Which of the following accurately defines the control variable in pressure control ventilation?

• A. Volume delivered during expiration
• B. Pressure delivered during inspiration
• C. Time taken for each breath
• D. Flow rate maintained throughout ventilation

Answer: (B)

In pressure control ventilation, the control variable specifically refers to the component of the ventilatory cycle that is being regulated or set by the clinician. In this mode of ventilation, the primary focus is on maintaining a predetermined inspiratory pressure during the delivery of breaths. This means that while the patient is ventilated, the pressure delivered during inspiration will not exceed the set value, regardless of the volume that may be achieved as a result.

This setting is particularly important because it allows for the protection of the lungs from pressure-induced injury by preventing excessively high pressures from being delivered, which could harm lung tissue. Therefore, the definition of the control variable as the pressure delivered during inspiration is accurate, as it highlights the crucial role of pressure regulation in ensuring adequate, yet safe, ventilation for patients. This understanding of pressure control ventilation is vital for clinicians when managing patients requiring mechanical ventilation, especially those with compromised lung function.