6 ECG, Arrhythmia, ST and QT Monitoring
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To position the ST-point (3) relative to the J-point:
select either
J+60 or J+80. Select J Point and use the arrow keys to move the J-Point and position
the ST-point at the midpoint of the ST segment.
To position the ST-point directly:
select
ST Point and use the left and right arrow keys to position the ST point at the midpoint of the
ST segment.
4 Select the Apply Changes pop-up key to activate the new ST measurement points and recalculate
all ST values.
The most recent ST Points adjustment time is displayed in the
Adjust ST Points window. This
information is cleared when a patient is discharged or when a new Profile is loaded into the
monitor.
5 To update the ST snippet shown in the Adjust ST Points window, select the Update pop-up key.
ST Alarms
ST alarms are yellow alarms. Each ST lead has its own alarm limit. ST alarms are triggered when an ST
value exceeds its alarm limit for more than one minute. Switching ST alarms off switches off alarms for
all ST leads.
If more than one ST measurement is in alarm, the monitor only displays the alarm message of the ST
lead which is currently furthest from its set alarm limits.
Changing ST Alarm Limits
The monitor can detect alarms on each ST lead separately, so you can set high and low ST alarm limits
individually for each ST lead. When two contiguous leads are available, ST alarms will be generated
when ST values of the two contiguous leads are outside the limit. When no contiguous lead is available
an ST alarm is generated when the ST value of the single lead is outside the limit.
Set the high and low alarm limits based on your assessment of the patient's clinical condition, unit
protocols, physician orders or medication-specified limits. A good guideline is + 1.0 mm or - 1.0 mm
from the patients's ST, or follow your hospital protocol.
1 In the Setup ST Analysis menu, select the alarm to be adjusted.
2 Select the appropriate setting.
STE Alarms
The STE alarm is a yellow alarm. It can be switched on and off in the Setup ST Elevation menu but
the limits can only be changed in Configuration mode. The STE alarm limits are gender specific and
can be set individually for limb leads, V2/V3 leads, and V1/V4/V5/V6 leads. The default values, for
example on V2 and V3 1.5 mm for females and 2.0 mm for males, are based on the recommendations
from the American Heart Association and American College of Cardiology.
The ST Elevation measurements with automated J-point determination generate ST Elevation alarms,
in addition to the ST measurements at the user-defined ST point (J+offset), which may be useful for
ST depression alarms. When ST and STE analysis are both in use, this may result in redundant alarms
for ST elevations. Because of the different measurement points, there may be different values
obtained. Thus there could be an ST alarm and an STE alarm but the STE alarm may announce sooner
based upon the values obtained.
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