Metabolic<unk> osis:
PaCO2 = 1.5 (HCO3) + 8 ± 2
PaCO2 = last two digits of pH
PaCO2= ↓ 1.0–1.5per ↓ 1mEq/L HCO3
Metabolic alkalosis
PaCO2 = 0.9 (HCO3) + 9
PaCO2= ↑ 0.5–1.0 mm per ↑ 1mEq/L HCO3
Respiratory<unk> osis and alkalosis (acute<unk> -base changes<unk> d on PCO2 and HCO3):
∆H+=0.8 (∆PaCO2)
For every ↑ or ↓ of PCO2 by 1 the pH changes by 0.008
For every ↑ or ↓ of HCO3 by 1 the  pH changes by 0.015
Estimate of<unk> line PCO2 in patients with Acute Respiratory<unk> osis:
Estimated<unk> line PCO2 = 2.4 (admission measured HCO3 – 22)
Chronic respiratory<unk> osis
HCO3 increases by 4 for every 10 mmHg ↑ in pCO2 above 40
∆H+=0.4 (∆PaCO2)
In chronic respiratory<unk> osis, kidneys retain HCO3, which takes a few days
Chronic respiratory alkalosis
HCO3 decreases by 5 for every 10 mmHg decrease in pCO2 below 40
∆H+=0.5 (∆PaCO2)
Takes few days also
Maximal compensation is HCO3 ~12-15 mEq/L
Acid-base disorders
Metabolic acidosis
Ventilator high pressures
Metabolic alkalosis
Jet Propulsion Fuel 8 toxicity
Respiratory acidosis
Hypercapnia
Respiratory alkalosis