Question

A 24-year-old with diabetic ketoacidosis is admitted to the ED and his blood glucose on arrival was 780. He has been started on an insulin drip and has received one amp of bicarb. The nurse will be doing finger stick blood sugars every hour. ABG results are: pH= 7.31 PaCO2= 25 mm/Hg HCO3=12 mmol/l 1. The graduate nurse asks the preceptor to help with interpretation of the blood gases. How should the preceptor interpret these values and explain the reasons for the changes?

Answer 1

Normal arterial blood gas values are

• pH :7.35 -7.45
• PaCO2:35-45 mm Hg
• HCO3:22-26 mEq/l
• PaO2:80-95 mm Hg

According to the values of the patient mentioned above he is in a state of partly compensated metabolic acidosis. Metabolic acidosis due to decreased HCO3 and slightly acidic pH. The pH value is near to the normal range which made the result partially compensated.

• If pH is less it is acidosis, if pH is more it is alkalosis.
• To find out whether disturbance related to respiratory or metabolic. Respiratory acidosis: If PaCO2 value more than 40 mmHg then it is respiratory acidosis,and if serum HCO3 is less than 24 mEq/L then it is metabolic acidosis..
• Here PaCO2 is low reflecting the attempt of lungs to compensate.In metabolic acidosis if pH is less than 7.35and HCO3 is less than 22 mEq/L and if the PaCO2 is less than 35 mm Hg, carbon dioxide is being exhaled out to minimize the acidosis and it is respiratory compensation.