Proper Anterior-Posterior Pad Placement for Defibrillation
For anterior-posterior (AP) pad placement, place the anterior pad to the left of the sternum and the posterior pad behind the heart in the infrascapular region, with both pads directly against the skin to maximize defibrillation effectiveness.
Anterior-Posterior Pad Placement Technique
Anterior Pad Placement:
- Position the anterior electrode to the left of the sternum 1
- Place directly against the chest wall
- For patients with breasts, place the pad under rather than over breast tissue 1
- Ensure good skin contact with no air gaps
Posterior Pad Placement:
- Position between the scapulae, behind the heart 1
- Either right or left infrascapular position is acceptable 2
- Place directly against the skin
- Ensure the pad is flat against the back
Effectiveness of Anterior-Posterior Placement
The anterior-posterior configuration has demonstrated superior effectiveness compared to anterior-lateral placement:
- AP placement shows higher overall success rates (87% vs 76%) 1
- Requires lower energy for successful cardioversion 1
- A 2024 study found AP placement was associated with higher rates of return of spontaneous circulation (ROSC) compared to anterior-lateral placement in out-of-hospital cardiac arrest patients 3
Technical Considerations for Optimal Defibrillation
- Use electrolyte-impregnated pads to minimize electrical resistance 1
- Recommended pad diameter is 8-12 cm 1, 4
- Remove excessive chest hair if necessary, but prioritize minimizing delay in shock delivery 1, 4
- Ensure the skin is dry before pad application 4
- Remove any medication patches from the area where pads will be placed 4
- For patients with implanted devices (pacemakers/ICDs), position pads at least 8 cm away from the device 4
Common Pitfalls to Avoid
- Placing pads over breast tissue - reduces current flow to the heart 1
- Excessive electrode separation - particularly problematic in patients with emphysema 1
- Placing pads directly over implanted devices - can damage the device and reduce defibrillation effectiveness 4
- Failing to ensure good skin contact - increases impedance and reduces current delivery 1
Special Considerations
- For patients with emphysema, placing the anterior electrode to the left of the sternum reduces the amount of pulmonary tissue between the pad and heart 1
- For large-breasted individuals, place the left electrode pad lateral to or underneath the left breast 1, 4
- If initial pad position proves unsuccessful, consider an alternative arrangement 1
The anterior-posterior pad placement is particularly beneficial when the pathology involves both atria, such as in patients with atrial septal defects or cardiomyopathy 1.