Medical-Surgical Intensive Care Unit  



ST Segment Monitoring With Datex Monitors

All the monitors in CSRU/MSICU have ST segment monitoring as soon as ECG monitoring is started; the alarms are defaulted OFF. Alarms may be left off at the nurses discretion; HOWEVER: the ST alarms MUST be on in the following cases:

  1. pt has chest pain;
  2. ALL cardiac surgery patients (CVT)
  3. ALL MI patients
  1. Alarm defaults will be set to detect an ST segment elevation of +2 mm.This may be adjusted according to pt. condition.
  • This is the default set by the manufacturer. The default can be changed based on the patient's condition.
  1. Changes to defaults (eg increasing elevation default from +2 with pericarditis etc)  should be documented on the ICU flowsheet as well as the Kardex. If you are increasing the default because of  new ST elevation, obtain a 12 lead and notify the MD.
  • Changes need to be documented to allow information to be passed on to team members.
  1. Patient must be supine to establish baseline "picture" of ST segments
  1. Audible alarms and territory alarms will be defaulted to "off"; with your initial assessment, determine the need(according to pt condition) for the alarms to be on/off and activate alarms as needed.

    Alarms that are usually on may be turned off for mobilizing patients and patient transfer.
  1. Select the ECG leads to be displayed on the monitor specific to the areas of the heart at risk for ischemia:
    • RCA:  lead II or III
    • LCA: lead V2 or V3
NOTE: ST segments may be falsely elevated due to electrolyte imbalances, changes in patient position, hyperventilation, changes in lead placement, etc.


  1. To View  ST Segments

    To change the ECG  'User' leads viewed on the monitor/and the user ST segments being monitored the following needs to be done:

    1. Depress the ECG key.
    2. Select one of the ECG 1, ECG 2, or ECG 3 options.
    3. When selected another menu appears, select desired lead.
    4. Press to confirm choice. The desired lead will now be viewed on the monitor, and is one of the user ST segments being displayed on the ST digital display.

    To view and print ST analysis:

    1. Depress 'ECG'
    2. Select 'ST View'
    3. Select 'Print QRS/ST'
      (At this time the page viewed as well as a page of ST trends will be printed.) 

    To manually save new QRS reference:

    1. While in the 'ST View' screen select 'Save new QRS'.  This will create a new QRS as reference. A total of 6 references is possible to be saved by the user.

    To erase a saved QRS:

    1. While in the 'ST View' screen select 'Erase QRS'
    2. Press the 'Erase QRS' option and scroll through options of saved QRS to select the desired one to be erased.
    3. Press when desired QRS is seen.  It will be erased.
    4. Please note that the initial QRS that is saved by the monitor cannot be erased.

    To view Reference QRS that have been saved:

    1. While in the 'ST View' screen select 'Reference QRS'
    2. Press the 'Reference QRS' option and scroll through options of QRS saved.  For each option press to view.

    To View ST Trends:

    1. In the 'ST View' screen select 'ST Trends'
    2. Under the 'Leads' option select desired lead view, by pressing on the option and scrolling through.
    3. The time scale of the trend view may also be selected under the 'Time scale' option.  Time scale of 30 min to 72 hrs is available.
  1. Documentation:
    1. ST alarm activation and changes to limits must be documented on the ICU flowsheet as well as the Kardex.
    2. on initial assessment, document ST values in the assessment section of the flowsheet


  1. Drew, B. (    ).  Bedside ECG monitoring.  AACN Clinical Issues.  25-33.

  2. Drew & Kirchoff (1999).  Multi-lead ST segment monitoring in patients with acute coronary syndromes: A consensus statement for health care professionals.  American Journal of Critical Care, 8(6), 372-386.

  3. Drew & Sparacino. (1991).  Accuracy of bedside ECG monitoring: A report on current practices of critical care nurses.  Heart Lung 20(6), 597-608.

  4. Drew, Pelter, Adams, Wung, Chou, and Wolfe.  (1998).  12 Lead ST Segment monitoring versus single lead maximum ST segment monitoring for detecting ongoing ischemia in patients with unstable coronary syndromes.  American Journal of Critical Care, 7(5), 355-60.

Developed by: Rachelle McCready, Clinical Educator, Critical Care LHSC--UC

September 2004

reviewed July 2008;Aug 09

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