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How To Choose Pulse Oximeter

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Since pulse oximeter help in checking the blood flow, heart rate, and oxygen saturation levels at home, it is very important to select a device that shows correct details. Before buying a pulse oximeter, make sure that you go through all the factors mentioned below:

1. Accuracy:

Pulse Oximeter Accuracy

Accuracy is one of the first things that you should check for before buying the pulse oximeter. Most of the devices deliver results within ±2% of the actual blood oxygen saturation level. This level of precision is helpful in analyzing the trend. You can also check whether your SpO2 levels are within a normal range or not.

Apart from this, it is also recommended to buy a pulse oximeter from a reputed and well-known brand as these devices offer more accurate details. You can even take your doctor’s recommendation to know which brand provides the best result.

2. Finger Size:

Finger Size Pulse Oximeter

The pulse oximeter that you buy must fit in your fingers properly otherwise it will generate incorrect readings. In some cases, the oximeter might not show any reading at all. But, how do you decide which one will fit your finger perfectly?

Most of the latest models come with an adjustable spring system that lets you adjust the pulse oximeter according to the finger size. These models can accommodate a wide range of finger sizes and can be used by both children and adults.

If you are planning to share the pulse oximeter within your family, you must buy an adjustable model.

However, if you are buying the pulse oximeter for your children, you should select the model that is made especially for the pediatric purpose. The sensors in such pediatric devices are calibrated correctly to get the job done in the right way.

3. Display Size and Readability:

Pulse oximeters Parameters

Since it is a small device, you should pay attention to see the numbers on the display. The pulse oximeter’s display size determines how easily you can see the readings.

It is always good to have large numbers on the display and different ways of arranging the data. You can choose the arrangement that you are comfortable with.

4. Bright Visible Display:

Check for a pulse oximeter that comes with a backlit display. There are many models available with different backlit and color combinations. You can select a combination that you like the most. It is totally your personal choice.

Some models even allow you to adjust the brightness levels so that it is comfortable to check the readings under any lighting conditions. We would suggest you to check for a pulse oximeter where the display offers multiple viewing angles. This will prevent your eyes from further straining.

5. Warning Systems:

There are 3 warning systems that you should check for:

  • Irregular Heartbeat: If your heartbeat is not steady and constant, the pulse oximeter generates a sound warning or alarm. It also includes any arrhythmia of the heart too.
  • Low SpO2: Even though you can see the reading on the display, a warning in the form of a beep or buzzer is helpful if the SpO2 levels drop down. You can even face dizziness or blurred vision if there is an inadequate supply of O2 concentration.
  • Low Battery: For the patients or users who rely on the oximeter for their health management, a low battery indicator is necessary. With the help of this indicator, you can charge or replace the battery so that the device is working fine.

Pulse Oximeter Readings Chart

Oxygen Level Chart

Heart Rate Readings Chart

Heart Rate Chart

6. Response Time:

Earlier, the pulse oximeters used to take around 30 seconds to show the reading. The modern devices take around 10 seconds to display accurate results.

7. Durability:

Durability is another important factor that you should consider before buying a pulse oximeter. A durable device prevents the damage of the unit and does not show inaccurate readings.

A good quality oximeter can provide the correct result every time you use it. Thus, buying an oximeter that is not durable can indirectly put your life at risk.

A durable unit is generally waterproof and can even withstand any condition. Even if you drop it on the ground, it will work fine. They are also resistant to humidity. Most of the times, incorrect reading or device failure is caused due to the humidity.

Some pulse oximeters even come along with removable silicon covers that guard the device against scratches or damage caused while using it. Some pulse oximeter units have shells that made using ABS (Acrylonitrile Butadiene Styrene) plastic that is more durable than the models that are made using polypropylene plastic shells.

8. Battery Life:

If you need to use the pulse oximeter daily, you must buy a device that can provide you continuous support. This is where the battery life comes into the picture.

To keep the oximeter working always, you can either buy a model that is powered using lithium batteries (that are rechargeable mostly) even though it is costly, or else you can buy a cheaper model that supports AAA batteries where it provides a minimum of 30 working hours.

9. Automatically Activated:

Automatically activated pulse oximeters are the ones that turn on automatically when you place your finger or toe in it. Even though it is not a very important feature, it can be helpful in some tricky situations where you need to check your pulse rate or SpO2 levels.

10. Ease of Usage:

A pulse oximeter should always be easy to use and must not require any technical knowledge so that anyone at home can use it without any assistance.

The finger oximeters are generally easy to use. All you have to do is clip the device on your finger and turn on the button and wait for a few seconds for the result. A large display or screen makes it easier to check the readings.

Some models of oximeters display the readings in different ways making it easier to read and understand the details. These added benefits can make it easy to use an oximeter.

11. Portability:

The patients who need to monitor their SpO2 levels usually carry the oximeter with them always. Even some pilots or sportsmen use an oximeter. In such cases, the oximeter should be portable so that you can put it in your pocket or handbag. All the oximeters that we have mentioned in the list are portable and easy to carry.

The size of most of the pulse oximeter is around 2 inches long and 1 inch wide. This size is good enough to fit in the pocket. However, if you are carrying it in your pocket, chances are device may turn on accidentally. Thus look for a model that comes with either a lanyard so that you can hang it around your neck or the model that comes with a carrying case.

12. Popularity:

You can understand the popularity of any product by going through user reviews. The same is the case with pulse oximeters too. Go through the user reviews thoroughly to understand the product and whether the users are happy and comfortable with the oximeter of that particular brand or not. If yes, you can buy the oximeter with the best user reviews.

13. Price:

You can easily find a good quality pulse oximeter within a price range of Rs. 2000 – Rs. 5000. The more advanced models show your reading history, backlit lighting, etc. might cost a bit more but they are worth investing in.

14. Warranty & Return Policy:

If a manufacturer is providing a good warranty and customer support service along with easy return policies, it is another sign that the product can be trusted. Prefer buying the pulse oximeter from brands that offer a maximum warranty. The warranty period varies between 6 months to 1 year.

15. Additional Features:

Even though these additional features do not have any direct impact on the performance of the oximeter, they can be helpful in making the device more user-friendly. Some of the interesting additional features that you can check for are:

  • Automatic Battery Preservation Mode (Auto Shut-off): If the device has not been used for a certain amount of time, the oximeter turns off automatically. This feature is helpful in improving the battery life of the oximeter.
  • History Save Feature (easy access to previous readings): This feature helps you go back and check the older reading and compare it with current readings so that you can track and maintain a tab on your body’s performance. The comparison becomes easier here.

Types of Pulse Oximeters:

There are five types of oximeters available in the market. They are as follows:

Pulse Oximeter Types

1. Finger Pulse Oximeter:

The finger pulse oximeters are also called as Portable pulse oximeters. As the name suggests, these types of oximeters are used on the fingertips. They are small and portable and can be directly clipped on the finger. When you clip it on your finger, the display screen will show the results within seconds.

The finger pulse oximeters are battery operated and can be used to check blood oxygen levels at your home. They are easy to use, portable, and come at an affordable price making it ideal for use at home by the patients.

2. Handheld Pulse Oximeter:

The handheld oximeters are a bit sophisticated than the finger pulse oximeters. They generate more accurate results when compared to the finger pulse oximeters.

The handheld pulse oximeter consists of 2 parts – the probe and the display screen. The screen here is a handheld screen. The two parts of the oximeter are connected using a cable.

The probe is attached to the patient’s finger (usually the index finger) and you can see the blood oxygen levels on the screen.

These types of pulse oximeters can provide continuous oxygen saturation monitoring and are commonly used in hospitals, ambulances, emergency medical services (EMS), and medical institutes.

3. Tabletop Pulse Oximeter:

The tabletop oximeters are a bit bigger than handheld oximeters but very similar to them. The tabletop oximeters also come in 2 parts – the probe and the display screen and both are connected using a cable. The tabletop oximeters are used in hospitals and other medical facilities.

Some models of tabletop oximeters also come with audio and visual alarms that are helpful in alerting the people around whenever there is a fall in pulse rate or blood oxygen levels.

These types of oximeters also come with a plethysmograph display. This makes them perfect for monitoring newborn babies, kids, and adults. They can even store data of several patients (around 100).

4. Wrist-Worn Pulse Oximeter:

Similar to wristwatches, the wrist-worn oximeters can be worn on your wrist and are helpful for continuous monitoring.

In most of the cases, doctors prefer monitoring your blood oxygen levels even while you are sleeping. The wrist-worn oximeter can be helpful in such instances.

There is a probe that is attached to the finger of the patient. You can see the reading on a screen that can be worn on the wrist. The probe and the display screen are connected using a short cable that does not cause any disturbance in your daily routine.

Some of these oximeters can even store the data. A few wrist-worn pulse oximeters allow wireless connectivity using Bluetooth and transfer the data. Some models even offer USB connectivity to make it easy to transfer the data.

5. Pediatric Pulse Oximeters:

The pediatric pulse oximeters are designed especially for infants or kids below an age group of 4 years. These are finger pulse oximeters but designed in such a way that they will fit in the small fingers of the babies and deliver correct results.

Since regular finger pulse oximeters are big, they don’t work well on the fingers of kids. Thus, pediatric pulse oximeters are used to monitor the blood oxygen levels in children or infants.

Some models of pediatric pulse oximeters come with an alarm to alert you whenever the oxygen saturation level is going below the safe range. Some even come with an anti-motion feature. Thus, even if the child is moving the hands, the oximeter provides accurate results.

How do Pulse Oximeter Devices Work?

The pulse oximeters are used to measure the quantity of oxygen that is carried in the blood hemoglobin, also called as SpO2.

SpO2-pulse-oximeter

The device uses light to monitor the oxygen saturation level. When the light is emitted from the light sources, it goes across the pulse oximeter probe and reaches the light detector.

It uses two different lights to analyze the hemoglobin. First is the red light with a wavelength of around 650 nm. Second is the infrared light with a wavelength of 950 nm.

oxy Hb i.e. hemoglobin with oxygen generally absorbs more infrared light than red light. deoxy Hb, on the other hand, absorbs more red light than infrared light.

The pulse oximeter determines the oxygen saturation by comparing the amount of red light and infrared light that is absorbed by the blood. Depending on the amount of oxy Hb and deoxy Hb present, the ratio of the amount of red light absorbed is then compared to the amount of infrared light absorbed changes.

For e.g., at 100% saturation, reading looks like this:

Pulse Oximeter 100%

25% saturation, reading looks like this:

Pulse Oximeter 25%

Benefits of Using a Pulse Oximeter:

Some of the advantages of using a pulse oximeter are as follows:

  • During High Altitude Sports: Using a pulse oximeter while playing high altitude sports can alert you whenever there in oxygen deprivation issue. Using a pulse oximeter at such high altitudes, you can determine the arterial blood oxygen levels.
  • For COPD Management: If you suffer from COPD i.e. chronic obstructive pulmonary disease, you must carry a pulse oximeter with you always. COPD is a serious health condition that requires constant monitoring of blood oxygen levels and whenever there is a lack of oxygen delivery in the lungs, the patient requires immediate medication.
  • For Asthma Patients: If you are suffering from asthma, using a pulse oximeter can alert you immediately whenever the airways are getting restricted. An instant alert can prepare you so that you can use an inhaler before the situation becomes worse.
  • It monitors the oxygen saturation levels in the blood, especially for those suffering from sleep apnea.
  • The pulse oximeters help in alerting the hospital staff whenever the oxygen levels become low.
  • It helps in measuring the saturation level of oxygen in the blood for patients who are under anesthesia.
  • Whenever the reading passes beyond the safe limits, it notifies you.

Warnings:

While using a pulse oximeter, there are a few things that you should take care of. Some of the pointers that you should take care of are:

For People with Dark Skin:

You should not use the oximeter on painted fingers or nails as it can overestimate the SpO2 levels. Some experts even say that the pulse oximeter does not work on jaundiced or dark pigmented skin.

Many studies have been conducted over dark-complexioned individuals and the results show that even the most advanced pulse oximeter devices show incorrect blood oxygen concentrations.

You can overcome this issue by placing the sensor over your earlobe or on the wrist as the pigmentation in these areas is light comparatively.

Emergency Situation:

Whenever the SpO2 levels fall below 80%, you might have to rush to the hospital. Whenever the blood oxygen levels hit 80% or less, the pulse oximeter may provide incorrect readings. Your oxygen level might be lower than what the device is claiming and thus, medical assistance is required immediately.

Carboxyhemoglobin:

If you have any condition where the carbon dioxide levels in the blood shoot up, you must verify the pulse oximeter readings by using a blood-gas analysis.

Even though the oximeters are helpful in the treatment of many pulmonary and circulatory ailments, they can’t distinguish between the hemoglobin cells that are carrying oxygen and ones carrying carbon dioxide.

Relying completely on the oximeter readings can be risky in such situations. You should check the doctor immediately.

Frequently Asked Questions

1. Do all the pulse oximeters come with auto power off feature?

After few seconds of inactivity the devices turn off as most of them are designed to save power. But all the pulse oximeters do not have this feature.

2. Do pulse oximeter measure co2 retention?

The pulse oximeter measure only oxygen in blood and pulse rate, it do not measure co2 retention.

3. Do the pulse oximeter keep permanent records?

The readings are lost as the power is turned off, till the power is on it keeps updating the oxygen and pulse rate reading. It does not keep permanent records.

4. How accurate are finger pulse oximeters?

The oxygen levels from a pulse oximeter are reasonably accurate. Based on your saturation level it gives 2% under or 2% over.

5. What is normal SpO2 level?

Good blood oxygen levels are necessary for the supply of energy to your muscle needed to function that increases during sports. Poor blood oxygenation is when SpO2 value is below 95%.
Normal SpO2 values vary between 95 and 100%

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