What is a Pulse Oximeter?
Health awareness is more and more in the focus. So it happens that many people want to control their vital signs at home. In addition to devices for blood pressure measurement, there are pulse oximeters. These show you, in addition to the current pulse rate, the oxygen saturation of the blood. This value is a good body with oxygen supply. Especially in chronic lung diseases, asthma or sleep apnea syndrome, this value is important. Also, more and more athletes are about to monitor their vital signs in training, to make the training even more effective.
There are different models of the pulse oximeter, so you can measure a finger or wrist. In our comparison, we present 6 pulse oximeters in detail. In the following guide, we will show you how pulse oximeters work and how to find the right model for you. Besides, you can check the criteria for buying the pulse oximeter and the current pulse oximeter tests.
1. PULOX PO-200 Pulse Oximeter with Rotating Display
The PO-200 from PULOX is a pulse oximeter with a finger clip. The little device can simply be used to measure your pulse and your oxygen saturation. On the left, you see your oxygen saturation in percent and on the right your pulse in beats per minute. When you turn the device, the display also rotates. So you can read the values from every perspective. The OLED display shows the pulse wave and the values in large numbers. The oxygen saturation values are measured within a measuring range of 35 to 99 percent. The pulse rate is 30 to 250 beats per minute in a wide range of measurement that many other devices offer in our comparison.
There are different variants of the pulse oximeter. This model measures your vital signs directly as a finger clip. There are other models with an extension of the measuring sensor or the devices that measure at the wrist. In our guide, we show you the respective characteristics of these devices.
According to the manufacturer, the batteries last up to 40 hours in continuous operation. If you do not use the pulse oximeter for a long time, it will switch off due to the battery saver function. The package includes a bag, a case, a silicone case, a carrying strap, the user manual, and batteries. This model measures 57 x 33 x 32 millimeters and weighs 50 grams, making it easy to handle.
The measurement of the pulse takes place in bpm. That means “beats per minute” or in German “beats per minute”. The value also indicates how often your heart beats within a minute.
2. Medisana PM 100 Pulse Oximeter with Versatile Adjustable Display
The Pulse Oximeter by Medisana measures your oxygen saturation and your heart rate. On the display, you can display the values either as a bar chart or as a wave chart. Also, six display variants can be set. The PM 100 pulse oximeter has a one-touch operation. You can switch it only with finger pressure and then measure your vital signs. The device is designed as a finger clip, so it’s easy to use. You can set ten brightness levels in the display. So you have a readable display even in sunlight.
The visual representation of the pulse and oxygen saturation in the form of curves, you can see if the sensor is right. If the waves or bars are visible, the sensor is in the right place. The following waves or bars may cause the sensor to be misplaced or blood pressure low. Further possible measuring errors of the pulse oximeter can be found in the guideline section of this comparison.
The measurement range of oxygen saturation is this device between 70 and 100 percent. The pulse rate is measured in the range of 30 to 235 beats per minute (bpm). The PM 100 from Medisana has a battery-saving automatic switch-off. It is 5.8 x 3.4 x 3.5 inches tall and weighs 53 grams. This allows you to take it anywhere in your pocket or trouser pocket. The scope of delivery includes the pulse oximeter PM 100, a carrying strap, batteries, and the operating instructions.
3. Beurer PO 40 Pulse Oximeter Helps with a Smooth Measurement
The Beurer pulse oximeter from Beurer uses the finger clip to measure your current pulse rate and oxygen saturation. It also determines the pulse modulation index. To turn on the device you only need a finger pressure and the sensor starts measuring. The values are displayed on the large, colored display. As they are displayed, you can specify any of the six setting variants. The brightness of the display can be adjusted to your environment with ten settings. The pulse rate measures the device in a range of 30 to 250 strokes and the measuring range for the oxygen saturation is 70 to 100 percent. The pulse modulation index measures between 0.3 and 20 percent.
The measurement by pulse oximetry should be done at rest so that the values are meaningful. The Beurer pulse oximeter displays symbols as soon as the measurement becomes too restless. This is important so you do not mistakenly interpret incorrect values as correct.
This model is powered by two AAA batteries. To protect these, an automatic switch-off is integrated into the device. The PO 40 from Beurer has compact dimensions of 57 x 35 x 30 millimeters and weighs 55 grams in the average range. The scope of delivery includes a belt pouch and a band for hanging.
4. Kungfuren Pulse Oximeter with Color Display
The pulse oximeter from Kungfuren is a total of 6.0 x 3.5 x 3.2 inches and weighs 50 grams. This makes it handy, so you can take it on walks or vacation. The values determined are displayed in bar and waveform and can be read on the color display. The pulse rate is determined in a measuring range of 30 to 250 beats. Oxygen saturation is measured by the Kungfuren pulse oximeter in a good range of 35 to 100 percent.
The display of the measured values takes place within 10 minutes. This fast display is especially important in emergencies so that the necessary measures can be taken as quickly as possible.
For operation, the pulse oximeter requires two AAA batteries. According to the manufacturer, this energy ensures operation for over 20 hours. If you do not use the device for more than 16 seconds, it will switch off automatically. The package includes a user manual, a silicone case, and a storage bag.
Yes, as soon as you turn the pulse oximeter, the display will turn. So you can always read the values well.
5. Beurer PO 30 Pulse Oximeter with Battery Change Indicator
The Beurer Pulse Oximeter PO 30 determines your current oxygen saturation and pulse rate. Also displayed are the pulse column and the pulse wave. You can read the measured values from a colored display. As soon as you turn the device, the display changes automatically so that you can see the values well at all times. The color display has four view perspectives and two representations. The brightness of the display can be adapted to your environment. The dimensions of the Beurer PO 30 are 61 x 36 x 32 millimeters and the weight is around 57 grams.
According to the manufacturer, the pulse oximeter is powered by three AAA batteries. The battery compartment is located on the bottom of the device so you can easily insert or change the batteries. The display shows how full the batteries are left. If they are empty, it will also be displayed so that you can change the battery early. Beurer grants a 5-year warranty on the device.
The measurement range of the vital signs is indicated by some providers as follows:
- Oxygen saturation: 0 to 100 percent
- Pulse frequency: 0 to 254 beats per minute
6. PULOX PO-300 Pulse Oximeter for Long-Term Measurements
The PULOX PO-300 is the highest-priced model in our comparison. But it also offers you interesting features. This allows you to observe your vital signs over a longer period. For this purpose, the PULOX PO-300 has internal memory. A CD containing software for your Windows PC is included in the delivery. With it, you can load all data on your PC and print out there for the next doctor’s visit. Oxygen saturation levels are measured by this pulse oximeter in a range of 35 to 99 percent. The measurement range of the pulse rate for this device is between 30 and 250 beats per minute.
The device offers an alarm function, which you can define independently. This alerts you if your values fall below your norms. Your norm values may differ from the general norms due to illnesses. In our guide, you will later learn in which area the measurement results are optimal and who defines your limit values.
The pulse oximeter is powered by a battery. You can charge this either on the PC or via a charging cable. A battery charge should last for up to 24 hours according to the manufacturer. The determined values can be read on a large color display. The color display in the OLED display is rotatable so that you can always easily recognize your values. The pulse is displayed wavy.
These are the dimensions of the pulse oximeter PO-300:
- Size: 57 x 32 x 30 mm
- Weight: 50 grams including battery
What is a pulse oximeter and how does it work?
A pulse oximeter is a device that allows you to measure the oxygen saturation of the arterial blood without the need for arterial blood sampling. These devices show you the current pulse rate. Depending on the device, there is an extension with a clip or adhesive sensor. Smaller, handy devices can be opened so that you place your finger directly into the device.
The measurement of the oxygen content is carried out by light remission. On one side of the sensor or clip are two monochromatic LEDs emitting light of different wavelengths. Red light and an infrared LED are used. On the other side of the clip, a sensitive photodiode is mounted, which measures the incoming light components.
In the blood, more precisely in the red blood cells, is hemoglobin. This blood component ensures that oxygen can be transported in the blood. However, not every hemoglobin particle carries oxygen. When loaded with oxygen, it is called oxygenated hemoglobin. Without oxygen, it is called deoxygenated hemoglobin. These two forms absorb the wavelengths of the lights differently.
Deoxygenated hemoglobin absorbs red light much better than oxygenated. Infrared radiation is increasingly absorbed by oxygenated light. The photodiode detects which light arrives at which parts and thus has not been absorbed. In this way, the oxygen saturator can calculate how high the oxygen saturation in the blood is.
The absorption of light does not depend solely on the oxygen loading of hemoglobin. The skin and other tissue influence it. A pulse oximeter, therefore, does not measure the absolute value but the relative value. Blood flow is important for the relative value, so the devices measure oxygen saturation and pulse rate simultaneously. The oxygen saturation value measured by the instrument is called SpO2. It is not to be confused with oxygen saturation, which was determined by utilizing a blood test. This value is called the SO2. For a meaningful measurement, the two lights mustn’t come into contact with the ambient light. For this reason, the sensor is designed in the form of a clip or as an adhesive sensor, since they shield the light.
To illustrate the levels of oxygen saturation, arterial oxygen saturation is referred to as SaO2 and venous oxygen saturation as SvO2.
How do I measure correctly?
The oxygen saturation can be measured with a pulse oximeter at different parts of the body. The most popular place is the fingers. On the toes, the ear lobes or in infants on the heel, you can also determine the values. For infants or adults for long-term use, there are adhesive sensors. This makes it possible to determine meaningful values at any time during movements. For the application on the earlobe, there are smaller clips to ensure that not too much ambient light can falsify the measurement.
The most important thing is that the light sources and the photodiode face each other. Only then can the diode measure the incoming light rays. Measure on the finger or toe should the light source be on top of the finger or toenail. The clip or adhesive sensor should be snug, but not cut. During the measurement, you should keep your fingers, toe or earlobe as calm as possible.
Certain movements or shocks may inadvertently give impulses to the pulse oximeter so that it defines them as a pulse wave. This can lead to falsely high or false low values.
Which finger should I measure?
The finger on which you attach the sensor usually does not influence the measurement result. Due to the practicability, preference is given to using an index or middle fingers. However, you can use any finger for it, if the sensor can be well-positioned.
Do you want to keep an eye on oxygen saturation over a long period? Remember to reposition the sensor at regular intervals. If it is used too long on a finger, it can lead to painful pressure points. Alternatively, you can use adhesive sensors. These are skin-friendly and cause – if used correctly – no pressure points.
Which measuring errors are possible?
As easy to handle pulse oximeters are, it can still lead to measurement errors. These are presented here so that you can avoid them:
- Wearing blue, green or black nail polish
- Acrylic nails
- Cold fingers
- Centralization by shock or hypothermia
- Strong movements or vibrations
- Nail fungus
- Low methemoglobin level
- Infrared heat lamp near the sensor
- Low blood pressure
Infrared radiation and the red light from the pulse oximeter can not penetrate through certain nail polish colors or acrylic reinforcements. As a result, too few light pulses arrive in the photodiode so that the device displays incorrectly low values. Some devices do not measure in these situations.
If you have painted fingernails and can not measure your toes, you can turn the sensor over. For some devices, this helps to find more accurate values when the light now penetrates through the fingertip first. However, an exact measurement is not possible here either.
In the case of shock or hypothermia, the body usually reverses the blood supply. Vital organs such as the brain, heart, and lungs are still well supplied with blood, while the extremities are less well supplied with blood. This condition is referred to in medicine as centralization. The result is that fingers and toes become colder and paler. Again, it comes to false results. In shock, therefore, the arterial oxygen saturation should be done by medical personnel. Due to the proximity to the brain, you can try the measurement on the earlobe in this state.
Also, the rays of the infrared heat lamp or substances such as methylene blue – a colorant u.a. for fibers and paper – can falsify the measurement results and represent lower. If the blood pressure is low, the absorption of the rays changes so that incorrect values are possible. An indication of low blood pressure may be weak or uneven pulse waveforms on the device. Also, nail fungus or altered blood levels can cause low readings.
All these mentioned measurement errors lead to low oxygen saturation values. If the levels continue to decrease after eliminating the sources of interference, you should inform your doctor immediately. Alternatively, you can call the rescue service.
Carbon monoxide, like oxygen, also saturates hemoglobin. The pulse oximeter does not detect whether it is vital oxygen or carbon monoxide and therefore indicates a high oxygen concentration. Carbon monoxide poisoning can only be detected by blood gas analysis with arterial blood or a special pulse oximeter using the 7-wavelength method.
The pulse modulation index is also often called the perfusion index. This value indicates the strength of the pulse. It tells you how much blood flows through your finger or another part of the body within a certain time. This value depends on several factors:
- Height of the pulse
- Measuring location
- Physical state
- From person to person
The value is between 0.02 and 20 percent. Several measurements allow you to determine your individual and optimal pulse modulation index. If this value is above the currently measured value during the long-term measurement, this may be a measurement error.
A sudden low perfusion index can also be the cause of a drop in blood pressure or reduced blood flow to the body part, where you measure the values. If the value does not return to the normal range after the position check, it makes sense to inform medical personnel about this.
Which values are normal?
Healthy adults have oxygen saturation between 96 and 99 percent. Certain illnesses or age was slightly lower this norm. For example, long-term smokers can be accustomed to an oxygen saturation of 85 percent and thus optimally supplied with oxygen, while in healthy persons this value would cause a feeling of respiratory distress.
Which values are optimal for you and from when you should call a doctor, it is best to clarify with your family doctor. He can advise you in detail.
The standard values of the pulse
In adults, the pulse rate is usually between 60 and 80 beats per minute. The value is given in bpm and refers to “beats per minute” – how often your heart beats per minute. The normal value can be customized. So many athletes usually have a lower frequency. The pulse increases, for example, during exertion, stress or fever. It makes sense, therefore, to use the pulse oximeter in rest periods so that meaningful values can be read off.
In infants and children, the normal pulse rate is higher because they have lower blood pressure and thus equalize blood volume per minute. Newborns can have a resting heartbeat of 130 to 140 beats per minute. For children between the ages of 2 and 10, it is between 80 and 100. From about 10 years, the norm values apply to adults.
Why is good oxygen saturation of the blood so important?
Oxygen needs every cell of your body to perform its function. From the lungs, the inhaled oxygen gets into the blood and from there into every cell. For all cells to be supplied with it, the hemoglobin must be sufficiently oxygenated.
If this is not the case, the cells are insufficiently supplied with oxygen. Even the brain, the heart, and the lungs are not getting enough of it. If the condition lasts longer, the lack of oxygen can lead to dangerous phenomena such as:
- Shortness of breath.
Prolonged oxygen deficiency can lead to organ damage and permanent cognitive restrictions. Therefore, it is important to get medical help at measured low values.
What do the measured values of the pulse oximeter say?
When used correctly, the pulse oximeter reliably measures oxygen saturation and pulse rate. Oxygen saturation indicates how much oxygen the hemoglobin carries in your blood. If the value is in your standard range, you can rest assured.
Too low an oxygen saturation can, for example, have these causes:
- Too low respiratory rate.
- Too little breathing depth.
- Chronic lung diseases.
- Too little oxygen in the inhaled air.
- Diseases that prevent the transport of oxygen from the lungs to the blood, for example, pulmonary edema.
If a low value occurs, first check if there is a measurement error. Also, check if the clip is in the correct position. If the low value persists, you should inform your doctor immediately. For bridging you can, if present, increase your oxygen supply slightly.
If your device displays too high SpO2 levels, the cause may be too much oxygen. If it happens more often, talk to your doctor. Optionally, the oxygen supply can be lowered slightly. Even in people without additional oxygen, the device can display a value of 100 percent oxygen saturation. This usually happens because of a device-internal measurement error or because you breathe too much – for example in case of excitement or exertion.
Too high or too low pulse rate
The displayed pulse rate also provides an insight into your health status. If the measured value is above your norm values, these causes can be behind:
- Physical exertion.
- Hormonal causes such as increased thyroid levels.
- Medicines like catecholamines.
- States of shock.
If you measure elevated frequencies, you should re-measure at a later date. If the pulse does not fall within the normal range, you should inform your doctor.
Observe the course of the pulse over a few seconds to minutes. If it fluctuates greatly, checks the sensor position. If he continues to jump, seek medical attention as it could be an arrhythmic heartbeat.
If you measure low pulse rates, these causes can be behind it:
- Medicines like metoprolol or tranquilizers.
- Diseases of the heart.
Again, you should check the sensor position and consult a doctor if the measured value is below your standard value.
The pulse curve
Most pulse oximeters represent the pulse using a pulse curve or bars. This display provides a good insight into your pulse rate. If you observe the waves or bars, with regular heartbeats you can see that the distance between the waves is even. If this distance is different from wave to wave, this may be an indication of an irregular heartbeat. The height of the wave is also meaningful. If the waves or bars are of different heights, a measurement error could be behind it. For high-quality equipment, such as those used in hospitals, it can also be read here whether your blood pressure is in the normal range.
Although the values of the pulse oximeter are meaningful when used correctly, you should not rely on it blindly. If you have shortness of breath despite having good SpO2 levels, you should call a doctor.
When do I need a pulse oximeter?
In medical practices, hospitals, ambulances, and pharmacies, these devices are standard equipment. But even in private households, the application is becoming increasingly popular. Taking care of relatives who need care can make a pulse oximeter worthwhile. Here you can see at a glance whether the heart rate and the oxygen saturation are in the normal range. Above all, if your relative verbally can not express himself, if he feels unwell, it can be of great help.
A pulse oximeter is also useful if you are under oxygen, have a tracheostomy tube or use an apnea device at night. This allows you to measure at any time whether the oxygen supply is sufficient and acting quickly if needed. In other chronic lung or heart diseases, the use of a pulse oximeter is popular. Allows you to accurately document your disease history and detect deterioration on time. Those who generally want to keep an eye on their health can, in addition to the regular blood pressure measurement, additionally determine the SpO2 value.
If an emergency occurs in your household or if you have the pulse oximeter in an emergency with you, you can provide the rescue service with helpful information on the vital signs. Therefore, it is worthwhile to carry the small devices for your finger at any time. There are also carrying straps or smaller bags.
Does the health insurance pay the pulse oximeter?
In some cases, your GP or a specialist may prescribe a pulse oximeter. If the use is medically justified, the health insurance pays the pulse oximeter or grants a subsidy. Prescribed devices are mostly high-quality models that are also used in nursing homes or other facilities.
In these cases, the health insurance company can pay the pulse oximeter:
- Chronic obstructive pulmonary disease (COPD).
- Long-term continuous oxygen therapy.
- Heart disease.
- Other lung diseases.
It is therefore worth asking before purchasing whether the costs can be covered in your case.
What types of pulse oximeters are there?
There are several types and designs of the pulse oximeter. Especially for the home area models are popular in which the display is on the finger clip. They are small, handy and easy to use. Besides, they fit into almost any trouser pocket and can easily become an everyday companion.
Some models have an extension to which the sensor is attached. The display is located on the device, which can be held in the hand or placed on the table. Mostly they are used in medical practices or hospitals. Here you can replace the finger clip with an ear clip or an adhesive sensor and thus have the opportunity at any time to adapt the device to your needs.
Many of these handheld pulse oximeters have memory space, giving you control over the measured values. Also, tones can be set and you can tell from the sound whether the values are in the normal range or not.
Especially for nocturnal measurements, pulse oximeters are suitable for the wrist. Here the sensor is attached to an extension so you can put your finger in it. This reduces the risk that the sensor will slip. Also for athletes who want to check their oxygen saturation during sports, these devices are popular.
What should I pay attention to when buying a pulse oximeter?
There are numerous types and variants of pulse oximeters on the market. To find the right device for you, we present the most important purchase criteria here.
Depending on the size of the device, the display size changes. So there are small displays that only show the measured values. Larger, however, indicate the pulse curve, which can provide a good statement about the accuracy of the measurement. Here it depends on whether you need to observe the pulse curve or not. It is also important whether you want to use the device outdoors. Because here it may make sense to vary the brightness of the display, so you can read the values well even when exposed to sunlight.
Illumination brings either display with OLED or LED. OLED displays show the values a bit more rich in contrast and fuller. OLED refers to organic light-emitting diodes. In contrast to the conventional LED, the luminance is lower here. This means that the brightness is more pleasing to the eye. The disadvantage of this is that this technology needs more energy. Displays with LEDs are usually a bit bigger and last longer.
Depending on the situations in which you want to use the pulse oximeter, the weight can be a decision criterion. Small devices for the finger are lightweight and can be taken anywhere. Larger devices with a sensor extension are heavier and optimal for household use.
Pulse oximeters can be operated with batteries, a rechargeable battery or the direct connection to the socket. If you want to use the device flexibly, batteries or a rechargeable battery are recommended. If you use the device for a long time, it may make sense to use batteries. All you need to do here is change the batteries and do not wait for the battery to charge. For a few measurements, a battery is good, since you do not have to keep any spare batteries here. Make sure that the batteries are included. If not, you should get them in advance so you can use your new pulse oximeter in an emergency.
Many devices turn off automatically after a few seconds if the sensor can not detect your finger. This has the advantage that the device saves energy if you accidentally remove the sensor at night or while exercising.
Some pulse oximeters use tones to show how high your pulse rate and oxygen saturation are. The speed of successive tones reflects the pulse. The height of the sound indicates how high or low your oxygen saturation is. Most often: The shriller the sound, the better the oxygen saturation. You can usually change the sound volume so that the sound adapts to your environment and is easy to hear. The mute function is also possible if you want to use the pulse oximeter while you sleep.
If you want to check whether your oxygen saturation drops at night, the audible alarm at night can be useful. It wakes you up as soon as your oxygen saturation drops below the given value.
Larger pulse oximeters in particular offer the option of storing the determined values. This allows you to compare past values with current ones without having to write down the values. It also makes it easy for you to show your doctor the values so he can get an idea of your disease.
A memory function does not offer every device. If you want or need to use this feature, you should pay special attention to it.
A few devices offer the possibility to transfer the data to the PC. This usually requires the installation of software. The advantage here is that you can observe a long-term course. Also, you can print out the values and take them to the next doctor’s appointment. This will also give your doctor a comprehensive insight into your disease.
Use of pulse oximeters in children
Fingersensoren is often too small for small children or infants, so it can lead to increased measurement errors. Therefore, it is advisable to use a device in which you can swap the finger clip for an adhesive sensor. Because with this adhesive sensor you can also determine exact values in a baby.
On some devices, the inside of the clip is very soft and adaptable. So even with the normal finger clip, the measurement in children is possible.
Where can I buy a pulse oximeter?
The pulse oximeter can be purchased online and offline. Sometimes discounters offer special promotions so you can buy a device there. You will find them permanently in the assortment in medical supply stores, pharmacies and consumer electronics stores. Buying in such stores has the advantage of being able to ask questions and get instruction in proper handling. However, your desired model may not be available at the moment, so you’ll have to wait a few days. When buying on the internet, all models are permanently available. You also have the opportunity to shop around the clock and are not bound to opening hours.
You do not want to buy a pulse oximeter, you just want to borrow it? Some pharmacies or medical supply stores offer the possibility to rent devices for a certain time. In the long term, this variant is more expensive than buying your device.
Cleaning the pulse oximeter
The pulse oximeter has direct skin contact and can be used by several people. For this reason, it is important that you thoroughly clean the device, even in your household. To prevent the multiplication of potential pathogens. Besides, a dirty sensor can falsify the measurement results. Since the devices are medical devices, they are usually very robust. Cleaning with disinfectants or alcoholic solutions do not harm the materials. It is recommended that you clean the device after each use:
- Cleaning the housing.
- Cleaning the extension cable.
- Cleaning the inside and outside of the finger or ear clip.
Make sure that the cleaning cloth is not too wet to prevent liquid from getting into the device. After cleaning, allow the pulse oximeter to dry and store it in a place protected from the sun’s rays. Some devices include pockets or boxes for storage.
If you use adhesive sensors, you should discard them after each use because they are no longer optimal for frequent use. Also for hygienic reasons, this makes sense.
Is there a pulse oximeter test of Stiftung Warentest?
The Foundation’s testers have not yet performed a pulse oximeter test. However, they tested 18 heart rate monitors in April 2011. Including devices with and without a chest strap and a model in ring form. The models with chest strap delivered almost the same values in the test as in the ECG control. Some devices had many features, so the simplicity of operation suffered. You can read the entire review here for free. We will inform you here as soon as Stiftung Warentest carries out a pulse oximeter test.