Acid Base II
Algorithm Metabolic Disorders
Met acidosis
Algorithm Respiratory disorders
- Look at pH
- Look at CO2
- Ask, Is there another problem?
- 3a. Check Anion Gap
Hi: respiratory acidosis
Low: Respiratory alkalosis
3b. Is this Acute/Chronic?
3c. Is Bicarb appropriate?
- With the Dime changes accounted for, is the expected = given (measured)
Dime change CO2, every 10 CO2, pH changes by
- 0.08 if acute.
- 0.04 if chronic.
Dime change CO2, every 10 CO2, pH changes by
- 0.08 if acute.
- 0.04 if chronic.
Dime Change, every 10 CO2
- 1 Bicarb if acute
- 3 Bicarb if chronic
Dime Change, every 10 CO2
- 2 Bicarb if acute
- 4 Bicarb if chronic
✏
- too much bicarb, Met Alk
- too little bicarb, Met Acid
- Look at pH: Low
- Look at CO2: also Low
- Are there other problems?
3a. Check Anion Gap: normal is 12 on shelf/step2
- real life: Albumin x 3 = normal anion gap
⚠3b. Is PCO2 appropriate?
3c. In setting of Metabolic Acidosis, is there another Bicarb abrnomality?
Winters Formula: 1.5 Bicarb + 8
Measured > Expected
Respiratory Acidosis
Measured < Expected
Respiratory Alkalosis
Delta Delta? ehhh, too hard
Add Back
✏ Normal Gap = 12, so if Gap is 30, there is 18 hydrogen ions.
- These 18 H correspond to 18 Bicarb
- add 18 Bicarb to the measured Bicarb to find out our starting Bicarb (e.g. 28)
Bicarb Normal = 24
Too much Bicarb (from V large Anion Gap)
Anion Gap Acidosis with Metabolic Alkalosis
Too little Bicarb (<24)
Anion Gap Acidosis w/ a NonGap Metabolic Acidosis
Met Alkalosis (easier)
- check pH: Hi
- Check CO2: high
⛔ Stop
- Metabolic Alkalosis is Hyperaldosterone state
✏ Dustyn's Advice: This is Hard. If you don't master it, just take the hit on the shelf/step2. Its rare enough that you shouldn't waste time on a problem you will probably get wrong anyway
How to perform:
calculated Gap - 12- Add this to measured Bicarb
- is it higher or lower than 24? Too high (combined met alkalosis), and vice versa