MATHEMATICAL MODELLING OF NON-INVASIVE PRESSURE SUPPORT VENTILATION: INVESTIGATION OF TIDAL VOLUME INSTABILITY - Quantitative Medical Data Analysis Using Mathematical Tools and Statistical Techniques - page 291

a

H a L

Unstable flow cutoff values
Psen = 15, R = 20, f = 20

1

0.8

0.6

0.44

0.36

0.4

0.37

0.26

0.30

0.14

0.2

0.15

0.22

0.09

0.13

0.12

0.08

C

0.04 0.06 0.08 0.1 0.12 0.14

a

H b L

Unstable flow cutoff values
Psen = 1, R = 20, f = 20

1

0.8

0.8 0.76 0.80

0.75

0.60

0.7

0.61

0.6

0.61

0.47

0.47

0.4 0.4

0.29

0.29

0.3

0.2

0.10

0.16

0.18

0.16

0.09

0.05 - 0.1

0.07

0.05

C

0.04 0.06 0.08 0.1 0.12 0.14

Fig. 4. Unstable ow cut-o values: C = 0:06, 0:08, 0:10 and 0:12 L/ cmH 2 O,
R i = R e = 20 cmH 2 O/L/s, P set = 22 cmH 2 O, P peep = 5 cmH 2 O, t tot = 6
s, f = 20 breaths/minute: (a) P sen = 15 cmH 2 O; (b) P sen = 1 cmH 2 O. The
diamonds () indicate unstable ow cut-o region in which t tot changes
from t tot = 60=f to t tot = 120=f. The boxes () indicate unstable ow
cut-o region in which t tot changes from t tot = 120=f to t tot = 180=f. The
triangles (NN) indicate unstable ow cut-o region in which t tot changes from
t tot = 180=f to t tot = 240=f, and the dots () indicate unstable ow cut-o
region in which t tot changes from t tot = 240=f to t tot = 300=f.