Transcutaneous Pacing

• TCP Mode: Demand (senses intrinsic beats) or Fixed (asynchronous)
• Rate: Typically 60-80 bpm (adjust to patient needs)
• Output: Start at 0mA, increase by 10mA until capture, then add 10% safety margin
• Capture threshold: Usually 40-80mA (may need up to 200mA)
• Sedation: Analgesia and anxiolysis required for conscious patients

Indications

• Symptomatic bradycardia: HR typically <50 with hypotension, altered mental status, chest pain, or signs of shock
• High-degree AV blocks: Mobitz II, complete (3rd degree) heart block
• Atropine-refractory bradycardia: When 0.5mg doses (max 3mg) ineffective
• Bradyasystolic arrest: As part of resuscitation (controversial efficacy)
• Post-cardiac surgery: Temporary pacing failure
• Overdose/toxicity: Beta-blocker, calcium channel blocker, digoxin toxicity

Absolute Contraindications

• Severe hypothermia: (<30°C/86°F) - heart is refractory; rewarm first
• Asystole for prolonged period: Pacing cannot restart a heart that has no electrical activity

Relative Contraindications

• Pediatric patients (smaller pads, different thresholds)
• Conscious patients without adequate sedation/analgesia
• Extensive chest burns or trauma (pad placement issues)

Essential Equipment

• Defibrillator/pacer: With TCP capability (most modern defibs have this)
• Pacing pads: Combination pads for pacing AND defibrillation (check expiration)
• Monitoring: Continuous ECG (use separate leads, not just pads), SpO2, BP
• Sedation: Fentanyl, midazolam, ketamine, or etomidate
• Airway equipment: BVM, suction, oxygen, intubation supplies ready
• IV access: At least one, preferably two large-bore IVs

Pad Placement Options

• Anterior-Posterior (preferred): Anterior pad over left precordium (avoid sternum), posterior pad between scapulae
• Anterior-Lateral: Right infraclavicular + left lateral chest (apex)

Patient Preparation

• Position: Supine or semi-recumbent
• Skin prep: Dry skin, clip excessive hair (don't shave - causes microabrasions)
• Remove patches: Medication patches (nitro, fentanyl) - can cause burns
• Explain procedure: If patient conscious, warn about discomfort

Step 1: Prepare and Position

Attach ECG monitoring leads (separate from pacing pads for accurate rhythm assessment). Place pacing pads in anterior-posterior position. Ensure good skin contact - press firmly to remove air bubbles.

Step 2: Connect and Configure

Connect pads to defibrillator/pacer. Select PACE mode (not defibrillator mode). Set initial rate to 60-80 bpm. Set output (mA) to 0 initially.

Step 3: Sedate Patient (if conscious)

TCP is painful. Provide analgesia and sedation per your local protocols. Ketamine is often preferred for hypotensive patients as it maintains blood pressure. Titrate to comfort while maintaining airway.

Step 4: Initiate Pacing

Turn pacer ON. Starting at 0mA, gradually increase output by 10mA increments. Watch monitor for pacer spikes followed by wide QRS complexes. Continue increasing until electrical capture achieved.

Step 5: Confirm Capture

Electrical capture: Pacer spike followed by wide QRS complex

Mechanical capture (CRITICAL): Palpate RIGHT radial or femoral pulse - must match paced rate. Left-sided pulses may show artifact from muscle contraction.

Step 6: Set Safety Margin

Once capture confirmed, increase output by 10% above threshold (e.g., if capture at 70mA, set to 80mA). This ensures consistent capture with patient movement or changes.

Step 7: Reassess and Monitor

• Continuous ECG monitoring for capture
• Frequent BP checks (should improve)
• Assess mental status (should improve)
• Monitor for loss of capture
• Arrange for transvenous pacing or definitive treatment

Signs of Electrical Capture

• Pacer spike followed by wide QRS complex
• QRS morphology consistent (looks the same after each spike)
• Rate on monitor matches set pacing rate

Signs of Mechanical Capture

• Palpable pulse at paced rate (check RIGHT side)
• Improving blood pressure
• Improving mental status
• Improved skin color/perfusion
• SpO2 waveform correlating with paced rate

• A-P placement: Anterior-posterior pad placement typically requires 10-20% less energy for capture
• Right pulse: Always check the RIGHT radial pulse - left side shows artifact from pectoral muscle contraction
• Demand vs Fixed: Use demand mode if patient has any intrinsic rhythm; fixed mode for complete asystole
• Failure to capture: If no capture at max output, try repositioning pads, new pads, or anterior-posterior position
• Don't forget sedation: TCP causes significant chest wall muscle contraction - it's painful!
• Backup plan: Have push-dose epinephrine or dopamine ready if pacing fails

Failure to Capture

• Increase output: Go up in 10mA increments to maximum (usually 200mA)
• Check pad placement: Ensure good contact, no air bubbles, dry skin
• Reposition pads: Try anterior-posterior if using anterior-lateral
• Replace pads: Old or dried-out pads may not conduct well
• Check connections: Ensure cable securely connected to defibrillator
• Consider causes: Severe acidosis, hyperkalemia, large pericardial effusion can increase threshold

Intermittent Capture

• Increase output by 10-20mA above threshold
• Secure pads - patient movement can disrupt contact
• Reduce patient movement with adequate sedation

Oversensing (failure to pace)

• Pacer detects artifact as native beats and inhibits pacing
• Solution: Switch to fixed (asynchronous) mode
• Reduce movement/tremor, secure ECG leads

Undersensing (competes with native rhythm)

• Pacer doesn't see native beats, fires regardless
• Solution: Increase sensitivity, reposition ECG leads
• Risk of R-on-T if pacing spike hits native T-wave

Pediatric TCP

• Use pediatric pads if available (<10kg or <1 year)
• Anterior-posterior placement preferred
• Start rate at 100 bpm for infants, 80 bpm for children
• Capture thresholds generally similar to adults

Obesity

• May require higher output for capture
• Anterior-posterior placement more effective
• Apply firm pressure to pads if possible

Pacemaker/ICD Patients

• TCP can be used if internal device fails
• Place pads at least 8cm from device generator
• Device may need interrogation/reprogramming after

Hypothermia

• Below 30°C - heart may not respond to pacing
• Rewarm patient while attempting pacing
• Consider passive rewarming + warm IV fluids

1. American Heart Association. (2020). 2020 AHA Guidelines for CPR and ECC. Circulation. 142(16_suppl_2):S366-S468.
2. Zoll Medical Corporation. (2020). Transcutaneous Pacing Clinical Guide.