How do the lungs give blood oxygen

Use the Blood Oxygen app on Apple Watch Series 6

The blood oxygen app allows you to measure the oxygen content in your blood directly via your wrist, if necessary. This will give you information about your general health.

Measurements taken with the blood oxygen app are not intended for medical use, but are only used for purposes related to general fitness and general wellbeing.

The blood oxygen app is only available in certain countries and regions. Find out where the Blood Oxygen app is available here.

What is blood oxygen?

Blood oxygen is the percentage of oxygen that your red blood cells carry from your lungs to the rest of your body. The better your blood performs this important task, the better your general well-being.

As a rule, a person has a blood oxygen content of 95-100%. But there are also people who can lead a normal life with a blood oxygen content of less than 95%. Slightly lower values ​​are to be expected for measurements during sleep, and for some users the value may be below 95%.

Use the blood oxygen app

Make sure you meet the following requirements and follow these steps to set up the Blood Oxygen app.

Set up blood oxygen app and background measurements

  1. Open the Health app on the iPhone.
  2. Follow the instructions on the screen. If you're not prompted to set it up, tap the Explore tab, then tap Airway> Blood Oxygen> Set Up Blood Oxygen.
  3. After the successful setup, open the blood oxygen app on your Apple Watch to measure your blood oxygen content.

If you still don't see the Blood Oxygen app on your Apple Watch, you can search for "Blood Oxygen" in the App Store on your Apple Watch and download the app.

The Blood Oxygen app is installed during the Health app setup. If you've deleted the Blood Oxygen app, you can reinstall it. If you have previously successfully set up the Blood Oxygen App, visit the App Store on your Apple Watch and download the Blood Oxygen App from there.


Take a blood oxygen test

With the blood oxygen app you can take a measurement of your blood oxygen content at any time.

  1. Make sure that your Apple Watch is comfortable, but not too loose.
  2. Open the Blood Oxygen app on your Apple Watch.
  3. Hold still and make sure Apple Watch is flat on your wrist, display facing up.
  4. Tap Start and hold your arm still for 15 seconds.
  5. Wait, the measurement will take 15 seconds. After the measurement, the results are displayed.
  6. Tap on "Done".

This is how you get the best results

  1. Place your arms on a table or in your lap while taking the measurement. Let your wrist and palm rest relaxed, and keep them as still as possible.
  2. Make sure your Apple Watch isn't too loose on your wrist. The band should be tight, but not too tight, and the back of the Apple Watch should touch your wrist.
  3. Make sure the back of your Apple Watch is flat on the top of your wrist. If the bones of your wrist get in the way, move your watch upwards of 2–5 cm away from your wrist.

Other factors

Even in ideal conditions, the Apple Watch may not always provide reliable results when it comes to measuring blood oxygen levels. For a small percentage of users, various factors can prevent blood oxygen measurements from being possible.

  • Skin blood flow can affect measurements. It is very different from person to person and is also influenced by environmental conditions. If you z. For example, if you are outdoors and the temperature is low, the blood circulation in your wrist may be too low for the sensor to take a reading using the Blood Oxygen app.
  • Permanent or temporary changes to the skin, such as some tattoos, can also impair measuring ability. The ink, pattern, and saturation of some tattoos can block the light from the sensor, making it difficult for the Blood Oxygen app to measure.
  • Movement is another factor that can affect the outcome of measurements, whether they were taken in the background or by yourself. In certain postures, such as when your arms are close to your body or your fingers form a fist, a successful measurement is not possible.
  • If your resting heart rate is too high (over 150 beats per minute), you will also not be able to successfully take blood oxygen measurements.

Background measurements information

The Blood Oxygen app on your Apple Watch regularly measures your blood oxygen levels when background measurements are turned on. Typically, these measurements are taken when you are not moving. Depending on how active you are, the number of measurements taken per day and the time between these measurements will vary. When a blood oxygen test is taken, a bright red light will shine on your wrist, which may be more noticeable in darker surroundings. If the light bothers you, you can turn off the background measurements.

  1. Open the Settings app on the Apple Watch.
  2. Tap Blood Oxygen, then turn off “Asleep” and “In Theater Mode”.

While sleeping, blood oxygen measurements are only taken if the "Sleep tracking with Apple Watch" setting is enabled.

How the blood oxygen app works

The Apple Watch Series 6 is equipped with a redesigned optical heart sensor that can now perform blood oxygen measurements. During a blood oxygen measurement, the back of the crystal lights up with red and green LEDs as well as infrared light on your wrist. Photodiodes then measure how much light is reflected.

Modern algorithms use this data to calculate the color of your blood. The color determines your blood oxygen levels - light red blood contains more oxygen, whereas dark red blood contains less oxygen.

View health data

All blood oxygen measurements - whether they were taken in the background or by yourself - are saved in the Health app on your iPhone.

  1. Open the Health app.
  2. Tap the Explore tab, then tap Airway> Blood Oxygen.

You can also filter measurements and e.g. B. only show those that were performed while sleeping or at high altitude.

useful information

  • Measurements with the blood oxygen app are not intended for medical use, including self-diagnosis or medical advice, but are only used for purposes of general fitness and general wellbeing.
  • The Blood Oxygen app is intended for users who are at least 18 years old.

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