6-22
In APRV mode, you need to set the following ventilation parameters:
1. [O
2
%]: Oxygen concentration
2. [Phigh]: High pressure
3. [Thigh]: Time of high pressure
4. [Plow]: Low pressure
5. [Tlow]: Time of low pressure
6. [Tslope]: Time of pressure rising
7. [TVapnea] or [ΔPapnea]: Tidal volume or inspiration pressure in apnea ventilation
cycle
8. [fapnea]: Frequency of apnea ventilation
9. [Apnea Tinsp]: Inspiration time of apnea ventilation
10. [F-Trig] or [P-Trig]: Inspiration trigger level
6.5.12 AMV
AMV refers to adaptive minute ventilation, which is a ventilation mode that adjusts the
patient’s ventilation parameters based on minimum work of breathing (WOB). The user only
needs to enter the patient’s ideal body weight (IBW) and target minute ventilation volume
percentage, the ventilator will calculate the tidal volume and breathing frequency with the
minimum WOB using the Otis equation. It will also adjust the I:E ratio depending on the
measured lung time constant. AMV is only suitable for adult and pediatric ventilation.
Otis equation:
Where, f is the breathing frequency under minimum WOB, MV is target minute volume, V
d
is volume of patient’s physiological dead space, RC
exp
refers to time constant of lung, a is
coefficient of waveform, For sine-wave, a=2π
2
/60.
Target minute volume is calculated by the following formula:
Target minute volume MV= Minute volume %×f
default
×TV/IBW×IBW/1000
Where, TV/IBW refers to ideal body weight tide volume. IBW is ideal body weight. f
default
is
a group of defaults related to IBW, which values are listed as below:
IBW (kg) f
default
(/min)
[3, 9) 35
[9, 13) 30
[13, 17) 25
[17, 23) 20
[23, 29) 15
[29, 36) 14
[36, 200) 12
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