4 Tests That Evaluate Your Oxygen

4 Tests That Evaluate Your Oxygen

Oxygen is vital to life, and getting enough oxygen is vital to sustained health. But if you have a long-standing respiratory condition like bronchiectasis, chronic obstructive pulmonary disease (COPD), chronic bronchitis, cystic fibrosis, pulmonary hypertension, sarcoidosis, or sleep apnea, you may have low blood oxygen levels that undermine your health and vitality.

As board-certified pulmonologists who conduct comprehensive oxygen evaluations on a routine basis, our expert team at Fivestar Pulmonary Associates in Allen, McKinney, and Plano, Texas, can determine if you require the aid of supplemental oxygen to help your body and organs function normally. 

Read on as Dr. Anthony Nebor, Dr. Asif Najmuddin, and Dr. Deepthi Gandhiraj explains the ins and outs of the four testing techniques we use to evaluate oxygen levels when we prescribe oxygen therapy. 

1. Pulse oximetry

Hemoglobin is the protein in your red blood cells that’s responsible for transporting oxygen around your body. Pulse oximetry is a simple, noninvasive test that measures how much oxygen the hemoglobin in your blood is carrying. 

How it works

Done as a one-off spot measurement of your oxygen saturation levels, pulse oximetry involves placing a sensor called an oximeter on your fingertip or earlobe. The device shines two lights — a red light and an infrared light — through your skin to determine how much oxygen is in your blood.

What it tells us

Blood that’s rich in oxygen absorbs more infrared light and allows more red light to pass through it, while blood that’s deficient in oxygen absorbs more red light and lets more infrared light pass through. Blood that doesn’t have enough oxygen appears bluer. 

The oximeter display shows the percentage of oxygen in your blood. A healthy, normal blood oxygen saturation level is around 95–100%, and a reading that’s significantly lower than this can indicate the need for oxygen therapy. 

Our team can use pulse oximetry as a one-off oxygen saturation test, or we can use it to measure your oxygen levels through time, including when you’re active and when you’re asleep. 

2. Blood gas testing

We use blood gas testing to get an accurate measurement of the oxygen and carbon dioxide levels in your blood. This test helps us assess how well your lungs are working, and whether they exchange oxygen and carbon dioxide as efficiently as they should. 

 There are two types of blood gas tests: an arterial blood gas test, which assesses the oxygen and carbon dioxide levels in blood taken from your wrist, and a capillary blood gas test, which measures the oxygen and carbon dioxide levels in blood taken from a smaller vessel in your earlobe. 

How it works

We take a small blood sample, usually from an artery in one of your wrists or the inside of your elbow. If we need to take it from your earlobe, we apply a special cream first to help increase blood flow to the area.

Although the cream makes your earlobe feel red and hot for a brief amount of time, it helps ensure the capillaries in your earlobe contain the same amount of oxygen as arterial blood. We collect a blood sample by pricking your earlobe and catching the droplets. 

What it tells us

From your blood sample, we can learn your exact:


Abnormal blood gas testing results may mean that your body isn’t getting enough oxygen, or isn’t getting rid of enough carbon dioxide. High carbon dioxide levels may be a sign that your breathing is shallow when you sleep, indicating the possible need for supplemental oxygen at night. 

3. Long-term oxygen therapy assessment

If pulse oximetry and blood gas testing reveal low oxygen levels, a long-term oxygen therapy assessment can help our team determine whether your levels are low enough to benefit from ongoing oxygen therapy. 

How it works

Our team conducts a long-term oxygen therapy assessment when your lung condition is stable, and you don’t have an active chest infection. The multi-part evaluation involves measuring your blood gasses on two separate occasions, usually a few weeks apart.

 First, we test your oxygen levels when you’re seated. We may also administer a walking test to see if your oxygen levels drop when you’re active — and if supplemental oxygen helps you stay active longer. 

What it tells us

If we determine your oxygen levels are low enough to require oxygen therapy, we check your blood gasses again while you’re breathing supplemental oxygen through a nasal cannula or face mask. This final testing process helps us determine how much supplemental oxygen you need to restore optimal blood oxygen levels.

4. Laboratory testing or diagnostic imaging 

To get a complete picture of your respiratory health, we may also order blood work along with chest X-rays. Although this component of a comprehensive oxygen evaluation doesn’t exactly assess your oxygen levels, it helps us gain better insight into your pulmonary function, lung damage, and overall treatment needs. 

To learn how you can benefit from the oxygen evaluation services available at Fivestar Pulmonary Associates call or click online to schedule a visit at our nearest office today.

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