## Core Concept
Controlled ventilation is a mode of mechanical ventilation where the ventilator delivers a set number of breaths at a set tidal volume, rate, and inspiratory pressure, without allowing the patient to breathe spontaneously. This mode is often used in patients who require full respiratory support and are unable to breathe on their own.

## Why the Correct Answer is Right
In controlled ventilation, the **patient is passive**, meaning they do not initiate breaths and the ventilator provides all breaths. The **ventilator is active**, delivering breaths according to preset parameters. This mode is characterized by **IPPV (Intermittent Positive Pressure Ventilation)**, where the ventilator provides positive pressure breaths at a set rate. Therefore, the correct statements are that the patient is passive (b), the ventilator is active (c), and IPPV (d) is a characteristic of this mode.

## Why Each Wrong Option is Incorrect
- **Option A:** Patient is active - This is incorrect because in controlled ventilation, the patient does not initiate breaths and is therefore passive.
- **Option E:** Ventilator is passive - This is incorrect because in controlled ventilation, the ventilator is actively delivering breaths according to preset parameters.

## Clinical Pearl / High-Yield Fact
A key point to remember is that controlled ventilation is typically used in patients who are paralyzed or under the effect of neuromuscular blocking agents, ensuring that the patient does not make any spontaneous breathing efforts. This mode requires careful monitoring to avoid complications such as barotrauma or volutrauma.

## Correct Answer: B.