External pacing (transcutaneous pacing) [advanced]

Table of Contents

Before you start

Indications: haemodynamically unstable bradycardia (unresponsive to atropine); complete heart block; Mobitz type II second-degree heart block when haemodynamically unstable; sudden witnessed asystole secondary to cardioversion/drugs/conduction defect; override pacing of tachycardias refractory to drugs and cardioversion (rarely used)

Setting up

  • Anaesthetist must be present to sedate patient (most patients cannot tolerate pacing >50mA)
  • Apply 3-lead cardiac monitoring (clockwise from right arm Ride Your Green Bicycle) and connect lead to external cardiac monitor or defibrillator machine
    • Red: anterior aspect of right shoulder
    • Yellow: anterior aspect of right shoulder
    • Green: left anterior superior iliac spine
    • Black: not present on defibrillation machine
  • Apply defibrillator pads (in AP position) after shaving chest if required
    • ‘Right’ pad: place longitudinally on left sternal edge
    • ‘Left’ pad: place longitudinally on left paraspinal muscles (in line with anterior pad)
  • Connect pads lead to defibrillator machine
  • Set defibrillator machine monitoring trace to ‘pads’


  • Set defibrillator to pacing mode
  • Set onscreen pacing rate (default usually  ̴ 70bpm) and energy (default starting energy usually  ̴ 30mA)
  • Click onscreen start pacing button
  • Observe the monitor to see if QRS complexes follow every pacing spike – if not, increase the energy until they do – ‘electrical capture’ (usually occurs at 50-100mA)
  • Next check the patients pulse corresponds to the induced QRS complexes – ‘mechanical capture’
  • Seek senior help and definitive management

Note you can touch the patient during.

Pacing set up
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