Table 1

Summary of test results with continuous flow and the demand-flow system

Simulated breaths

Δ (cmH₂O)

WOBi (J l^-1)

PTPi (cmH₂O s)

WOBe (J l^-1)

Vt (ml)

Rate (min^-1)

CF

DFS

CF

DFS

CF

DFS

CF

DFS

330

12

-10

+6

-4

+4

0.85

0.37

12

5.1

0.51

0.26

450

12

-13

+9

-6

+5

1.2

0.50

17

6.8

0.69

0.38

660

12

-20

+14

-9

+7

1.8

0.78

26

11

1.1

0.61

420

24

-24

+16

-15

+17

2.2

1.5

16

10

1.4

1.2

Simulated breaths: Vt, tidal volume; rate, breathing frequency. Δ; deviation of mean proximal airway pressure from set during inspiration (negative value) and expiration (positive value). WOBi; inspiratory imposed work of breathing. PTPi; inspiratory imposed pressure time product. WOBe; expiratory imposed work of breathing. CF, continuous flow. DFS, demand-flow system.

van Heerde et al. Critical Care 2006 10:R103   doi:10.1186/cc4968