Mindray Passport 5-Lead, Service Manual

Page: 54 / 544

Operation (5-Lead, 5L, LT) Operation (5-Lead, 5L, LT and XG)
1 - 42 0070-00-0420 Passport 5-Lead, 5L, LT, XG Service Manual
Oximetry Operating Modes
The Passport’s three operating modes for SpO
2
enable it to make accurate measurements
despite differing levels of patient activity. In all three modes, the Passport updates its
measurements with every pulse beat. Data from the most recent beat replaces data from the
earliest beat and new averages are determined and displayed. The three modes are: 1
(default setting), 2, and 3.
1.
the default operating mode, uses a 5 to 7 second averaging time and is useful in
situations in which the patient is relatively inactive.
2. this mode uses a 2 to 3 second averaging time and therefore is more affected by patient
motion. It is useful for special applications that require a fast response time, such as
sleep studies.
3. this mode uses a 10 to 15 second averaging time and consequently is least affected by
patient motion. In this mode, pulse rate is not displayed and there is no pulse tone.
Pleth Auto Scaling
The Pleth waveform is automatically scaled when using Nellcor® SpO
2
. There is no
adjustment that can be made to the pleth waveform size.
Changing Operating Modes
To change from 1 to 2 or 3, select SpO
2
in the menu and toggle through the choices of 1, 2,
and 3 using the up and down arrow keys. Press SELECT (2) then END (3) to lock the choice
in and return to monitoring mode. See “Use of Menus” on page 23 for details on using
menus.
The operating mode will be displayed in the pleth waveform window.
1.3.10 Respiration Monitoring
The Passport Monitor offers two kinds of respiratory monitoring: thoracic impedance and
CO
2
waveform. Either method may be used to ensure that the patient in not apneic, and both
methods offer certain benefits and limitations.
WARNING: Thoracic respiration measurement may interfere with some
pacemakers. Refer to the pacemaker’s manual.
1.3.10.1 Thoracic Impedance
The Passport Monitor presents a small electrical signal across the RA and LA ECG limb leads.
This signal changes as the patient’s chest wall rises and falls during the breath cycle. The
advantage of the thoracic impedance method is that respiration is obtained non-invasively
and without any extra cost. Disadvantages include loss of signal when “choke blocks” are
utilized, possible cardiac interference, and missed apneic events.
Choke blocks are electrical filters that may be used in electro-cautery environments where
ECG interference can be substantial. These filters remove the electro-cautery noise, but also
block the signal used by the Passport Monitor to measure respiration.