Treaton MV200, User Manual

Page: 192 / 222

Appendix 2.7 Stress index (SI)
App.2-6
Figure App.2.4 – Volume control: pressure graphs at normal (SI = 1), low (SI < 1) and high
(SI>1) stress-index
Figure App. 2.5 – at the correctly selected PEEP the pressure increases linearly
If PEEP and Vt values are selected properly, the whole range of the inspiratory pressure values
lies on the linear part of the curve V (P), between points A and B (case I).
The idea of Ranieri - under these conditions the pressure in the circuit should increase accord-
ing to the following law:
P(t) = a×t
b
+ c,
where: c – corresponds to the pressure at the beginning of the inspiration (point A),
b – stress index SI .
At b=1 the equation becomes linear.
Appendix 2.8 Patient’s respiratory effort P0.1
The value P0.1 characterizes the patient's ability to the independent breathing. P0.1 value is the
pressure difference between the moment of start of the inspiration (t = 0) and moment of com-
pletion of 100 ms in the occluded circuit. This pressure difference is generated by the inspiratory
effort of the patient. P0.1 measurement is valuable for the physician in the specific conditions of
patient’s ventilation and performed by the device with the current settings of the inspiratory trig-
ger. Change of sensitivity or trigger type will change the moment of activation of the inspiratory
trigger and is likely will change the measured value of P0.1.
V
P
A
B
P(t)
F(t)
P(t)
F(t)
P(t)
F(t)
I
SI=1.0
II
SI=0.8
III
SI=1.4