Gas Exchange
Arterial Blood Gas
Pulse Oximetry
Pulse Oximetry with Walking
Shunt Study
Arterial Blood Gas
Arterial blood gas is a blood sample test ordered by your physician to evaluate measurements of oxygen level, carbon dioxide (effectiveness of respiration), and several other parameters. Generally, it is indicated when your physician needs to evaluate the effectiveness of your breathing.
- This sample is drawn at the pulse site at the wrist.
- The technologist will apply a local anesthetic at the site if indicated.
- An oximeter clip will be placed on your finger to correlate with the blood values if further oxygen testing is indicated
- Pressure will be held at the site for several minutes to assure that there is no bleeding.
Collecting an Arterial Blood Gas Sample
Return to Top
Pulse Oximetry
Oximetry is a procedure, which measures the oxygen level in your blood, without having to take a blood sample, on a continuous basis.
- A painless clip is placed on your fingertip or ear lobe, while the technologist monitors the reading on a device attached by a wire.
- The reading may be monitored for several minutes while you are seated at rest to evaluate your oxygen level without supplemental oxygen. Then, if needed, supplemental oxygen may be provided by means of a nasal cannula. The amount delivered will be adjusted to bring you to the level your physician has ordered.
Return to Top
Pulse Oximetry with Walking
The technologist may have you walk with the sensor clip in place to observe your response to exertion. If your oxygen level decreases, you may be asked to repeat the test with supplemental oxygen increased to the next setting. This process may be repeated several times, until your oxygen level is adequate
Patient does a Pulse Oximetry walk to determine oxygen needs.
Return to Top
Shunt Study
A shunt study is a procedure to determine if a patient has a lack of response to supplemental oxygen, indicating a shunt problem.
Performing the test
- You will sit in a comfortable chair on a mouthpiece wearing noseclips.
- You will breathe normally on the mouthpiece for approximately 20 minutes breathing 100% oxygen.
- An arterial blood gas will be taken from your wrist to be analyzed immediately.
- You may then be asked to breathe rapidly on the mouthpiece while a second blood gas sample is taken.
A technologist will instruct you on how to perform the test and coach and encourage you to do your best.
Return to Top
