Recommended Initial Energy Output and Safety Margin for Transcutaneous Pacing (TCP)
The recommended initial energy output for transcutaneous pacing (TCP) is 70-100 mA, with anteroposterior pad placement being superior to anterolateral placement due to lower energy requirements for capture (approximately 33 mA less on average). 1, 2
Initial Settings and Approach
- Start with an output of 70-100 mA and increase in increments of 10 mA until capture is achieved 2, 3
- Use anteroposterior electrode configuration whenever possible, as it requires significantly less energy for capture (mean threshold of 93 mA vs. 126 mA for anterolateral placement) 1
- Set an appropriate safety margin of 10-20 mA above the capture threshold to ensure consistent pacing 2
- The mean threshold energy requirement is approximately 0.12 joules/beat regardless of pad size 4
Confirming Mechanical Capture
- Mechanical capture must be confirmed by assessing arterial pulse or waveform, not just electrical capture on ECG 2
- Use alternative monitoring methods such as arterial pressure monitoring and pulse oximetry when ECG assessment is difficult 2
- Do NOT attempt to manually palpate pulses during active pacing due to risk of electrical shock to providers 2
- Consider using different ECG leads if pacing artifact obscures QRS complex visualization 2
Special Patient Considerations
- Higher current may be required in patients with emphysema or pericardial effusion 2
- Pediatric patients have similar current requirements to adults (mean output of 51-63 mA depending on electrode size) 4
- Smaller electrode sizes may be necessary for children weighing less than 15 kg 4
- Provide adequate sedation and analgesia for conscious patients, as TCP is associated with significant discomfort 2
Technical Considerations
- TCP produces a QRS pattern resembling left bundle branch block 3
- Simultaneous atrial capture is possible but requires much higher energy (138 ± 25 mA) than ventricular capture alone (74 ± 14 mA) 5
- TCP is associated with similar ECG and hemodynamic responses to transvenous pacing 3
- Continuous cardiac monitoring is necessary until pacing is no longer required 2
Important Limitations and Cautions
- TCP should be considered a bridge to more definitive therapy 2
- Pacing is not effective for asystolic cardiac arrest and may delay or interrupt chest compressions 6
- TCP is reasonable for healthcare providers to initiate in patients with symptomatic bradycardia who do not respond to atropine 6
- For patients likely to require prolonged pacing, transition to transvenous or permanent pacing is recommended 2
- Allow at least 1 minute between consecutive energy increases to avoid myocardial damage 6