Pulse oximeter - uses, types, history, dimensions & precautions

What is pulse oximeter?

A pulse oximeter is a medical device that is used to measure a person's heart rate and blood's oxygen saturation level (spO2). It is a small, portable device that is commonly clipped to a fingertip or earlobe. Pulse oximeters are frequently used in healthcare units and at home by patients to monitor their oxygen levels, particularly for those with respiratory problems or during physical activity. After the exposure of COVID-19, a global pandemic the use of pulse oximeter has been increased at home by patients who are home quarantined.

Overview / Product Profile of pulse oximeter:

Pulse oximeter is a small, portable device that commonly clipped to a fingertip, earlobe and sometimes also on toe. It works by emitting light waves that travel through your skin and blood vessels. The pulse oximeter is capable of measuring the oxygen saturation level because oxygenated blood absorbs light differently than deoxygenated blood. Additionally, it calculates your heart rate by identifying the rhythmic variations in blood volume.

A pulse oximeter typically works as follows:

1) Light emission:Through a sensor typically attached to a person's finger, earlobe, or other body part with good blood flow, the pulse oximeter emits two separate wavelengths of light, typically red and infrared, into the tissue.

2) Light absorption: The amount of light at certain wavelengths that is absorbed by oxygenated and deoxygenated haemoglobin in blood varies. The pulse oximeter's photo-detector calculates the amount of light that enters the tissue and reaches it.

3) Calculation: The pulse oximeter measures the ratio of absorbed light at each wavelength and establishes the blood's oxygen saturation level. By examining the fluctuations in the observed light intensity that correlate to the pulsatile characteristic of blood flow, it also calculates the user's pulse rate.

4) Display: The pulse oximeter's screen shows the heart rate and oxygen saturation level in real time. The usual range for healthy people is 95% to 100% when oxygen saturation is stated as a percentage.

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Dimensions:

The dimensions of standard pulse oximeter are:

Length: 

The length of a typical pulse oximeter can range from 2 inches (5 cm) to 4 inches (10 cm).

Width: 

The width of a pulse oximeter is typically around 1 inch (2.5 cm) to 2 inches (5 cm).

Height/Thickness:

 The height or thickness of a pulse oximeter is often around 1 inch (2.5 cm).

Note: The above dimensions may vary slightly depending on the manufacturer and specific design of the device. It's always advisable to consult with the manufacturer's specifications and guidance for accurate measurements.

Uses of pulse oximeter:

1) Monitoring of Oxygen: The main function of a pulse oximeter is to keep track of the blood's level of oxygen saturation, also known as SpO2 (peripheral capillary oxygen saturation). This measurement aids in determining how efficiently oxygen is delivered to the body's tissues and organs. Monitoring oxygen levels and making sure patients are receiving appropriate oxygen therapy are particularly helpful for people with respiratory diseases including chronic obstructive pulmonary disease (COPD),  , or pneumonia.

2) Diagnosis and Assessment: Pulse oximeters are used by medical experts to help in the diagnosis and evaluation of a variety of medical disorders. They can aid in detecting hypoxia (low oxygen levels) or difficulties brought on by respiratory distress. The severity of respiratory diseases is assessed using pulse oximetry values, along with other clinical examinations, to help determine the best course of treatment.

3)Anaesthesia and Critical Care: Pulse oximeters are essential tools in the administration of anaesthesia during procedures and in intensive care units (ICU). During procedures, anaesthesiologists use them to keep an eye on the patient's heart rate and oxygen saturation levels, assuring the patient's safety and maximising oxygen delivery.

4) Sleep Disorders: Pulse oximeters are sometimes used in the diagnosis and management of sleep disorders, such as sleep apnea.

5) Sports and fitness: Athletes and fitness lovers use pulse oximeters to keep an eye on their heart rates and oxygen saturation levels while engaging in physical activity. Individuals can gauge their workout intensity, endurance, and recuperation by monitoring their oxygen saturation and heart rate. This knowledge can be used to enhance workout regimens, track performance, and ensure safety while engaging in strenuous exercises or activities performed at high altitudes.

Types of pulse oximeter:

There are primarily two types of pulse oximeters available:

Finger Pulse Oximeter:

The most popular and commonly used kind is the finger pulse oximeter. They attach to the tip of the finger and are compact, portable gadgets. They typically comprise of a clip with an integrated sensor that emits and detects light, a screen that displays the oxygen saturation (SpO2) percentage and pulse rate, and occasionally a small button for setting adjustments. The finger pulse oximeter is simple to use and appropriate for both clinical and home use.

Handheld Pulse Oximeter:

Handheld pulse oximeters are comparatively larger than finger pulse oximeters and frequently have a display screen that may be carried in the hand or set on a stand. They are frequently employed in clinical environments, such hospitals or clinics, where it may be necessary to frequently monitor a number of patients. Handheld pulse oximeters typically contain extra functions, such as data recording and analysis capabilities, and can link to external devices for data transfer or integration with patient monitoring systems.

Both handheld and finger pulse oximeters deliver precise and reliable oxygen saturation readings. The majority of handheld pulse oximeters, however, are more advanced and provide further features appropriate for usage in the medical industry.

Precautions with pulse oximeter:

1) Positioning: Follow the manufacturer's directions to place the pulse oximeter correctly on your finger, earlobe, or other suitable body region. Check any obstacles that can affect the sensor's readings, such as nail polish, dirt, or extreme movement.

2) Cleanliness: Keep the sensor area clean and free from dirt, oils, or lotions that could affect the accuracy of the readings. Wipe your finger or the sensor site with a clean, dry cloth before using the pulse oximeter.

3) Ambient Light: To ensure accurate results, keep the pulse oximeter sensor away from bright, natural or artificial light. Use the pulse oximeter in a well-lit area or adhere to the lighting requirements specified by the manufacturer.

4) Movement: During the measurement process, avoid moving your hand or finger. Excessive movement can cause measurements to be off. Avoid talking or moving about a lot when using the pulse oximeter, and try to sit or lie down in a comfortable position.

5) Temperature: The accuracy of pulse oximeter results might be impacted by extreme temperatures. Ensure that the appliance is used within the manufacturers recommended temperature range.

6) Blood Circulation: Inaccurate readings can be caused by poor blood circulation or by diseases like Raynaud's disease or hypotension that alter peripheral blood flow. Consult a healthcare provider if you have any questions about your circulation.

7) Calibration and maintenance: For pulse oximeter calibration, upkeep, and battery replacement, according to the manufacturer's recommendations. To guarantee accurate readings, check the batteries frequently and swap them out as necessary.

8) Medical Advice: Keep in mind that a pulse oximeter should only be used as a tool for measuring oxygen saturation and pulse rate and not as a replacement for qualified medical guidance. Consult a healthcare provider if you are worried about your health or the results of the pulse oximeter.

History of pulse oximeter:

The invention of the pulse oximeter and the subsequent development of the technology began in the 1970s.

In the 1930s, it was first suggested that blood oxygen saturation levels may be determined by measuring light absorption. However, important advancements in the creation of a useful and precise device weren't made until the 1970s. The first pulse oximeter was created in 1972 by a Japanese bio-engineer named Takuo Aoyagi. Aoyagi's pulse oximeter sent light through a patient's tissue, usually a finger or earlobe, using two light emitting diodes (LEDs) of different wavelengths—one red and one infrared.

The hypothesis behind pulse oximetry is based on how differently oxygenated blood and de-oxygenated blood absorb light. De-oxygenated haemoglobin absorbs more red light and permits more infrared light to pass through, whereas oxygenated haemoglobin absorbs more infrared light and permits more red light to pass through. The device can determine the blood's oxygen saturation level by calculating how much light is absorbed by the blood.

Pulse oximeters improved significantly in the 1980s, becoming more portable, inexpensive, and trustworthy. More precise measurements and better user interfaces were made possible by the invention of microprocessors and digital signal processing. As a result, hospitals, clinics, and emergency medical services began to use pulse oximeters more frequently.

Pulse oximeters have developed and incorporated cutting-edge technologies over time. Patients can now check their oxygen saturation levels at home or while engaging in physical activity because to the devices' smaller, more portable, and user-friendly developments. A graphical display, alarm systems to notify healthcare professionals of unusual readings, and the capacity to store and analyse data are all common elements of contemporary pulse oximeters.

The COVID-19 pandemic in recent years brought to light the significance of pulse oximeters as a home monitoring device for patients with respiratory symptoms. They were frequently used to gauge oxygen saturation levels and spot the first indications of oxygen desaturation, assisting in the identification of people who might need medical attention.

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Frequently Asked Questions (FAQs)

What does Pulse Oximeter measure?

A pulse oximeter measures two vital parameters: oxygen saturation and pulse rate. Oxygen saturation, often referred to as SpO2, is the percentage of oxygen-carrying hemoglobin in the blood compared to the maximum capacity. It indicates how effectively oxygen is being transported to various parts of the body. The pulse rate, also known as the heart rate, measures the number of times the heart beats per minute and provides information about the overall cardiovascular health.

Which finger to use for Pulse Oximeter?

The index finger is commonly used for placing the pulse oximeter sensor. However, in situations where the index finger is not suitable, other fingers such as the middle finger or ring finger can also be used as alternatives.

What if Pulse Oximeter reading is too low?

A low pulse oximeter reading indicates insufficient oxygen levels in the blood, requiring immediate medical attention.

What is normal range for Pulse Oximeter?

The normal range for a pulse oximeter, which measures oxygen saturation level in the blood, is typically between 95% and 100%.

What are the two readings in Pulse Oximeter?

A pulse oximeter typically provides two readings:

1.Oxygen Saturation level (SpO2) in bloodstream

2.Pulse rate or Heart rate

What is PI in Pulse Oximeter?

In pulse oximeters, PI stands for Perfusion Index. It is a numerical value that represents the strength of the pulse signal detected by the oximeter. The Perfusion Index measurement is often displayed as a percentage or a numerical value ranging from 0.1 to 20. A higher Perfusion Index indicates a stronger pulsatile signal and suggests better blood flow to the monitored area.

Where to place Pulse Oximeter on newborn / baby / infants?

The pulse oximeter sensor should be placed on a newborn's, baby's, or infant's foot or hand. Specifically, it should be placed on the foot if the baby is over 2.5 kg (5.5 lbs) or on the hand if the baby is under 2.5 kg (5.5 lbs). The sensor should be snug but not too tight, and the baby's foot or hand should be warm and dry. It's important to follow the healthcare professional's guidance when using a pulse oximeter on a newborn, baby, or infant.

How to read Pulse Oximeter?

Does anaemia affect Pulse Oximeter reading?

Yes, anaemia can affect pulse oximeter readings. Since anaemia is characterized by a reduced number of red blood cells or a decrease in their ability to carry oxygen, it can lead to lower oxygen saturation levels. This can result in a lower SpO2 reading on a pulse oximeter.

Who invented Pulse Oximeter?

The pulse oximeter was invented by Takuo Aoyagi, a Japanese bioengineer, in the 1970s while working at Nihon Kohden Corporation.