If inspiratory flow is reduced but the rate does not change, what is expected to decrease?

• A. Expiratory time
• B. Gas distribution
• C. I:E ratio
• D. Inspiratory time

Answer: (A)

In a scenario where inspiratory flow is reduced while the rate of respiration remains unchanged, the expected outcome is a decrease in expiratory time. With a constant respiratory rate, a reduction in inspiratory flow results in a longer inspiratory time, which, in turn, reduces the time available for expiration if the total cycle time remains the same.

Each respiratory cycle consists of both inspiratory and expiratory phases. When the inspiratory phase takes longer due to decreased flow, the expiratory phase must shorten to maintain the same cycle frequency. Thus, maintaining the same respiratory rate with reduced inspiratory flow leads to a direct relationship where expiratory time decreases to accommodate the extended duration of the inspiratory phase.

In contrast, gas distribution may remain relatively unchanged or vary depending on multiple factors like lung compliance and resistance. The inspiratory to expiratory (I:E) ratio might also be affected but not in the same predictable manner as expiratory time, making it a less accurate answer in this context. Thus, the focus on the balance of time within each respiratory cycle explains why a decrease in expiratory time is expected under these circumstances.