1. Acidosis and Alkalosis

2. The Henderson-Hasselbach Equation….. The lungs control the volume of CO 2 The kidneys control the volume of BCO 3 -

3. Acidosis or Alkalosis…. What is the normal pH range?

4. CO 2 and HCO 3 - What is the normal range of pCO 2? What is the normal range of HCO 3 - ?

5. What’s going on here? pH 7.2 pCO 2 9.3 kPa HCO 3 - 28mmol/L pO 2 7.9kPa Normal Ranges pH 7.35 – 7.45 pCO 2 4.5 – 6.1 HCO 3 - 22-28 1)Look at the pH, is this acidosis or alkalosis? 2)Look at the pCO 2, is it high or low? 3)Look at the HCO 3 - is it high or low? Respiratory acidosis

6. Asthma Attack Metabolic or respiratory? Acidosis or alkalosis? Compensation mechanism? Respiratory Acidosis – constriction of airways None – asthma attack is acute so compensation mechanisms are too slow

7. DKA Metabolic or respiratory? Acidosis or alkalosis? Compensation mechanism? Metabolic Acidosis - ketones Hyperventilation to lower CO 2 (respiratory alkalosis)

8. Vomiting Metabolic or respiratory? Acidosis or alkalosis? Compensation mechanism? Metabolic Alkalosis – loss of electrolytes Slower breathing to retain CO 2 (respiratory acidosis)

9. Panic Attack Metabolic or respiratory? Acidosis or alkalosis? Compensation mechanism? Respiratory Alkalosis – due to low CO 2 None – panic attack is acute so compensation mechanisms are too slow

10. Sepsis Metabolic or respiratory? Acidosis or alkalosis? Compensation mechanism? Metabolic Acidosis – lactic acid Hyperventilation to lower CO 2 (respiratory alkalosis)

11. Case Example A 60 year old man presented to A&E after suffering from SOB, pyrexia and a productive cough over the last 2 days. He has a history of COPD. An ABC was performed and the following values were obtained: pH: 7.2, pCO 2 : 9.3kPa, HCO 3 - : 27mmol/L, pO 2 : 7.9kPa pH = 7.35 – 7.35 pCO 2 = 4.5-6.1 HCO 3 - = 22-28 Respiratory acidosis

12. Case Example An 80 year old man presents with a 2 day history of persistent vomiting. He is lethargic and has myalgia. He has gastroenteritis and is dehydrated. An ABC was performed and the following values were obtained: pH: 7.5, pCO 2 : 6.0kPa, HCO 3 - : 37mmol/L, pO 2 : 11.3kPa pH = 7.35 – 7.35 pCO 2 = 4.5-6.1 HCO 3 - = 22-28 Metabolic alkalosis

13. Acidosis and Alkalosis