Congrats to the readers, most of you understood the point. Here is my analysis.
| ABG | |
|---|---|
| pH | 7.46 |
| pCO2 | 66 |
| pO2 | 61 |
| calc HCO3 | 46 |
1. The patient is alkalotic, therefore the patient clearly has a metabolic alkalosis.
2. I had to look up the compensation for metabolic alkalosis (I remember the Winter’s equation but not this equation). The predicted pCO2 = 0.7*HCO3 + 20 (range of 5).
3. Therefore, we would expect a pCO2 of 52 (range 47-57). Since the pCO2 is greater than that, we also have a primary respiratory acidosis.
One commenter (one of my interns at UAB) wrote a wonderful summary of how this might occur. I quote:
He has a multiple reasons for a metabolic alkalosis:
1) renal compensation for resp. acidosis
2) hypokalemia and hypochloremia from diuresis
3) hyperaldo from CHF
4) Post-hypercapnic
I decided to give him a couple of doses of acetazolamide to ameliorate his metabolic alkalosis. We did that yesterday and again today. We did decrease his bicarbonate, but he continues to have a respiratory acidosis.
The reason that I presented this case was to make the points that my intern made above, and to remind us all that metabolic alkalosis and respiratory acidosis is a relatively common combination. Treating the metabolic alkalosis can help in treating the respiratory acidosis.
