## Core Concept
The patient's symptoms of itching and somnolence after receiving epidural morphine, along with the blood gas results showing respiratory acidosis (pH 7.24, PaCO2 58), indicate opioid-induced respiratory depression. This is a life-threatening condition that requires immediate intervention. The epidural morphine can cause systemic effects, including respiratory depression, due to its absorption into the bloodstream.

## Why the Correct Answer is Right
The correct approach to manage opioid-induced respiratory depression involves administering a medication that can rapidly reverse opioid effects without causing significant harm. Naloxone is an opioid receptor antagonist that can effectively reverse opioid-induced respiratory depression. It works by competitively inhibiting the action of opioids at opioid receptors, thereby restoring normal respiratory function.

## Why Each Wrong Option is Incorrect
**Option A:** This option is not provided, but typically, other treatments might include supportive care like oxygen therapy or mechanical ventilation, which are important but not the initial therapy for reversing opioid-induced respiratory depression.
**Option B:** This option is also not provided, but other pharmacological interventions might not be as immediate or effective as naloxone in reversing opioid effects.
**Option C:** Similarly, without the specific details, any other medication that does not directly counteract opioid effects would not be the first line.
**Option D:** Assuming this is not naloxone, any alternative would not provide the immediate reversal of opioid effects that naloxone does.

## Clinical Pearl / High-Yield Fact
A key point to remember is that naloxone is the antidote for opioid overdose, including situations of opioid-induced respiratory depression. It is crucial to administer naloxone promptly in such cases, as delays can lead to serious morbidity or mortality. The typical dose of naloxone for adults is 0.4-2 mg intravenously, which can be repeated as necessary.

## Correct Answer Line
**Correct Answer: B. Naloxone.**