6. PRIMARY DISORDER
Resp and Metab are on opposite sides of
acidosis and alkalosis.
Easy :- Primary disorder tallies with pH.
7. (Resp + Metab) acidosis/alkalosis.
Calculate (Δ Value/Normal value) for
pCO2 and HCO3.
Larger value is the primary.
8. COMPENSATION
Resp Metabolic
Acidosis Alkalosis
HCO3 pCO2 X 0.7
X 0.1
X 0.4 I
N
C
a/c R
c/c E
pCO2 A HCO3
S
HCO3 I
X 0.2 N pCO2 X 1.2
X 0.5 G
Alkalosis Acidosis
9. 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
10. ΔAG REVELATIONS
ΔAG = ΔHCO3; All is well.
ΔAG > ΔHCO3 = HAG Met Acid + Meta
Alk.
ΔAG < ΔHCO3 = HAG Met Acid + NAG
Met Acid.
11. NAGMA – SO WHAT?
Calculate Urine AG = (Na + K) – Cl
Normal UAG = 0 ≈ GI loss (diarrhoea)
UAG > 0 ≈ Urinary loss (RTA)
12. APPENDIX
High RBS needs corrected Na.
Corrected Na = Na + [(RBS-100)/100] X 1.4.
13. 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
14. HOW MUCH HCO3
HCO3 deficit = (ideal – actual) X 0.5 X
lean body wt.