Invivo Magnitude 3150M, Руководство по эксплуатации

Страница: 70 / 80

E-2
4. Checking electrode contact quality with Electrode Impedance Meter (IRI part number
9392) - In addition to the reasons described above, electrode contact is also important
when assessing ECG signal quality. A standard means to evaluate electrode contact
quality is to measure the electrical impedance between electrodes to verify the impedance
is acceptable low (usually below 8000 ohms, but below 2000 ohms for best results). An
Electrode Impedance Meter is provided with each Omni-Trak 3150 Monitoring System
to permit these electrode contact quality checks. The Electrode Impedance Meter is
attached to the patient skin electrodes and each set of readings (i.e. LA, RA, LL, RL)
must be evaluated. Since only 3 lead wires can be connected simultaneously, the user
will need to check the fourth lead wire by reattaching one of the 3 lead wires from the
other electrodes to the fourth electrode (refer to the instructions on the Electrode
Impedance Meter). If electrode contact is poor (impedance greater than 8000 ohms),
remove and discard the electrode, abrade the skin further using the Trace Aid gel, and
always apply a new Quadtrode
®
Electrode. Never reuse a removed electrode since its
adhesive may not securely fasten the Quadtrode
®
Electrode to the skin. Re-check
electrodes’ impedance with Electrode Impedance Meter for the acceptable impedance
level.
5. ECG Patient Cable and Lead Wires - The Invivo Research 9240 ECG Patient Cable and
Lead wires are specially designed for use in the MRI bore. The 9240A Lead Wires are
constructed of special material to help reduce the amount of radio frequency energy
which can flow through these wires. This lead sire set must always be used during
monitoring in the MRI bore. The gray 9240B ECG Patient Cable is constructed of
similar materials as other standard ECG cable, and no portion of this gray cable should
be placed within the MRI bore. If this is done excessive currents could flow through the
cable and lead wires, which can result in skin burns. Always use the Invivo Research
9240 ECG Patient Cable Set when monitoring with the Omni-Trak 3150 Monitor in the
MRI bore.
6. Other Electrical Conductors Inside the MRI Bore - No other electrical conductors (e.g.
wires, leads, probes, etc.) should be placed within the MRI bore at the same time as the
ECG Lead Wires. Electrode heating risk increases when multiple conductive cables and
sensors are placed in the bore with patient. Mixing of conductors from various
manufacturers (catheters, temperature sensors, etc.) is not recommended. Multiple
electrical conductors within the MRI bore can allow cross-coupling between these
various conductors, and appear as a large antenna for RF energy pick-up, which
will
result in electrode heating, and possibly, skin burns. It is always important to identify if
the patient has any metallic wires, conductors, implants, stents, etc. within his/her body
which will act as cross-coupling conductors. If these are present, ECG monitoring may
not be able to be performed without experiencing electrode heating. It is important to
note that non-conductive tubes, air-lines, etc. can be used without any problems. These
include NIBP cuffs and air-lines, End-Tidal Carbon Dioxide and/or Oxygen air-lines, and
fiberoptic pulse oximetry sensors. These items usually do not include electrically
conductive materials in their construction, and can be safely used within the MRI bore
with the ECG Lead Wires.