Using the examples in Table 4, interpret the values and place each into one of the four acid/base categories.
Table 4. Acidosis/Alkalosis Examples.| Example | pH | pCO2 | HCO3- |
| 1. | 7.23 | 60 | 24 |
| 2. | 7.23 | 40 | 17 |
| 3. | 7.64 | 23 | 24 |
| 4. | 7.64 | 40 | 41 |
Remember the reference ranges:
| Reference Range |
| Blood pH | 7.35-7.45 |
| HCO3- | 22-26 mmol/L |
| pCO2 | 35-45 mmHg |
Steps to interpret arterial blood gas (ABG) values:
- Look at the pH to determine acidosis or alkalosis.
- Compare the pCO2 and HCO3- to the normal values. If the pCO2 is abnormal, it's a respiratory problem. If the HCO3- is abnormal, it's a nonrespiratory (metabolic) problem.
Interpretation of Examples
Example 1: The pH is low, indicating it is acidosis. The pCO2 is high and the HCO3- is within range, so the problem is respiratory. The interpretation is respiratory acidosis.
Example 2: The pH indicates acidosis. Examining the pCO2 is within range and the HCO3- is low, we can determine the problem is nonrespiratory. The interpretation is nonrespiratory (metabolic) acidosis.
Example 3: The pH is high, which is alkalosis. The pCO2 is low and the HCO3- is within range, so the interpretation is respiratory alkalosis.
Example 4: The pH value indicates alkalosis. The pCO2 is within range and the HCO3- is high, the interpretation is nonrespiratory (metabolic) alkalosis.
