GE HEALTHCARE B20, User'S Reference Manual

Page: 223 / 320

Pulse oximetry
13-7
Sensitivity (Masimo SpO
2
configuration only)
Adjusting the Masimo SpO
2
sensor sensitivity level.
− Use the Normal sensitivity setting for normal patient monitoring purposes.
− Use the Maximum sensitivity setting for improved poor perfusion performance and for
faster tracking of rapid SpO
2
saturation changes.
Beat Sound Volume
Adjusting the SpO
2
beat volume also affects the beat volume of ECG.
When SpO
2
is monitored, the monitor provides a variable pulse beep so that the tone of the
pulse beep rises with increasing oxygen saturation and falls as saturation decreases. You can
select the volume from 1 (soft) to 10 (loud). With selection 0 there is no audible sound.
HR Source Selects the heart rate source. If the ECG signal is affected by too much noise for a reliable heart
rate calculation, heart rate can also be calculated from invasive pressure (
Art/ABP/UAC ) or
plethysmographic pulse waveform Pleth . The selected heart rate source is displayed above the
numerical display of the heart rate. The color of the heart rate is the same as that of the source
parameter.
The
AUTO selection priorities for heart rate calculation are: ECG (the lead with highest R-wave),
pressure (Art/ABP/UAC) and plethysmographic pulse waveform.
SpO2 Alarm Alarms can be adjusted in this menu or in the Alarms Setup menu which opens by pressing the
Alarms Setup
key.
Alarm Delay (Masimo SpO
2
configuration only)
Adjusting alarm delay time in SpO2 Alarm menu. Medium priority ‘SpO
2
Low’ alarm appears
according to the selection.
Adjusting the delay time. It can be 0s, 5s, 10s, 15s.
Data update and averaging
Nellcor OxiMax data averaging and updating
The Nellcor OxiMax algorithm automatically extends the amount of data required for
measuring SpO
2
and pulse rate depending on the measurement conditions. During normal
measurement conditions in the normal response mode, the averaging time is 6 to 7 seconds.
During difficult measurement conditions, which can be caused by low perfusion, motion,
ambient light, electrocautery, other interference, or a combination of these factors, the OxiMax
algorithm automatically extends the dynamic averaging time required beyond 7 seconds.
If the resulting dynamic averaging time exceeds 20 seconds, the pulse search condition will be
set, while SpO
2
and pulse rate values continue to be updated every second.
As the measurement conditions become even more difficult, the amount of data required
continues to expand. If dynamic averaging time reaches 40 seconds, the pulse timeout
condition will be set and the module will report a zero saturation indicating a loss-of-pulse
condition.
Masimo SET data averaging and updating
For Masimo SET technology, when using the default averaging time of 8 seconds, there is a
maximum data-averaging signal processing time of 10 seconds from real time plus an
additional delay of 2 seconds to update the displayed waveform. Audible alarms are delayed
until an alarm limit violation occurs for at least 5 seconds.