Te equals?

Te equals?

• A. TCT - Ti
• B. Ti = TCT / (I + E)
• C. Te / Ti
• D. 60 / RR

Answer: (A)

Te is the expiratory time, the portion of the breath spent exhaling. The whole breathing cycle (TCT) is the sum of the time spent inhaling (Ti) and exhaling (Te), so Te = TCT − Ti. This direct relation makes Te easy to compute once you know the total cycle time and how long the inhale lasts. If you know the I:E ratio, you can also express the times as Ti = TCT × [I/(I+E)] and Te = TCT × [E/(I+E)], which is another way to see Te in relation to the cycle. The form Ti = TCT / (I+E) would not be correct, since Ti scales with I/(I+E), not the reciprocal. Te/Ti gives a ratio, not the absolute Te. And 60/RR yields the total cycle time (per breath), not the expiratory time by itself.

Te is the expiratory time, the portion of the breath spent exhaling. The whole breathing cycle (TCT) is the sum of the time spent inhaling (Ti) and exhaling (Te), so Te = TCT − Ti. This direct relation makes Te easy to compute once you know the total cycle time and how long the inhale lasts.

If you know the I:E ratio, you can also express the times as Ti = TCT × [I/(I+E)] and Te = TCT × [E/(I+E)], which is another way to see Te in relation to the cycle. The form Ti = TCT / (I+E) would not be correct, since Ti scales with I/(I+E), not the reciprocal. Te/Ti gives a ratio, not the absolute Te. And 60/RR yields the total cycle time (per breath), not the expiratory time by itself.