PRIMARY DISORDER Resp and Metab are on opposite sides of acidosis and alkalosis. Easy :- Primary disorder tallies with pH.
(Resp + Metab) acidosis/alkalosis. Calculate (Δ Value/Normal value) for pCO2 and HCO3. Larger value is the primary.
COMPENSATION Resp Metabolic Acidosis Alkalosis HCO3 pCO2 X 0.7 X 0.1 X 0.4 I N C a/c R c/c EpCO2 A HCO3 S HCO3 I X 0.2 N pCO2 X 1.2 X 0.5 G Alkalosis Acidosis
JUMPING THE ANION GAP Always calculated for metabolic acidosis. AG = Na – (Cl + HCO3) = <10 normally. High AG ≥ 10 ΔAG = Excess anions = AG – 10 (Anions neutralized by HCO3) Original HCO3 = ΔAG + HCO3
ΔAG REVELATIONS ΔAG = ΔHCO3; All is well. ΔAG > ΔHCO3 = HAG Met Acid + Meta Alk. ΔAG < ΔHCO3 = HAG Met Acid + NAG Met Acid.
NAGMA – SO WHAT? Calculate Urine AG = (Na + K) – Cl Normal UAG = 0 ≈ GI loss (diarrhoea) UAG > 0 ≈ Urinary loss (RTA)
APPENDIX High RBS needs corrected Na. Corrected Na = Na + [(RBS-100)/100] X 1.4.
HCO3 THERAPY pH < 7.2 and HCO3 < 5 – 10 mEq/l Inadequate ventilatory compensation Elderly on β-blockers in severe acidosis with compromised cardiac function Concurrent severe AG and NAGMA Severe acidosis with renal failure/intoxication
HOW MUCH HCO3 HCO3 deficit = (ideal – actual) X 0.5 X lean body wt.