Fig. 1:
Tetra-polar impedance measurement scheme. From [1] by permission.
Fig. 2:
Basic concept of FIM-6. From [2] by permission.
Fig. 3:
Block diagram for TPIM configuration.
Fig. 4:
Electrode placement for linear TPIM measurement for lung ventilation.
Fig. 5:
Block diagram for the arrangement of the FIM-6 system.
Fig. 6:
Circuit for the current drive section for the FIM-6 system designed in the Proteus software (Labcenter Electronics Ltd, England) [7].
Fig. 7:
Electrode placement for FIM-6 for measurement at the mid-region of the chest.
Fig. 8:
Electrode placement for measurement at the lower left lung (top) and the lower right lung (bottom).
Fig. 9:
Electrode placement for measurement at the lower left lung from the back.
Table 1:
Reading for the percentage change in impedance for different separation of potential electrodes for FIM-6 during lung ventilation. The first column shows the separation between the potential electrodes in cm. The second and third column show the FZ values for breathe in and breathe out, respectively, in ohms. The last column shows the percentage change in impedance with the value on breathe out as the reference.
| Separation between potential electrodes (cm) | Breathe in impedance (ohms) | Breathe-out impedance (ohms) | Percentage change (Ref: breathe out) |
|---|---|---|---|
| 10.0 | 21.30 | 18.89 | 12.76 |
| 12.5 | 28.98 | 24.63 | 17.66 |
Table 2:
Reading for the percentage change in impedance for arrangement of FIM-6 electrodes on the right lung and left lung during lung ventilation. The first column shows the arrangement scheme for the electrodes in the lung region. The second and third column shows the FTZ values for breathe in and breathe out in ohms. The last column shows the percentage change in impedance.
| Arrangement | Breathe in impedance (ohms) | Breathe out impedance (ohms) | Percentage change (Ref: breathe out) |
|---|---|---|---|
| Lower right lung | 29.52 | 25.32 | 16.58 |
| Lower left lung | 19.13 | 15.19 | 25.90 |
Table 3:
Reading for the percentage change in impedance for arrangement of FIM-6 electrodes on right and left lung during lung ventilation. The first column shows the study region. The second column shows the arrangement scheme of electrodes for FIM-6 configuration. The third and fourth column shows the FZ values for breathe in and breathe out in ohms. The last column shows the percentage change in impedance.
| Arrangement | Breathe in impedance (ohms) | Breathe out impedance (ohms) | Percentage change (Ref: breathe-out) | |
|---|---|---|---|---|
| Lower right lung | Initial | 15.35 | 12.87 | 19.27 |
| Shifting of current electrodes only | 12.38 | 9.90 | 25.05 | |
| Shifting of both current electrodes and potential electrodes | 27.23 | 21.29 | 27.90 | |
| Left lung | Back part of the left lung | 18.56 | 16.09 | 15.35 |