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Tuesday, February 10, 2015

{ABGs} Arterial Blood Gases: The Ultimate Beginners Guide

ABGs, Arterial Blood Gases, nurse, lab draws, respiratory alkalosis, respiratory acidosis, metabolic alkalosis, metabolic acidosis, pH, Acid-Base Imbalances

Arterial Blood Gas

It's a lab we draw from the patient's artery that tells us the patient's arterial oxygen (PaO2), arterial carbon dioxide (PaCO2),  arterial oxyhemoglobin saturation (SaO2), bicarb (HCO3), and acidity (pH). It's often used in ICUs. It is a very important lab draw that is vital in caring for critically ill and patient's in respiratory distress.
Typically, blood is drawn from the radial artery, but it can also be drawn from the femoral artery, or from an art line that's already in place. 

Here's a short 3 minute video on Collecting an ABG Sample in a patient's wrist. They're British (so I love the accent). You can skip ahead to the 2 minute mark to watch him insert the needle. 

Basically you'll prep the same you would for a venous puncture, except you're looking for an artery, not a vein. So feel for the radial pulse. Try to palpate it up and down the wrist a little bit until you feel comfortable in knowing the location of the artery. 

The sample should be put on ice immediately after it is drawn. 

Pressure should be held on the puncture site for several minutes so that the patient doesn't develop a hematoma.

Normal Lab Values

These are lab values you should probably commit to memory. It'll be nice to know for tests, NCLEX and in clinical settings. 

  • pH - 7.35 - 7.45
  • PaCO2 35 - 45
  • HCO3 22 - 26

Acidosis or Alkalosis??

Acidosis is when the pH is below 7.35

Alkalosis is when the pH is above 7.45

Respiratory or Metabolic?

Respiratory is when PaCO2 is off.

Metabolic is when HCO3 is off.

When in ROME...

I love Pinterest guys. I didn't know this factoid until long after my acid-base imbalance questions in pathophysiology and medical-surgical courses. 

Respiratory Opposite
Metabolic Equal

There you have it. When in ROME.

This week I'll post about each 4 imbalances (respiratory alkalosis/acidosis, metabolic alkalosis/acidosis). If I included all that here it would be too long of a post.

Metabolic Acidosis
Metabolic Alkalosis
Respiratory Acidosis
Respiratory Alkalosis

But in a nut shell-- BAM!  That's ABGs.

I didn't go into too many details on this post, so if you'd like more information I have an ebook on for $3.99 that explains everything so much better. I also work through practice problems with you- step by step. I know how confusing this can be. It took me four different teachers, and four different classes until I FINALLY learned acid-base imbalances the correct way. So check it out! Easy Guide to Interpret Acid-Base Imbalances. It's cheaper than your lunch, and you don't even need to have a kindle to read it!! Thanks!!

What are you having troubles understanding in school right now? Leave a comment below!!




  1. this is AWESOME! Thank you so much!

  2. You're most definitely welcome! This took me forever to "master". I try to help when I can. haha. Happy Thanksgiving!

  3. going to use this with my nursing students! thanks!

    1. Thank you!! Good luck to you and your students. :)

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