Further, the use of an awake animal model avoided anesthetic related effects on HRV; for example, anesthetized rats exhibited an inverse RSA wherein R-R intervals during inspiration had longer durations than those of expiration [ 4, 19, 34].
The contribution of continuous TGI to total inspired VT can be estimated from the duration of inspiration (TI) and Vc as: VTc 5 TI × V̇c.
Assuming that the duration of inspiration and expiration was the same, the airflow rate for inspiration alone was twice the minute volume.
As can be readily seen, the biggest difference between these APRV breaths is the duration at inspiration and expiration.
Short train stimulation (75 100 μA, 0.2 ms, 100 Hz, 3 5 pulses) delivered during the early- or mid-term of inspiration augmented the inspiratory duration, but switched the inspiration off when delivered during the later stage of inspiration.
There was considerable variability in the F-APRV settings (i.e., duration at inspiration and expiration) in the papers reviewed, and in multiple papers, the settings were not defined, and thus not included in this review.
During pressure support ventilation (PSV), the patient's effort determines volume and duration of inspiration.
Increased stretch receptor activity shortens the duration of inspiration in animals [ 1], human newborns, and children [ 2- 9].
Numerous studies indicate that duration of inspiration relative to the duration of the total respiratory cycle (for example, Ti/Ttot ratio) should be an important determinant of diaphragmatic fatigue [ 35, 53- 55].
