ABG

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A 70-year-old woman was recently treated for pneumonia with antibiotics. After 1 week on antibiotics, she started developing severe diarrhea of 6–7 loose, watery stools per day. The diarrhea has been present for 3 days. She also has a decreased appetite, feels nauseous, and has not been drinking a lot of fluids. She feels very weak and dizzy. She lives alone, so she called 911 and was brought to the emergency department. She is diagnosed with diarrhea, presumptive Clostridium difficile. 

  • Patient medical history: Clostridium difficile 2 years prior.
  • Physical examination: temperature 99.0°F; pulse 100 beats per minute; respirations 24 per minute; and blood pressure 90/50 mmHg, which dropped to 70/40 mmHg when seated. Examination unremarkable except for dry mucous membranes and generalized mild abdominal tenderness with palpation.
  • Laboratory findings reveal:
  • Chemistry panel: sodium 135 mEq/L; potassium 3.4 mEq/L; chloride 100 mmol/L; HCO3- 12 mEq/L; blood urea nitrogen 40 mg/dL.
  • Creatinine: 1.2 mg/dL.
  • ABG: pH 7.22, PaO2 85 mmHg, PaCO2 20 mmHg, HCO3- 12 mEq/L.

Activity

  1. Analyze the ABG and determine the acid–base disturbance.
  2. Calculate the compensation response and determine if it is appropriate.
  3. This item is optional. Calculate and interpret the anion gap.
  4. Discuss the diagnosis.
  5. Develop a treatment plan.