The acid base status of a patient reveals a pH = 7.46 and pCO2=30 mm Hg. The patient has a paially compensated primary:
Answer is C (Respiratory alkalosis): A pH of 7.46 (alkalosis) and a reduced pCO2 (30 mmHg) suggests a diagnosis Respiratory alkalosis. The change in CO2 (alkalosis) is in-keeping with the pH change (alkalosis) thereby suggesting a primary diagnosis of Respiratory alkalosis. Rules to acid base disorders: Review pH < 7.35 is acidosis ; pH > 7.45 is alkalosis 1deg change in HCO3 is termed as metabolic (Normal HCO3- = 22 -- 30 meq/I) 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 alkalosis CO, is reduced) the problem is termed respiratory If change in CO2 is opposite with the pH (if there is alkalosis and CO2 is raised) problem is termed as compensatory respiratory. Stap I : What is the pH Normal pH 7.35 - 7.45 pH of patient 7.46 Inference pH is increased Acid / Base disorder Alkalosis Step II : Is it metabolic or Respiratory If change in pCO2 is inkeeping with pH (if in alkalosis pCO2 is reduced) the primary acid base abnormality is respiratory. The patient in question thus has primary respiratory alkalosis which may have been paially compensated (data On NCO 3 values to assess the extent of compensation is not provided in the question).
Metabolic acidosis
Metabolic alkalosis
Respiratory alkalosis
Respiratory acidosis