case!!!

A 18 year-old female is admitted to the emergency room with a suspected drug overdose. Her respiratory rate is slow (4-8 times/minute) and shallow. Arterial blood gases reveal a PCO2 of 80 mm Hg and PO2 of 60 mm Hg.

• What is the cause of this woman's high PCO2 and low PO2?
• Hypoventilation almost always causes an increase in PCO2. Explain.
• Even though her PO2 increases to 90 mm Hg with institution of oxygen therapy, her PCO2 remains elevated. Explain.

WARNING:
This question might be easy for you guys. However, SHARING is CARING!!! [Sorry cause answer is not provided]

Wassalam.