So I got pimped mercilously by my attending two days ago, while I was sick, feeling like crap, and had only seen my patient for like 20 minutes. So it never happens to you, I present the quick’n’dirty acid-base disorder step-by-step guide:

1. Get a blood gas. Put it in ice, send it to the lab.
2. Look at pH: Less than 7.4? Acidosis. Greater than 7.4? Alkalosis.
3. Look at pCO ₂ and bicarb. Do they move in the same direction as the pH, or the opposite direction? (Nl pCO ₂ = 40, nl bicarb = 24.) If they move in the sa ME direction, it’s primary ME tabolic. If they move in a diffe RE nt direction, it’s primary RE spiratory.
4. Is the non-primary system compenstating appropriately? (Calculate that with those annoying equations I can never remember.)
5. Is there an anion gap? (Na – Cl – bicarb > 12) If no, you’re done.
6. If yes, take the anion gap – 12. Add that to the bicarb level. If it’s greater than 26, you’ve got a metabolic alkalosis as well. If it’s less than 22, you’ve got a non-anion gap metabolic acidosis, too. Classic pimping: You can have 3 disorders co-existing, but not 4. (Your lungs can either be making respiratory acidosis or alkalosis, not both.)

And on to the mnemonics for the causes:

Anion Gap Metabolic Acidosis: MUDPILERS

• Methanol
• Uremia
• DKA/Alcoholic KA
• Paraldehyde
• Isoniazid
• Lactic Acidosis
• Etoh/Ethylene Glycol
• Rhabdo/Renal Failure
• Salicylates

Non-Anion Gap Acidosis: HARDUPS

• Hyperalimentation
• Acetazolamide
• Renal Tubular Acidosis
• Diarrhea
• Uretero-Pelvic Shunt
• Post-Hypocapnia
• Spironolactone

Acute Respiratory Acidosis (Chronic Respiratory Acidosis = COPD/restrictive lung dz): any hypoventilation state

• CNS Depression (drugs/CVA)
• Airway Obstruction
• Pneumonia
• Pulmonary Edema
• Hemo/Pneumothorax
• Myopathy

Metabolic Alkalosis: CLEVER PD

• Contraction
• Licorice*
• Endo: Conn’s/Cushing’s/Bartter’s)*
• Vomiting
• Excess Alkali*
• Refeeding Alkalosis*
• Post-hypercapnia
• Diuretics

* = Associated with High Urine Cl levels

Respiratory Alkalosis: CHAMPS (think speed up breathing)

• CNS disease
• Hypoxia
• Anxiety
• Mech Ventilators
• Progesterone
• Salicylates/Sepsis

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