What is a Pulse Oximeter?
A pulse oximeter is a small, lightweight medical device that easily attaches to a patient’s finger or earlobe. It is used to measure two things – oxygen saturation of the blood and pulse rate. Oxygen saturation, also known as SpO2, measures the percentage of oxygenated hemoglobin in the blood relative to the total amount of hemoglobin. Normal SpO2 levels for healthy individuals range from 95% to 100%. Pulse rate is a measurement of heart rate in beats per minute.
How Does it Work?
A pulse oximeter uses a source of light, usually red and infrared, and a light detector to pass light through the skin and measure how much light is absorbed by blood. Deoxygenated hemoglobin absorbs more infrared light while oxygenated hemoglobin absorbs more red light. By measuring the amount of light absorbed at each wavelength, the oximeter can calculate the concentrations of oxygenated and deoxygenated hemoglobin and determine oxygen saturation.
At the same time, each time the heart beats, more blood flows through the blood vessels which changes the absorption of light. The Pulse Oximeter detects these changes in absorption over time and calculates the pulse rate. Modern pulse oximeters do these light absorption measurements and calculations very quickly through advanced microprocessors allowing continuous, non-invasive monitoring of oxygen levels and pulse.
Components of a Pulse Oximeter
All pulse oximeters contain three main components – a light emitter, a photodetector, and a microprocessor. The light emitter, usually a pair of LED lights, one red and one infrared, shines light into the skin. The photodetector, positioned on the opposite side, detects the amount of light that passes through and is not absorbed by tissue and blood. It converts the light signal into an electrical signal sent to the microprocessor. The microprocessor then analyzes the signals to calculate oxygen saturation and pulse rate values displayed on an LED or LCD screen. Some oximeters may also include memory to store readings and allow downloading of data. Advanced models offer additional features like alarms and storage of historical trend data.
Accuracy and Advantages
When used properly on appropriate tissue sites like fingers, earlobes or toes, pulse oximetry provides a very accurate, non-invasive way to monitor blood oxygen levels and pulse. Accuracy ranges from 2-3% for most oximeters. This allows for detection of both hypoxemia (low oxygen) and pathological states like anemia. Pulse oximetry is also very useful for monitoring patient oxygen therapy and response to treatment. Other key advantages include ease of use at the bedside or in transportation, continuous monitoring capability, display of simultaneous readings, cost-effectiveness and portability.
Limitations and Alternative Technologies
Though very useful, pulse oximetry does have some limitations. Readings can be affected by things like poor circulation, skin pigmentation, nail polish, motion artifact and low perfusion states. Nail beds may not always provide accurate readings too. In very severe hypoxemia, readings may actually be higher than actual oxygen levels. Alternative techniques like measuring oxygen levels in arterial blood samples via an arterial blood gas analysis provide more accurate readings but are more invasive. Newer technologies like mobile apps employing photoplethysmography are exploring non-invasive ways to supplement pulse oximetry.
Pulse oximetry provides a simple, affordable and effective way to continuously monitor blood oxygen saturation levels and pulse rate at the bedside or during transport. Though not 100% accurate in all conditions, most modern pulse oximeters have very good accuracy when used appropriately. It has become an indispensable tool in medical monitoring, from spot-checking in general practice to closely tracking patient response to treatment in critical care settings. With technological advances, pulse oximetry will continue evolving to provide even more useful features and monitoring capabilities.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
About Author – Ravina Pandya
Ravina Pandya,a content writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemicals and materials, etc. With an MBA in E-commerce, she has expertise in SEO-optimized content that resonates with industry professionals. LinkedIn Profile