Mindray VS 8A, Operator'S Manual

Page: 89 / 278

8 - 7
NOTE
•
The desat alarm is a high level alarm notifying you of potentially life
threatening drops in oxygen saturation. When the SpO2 value is below the
desat alarm limit and desat alarm switch is set on, the message “SpO2 Desat”
is displayed.
•
You can switch off the SpO2 Desat alarm only when SpO2 Desat Alarm Off is
enabled. For more information, see section
7.6.7 Setting the Switch of the
SpO
2
Desat Alarm Off .
8.6.2 Nellcor Sat-Seconds
TM
Alarm Management
With traditional alarm management, high and low alarm limits are set for monitoring
oxygen saturation. During monitoring, once an alarm limit is violated, an audible alarm
immediately sounds. When the patient SpO
2
fluctuates near an alarm limit, the alarm
sounds each time the limit is violated. Such frequent alarms can be distracting. Nellcor’s
Sat-Seconds alarm management technique is used to reduce these nuisance alarms.
The Sat-Seconds feature is available with the Nellcor SpO
2
to decrease the likelihood of
false alarms caused by motion artifacts. With Sat-Seconds alarm management, high and
low alarm limits are set in the same way as those with traditional alarm management. A
Sat-Seconds limit is also set. The Sat-Seconds limit controls the amount of time that
SpO
2
saturation may be outside the set limits before an alarm sounds.
The method of calculation is as follows: the percentage points of the SpO
2
saturation
falling outside the alarm limit is multiplied by the number of seconds remaining outside
the limit. This can be stated as the equation:
Sat-Seconds = Points × Seconds
Only when the Sat-Seconds limit is reached, the monitor gives a Sat-Seconds alarm. For
example, the figure below demonstrates the alarm response time with a Sat-Seconds
limit set at 50 and a low SpO
2
limit set at 90%. In this example, the patient SpO
2
drops to
88% (2 points) and remains there for 2 seconds. Then it drops to 86% (4 points) for 3
seconds, and then to 84% (6 points) for 6 seconds. The resulting Sat-Seconds are:
% SpO
2
Seconds Sat-Seconds
2× 2= 4
4× 3= 12
6× 6= 36
Total Sat-Seconds= 52