What laboratory finding would correlate with an opioid overdose?

• A. HCO₃⁻ 24 mEq/L
• B. pCO₂ 60 mmHg
• C. pH 7.4
• D. pO₂ 92 mmHg

Answer: (B)

In the context of an opioid overdose, elevated levels of carbon dioxide in the blood, indicated by an arterial blood gas measurement showing a partial pressure of carbon dioxide (pCO₂) of 60 mmHg, are significant. Opioid overdose typically leads to respiratory depression, which results in hypoventilation and an accumulation of carbon dioxide in the bloodstream due to inadequate removal through exhalation. This elevated pCO₂ reflects hypercapnia, which often accompanies respiratory failure or decreased respiratory drive associated with opioid toxicity.

A pCO₂ reading of 60 mmHg suggests a state of respiratory acidosis, which is commonly found in patients who are unable to adequately ventilate due to opioid effects. The other laboratory findings provided do not correlate with the expected changes seen in opioid overdose. For instance, normal bicarbonate levels, a pH of 7.4, and a pO₂ of 92 mmHg do not show the alterations consistent with the hypoventilation and resultant acid-base imbalance typically observed in these situations. Thus, the finding of elevated pCO₂ is a key indicator of the physiological impact of opioid overdose.