This document discusses pulse oximetry, which measures the amount of oxygenated hemoglobin in the blood. It describes how the first oximeter was introduced in 1935 and improved upon in 1972. A pulse oximeter uses light-emitting diodes and photodetectors to measure how much red and infrared light is absorbed by oxygenated and deoxygenated hemoglobin, allowing it to calculate blood oxygen saturation levels in a non-invasive manner based on Beer-Lambert law. The principles, components, procedure, factors affecting readings, and purposes of pulse oximetry are outlined.

1. PULSE
OXIMETRY
Akash Sardar
Student(4th Year)
Bio Medical Engineering Dept.

2. INTRODUCTION
The first oximeter was introduced by
Karl Matthews –in the year 1935.
 First oximeter to measure O2
saturation.
Dr.Takuo Aoyagi (1972)
 Pulsatile changes in absorption of
red and infra-red light to measure
arterial oxygen saturation.

3. PULSE- OXIMETER
A pulse-oximeter measures the
amount of saturated oxygen in blood.
It is a non-invasive method.
 It depends on The combination of
both Beer’s Law and Lambert’s Law.

4. BEER-LAMBERT LAW
 The combination of both Beer’s Law and
Lambert’s Law
 Beer-Lambert’s Law– The absorption of
light is proportional to the concentration
and thickness of the sample.

6. THE INSTRUMENT

7. PRINCIPLES
 Pulse oximetry is based on the differential
absorption of light by oxyhemoglobin and
deoxyhemoglobin.
 The oxygenated blood absorbs red light
while the deoxygenated blood absorbs
infrared light.

8. PRINCIPLES
 Pulse oximeter
consists of two
light emitting
diodes at
660nm&
940nm.
 Isobestic point.

9. BLOCK DIAGRAM

10. PROCEDURE
A photo detector in the sensor measures
unabsorbed light from the LEDs.

11. PROCEDURE
The resulting signal is inverted and
resembles as per the diagram below.

12. BLOOD CONCENTRATION

13. FACTORS EFFECTING THE PULSE
OXIMETER READING
 Major body motion .
 Blood flow blocked due to pressure on arms
or fingers .
 Probe attached incorrectly .
 Excessive ambient light (panel lamp,
fluorescent lamp, infrared heating lamp,
direct sunlight, etc.)

14. PURPOSE OF THE PULSE
OXIMETER
Screening for sleep apnea syndrome.
Hospitalization of patients with chronic
respiration diseases.
If a patient’s blood oxygenation is
unstable.
Home oxygen therapy.

15. THANK YOU