Internal diameter (mm) | Length (mm) | Calculated flow ratio compared with 18G cannula | Actual flow ratio compared with 18G cannula | Actual flow ratio compared with 18G cannula | |||||||
50 mm Hg | 100 mm Hg | 150 mm Hg | 200 mm Hg | 20 mL/min | 30 mL/min | 40 mL/min | 50 mL/min | ||||
18G cannula | 0.9 | 45 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
20G cannula | 0.8 | 32 | 0.88 | 0.91 | 0.78 | 0.78 | 0.77 | 0.84 | 0.78 | 0.79 | 0.81 |
5Fr umbilical line | 1.372 | 400 | 0.61 | 0.52 | 0.37 | 0.37 | 0.36 | 0.17 | 0.15 | N/A | N/A |
4Fr umbilical line | 1.067 | 400 | 0.22 | 0.35 | 0.25 | 0.31 | 0.25 | N/A | N/A | N/A | N/A |