Case #1

The patient is a 35 year -old female with AIDS brought to the emergency room with a fever of 39oC and a three month history of copious diarrhea.

On physical exam the patient is a well-developed, thin female in moderate distress. Vital signs-(supine) blood pressure 100/60, pulse 100 and (standing) blood pressure 80/40, pulse 125, respirations 18 and she was afebrile. HEENT exam was normal. Cardiac exam demonstrated an S1 and S2 without S3, S4 or murmur. Lungs were clear to auscultation and percussion. The abdomen was supple and minimally tender to palpation. Bowel sounds were hyperactive. Stool was guiac negative. Extremities were without cyanosis, clubbing or edema. Neurological exam was intact.

Laboratory Data

Chemistry

Normal Values Arterial Blood Gas
Sodium 136 136-146 mmol/L pH 7.35
PCO2 27 mmHg
PO2 90 mmHg
bicarbonate 14 mmol/L

Potassium

3.4 3.5-5.3 mmol/L
Chloride 112 98-108 mmol/L
Total CO2 14 23-27 mmol/L
BUN 30 7-22 mg/dl

Creatinine

1.5 0.7-1.5 mg/dl

Glucose

105 70-110 mg/dl

Questions

1. What is/are the critical course of events that is going to alter her acid-base status?  Answer

2. What Acid base abnormalities would you expect based on this information?   Answer

3. What physical findings would you expect to see from such an acid base disturbance?   Answer

4. Review her blood gases. What is the primary acid-base abnormality? How did you decide that?   Answer

5. Calculate the anion gap in this patient. What is the normal anion gap. What is the gap due to in normals?   Answer

6. What is her bicarbonate gap?   Answer

7. Obviously this patient has nonanion gap metabolic acidosis  What is the relationship between the  bicarbonate gap and the anion gap?    Answer

8. Is there a compensatory mechanism for metabolic acidosis? How is that brought about? What are the sensors and effectors for metabolic acidosis?   Answer

9. What is the predicted compensatory response?    Answer

10. Is his respiratory compensatory effort appropriate? Can respiratory compensatory effort fully compensate for metabolic acidosis?   Answer

11. Is this a simple or mixed disorder? How did you come to that conclusion?   Answer

12. What clinical condition(s) is (are) responsible for the acid-base disturbance in this patient?   Answer

13. What are the physiologic mechanisms responsible for the generation of this disturbance?   Answer

14. What are the other causes for non-anion gap metabolic acidosis?   Answer