Mindray BeneHeart D3, Руководство оператора

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12-4
12.5.4 Sat-Seconds Alarm Management
With traditional alarm management, high and low alarm limits are set for monitoring oxygen saturation. During
monitoring, as soon as an alarm limit is violated, an audible alarm immediately sounds. When the patient’s SpO
2
value
fluctuates near an alarm limit, the alarm sounds each time the limit is violated. Such frequent alarm can be distracting.
The Sat-Seconds feature is available with the Nellcor SpO
2
module to decrease the likelihood of false alarms caused by
motion artifacts. 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 number of percentage points that the SpO
2
saturation falls outside the alarm limit is multiplied by the number of seconds that it remains 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. 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’s
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:
Points Seconds Sat-Seconds
2× 2 = 4
4× 3 = 12
6× 6 = 36
Total Sat-Seconds = 52
After approximately 10.9 seconds, a Sat-Second alarm would sound, because the limit of 50 Sat-Seconds would have
been exceeded.
Saturation levels may fluctuate rather than remaining steady for a period of several seconds. Normally, the patient’s SpO
2
may fluctuate above and below an alarm limit, re-entering the non-alarm range several times. During such fluctuation,
the system sums the number of SpO
2
points, both positive and negative, until either the Sat-Seconds limit is reached, or
the patient’s SpO
2
re-enters the non-alarm range and remains there.
SpO
2
%
Second