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Table 1 Resistive loss coefficients (k) and equivalent linear resistances for air and helium/oxygen 78/22 for combinations of parabolic resistors used with the test lung

From: Bench experiments comparing simulated inspiratory effort when breathing helium-oxygen mixtures to that during positive pressure support with air

 

R [cm H20 L-1 s]

 

k

Q[L/min]

Air

He/O278/22

Rp5

3.3

22.5

1.0

0.4

36.0

1.6

0.6

52.5

2.4

0.8

Rp20

21.5

22.5

6.6

2.3

36.0

10.6

3.7

52.5

15.4

5.4

2xRp5

6.6

22.5

2.0

0.7

36.0

3.2

1.1

52.5

4.7

1.7

Rp5 + Rp20

24.8

22.5

7.6

2.7

36.0

12.2

4.3

52.5

17.8

6.2

2xRp20

43.0

22.5

13.2

4.6

36.0

21.1

7.4

52.5

30.8

10.8

  1. k is defined in the relationship Δ P = k 2 ρ U ¯ 2 , where ΔP is the pressure loss across the resistor, ρ is the gas density, and Ū is the mean gas velocity entering the resistor.
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BMC Pulmonary Medicine

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