A patient with salicylic acid poisoning has the following aerial blood gas analysis repo : pH = 7.12 : pCO2 18mmHg; HCO3= 12mmol/L. The resulting acid base abnormality can be best labeled as :
Answer is A (Metabolic acidosis with compensatory respiratory alkalosis): With pH < 7.35 (7.12) acidosis is confirmed. Abbnormal CO2 with change in opposite to expected. (acidosis should have increased CO2) indicates that the change in compensatory (compensatory respiratory alkalosis), Decreased bicarbonates with change in keeping with change in pH suggests that the problem is metabolic. Thus the whole picture represents metabolic acidosis with compensatory respiratory alkalosis. Explanation : Acid base disorders needlessly, confuse many people, but if a few simple rules are applied then interpretation and diagnosis are easy. pH < 7.35 is acidosis ; pH > 7.45 is alkalosis 1deg change in HCO3 is termed as metabolic (Normal HCO3- = 22 - 30 meq/l) if change in HCO3- is in keeping with the pH (i.e. if there is acidosis and HCO3- decreased) the problem is a Metabolic one. If change in HCO3 is opposite with the pH (if there is acidosis and HCO3" is increased or normal) the problem is compensatory metabolic. 1deg change is CO2 is termed as respiratory (Normal pCO2 = 35 - 45 mmHg) If change in CO2 is in keeping with the pH (if in acidosis CO2 is raised) the problem is termed respiratory If change in CO2 is opposite with the pH (if there is acidosis and CO2 is decreased or normal) problem is termed as compensatory respiratory. the pH (if there is acidosis and CO2 is decreased or normal) problem is termed as compensatory respiratory. STEP 1 : What is the pH. Normal pH pH of patient Inference Acidosis 7.35 - 7.45 7.12 pH is decreased Acidosis STEP II : Is it a metabolic or respiratory change Parameter Inference Is change towards acidosis or alkalosis Parameter Inference Is change towards Is change in Final Inference acidosis or alkalosis keeping with Is change in keeping with change in pH change in pH Final Inference pCO2 = 18mm Hg (Respiratory component) (Respiratory decreased component) pCO2 is decreased Alkalosis pCO2 = 18mm Hg pCO2 is Alkalosis No Respiratory component is compensatory No Respiratory component is compensatory pCO3- = 12 mmol/e (Metabolic component) (Metabolic decreased component) FICO3" is decreased Acidosis pCO3- = 12 mmol/e FICO3" is Acidosis Yes Metabolic component is primary Yes Metabolic component is primary STEP III : Final deduction Because metabolic component is primary and respiratory component is compensatory the acid base disorder is Metabolic acidosis with compensatory Respiratory alkalosis.
Metabolic acidosis with compensatory respiratory alkalosis
Metabolic acidosis with compensatory respiratory alkalosis
Respiratory acidosis with metabolic alkalosis
Metabolic acidosis