Introduction to Respiratory Care/Arterial blood gases
Appearance
Many methods exist to guide the interpretation of the ABG.
Step 1: Henderseon-Hasselbach equation
[edit | edit source][H+] = 24(PaCO2) / [HCO3-]
If the pH and the [H+] are inconsistent, the ABG is probably not valid.
pH | Approximate [H+] (mmol/L) |
---|---|
7.00 | 100 |
7.05 | 89 |
7.10 | 79 |
7.15 | 71 |
7.20 | 63 |
7.25 | 56 |
7.30 | 50 |
7.35 | 45 |
7.40 | 40 |
7.45 | 35 |
7.50 | 32 |
7.55 | 28 |
7.60 | 25 |
7.65 | 22 |
Is there alkalemia of acidemia present?
[edit | edit source]pH < 7.35 acidemia pH > 7.45 alkalemia
- This is usually the primary disorder
- You will need to check the PaCO2, HCO3- and anion gap
- An acidosis or alkalosis may be present even if the pH is in the normal range (7.35 – 7.45)