Ok, let's start with interpreting the lab values.
Arterial blood gases: pH 7.25; PaO2 60 mmHg; PaCO2 78 mmHg; HCO3- 34 mEq/l
- Serum sodium (Na+) 140 mEq/L
- Serum potassium (K+) 2.0 mEq/L
- Serum chloride (Cl-) 105 mEq/L
Ignore the ABGs for a second since your first question asks about electrolyte imbalances. You have 3 electrolyte levels here. Which one is out of range? If you have studied the normal ranges for serum electrolytes, this one should stick out to you like a sore thumb.
Serum sodium is 140. Normal range is what? 135-145 (varies slightly depending on the lab) so he's good there.
Serum chloride is 105. Do you know the normal range for this? High normals are usually around 106-107 so no problem here either.
Serum potassium is 2.0. This is what we call a critical
lab value. What's the normal range? Is this higher or lower than normal? What do we call it when there is an electrolyte imbalance involving potassium? What are the important things to monitor with an out-of-range potassium level?
Now, let's look at the ABGs:
pH 7.25. What's normal? If you said 7.35-7.45, you're right. So your pH is lower than normal which tells you that you have some kind of acidosis going on. How do you tell where it's coming from? Based on your PaCO2 and HCO3 values, right?
PaCO2 is 78 mmHg. What is the normal range for this? 35-45. CO2 is an acid and your level is elevated so you have more acid than normal and, voila, you have the cause of your acidosis. So what does this mean? CO2 is the respiratory piece of the puzzle right? So you're dealing with a respiratory acidosis (which should make sense with a patient with a respiratory pathophysiology).
HCO3 is 34 which means that this, too, is elevated. Normal range is 22-26. HCO3 is a base. You have an acidotic state, so why is the base level elevated as well? Have you learned about compensation yet? Unless the underlying problem is corrected, your HCO3 will continue to rise until it's able to get the pH within range. The kidneys are working here to correct the acidosis by excreting more carbonic acid and reabsorbing more bicarbonate to bring the serum level up.
EVERYTHING is out of range here. What does it mean when all values are out of range? It means you're dealing with a partially compensated state. In an uncompensated state of respiratory acidosis, the HCO3 would still be normal. It's elevated because the body is trying to compensate but you know that it's only partially compensated because your pH is still profoundly abnormal. A fully compensated state would give you a normal pH.