1. Ibrahim alzahrani R1 Quiz of the week

2. 18 years old male who presented with sever cough, greenish sputum and high grade fever (39.5). He developed sever nausea, vomiting and abdominal pain.

3. ABG : PH: 6.9 PaCO2: 52 HCO3: 7 PaO2:65 Electrolyte : Na = 139 Cl=95 K=4.8

4. Interpret this ABG. Explain the ABG results Do you want any further test ?

5. What is the expected HCO3 in respiratory acidosis?

6. Compensation in respiratory acidosis: acute respiratory acidosis the serum HCO3 increases by about 1 meq/L for every 10 mmHg elevation in the PCO2 Chronic respiratory acidosis: serum HCO3 increases by 3.5 to 4 meq/L for every 10 mmHg elevation in PCO2

7. For every increase in Pa CO 2 of 20mmHg above normal the pH falls by 0.1 For every decrease of Pa CO 2 of 10mmHg below normal the pH rises by 0.1.

8. What about A-a gradient ?

9. A-a oxygen gradient = PAO 2 - PaO 2. PAO 2 = (FiO 2 x 713) - (PaCO 2 ÷ 0.8) Simplified equation :

10. Back to the case How can you explain a HCO3 of 7?

11. 3 Step approach : Step 1: Establish the primary diagnosis: Step 2 :Assess the degree of compensation: indicative of a mixed acid-base disorder

12. Step 3: Determine whether or not the anion gap is elevated. This is especially important for patients with metabolic acidosis Serum AG = Na - (Cl + HCO3) = 139-(95+7)=37 If there is high anion gap then : Δ anion gap/ Δ HCO3 ratio (37-10)/(24-7)=1.6:1 If 1:1 ratio then it’s pure high metabolic acidosis. If < 1:1 : additional non anion gap metabolic acidosis If > 1:1 : Additional metabolic alkalosis

13. High anion gap metabolic acidosis

14. Final diagnosis ; DKA with by right middle lobe community acquired pneumonia.