Yesterday I provided this patient:
Interesting patient presented recently. He is HIV+ and has a 10 day history of large volume watery diarrhea. On the 3rd day his BMP showed. On admission his HCO3 was 19.
| Electrolyte panel | |||||
|---|---|---|---|---|---|
| Na | 149 | Cl | 128 | BUN | 13 |
| K | 3.0 | HCO3 | 12 | creat | 0.8 |
This is actually relatively easy.
1. What is the likely acid-base problem?
Given the large volume watery diarrhea, he likely has stool losses of bicarbonate.
2. How can we prove our assumption?
We obtained an ABG and a urine anion gap.
ABG: pH 7.2; pCO2 23; pO2 125; HCO3 9
Una 58; Uk 11; Ucl 156 – for Urine Anion Gap of -87. This is a profound negative anion gap and confirms our suspected diagnosis.
3. How would you treat this patient?
We considered 3 issues in treatment:
- Hypernatremia – patient had a free water deficit
- Metabolic acidosis – given the profound bicarbonate loss we had to give bicarbonate
- Hypokalemia – need to replete
We gave D5/W plus 2 amps of bicarbonate for 2 days and corrected the acidosis. The serum sodium decreased with the extra free water.
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This is not a tricky problem, but one that I rarely see. Developing a normal gap acidosis from diarrhea requires very large volume diarrhea. This patient had that problem secondary to MAC colon infection (diagnosis made on the first day).
{ 3 comments… read them below or add one }
How much D5/W was given?
How to calculate dosage of bicarb?
What if patient is diabetic?
Is it advisable to give D5/W and ad insulin in IV fluid to control sugar in diabetics?
@Ram, there are formulas to calculate free water deficit- here is one: http://www.mdcalc.com/free-water-deficit-in-hypernatremia
If high blood glucose is a problem, an insulin infusion can be run concurrently – both for the hyperglycaemia and also to prevent nephrogenic DI due to the hyperglycaemia