A PaCO2 of 50 mm Hg indicates which condition?

A PaCO2 of 50 mm Hg indicates which condition?

• A. Hypocapnia
• B. Hypercapnia
• C. Normal
• D. Respiratory alkalosis

Answer: (B)

PaCO2 shows how well the lungs are removing carbon dioxide. Normal arterial CO2 is about 35–45 mm Hg. A value of 50 mm Hg means CO2 is elevated, which is hypercapnia and usually results from inadequate ventilation or hypoventilation (for example, COPD, sedative overdose, neuromuscular weakness, or chest wall restriction). When CO2 is high, the blood tends toward respiratory acidosis if the metabolic system hasn’t compensated yet. The other concepts don’t fit: hypocapnia would be a low CO2 from overventilation; a normal PaCO2 would be around 35–45; respiratory alkalosis is driven by low CO2, not high.

PaCO2 shows how well the lungs are removing carbon dioxide. Normal arterial CO2 is about 35–45 mm Hg. A value of 50 mm Hg means CO2 is elevated, which is hypercapnia and usually results from inadequate ventilation or hypoventilation (for example, COPD, sedative overdose, neuromuscular weakness, or chest wall restriction). When CO2 is high, the blood tends toward respiratory acidosis if the metabolic system hasn’t compensated yet. The other concepts don’t fit: hypocapnia would be a low CO2 from overventilation; a normal PaCO2 would be around 35–45; respiratory alkalosis is driven by low CO2, not high.