A 26-year-old man is admitted through the emergency department to the hospital for a heroin overdose. His heart rate is 45 beats/min, and his blood pressure is 75/40 mm Hg. Which of the following best depicts the results from an arterial blood sample ?
pH PaCO2 (mm Hg)
A. 7.22 66 26
B. 7.34 29 15
C. 7.40 40 24
D. 7.47 20 14
E. 7.49 48 35
Correct answer and explanation will be posted next week.
2 comments:
I think that if blood flow is sluggish it would mean that CO2 would accumulate and hence I presume that answer E should be plausible. But i'm really not very confident on this.
The correct answer is A.
This man has a respiratory acidosis. Overdose with drugs that suppress ventilation (e.g., heroin, morphine, barbiturates, methaqualone, and "sleeping pills") often causes hypercapnia. In patients with an intact renal response, the respiratory acidosis causes a compensatory rise in plasma HCO3-, which lessens the fall in pH. However, the renal response requires several days to develop fully. The plasma HCO3- of 26 mEq/L (normal: 22-28 mEq/L) for this man is typical of acute respiratory acidosis with little or no renal compensation.
Choice B reflects metabolic acidosis.
Choice C is normal.
Choice D reflects respiratory alkalosis.
Choice E reflects metabolic alkalosis.
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