Final answer:
In pressure-targeted ventilation, the tidal volume (VT) is determined by the pressure difference, the inspiratory time, and the time constant. These factors together influence the amount of air delivered with each breath.
Step-by-step explanation:
During pressure-targeted ventilation, the tidal volume (VT) is determined by several factors, including the pressure difference across the lungs (the pressure set on the ventilator minus any existing pressure within the lungs), the inspiratory time which is the duration of each breath, and the time constant, which is a product of lung compliance and airway resistance. It is the combination of these settings that ultimately dictates how much air (VT) is delivered with each breath.
- The pressure difference contributes to the force driving air into the lungs, impacting the VT.
- Inspiratory time affects how long the set pressure is applied, influencing the total volume delivered.
- The time constant can limit the VT as it determines how quickly the lungs fill with air.
Therefore, the correct answer to the question is d: I, II, and III. In pressure-targeted ventilation, the VT is affected by the pressure difference, the inspiratory time, and the time constant.