What is a Pulse Oximeter?
What is a Pulse Oximeter?
This year, researchers at the University of Washington at Seattle found that of hospitalised patients with Covid-19, those with low blood oxygen saturations were 1.8 to 4.0 times more likely to die in hospital. This led many people to purchase pulse oximeters for use at home to check their blood oxygen saturation.
A pulse oximeter is a non-invasive device that can be used to measure the saturation of oxygen in the blood. They are easy to use and can be used by anyone, even people who aren’t medically trained.
In this article, we’ll cover how a pulse oximeter works and what they are used for.
What does a pulse oximeter measure?
A pulse oximeter is used to measure the percentage of oxygen in the blood (SpO2). Measuring the oxygen saturation of the blood is important to check that blood oxygen levels don’t dip too low.
A healthy person has no reason to think their blood oxygen saturation will dip to a dangerous level. Normal blood oxygen saturation is around 95% to 100%. If your blood oxygen is below 92% it’s an indicator of hypoxemia, a seriously low blood oxygen level, and could suggest a problem with breathing or circulation. If your blood oxygen saturation is 92% or below you should call 999.
Can a pulse oximeter detect heart rate?
Most pulse oximeters are also capable of measuring heart rate and will display this on the screen next to blood oxygen saturation. Pulse is measured in beats per minute (BPM). A normal adult heart rate is between 60 and 100 BPM, but generally, a lower resting heart rate is more healthy, indicating that your heart doesn’t have to work as hard to push blood around your body.
Who needs a pulse oximeter?
Pulse oximeters are used in medical settings like hospitals and emergency rooms to monitor patients’ conditions. They are also used in places like care homes for the same reason. Anyone can buy a pulse oximeter, and people who suffer from respiratory or circulator conditions often have one to monitor their own blood oxygen levels at home.
Conditions where blood oxygen saturation needs to be monitored:
- Lung cancer
- Asthma
- Pneumonia
- Arthritis
- Chronic obstructive pulmonary disease
- Cystic fibrosis
- Congestive heart failure
- Congenital heart disease
- Pulmonary fibrosis
- Pulmonary hypertension
People who suffer from these conditions might need to keep an eye on blood oxygen levels in particular when:
- Exercising or after exercising
- Transitioning from low to high altitudes
- They are unwell
The Nonin 2500 PalmSAT Pulse Oximeter is designed to be easy to use, even if you don’t have any medical training. It has a two-button operation and LED interface. It also comes with 72 hours of memory for storing multiple readings.
Can you use a human pulse oximeter on a dog?
We often hear people asking how to use a pulse oximeter on a dog, and whether they can use a pulse oximeter for human use on a dog. While it’s possible to measure a dog’s blood oxygen, you need to use a pulse oximeter designed for animal use specifically in order to get an accurate reading.
Pulse oximeters need proper contact with the skin in order to work, so any fur in the way will result in a failed or inaccurate reading. A study published by the National Library of Medicine found that the best pulse oximeter placement on a dog is the lip or tongue, but that ear, tail, and toe also offer acceptable sites if the dog is awake.
Can a pulse oximeter detect Afib?
Atrial fibrillation is a condition that results in an abnormally fast heart rate. The heartbeat could be considerably higher than normal and the rhythm of heartbeats is often chaotic when someone has atrial fibrillation.
A review on the limitations of pulse oximeters states that hospital-grade pulse oximeters are capable of detecting Afib through perfusing cardiac arrhythmias. However, it’s best to be examined by a doctor if you suspect you have Atrial fibrillation. You may experience racing or ‘fluttering’ sensations in your heart, dizziness, and tiredness if you have Atrial fibrillation.
What is Perfusion Index (PI) in pulse oximetry?
PI is the ratio of pulsatile blood flow to non-pulsatile static blood flow in someone’s peripheral tissue. There may be a decrease in pulsatile blood flow due to congenital disease or acquired constriction of major arteries. PI is read in percentages from 0.02%, a weak pulse; to 20%, a strong pulse.
Perfusion Index is useful to help determine the appropriateness of a site for pulse oximetry. A site with a high PI indicates that this would be an optimal place to measure pulse oximetry.
A pulse oximeter like the Nonin 2500 PalmSAT is ideal for use in hospitals, doctors’ offices, and care homes. It is compatible with Finger Clip Sensors, Flex Sensors, Soft Sensors, Forehead Sensors, Ear Clip Sensors, and Flexiform II Sensors making it highly adaptable for use on any site with a high PI.
The digital Pulse Oximeter: How it Works
When oxygen enters the body through the lungs it is passed onto red blood cells. Molecules in the red blood cells called haemoglobin are responsible for carrying oxygen around the body. Haemoglobin molecules carrying oxygen are called oxygenated haemoglobin.
Oxygen saturation is measured by calculating the percentage of haemoglobin which are carrying oxygen in the blood.
A pulse oximeter uses light to measure the saturation of oxygenated haemoglobin in the blood. The interior wall of one side of the pulse oximeter emits a beam of light that shines onto the other interior wall of the device. The light is received by a detector on this side of the device.
When a bodily extremity like a finger is positioned between these two sides the beam of light must pass through it to be received by the detector. Some of the light is absorbed by the finger and some passes through to the other side. The pulse oximeter calculates oxygen saturation depending on how much light is absorbed by the body.
A number of different physical factors affect how much light is absorbed by the body, including:
- The density of the object absorbing the light
- The length of the light path
- The number of oxygenated and deoxygenated haemoglobin in the bloodstream
Haemoglobin absorbs light, so the more haemoglobin there is in the bloodstream the less light will be received by the detector. The amount of light is also diminished if the artery it passes through is wider.
A pulse oximeter uses different wavelengths to measure levels of oxyhaemoglobin and deoxyhaemoglobin in the blood. oxyhemoglobin absorbs more infrared light and deoxyhemoglobin absorbs more red light.
Two light beams are used to analyse haemoglobin: red and infrared light. The device measures how much red light is absorbed versus how much infrared light is absorbed when the two light beams pass through the finger.
What is a Pulse Oximeter?
In this video, we’ll cover how a pulse oximeter works and what they are used for.
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