**Question:** Which of the following drug is associated with postoperative delirium and hallucinations -

A. Benzodiazepines (e.g., midazolam)
B. Opioids (e.g., fentanyl)
C. Sedative combinations (e.g., propofol-fentanyl)
D. Anxiolytics (e.g., lorazepam)

**Correct Answer: C. Sedative combinations (e.g., propofol-fentanyl)**

**Core Concept:** Postoperative delirium and hallucinations are side effects of certain medications used for anesthesia and sedation in the perioperative period.

**Why the Correct Answer is Right:** Sedative combinations often include benzodiazepines (e.g., midazolam), opioids (e.g., fentanyl), and sedative agents (e.g., propofol). Delirium and hallucinations can occur due to the synergistic effect of these drugs acting on the central nervous system (CNS).

**Why Each Wrong Option is Incorrect:**

**A. Benzodiazepines (e.g., midazolam):** Benzodiazepines are a separate group of drugs and are not always associated with postoperative delirium and hallucinations. They might contribute to sedation, but when used alone or in combination with other drugs, the risk of delirium and hallucinations is lower compared to the sedative combinations mentioned in option C.

**B. Opioids (e.g., fentanyl):** Opioids are commonly used in anesthesia and sedation, but they are not exclusively responsible for postoperative delirium and hallucinations. The combination of benzodiazepines and opioids increases the risk of these side effects.

**D. Anxiolytics (e.g., lorazepam):** Anxiolytics are a separate group of drugs that primarily target anxiety but, like benzodiazepines, are not solely responsible for postoperative delirium and hallucinations. These side effects are more likely to occur when benzodiazepines and opioids are combined, as in option C.

**Clinical Pearl:**

Postoperative delirium and hallucinations are more likely to occur when combined sedatives are used, as seen in option C. These side effects are generally less common with the use of single agents like benzodiazepines (option A) or opioids (option B).

**Explanation:**

Postoperative delirium and hallucinations are primarily caused by the synergistic effect of benzodiazepines and opioids acting on the CNS, which leads to altered mental status and hallucinations in patients after surgery. When using a combination of these drugs, their combined actions can create a higher risk of these side effects compared to using each drug individually or in combination with another drug (e.g., benzodiazepines + anxiolytics)

**Why it Matters:** Understanding the risk factors associated with postoperative delirium and hallucinations is crucial for