How should the specialist calculate the inspiratory time for a ventilator set at 25 breaths per minute with an I:E ratio of 1:3?

To calculate the inspiratory time for a ventilator set at a specific respiratory rate and I:E (inspiratory to expiratory) ratio, first understand the total cycle time for one breath. The total cycle time can be calculated using the formula:

Total cycle time (seconds) = 60 seconds / respiratory rate (breaths per minute)

In this scenario, with a respiratory rate set at 25 breaths per minute:

Total cycle time = 60 / 25 = 2.4 seconds

Next, the I:E ratio of 1:3 indicates that for every part of inspiratory time, there are three parts of expiratory time. This means the total time is divided into four parts (1 part for inspiration + 3 parts for expiration).

To find the inspiratory time, we divide the total cycle time by the sum of the parts in the I:E ratio:

Inspiratory time = Total cycle time / (1 + 3)
Inspiratory time = 2.4 seconds / 4 = 0.6 seconds

Thus, the correct answer is that the inspiratory time should be set to 0.6 seconds. This calculation ensures that the ventilatory support provided aligns with the desired I:E ratio and