pulse oximeter

The following guide will walk you through everything you need to know about pulse oximeters including how they work, benefits of owning one, how to use one properly, how to choose an oximeter that’s right for you, warnings about their use, and our top list of affordable and reliable monitors currently available.

Pulse oximeters are considered a suitable alternative, though by no means equal to, blood gas testing. A blood gas analysis is far more reliable, and also tells blood carbon dioxide levels. However, this test requires a trip to a lab facility for blood to be drawn. It can also be very expensive if a patient doesn’t have adequate healthcare insurance.

How Pulse Oximetry Devices Work

The way Pulse oximeters work is very simple. First, the device clips onto a fairly transparent part of the body such as a finger, toe, or earlobe.

Next, once activated, a light is emitted from the probe side of the oximeter and a light sensor is located on the other side. The light emitted consists of two distinct wavelengths of light (650nm and 805nm). Light is absorbed by both the hemoglobin in our blood and the oxygen molecules that may or may not be attached to them.

When calibrated correctly, the sensor can discern approximately how many hemoglobin cells are present in the blood passing through the artery nearest where the oximeter is attached, and how many of those cells have an oxygen molecule attached. This is called your peripheral capillary oxygen saturation or “SpO2.”

There are a number of factors that can effect the overall accuracy of these simple and affordable devices. Read “How to Use a Pulse Oximeter Properly” to make sure you’re getting the most reliable results possible.

Benefits of Using a Pulse Oximeter

Fitness Monitoring

Anyone who’s ever been out of shape knows how badly the body can struggle to maintain oxygen levels when heavy physical demands are suddenly placed on it. By monitoring your fitness progress with a pulse oximetry device, you can push your body to the limit, without pushing yourself to the point of complete exhaustion and/or sickness.

Being able to track changes to your pulse rate without having to do so manually is yet another fitness benefit of using these devices.

High Altitude Sports

A pulse oximeter can alert you to oxygen deprivation issues before they become a serious problem. Sports like mountain climbing, skydiving, hang gliding and any other sport or activity that puts a person in high altitude situations can benefit from the use of a pulse oximeter to determine arterial blood oxygen levels.

For COPD Management

A pulse oximeter should be carried on those who suffer from COPD at all times. Chronic obstructive pulmonary disease occurs when the cells in the lungs become damaged to such an extent the body can no longer repair them. This is a serious condition that requires the use of medication, lifestyle management, and the monitoring of blood oxygen levels to determine when the lungs aren’t delivering enough oxygen – alerting the patient when rescue medication and/or oxygen therapy are needed.

For Asthma Patient Care

Though not always as serious as COPD, many asthma patients suffer from debilitating daily asthma attacks that can leave them feeling like they’ll never be able to catch their breath again. For those with severe asthma, a pulse oximeter can alert them when their airways are becoming restricted – before it becomes really serious – alerting them to use their rescue inhaler before an attack occurs.

Piece of Mind for Pulmonary Patients

Aside from those already mentioned, there are several common and many rare pulmonary conditions that affect the lungs, and which can be life threatening. Those suffering from such conditions can definitely benefit from the use of a pulse oximetry device, to alert them of changes to their arterial blood oxygen levels before life threatening complications occur.

Low Maintenance

Once calibrated, pulse oximeters will work the same after two years as they did on the first day they were opened. All these devices perform a startup check of their circuitry when turned on, and will not run a scan unless they pass these built in tests. No calibration is ever needed, or even possible, with an at home oximetry device.

Low Cost

You really can’t argue with the cost of purchasing a pulse oximeter. Very few on the market cost more than $50 (USD) and the majority come with at least a 2-year warranty. Whether you’re using one for fitness monitoring, or because you have a condition that requires one, few at home health monitoring devices are as inexpensive.

Less Invasive Than Blood Gas Testing

For some people, going to a lab and being poked with a needle is a major source of anxiety. This is particularly true if you have to go for regular blood work and calluses have developed in the preferred extraction sites, making taking your blood not only frightening, but also extremely painful, too.

A pulse oximeter can’t tell what your carbon dioxide levels are, but if you’re not feeling well and your oxygen levels are confirmed as being low by your oximeter, you have all the reasons you need to get to a hospital immediately for treatment.

Accurate Pulse Reading

An obvious benefit. Whether you have a cardiopulmonary problem or just want to know what your pulse is, an oximeter offers far more reliable results than putting two fingers on an artery and trying to count your own heartbeat. This is especially true if you’re not feeling comfortable (anxious, racing heart, overexertion, etc.)

How to Use a Pulse Oximeter Properly

This section could also be titled “What Not to do When Using Your Pulse Oximeter.” Oximeters are very easy to use. Simply clip the device on your fingertip or earlobe (you can attach the clip over the wrist or top and bottom of the foot on infants), then turn the device on to take a reading. This is the easy part.

Below, you’ll find a list of variables that need to be avoided in order to get the best reading possible:

• Painted fingers and toenails can obstruct proper readings – use an earlobe instead in this case.

• Bright overhead lighting, including sunlight can effect readings – take your readings in rooms with normal or low-light conditions.

• Body movement including shivering, sneezing, etc., can all affect proper readings – don’t move while testing.

If you have any respiratory or circulatory condition, your pulse oximeter readings will need to be interpreted differently than you’ll find listed in the documentation that comes with the device (see “Warnings” further down the page).

Talk to your doctor or primary healthcare provider to learn how to read the results given by your oximeter to properly determine what’s happening in your body.

Before You Buy: What to Look for in a Pulse Oximetry Device

Accuracy

With any pulse oximeter, you’re going to want the device you choose to be guaranteed within 2% (plus or minus) of actual SpO2 levels. This number is determined during clinical testing of the oximeter’s technology, with samples that have known SpO2 levels.

The device also needs to be accurate up to 70% oxygen saturation. This means that even when your arterial oxygen levels aren’t ideal, the device will still give an accurate reading, prompting you in most cases to seek medical attention.

Warning Systems

There are 3 warning systems that you want to look for when choosing an oximeter:

Irregular Heartbeat: An alarm will sound warning you if your heartbeat isn’t steady and constant like it should be. This includes any arrhythmia of the heart that may be of concern.

Low SpO2: While you’ll be able to see this on the display, a warning beep or buzzer for low SpO2 concentrations can also be a lifesaver if you’re dizzy or have blurred vision do to inadequate O2 concentrations.

Low Battery: Whether this is an indicator or a noise, a low battery indicator is important for those who rely on an oximeter for disease management.

Portability

Most people who need to monitor their SpO2 with an oximeter will need to carry it on them at all times. If you’re using it for sport or because you’re a pilot, the device will still need to be portable enough that you can carry it around your neck, in your pocket, or securely on a belt holster. All the oximeters recommended further down the page are streamlined and very portable.

Lightweight

This fits in with the oximeter’s portability, but some units can have small dimensions yet still be heavy and downright uncomfortable to use. This is particularly true if the user is weak due to hypoxia resulting from cardiovascular and/or pulmonary disease.

How heavy or light a unit is also effects how durable it is, as heavier oximeters may get damaged easier if they’re accidentally dropped. Check reviews online and ask your healthcare professional for recommendations.

Durability

The difference between durable and cheap junk could mean the difference between life and death in a number of different scenarios, if you require constant monitoring of your SpO2 levels. A quality pulse oximeter will be able to withstand dropping it on the ground, and should be waterproof to withstand being dropped in water and also to protect it against humidity – known to cause inaccurate readings and/or device failure.

Fitment

Adjustable oximeters are the smart choice if you have large fingers and/or have tried non-adjustable units before and found them uncomfortable. Non-adjustable oximeters often receive criticism for squeezing too hard, or not hard enough. Adjustable brands allow you to dial in the comfort so you’re not dreading their use.

Automatically Activated

The ability to turn on automatically upon inserting a finger or toe into the device might seem like a novelty or convenience feature, which it sort of is. However, if you’re weak from low oxygen levels and frequently have to check your SpO2 on your own; once again, this feature could mean the difference between life and death in some cases.

Bright Visible Display

Look for a pulse oximeter with a backlit display. There are several backlight and font color combinations to choose from. The decision of whether one type is better than another is a matter of personal preference.

Some of the best oximeters have adjustable brightness to accommodate users under any lighting conditions they may find themselves testing in. Look for displays with multiple viewing angles so you don’t have to strain while reading the device.

Warnings

For People With Dark Skin:

You read earlier about not testing on painted finger or toenails. This is because color can lead to the device overestimating true SpO2 levels. This particular issue is a point of debate among professionals. Some will say these devices are not affected by dark pigment or jaundiced skin, while testing has verified there is at least some disparity between oximeter readings and blood-gas analysis in darker skinned individuals.(source)

There have been a number of clinical research studies performed on darker-complexioned individuals, primarily to help educate anesthesiologists on the proper care practices for their patients, in which it’s been shown that even the most advanced pulse oximetry devices can overestimate blood oxygen concentrations.(source)

This problem can be overcome by placing the sensor on an earlobe or, if possible directly on the wrist (if your wrist is small enough). The pigmentation in these areas is usually light enough to accommodate reliable readings.

Go to the Emergency Room if:

When SpO2 levels fall below 80% you need to go to the hospital. Pulse oximeters have been found to be very inaccurate in reading blood oxygen levels when levels hit 80% or less. With two or more readings in this range, your oxygen levels may be far lower than the device claims and medical intervention is necessary.

Carboxyhemoglobin:

If you have any condition that causes elevated carbon dioxide levels in the blood, the readings from your pulse oximeter must be verified using a blood-gas analysis. Unfortunately, while oximeters are very helpful in the treatment of a number of pulmonary and circulatory ailments, they cannot distinguish between hemoglobin cells carrying oxygen and those carrying carbon dioxide.(source)

Trusting solely on your pulse oximeter in such cases, could lead to severe complications, up to and including death. Talk to your doctor about how to interpret your readings appropriately and determine when you should seek emergency care.

Summary

Home use pulse oximetry devices are a great way to assess your arterial oxygen levels. In addition to people with cardiopulmonary conditions and/or diseases, a pulse oximeter is something that all pilots, mountain climbers, and endurance athletes should own for use when pushing their bodies to the limit under conditions where oxygen is at a premium.

Considering the low cost and relative accuracy (when manufacturer’s directions are followed), the ability to measure blood SpO2 and pulse with relative ease can benefit anyone and help to identify potential health problems such as anemia, low red blood cell count, and or heart and respiratory complications before they cause serious health complications.


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