• Sinus bradycardia
  • AV blocks
  • Idioventricular rhythm
 Patient Factors & Considerations

Prepare patient:

  • Remove clothing from chest and dry if necessary.
  • Attach ECG leads:
    • Apply ECG leads and electrodes and adjust ECG size and lead for a convenient waveform to display an R wave. Verify a proper R wave detection. The heart shape symbol flashes with each R wave when proper detection is taking place.
  • Attach MFE pads Anterior and posterior positions:
    • Anterior:
      • Place pad left midclavicular line and fourth intercostal space. Avoid nipple.
    • Posterior:
      • Pace pad under the left scapula next to the spine.
    • If unable to place anterior or posterior then revert to normal defibrillation positions.
    • MFE pads should be replaced after 8 hours (2 hours if using radiolucent stat-padz).

Demand pacing:

  • Demand pacing using the M series Monitor Defibrillator. The unit monitors the patient pulse via the ECG cable and delivers selected energy level only when the patient’s intrinsic rate falls below the set pacer rate. If the rate does not fall below this rate the pacer will not send a stimulus.
  • Turn selector switch to PACER. Display as per figure 1.
  • Turn the PACER RATE knob clockwise until screen displays the desired pacing rate. Variable rate from 30-180 pulse per minute (ppm).
  • Verify that pacing markers display on the ECG trace.
  • Turn the PACER OUTPUT (milliamps) knob clockwise slowly until ventricular capture is consistently achieved. Generally the amount of current varies widely however the range is normally between 50-90mA. The maximum current on the external pacer is 140mA.
  • Increase pacer output until symptoms resolve or rate of 100ppm is reached.
  • Note: when the unit is switched out of Pacer mode into defib or monitor modes and back again the pacer settings will remain unchanged. If the unit is turned off for more than ten seconds the pacer default settings will be restored.
  • Check for electrical capture by the presence of a pacing spike followed by a widened QRS complex (response to the stimuli), the loss of any underlying intrinsic rhythm, and the appearance of an extended, and sometimes enlarged T wave.
  • Check for mechanical capture by taking a pulse on the femoral, brachial or radial artery. Mechanical capture will be evident by a palpable pulse, rise in blood pressure and improvement in conscious state (if not sedated and paralysed).
  • Caution. If you suspect an inaccurate beat detection, change the selected
    lead to view the heart from a different angle. If this does not solve the
    suspected problem, change the selected size.

Standby pacing:

  • For certain patients at risk of symptomatic bradycardia, it may be advisable to use the unit in standby mode.
  • In this mode the unit automatically provides a pacing stimulus whenever the patient’s pulse drops below a predetermined level.
  • Patient’s ECG must be monitored using ECG leads and patient cables.

Establish effective pacing

  • Note: mA output at capture and run an ECG strip to document ECG morphology during capture.
  • Set mA output to 10% higher than the minimum mA output necessary to effect consistent ventricular capture.
  • Turn the pacing rate (ppm) below the patient’s pulse. The pacing rate should be set at a level sufficient for adequate cardiac output.
  • Check threshold periodically


Asynchronous pacing:

  • During asynchronous pacing the M series unit delivers an electrical stimulus regardless of patient’s pulse. If any of the following conditions are present, it may be necessary to operate the pacemaker asynchronously:
  • ECG electrodes are not available.
  • ECG artefact is present.
  • Patient has Ventricular Tachycardia.
  • Asynchronous pacing should only be performed in emergency situations when there are no other alternatives.
  • If ECG cables are used during asynchronous pacing, ECG waveforms display and you can determine whether capture was achieved. While asynchronous pacing without ECG cables, no ECG activity displays, so other means for determining capture such as checking pulse are necessary.

To pace asynchronously:

  • Turn Selector Switch to PACER
  • Press the Async Pacing On/Off softkey
  • Confirm that the ASYNC PACE message displays
  • While pacing a patient you should occasionally check the patient’s underlying rhythm to see if pacing is still required. This can be done quickly using the 4.1 Button.
  • Whilst the 4.1 button is held down the pacer delivers an electrical impulse at one quarter the displayed rate. This enables you to see the patient’s underlying rhythm while safely pacing. Releasing the button will return the unit to normal pacing.



Patient discomfort:

  • Explain procedure; consider changing pad placement to anterior /posterior positions, initiate pain management.
  • Diaphragmatic pacing is relatively frequent and may require sedation and ventilatory support at times.

Pacing problems, failure to:

  • Capture:
    • Where pacing spikes are not followed by a broad QRS complex, the current is insufficient to stimulate the heartbeat.
    • Increase current and consider other causes that might alter the threshold such as hypoxia, metabolic and electrolyte derangements.
    • Another possibility is that the patient is moribund.
  • Sense:
    • Over sensing:
      • Occurs when the pacer interprets artefact as intrinsic rhythm and inhibits itself from firing; this may result in blood pressure drop.
      • Reposition leads or electrodes and select the non-demand mode.
    • Under-sensing:
      • When the pacer fails to detect intrinsic activity and paces inappropriately.
      • Change the lead, and increase ECG size or reposition the electrodes.
  • Pace:
    • Document the rate threshold, output, underlying rhythm and any adjustments made.
Additional Information
Additional information

Extended Care:
Colour assist:


Document Control

Clinical Services

Responsible Manager
Head of Clinical Services


Published Date

Review Date

Clinical Resources Website

St John Ambulance Western Australia Ltd (ABN 55 028 468 715) (St John WA) operates ambulance and other pre-hospital clinical services. St John WA’s Clinical Resources, including its Clinical Practice Guidelines (Clinical Resources), are intended for use by credentialed St John WA staff and volunteers when providing clinical care to patients for or on behalf of St John WA, within the St John WA Clinical Governance Framework, and only to the extent of the clinician’s authority to practice.

Other users – Terms of Use

The content of the St John WA Clinical Resources is provided for information purposes only and is not intended to serve as health, medical or treatment advice. Any user of this website agrees to be bound by these Terms of Use in their use of the Clinical Resources.

St John WA does not represent or warrant (whether express, implied, statutory, or otherwise) that the content of the Clinical Resources is accurate, reliable, up-to-date, complete or that the information contained is suitable for your needs or for any particular purpose. You are responsible for assessing whether the information is accurate, reliable, up-to-date, authentic, relevant, or complete and where appropriate, seek independent professional advice.

St John WA expressly prohibits use of these Clinical Resources to guide clinical care of patients by organisations external to St John WA, except where these organisations have been directly engaged by St John WA to provide services. Any use of the Clinical Resources, with St John WA approval, must attribute St John WA as the creator of the Clinical Resources and include the copyright notice and (where reasonably practicable) provide a URL/hyperlink to the St John WA Clinical Resources website. 

No permission or licence is granted to reproduce, make commercial use of, adapt, modify or create derivative works from these Clinical Resources. For permissions beyond the scope of these Terms of Use, including a commercial licence, please contact medservices@stjohnambulance.com.au

Where links are provided to resources on external websites, St John WA:

  • Gives no assurances about the quality, accuracy or relevance of material on any linked site;
  • Accepts no legal responsibility regarding the accuracy and reliability of external material; and
  • Does not endorse any material, associated organisation, product or service on other sites.

Your use of any external website is governed by the terms of that website, including any authorisation, requirement or licence for use of the material on that website.

To the maximum extent permitted by law, St John WA excludes liability (including liability in negligence) for any direct, special, indirect, incidental, consequential, punitive, exemplary or other loss, cost, damage or expense arising out of, or in connection with, use or reliance on the Clinical Resources (including without limitation any interference with or damage to a user’s computer, device, software or data occurring in connection with such use).


Please read this cookie policy carefully before using Clinical Resources from St John WA.

The cookies used on this site are small and completely anonymous pieces of information and are stored on your computer or mobile device. The data that the cookies contain identify your user preferences (such as your preferred text size, scope / skill level preference and Colour Assist mode, among other user settings) so that they can be recalled the next time that you visit a page within Clinical Resources. These cookies are necessary to offer you the best and most efficient possible experience when accessing and navigating through our website and using its features. These cookies do not collect or send analytical information back to St John WA.

Clinical Resources does integrate with Google Analytics and any cookies associated with this service enable us (and third-party services) to collect aggregated data for statistical purposes on how our visitors use this website. These cookies do not contain personal information such as names and email addresses and are used to help us improve your user experience of the website.

If you want to restrict or block the cookies that are set by our website, you can do so through your browser setting. Alternatively, you can visit www.internetcookies.com, which contains comprehensive information on how to do this on a wide variety of browsers and devices. You will find general information about cookies and details on how to delete cookies from your device. If you have any questions about this policy or our use of cookies, please contact us.

St John Ambulance Western Australia Ltd © Copyright 2020, All Rights Reserved

Terms of Use | Privacy Policy | Copyright Statement & Disclaimer