVE DIAGNOSTIC TECHNIQUE, ALSO SUITABLE FOR TELEMEDICINE IN LOW RESOURCE REGIONS Considerations: Accurate measurement of respiration rate may help diagnosis Eye estimation not always reliable Attachment of equipment makes a baby cry changes respiration rate jeopardises measurement. Our objective: To develop a simple method for respiration rate monitoring leading to detection of pneumonia Should be suitable for rural areas, by operators with a little training Should have PC interfacing capability for Telemedicine Should not make a baby cry during measurement Our thinking: Electrical impedance of lungs changes on breathing. So employ such measurement to get respiration rate . Innovate a special palm-worn electrode probe, to be worn by the mother or a nurse who will hold or touch the baby on the thorax. Employ the same electrodes to detect heart rate if possible . Employ the same probe to perform Focused Impedance Measurements (FIM), conceived and developed at our laboratory earlier to detect non-ventilating masses in the lungs. V I Methods and Materials Tetra-polar Electrical Impedance Measurement (TPIM) placing 4 electrode as shown. Constant current at 10kHz ( 1mA) applied across a pair of adjacent electrodes. Potential measured across opposite pair of electrodes. References 1. United Nations Inter-Agency Group for Child Mortality Estimation. Levels and trends in child mortality report 2012, United Nations Children’s Fund. 2. Molholland E K et al. Standardized diagnosis of pneumonia in developing countries, The pediatric infectious disease journal, 1992 11(2), p 77-81 Discussion and Conclusion The main challenge of the present work was to measure the respiration rate without upsetting the babies and we have achieved this objective successfully. The measured Respiration Rate (RR) together with temperature and chest movement can be used as diagnostic tool for screening pneumonia in children. For rural areas where medical doctors are not available, the measured data can be transferred real time through telemedicine to a doctor. The same system with small modifications may be used to study localised lung ventilation indicating presence of any masses in the lung. Measurement from outside skin, Non-invasive Contact impedance eliminated in TPIM. Impedance of the central region around the 4 electrodes contributes more to measurement. Depth sensitivity gives lung information. Change of Localised transfer impedance between inspiration and expiration indicates ventilation of the lungs and indirectly indicates presence of any mass (if the change is less than normal for the particular location) If the measurement system can be made with very low noise, it may be possible to detect heart rate through pulsating blood flow in the arterioles and capillaries under the skin, as the electrical impedance changes with the amount of blood underneath. Results & Observations Raw plot of lungs ventilation measured on a 2 month old baby just recovered from pneumonia is shown below. Lower figure gives the FFT showing a peak at 0.6 Hz which is the one from respiration. This corresponds to a rate of 36 per minute. Verification The respiration rate was also measured manually looking at the chest and counting the breathing changes. The was noted using a watch. The value was similar, about 36 per sec. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 30 60 90 120 150 180 Frequency, Hz Rate per min Amplitude, arbitrary scale 1 0 2 Time, Sec Amplitude, arbitrary scale Further development The data acquisition software was enhanced to give a better graphical output with axes and grids. A switchable 50Hz notch filter was achieved using software. The respiration rate is displayed numerically after performing the FFT analysis and automatically choosing the position of the first peak. The top figure to the right shows the graphical respiration pattern and numerical value of rate from an adult, while the lower one shows that from a 2 year child (the child shown in the photograph, above-right), and the respiration rate. Noise reduction of circuitry being performed which may enable pulsating blood flow to be detected giving the heart rate as well. Electrodes and measurement Flexible Rubber pad with Velcro band. Metallic electrodes (Nickel coated Cu in the prototype, to be replaced by stainless steel). To make the pad comfortable to touch, covered with a cotton fabric with thick cotton buttons sewed at the location of the electrodes. The buttons were soaked with drops of saline for conduction. The mother or a nurse wears the electrode in the palm and either holds the baby touching the backside of the thorax with the electrodes, or places the hand with the electrodes on the chest of a lying baby or a sitting child. 18
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An electrical impedance based neonatal respiration monitor for pneumonia detection Shahnaj Parvin, Ahamad Imtiaz Khan, Kamrul Hussain, M Abdul Kadir and K Siddique-e Rabbani
Department of Biomedical Physics & Technology, Dhaka University, Dhaka, Bangladesh. Email: [email protected]
Second WHO Global Forum on Medical Devices 22-24 November 2013, Geneva, Switzerland Poster No. H.06 Abstract No: 169823
Abstract
There is no good detection technique for pneumonia as yet,
particularly for neonates and babies in low resource countries
where qualified doctors are not available. X-ray, normally used in
conjunction with other symptoms, is not available either.
Respiration rate in conjunction with other symptoms can give a
diagnosis, and electronic equipment interface is needed for a
telemedicine system, but a baby cries on connecting diagnostic
equipment, which changes the respiration rate jeopardising the
measurement. We developed an electrical impedance based
technique using an innovative palm-worn electrode probe
mounted on a flexible rubber pad and covered by a cotton sheet,
to be worn by the mother or a nurse, using a Velcro strap.
Necessary electronic circuitry, computer interface and software
were also developed. As the mother touches the baby’s thorax
using this palm-worn electrode pad the impedance variation of
lungs with respiration is displayed and recorded in a computer.
Later, using signal processing techniques the respiration rate is
obtained from acquired data. Pulsating blood flow also creates
changes in the data and heart beat rates may also be extracted
from the same measurement. Four electrode impedance
measurement technique was employed where current is passed
through two electrodes and the potential is measured between
the other two. Measurement on a 2 year child and a 2 month old
baby were successful – they did not cry!
Introduction
Looking for a cue: Major symptoms of Pneumonia • Unusually rapid breathing (in some cases, this is the only
symptom) • Increased body temperature (fever) • Severe chest indrawing • Cough
Pneumonia kills 1.2m every year1 (<5yrs age)
Mostly in low resource countries
In rural areas X-ray not available
Doctors not available Correct diagnosis difficult Over or Under medication
NEED TO LOOK FOR ALTERNATIVE DIAGNOSTIC TECHNIQUE, ALSO SUITABLE FOR TELEMEDICINE IN LOW RESOURCE REGIONS
Considerations: Accurate measurement of respiration rate may help diagnosis
Eye estimation not always reliable
Attachment of equipment makes a baby cry changes respiration rate jeopardises measurement.
Our objective:
To develop a simple method for respiration rate monitoring leading to detection of pneumonia
Should be suitable for rural areas, by operators with a little training
Should have PC interfacing capability for Telemedicine
Should not make a baby cry during measurement Our thinking:
Electrical impedance of lungs changes on breathing. So employ such measurement to get respiration rate .
Innovate a special palm-worn electrode probe, to be worn by the mother or a nurse who will hold or touch the baby on the thorax.
Employ the same electrodes to detect heart rate if possible .
Employ the same probe to perform Focused Impedance Measurements (FIM), conceived and developed at our laboratory earlier to detect non-ventilating masses in the lungs.
V I
Methods and Materials
Tetra-polar Electrical Impedance Measurement (TPIM) placing 4 electrode as shown. Constant current at 10kHz ( 1mA) applied across a pair of adjacent electrodes. Potential measured across opposite pair of electrodes.
References 1. United Nations Inter-Agency Group for Child Mortality Estimation. Levels and
trends in child mortality report 2012, United Nations Children’s Fund.
2. Molholland E K et al. Standardized diagnosis of pneumonia in developing countries, The pediatric infectious disease journal, 1992 11(2), p 77-81
Discussion and Conclusion
The main challenge of the present work was to measure the respiration rate without upsetting the babies and we have achieved this objective successfully.
The measured Respiration Rate (RR) together with temperature and chest movement can be used as diagnostic tool for screening pneumonia in children.
For rural areas where medical doctors are not available, the measured data can be transferred real time through telemedicine to a doctor.
The same system with small modifications may be used to study localised lung ventilation indicating presence of any masses in the lung.
Measurement from outside skin, Non-invasive
Contact impedance eliminated in TPIM.
Impedance of the central region around the 4 electrodes contributes more to measurement. Depth sensitivity gives lung information.
Change of Localised transfer impedance between
inspiration and expiration indicates ventilation of the lungs
and indirectly indicates presence of any mass (if the change
is less than normal for the particular location)
If the measurement system can be made with very low
noise, it may be possible to detect heart rate through
pulsating blood flow in the arterioles and capillaries under
the skin, as the electrical impedance changes with the
amount of blood underneath.
Results & Observations
Raw plot of lungs ventilation measured on a 2 month old baby just recovered from pneumonia is shown below. Lower figure gives the FFT showing a peak at 0.6 Hz which is the one from respiration. This corresponds to a rate of 36 per minute.
Verification The respiration rate was also measured manually looking at the chest and counting the breathing changes. The was noted using a watch. The value was similar, about 36 per sec.
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0 30 60 90 120 150 180
Frequency, Hz
Rate per min
Am
plit
ud
e, a
rbit
rary
sca
le
1 0 2 Time, Sec
Am
plit
ud
e, a
rbit
rary
sca
le
Further development
The data acquisition software was enhanced to give a better
graphical output with axes and grids. A switchable 50Hz notch filter
was achieved using software. The respiration rate is displayed
numerically after performing the FFT analysis and automatically
choosing the position of the first peak.
The top figure to the right shows the graphical respiration pattern
and numerical value of rate from an adult, while the lower one
shows that from a 2 year child (the child shown in the photograph,
above-right), and the respiration rate.
Noise reduction of circuitry being performed which may enable
pulsating blood flow to be detected giving the heart rate as well.
Electrodes and measurement
Flexible Rubber pad with Velcro band. Metallic electrodes (Nickel
coated Cu in the prototype, to be replaced by stainless steel).
To make the pad comfortable to touch, covered with a cotton fabric
with thick cotton buttons sewed at the location of the electrodes. The
buttons were soaked with drops of saline for conduction.
The mother or a nurse wears the electrode in the palm and either
holds the baby touching the backside of the thorax with the
electrodes, or places the hand with the electrodes on the chest of a
lying baby or a sitting child.
18
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