## Core Concept
Type II respiratory failure, also known as hypercapnic respiratory failure, is characterized by the inability of the lungs to remove carbon dioxide and provide adequate oxygenation. This condition involves both hypoxemia (low blood oxygen) and hypercapnia (elevated blood carbon dioxide levels). It typically results from disorders that affect the respiratory drive or the mechanical process of breathing.

## Why the Correct Answer is Right
The correct answer, , indicates that in type II respiratory failure, there is both hypoxemia (low PaO2) and hypercapnia (high PaCO2). This is because type II respiratory failure involves inadequate gas exchange leading to insufficient oxygen levels in the blood and an accumulation of carbon dioxide. This condition often arises from problems with the respiratory drive (e.g., narcotic overdose), neuromuscular disorders (e.g., myasthenia gravis), or severe lung diseases that affect the airways and lung parenchyma.

## Why Each Wrong Option is Incorrect
* **Option A:** - This option suggests only hypercapnia without mentioning hypoxemia, which is incomplete for the definition of type II respiratory failure.
* **Option B:** - This option indicates only hypoxemia without hypercapnia, which describes type I respiratory failure, not type II.
* **Option D:** - This option implies normal PaCO2 with hypoxemia, which does not align with the hypercapnic aspect of type II respiratory failure.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that type II respiratory failure often requires not just supplemental oxygen but also interventions to improve ventilation, such as mechanical ventilation or treatments aimed at enhancing respiratory drive and muscle strength. Causes can include chronic obstructive pulmonary disease (COPD) exacerbations, pneumonia, and conditions affecting the respiratory muscles or nervous system control over breathing.

## Correct Answer: C.