What are the two readings on a pulse oximeter?

Pulse oximeters are increasingly being bought for every home. You never know when you might need one. But do you know how to operate one when the time comes? This article will teach you all you need to know and more about the two readings on a pulse oximeter and show you the normal SpO2 chart too. Keep reading to find out!

Article summary

The two readings on a pulse oximeter are the pulse and blood oxygen rates. However, this article will also show you that the most common and normal Sp02 level is 95-100%. The chart also includes what happens when you deviate from that.

We’ll also cover the following topics and more:

  • When to worry
  • What causes inaccurate readings
  • Whether you can get different readings between the right or left hand
  • Best ways to the get correct reading on oximeter

What are the two readings on a pulse oximeter?

finger pulse oximeter

When you read the little screen on the device, you’ll find that it has two specific numbers. The first number might have a heart next to it, indicating pulse rate. The pulse rate is defined as the number of times your heart beats every minute.

The other number is the blood oxygen rate. It is the approximate oxygen level in your blood and, therefore, your body.

Both are crucial factors in assessing your health, especially when the body is in distress.

Normal SpO2 chart

Following are the values to remember when reading the blood oxygen levels outlined in the Normal SpO2 chart.

ConditionSpO2 (%)
Normal95- 100
The brain starts being affected80- 85
CyanosisBelow 67%

Cyanosis refers to the phenomenon when the skin starts turning blue or pink due to the lack of oxygen in the body. It usually indicates the level of oxygen is dangerously low.

When to worry.

A pulse oximeter chart will indicate the normal readings of a healthy body above. Meanwhile, the consensus on the amount of level before you should contact your health care provider varies. However, it is safe to say that below 90% oxygen, you should call a doctor or go to the hospital. If your oxygen is falling rapidly, you should also rush to the emergency.

What does a reading of 78 mean?

Fingertip Pulse Oximeter

A figure as low as 78 could mean drastic health effects. It generally indicates a condition known as hypoxemia. It is when not adequate O2 reaches the body’s tissues. You should already be headed to a hospital once you spot the reading falls below 88%. Waiting any longer could mean serious damage to the brain that may be difficult to reverse.

What causes inaccurate results?

There are now known to be several factors that can lead to inaccurate results. Here are the top reasons:

  • Fingernail polish on the finger where you put the device can alter results.
  • Moving the hand where the device has been installed.
  • In a recent study, even skin pigmentation has been known to alter results and make them inaccurate. So a person with dark skin may get inaccurate results.
  • If you’re smoking or eating edible tobacco, it can lead to changed results.
  • Although you can’t do anything about this one – skin thickness can also cause the readings o be off.
  • The body temperature can also affect the readings. Thus too much cold or hot weather can affect the final figure.
  • Certain medications that you may be using at the time can be a cause for changing the figure.
  • If the probe is fastened too tightly around the site of monitoring, it can lead to changed results.

The results vary by the minute

Though a little fluctuation is normal while the device is taking the reading, too much can be a sign of something else. You should ensure the following:

  • That the reading has been taken properly. The device should be kept on the finger for a minute or longer.
  • The device is reliable. When the need for oximeters ran higher than the supply, poorly made oximeters were also manufactured and sold. If you have such a device, it can be misleading to use it.
  • Your heart fluctuations are not too much. Contact your medical provider immediately if your readings are fluctuating and you also feel the effects like dizziness, chest pain, and trouble breathing.

What are dangerous levels to look out for?

Normal readings are important to figure out the dangerous ones. The SpO2 level should be ideally between 95-100%. Sometimes it can go down to 92% as well. But if it reaches below 90%, it’s time to get a check-up from the hospital or nearest clinic. Sometimes dropping O2 can be increased with the following tips:

  • Bring the air inside: Head outside to the balcony or open a window to reduce suffocation. It will circulate the air and might increase your blood O2.
  • Breathing exercises: There are plenty of breathing and meditation exercises online to improve your O2 levels. It’s best to keep practicing them rather than looking them up only when the problem arises. Meditating or practicing deep belly breathing daily can help reduce stress and clear your mind.
  • Reduce substance abuse: Smoking and alcohol will cause your O2 levels to decrease. Reduce or quit smoking entirely to help your lungs breathe better.
  • Try changing your device: sometimes the device could be showing inaccurate results owing to dark skin color, outside temperature or thickness of skin, or just a faulty device.

Long-term consequences of low readings

Long term consequences of hypoxemia can be many, and here’s a comprehensive list of the possible causes for the same:

  • Lung disease – If your oxygen level is always low, it could mean that your lungs aren’t functioning properly. It could be owing to external factors like smoking but also some diseases of the lungs.
  • Pulmonary embolism – if you’re getting the low figures all the time, it could also mean a clot in the lung’s artery. There fore causing less oxygen to reach the brain and blood.
  • Anemia: Low iron levels can cause anemia and less oxygen until low O2 causes less iron. The whole thing becomes a vicious cycle.
  • Asthma: Asthma is a condition in which the patient cannot breathe properly after an attack. Hypoxemia is more likely to occur in such patients.
  • Pneumonia: If you’ve got pneumonia, you are likely at more risk of developing hypoxemia.
  • Pulmonary edema: This is the clinical term for fluid in your lungs, making it difficult for you to breathe. Therefore it causes less O2 to travel to the brain.
  • Congestive heart failure: Some people experience difficulty breathing while having a heart attack because the O2 suddenly drops.

If the above conditions persist for long and cause hypoxemia, they should be treated immediately with supplemental oxygen. If this doesn’t happen, the patient can suffer from seizures, comas, or even brain death.

Patients with these things may get inaccurate results

There can be instances where your oxygen may be at the appropriate levels but show up as low. It could be owing to factors like underlying diseases in some patients. Here are some of that diseases:

  • Fever: Pneumonia or any other viral disease that causes the body temperature to rise or drop severely can cause the results to be inaccurate. The temperature even causes problems when the weather changes.
  • Diabetes: It was found in a recent study that people with type 2 diabetes can end up having inaccurate results in pulse oximetry. It is because these patients have increased levels of glycohemoglobin
  • Heart failure: A study now indicates that patients with previous experience of heart failure can have inaccurate readings. It is due to the impaired peripheral perfusion that compromises the reading.

Can the readings be over 100?

Readings can never be over 100 since the pulse oximetry readings are expressed in percentages. Therefore it is not possible to have a reading above 100.

Can you be anemic?

People with anemia will have low oximetric readings as compared to those who don’t have any. There are several types of anemia. The anemia that occurs due to iron deficiency will affect the oxygen content of arteries since it reduces the content of hemoglobin. Severe anemia will also show up on your readings.

However, if your anemia is due to a hemorrhage, it might not appear on the device.

It is possible that you are anemic, and your readings are normal. Therefore it’s always best to go with a blood test to determine your Hemoglobin levels.

Does it matter if it’s done on the right or left hand?

Since these readings are very sensitive, they can vary from finger to finger and hand to hand. It has been found, based on statistics, that the right hand’s middle finger and thumb are the most accurate in determining oxygen levels. It was found in a study that these locations demonstrated the highest O2 levels. The finger with the lowest O2 average value was the left middle finger.

Emotional and physical stress.

There have been significant studies to conclude that emotional and physical stress does affect pulse levels. Since both emotional and physical stress causes your heart to race, they will simultaneously raise your pulse beats per minute. Emotional stress due to poor mental health can cause anxiety characterized by rapid breathing. It affects the homeostasis of a healthy individual. Physical stress can also be due to exertion or some physical disease or injury.

Emotional or mental stress caused by academic exams has also been associated with rapid breathing, and lower O2 levels as the body tries to keep up with the rapid breathing.

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NameBluetooth Pulse Oximeter
Are Batteries IncludedYes
Number of Batteries2 AAA batteries require
Special featureBluetooth & app
Weight4.16 Ounces


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It's one of the best on the market.

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