Learn how temporary noninvasive cardiac pacing can protect your patient until normal conduction is restored or he receives a transvenous pacemaker.
WHEN ELECTRICAL conduction in your patient's heart is abnormal, transcutaneous pacing (TCP) can temporarily restore electrical activity. By continuously monitoring his cardiac rate and rhythm and delivering pacing impulses through his skin and chest wall muscles as needed, TCP causes electrical depolarization and subsequent cardiac contraction to maintain cardiac output. He may require TCP until his conduction system recovers or until he receives a transvenous pacemaker.
Indications for TCP include:
* hemodynamically unstable bradycardias that are unresponsive to atropine
* bradycardia with symptomatic escape rhythms that don't respond to medication
* cardiac arrest with profound bradycardia (if used early)
* pulseless electrical activity due to drug overdose, acidosis, or electrolyte abnormalities
* overdrive pacing for refractory tachyarrhythmias after failure of electrical cardioversion and drug therapy.
Contraindications to TCP include:
* severe hypothermia
* prolonged bradyasystolic cardiac arrest.
Setting the pace
Explain the purpose of TCP to your patient. Tell him it involves some discomfort, and that you'll administer medication as ordered to keep him comfortable and help him relax. Place him supine and expose his chest. Clip excessive body hair if necessary (shaving could cause tiny nicks in the skin, causing pain and irritation). Position the electrodes on clean, dry skin and set the pacing current output as shown in the photos.
Once the pace is set
Monitor your patient's heart rate and rhythm to assess ventricular response to pacing. Make sure that the device is appropriately pacing and sensing intrinsic beats. Assess his hemodynamic response to pacing by assessing his central pulses (see Cautions for using TCP) and taking blood pressure (BP) on both arms. If the reading in one arm is significantly higher, use that arm for subsequent measurements.
Also assess your patient's pain and administer analgesia/sedation as ordered to ease the discomfort of chest wall muscle contractions. Maintain electrical safety.
Document your patient's initial cardiac rhythm (including rhythm strip and 12-lead ECG if possible), the signs and symptoms that indicated his need for pacing therapy, the pacer settings (rate, current output, pacing mode), a cardiac rhythm strip showing electrical capture, the patient's pulse and BP, his pain intensity rating, analgesia or sedation provided, and his response.
The device and the manufacturer's multifunction electrodes (MFEs) shown here are used to deliver TCP.
1. Attach cardiac monitoring electrodes to your patient's chest and to the electrocardiogram (ECG) cable on the device. Following package instructions, apply the MFEs as follows:
* anterior electrode to the left of his sternum, centered close to the point of maximal cardiac impulse.
* posterior electrode on his back, to the left of the thoracic spinal column (directly opposite the anterior electrode).
2. Connect the MFEs to the appropriate cable, as shown. Turn on the device, and select synchronous (demand) or asynchronous (fixed-rate or nondemand) mode. Set the pacing rate (usually 80 beats/minute).
3. Set the pacing current output (in milliamperes, mA) as follows:
* Bradycardia: Start with the minimal setting and slowly increase output until the pacer spike appears on the monitor screen. (An external pacer's spike is wider and shorter than that of a transvenous pacer.) Continue increasing output until the ECG tracing indicates electrical “capture” (generally characterized by a widened QRS complex and broad T wave after each pacer spike, as shown here). Add 2 mA or set the output 10% higher than the threshold of initial electrical capture as a safety margin. (Threshold is the minimum current needed to achieve consistent electrical capture.)
* Asystole: Start with full output. If capture occurs, slowly decrease output until capture is lost (threshold) then add 2 mA or 10% more than the threshold as a safety margin.
Cautions for using TCP
* Watch for a change in your patient's underlying rhythm. Ventricular fibrillation would necessitate a different treatment—the definitive therapy is immediate defibrillation.
* Periodically check the area where the electrodes are placed for skin burns or tissue damage. Inspection and repositioning as needed can alleviate these problems.
* Avoid using your patient's carotid pulse to confirm mechanical capture because electrical stimulation can cause jerky muscle contractions that you might confuse with carotid pulsations. Femoral pulse assessments are more reliable.
Karen Craig is president of EMS Educational Services, Inc., in Cheltenham, Pa.
Source: Reprinted from How to provide transcutaneous pacing, Nursing2005, K Craig, October 2005.
The equipment shown is courtesy of Zoll Medical Corp.
ECC Handbook. Dallas, Tex., American Heart Association, 2004.
Zoll M Series Operator's Guide. Chelmsford, Mass., Zoll Medical Corporation, December 2004.
© 2006 Lippincott Williams & Wilkins, Inc.