Xducers & P-Monitors

7/30/2019 Xducers & P-Monitors

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Signal Measurements

What is a Sensor?

A sensor is a device that senses change inenvironment.

What is a Detector?

Detector is a device or circuit that senses change inenvironment and compares the change to a reference.

What is a Transducer? It is a device or circuit that converts a physical quantity

onto a measurable electrical quantity.


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Quantities.Sensor

Heat.. Resistors

Light.. Photodiode

Pressure. Piezoelectric crystal

Sound. Piezoelectric crystal

Chemicals. Ion Electrode

Biopotential. Skin electrode

Magnetic field. Coil

Etc..


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Human Vital Signs

What are the human measured vital signs?

ECG, SpO2, NIBP, Resp., Temp.

Why are vital signs important?

Vital signs give an indication of the patient

status: improvement or retardation, dead oralive.


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ECG

Before heart contraction, heart generateselectrical activity, this activity of arterial andventricular potential is transported to skin byhuman tissue.

Electrocardiogram (ECG) is the chart of heartelectrical activity per beat, taken by skin surfaceelectrodes and recorded by Electrocardiograph.

The Most importance of ECG is that it can help todiagnose arrhythmia.


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ECG Block Diagram

Pre-

AmplifierAmplifier Filtering

Display


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NIBP


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Blood Pressure

Blood Pressure is the measurement of blood

systolic and diastolic pressure during blood

circulation.

BP gives an indication of the hearts ability to

pump blood all around the body.

Types of BP are: NIBP and IBP.


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NIBP

It is the use of an inflatable bladder cuff tied

to the upper arm mainly and inflated with the

help of an air pump.

The cuff is inflated to a pressure initially in

excess of the systolic arterial pressure, and

then reduces to below diastolic pressure over

a period of about 30 seconds.


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NIBP Principle

When blood flow is nill, or unimpeded ,

pressure will be essentially constant. When

blood flow is present, but restricted, the cuff

pressure, which is monitored by the pressure

sensor, will vary periodically in synchrony with

the cyclic expansion and contraction of the

brachial artery.


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IBP Principle

Arterial blood pressure (BP) is most accuratelymeasured invasively through an arterial line.Invasive arterial pressure measurement is

done with intravascular cannulae. The cannulae must be connected to a sterile,

fluid-filled system, which is connected to anelectronic pressure transducer.

Again the pressure exerted by blood on thefluid will trigger the pressure sensor.


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Pulse Oximetry


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SpO2

A pulse oximetere is a medical device that indirectlymeasures the amount of oxygen in a patient's blood.

It is often attached to a medical monitor so staff cansee a patient's oxygenation at all times.

Oximetry is not a complete measure of respiratory

sufficiency. A patient suffering from hypoventilation,given 100% oxygen can have excellent blood oxygenlevels while still suffering from respiratory acidosis dueto high level of carbaminuheamoglobin.


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SpO2 Principle

it has a pair of small LEDs facing a photodiode

through a translucent part of the patient's body.

One LED is red (660 nm), and the other is

infrared(940 nm). Absorption at these wavelengths differs

significantly between oxyhemoglobin and its

deoxygenated form, therefore from the ratio ofthe absorption of the oxy/deoxyhemoglobin a

ratio can be calculated.


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Respiration Measurement


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Breath Count

The Respiration parameter in the patient

monitor just indicate the number of breaths

per minute the patient breath.

It takes use of the attached ECG cable to

calculate the chest resistance across the

diaphragm during inspiration and expiration.


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Body Temperature


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Body Temperature

By using a temperature sensor made of two

metals of different composition, the body

temperature is taken to the circuits inside the

machine to be processed and displayed.


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Thank You

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Xducers & P-Monitors