Respiratory alkalosis

Background

• alkalemia = pH >7.42
• respiratory alkalosis = pCO2 <38
• Cause = hyperventilation
• May lead to Hypocalcemia, Hypokalemia
• Check for a concurrent acid/base disturbance
  • always check for an AG
  • for every 10mm pCO2 <40, HCO3 expected to decrease by 1-3.5 mEq
  • if HCO3 < 24 - (40-pCO2)/10 x 2.5 (+/-1) then there is a superimposed primary metabolic acidosis
  • if HCO3 > 24 - (40-pCO2)/10 x 2.5 (+/-1) then there is a primary metabolic alkalosis, or acute respiratory alkalosis without time for metabolic compensation

DDX

1. Asthma
2. PE
3. DKA
4. Anxiety
5. Hypoxia
6. early Sepsis/fever/Pneumonia
7. Hyperthyroid
8. Sympathomimetics
9. Aspirin (Salicylate) Toxicity
10. Progesterone/pregnancy
11. Liver dz
12. CVA or other central cause

See Also

Acid-Base

Source

KAJI 2011 Tintinalli, Kaji 2011