image by: Emergency Medical Minute

HWN Suggests

Emergency Physicians Discuss Emergent Use of Pacemakers for Patients with Bradycardia

Specifically, there seems to be little to no disagreement on when to emergently pace bradycardic patients... The controversy is how to emergently pace. First, should transcutaneous pacing even be attempted? According to a lecture by Joe Bellezzo, MD, FACEP, featured on the Ultrasound Podcast (@ultrasoundpod), subtly titled, “Transcutaneous Is Just Stupid,” the answer is no. Why? First, he argues, it works less than half of the time, with a 40 percent capture rate. Additionally, patients are often diaphoretic or are sticky with nitroglycerin paste, the procedure is painful, most sedatives you would use—other than ketamine—might cause additional hypotension, and finally, the artifact from the…

read full article

Featured

 Pacing in the ED

Make sure you know how to use your device (and have the three lead attached). Most ED defibrillators will require you to turn them into “manual mode”, which will then enable you to access the pacing controls. The first one to adjust is the “pacing rate” – which enables you to choose the heart rate you want. Then adjust the “energy output”. This is the amount of mA you need to obtain “capture” – or for the pacemaker to work. If your patient is unwell, some sources say to start at the maximum energy and titrate down but general guidelines are start at 70mA and increase until 10mA above capture. If there is no capture at 130mA, re-site the pads, and re-try. You know when capture has been achieved when you see a vertical pacing spike followed immediately and every time by a complex.

 Therapeutics: Pacing Through Skin and Vein

Historically, it was taught to place pads at the anterolateral (AL) position with the positive electrode pad over the right upper anterior chest wall and the negative electrode over the left midaxillary line. This was generally the easiest placement as it did not involve rolling the unstable patient; however, new data has shown that anteroposterior (AP) placement may be more effective. AP placement is when the positive electrode is placed under the left scapula and the negative electrode pad is placed over the left parasternal chest wall. AP placement was proven to be capture at a lower current than the AL placement in the same patients, thus more effective.

Articles of Interest

Cardiac Pacing

The major disadvantage of transcutaneous pacing in the conscious patient is discomfort. The pacing impulse stimulates painful contraction of chest wall muscles as well as causing some direct discomfort.

Circulation: Electricity

It is possible to have electrical capture, but not mechanical capture. Thus, it is instrumental to assess both electrical and mechanical capture.

Completely disassociated

As is often the case with emergency management, the patient’s stability and etiology determine the initial approach. The unstable patients will often require pharmacotherapy in addition to transvenous or transcutaneous pacing to improve cardiac output. Pacing is indicated for symptomatic bradycardia. The quickest approach is transcutaneous pacing. This can be accomplished with the anterior/posterior position or anterior/lateral position.

Emergency Cardiac Pacing

The purpose of cardiac pacing is to restore or ensure effective cardiac depolarization. Emergency cardiac pacing may be instituted either prophylactically or therapeutically. Prophylactic indications include patients with a high risk for atrioventricular (AV) block. Therapeutic indications include symptomatic bradyarrhythmias and overdrive pacing. Pacing for asystole has very minimal success but has been used for this condition. Several approaches to pacing can be taken, including transcutaneous, transvenous, transthoracic, epicardial, endocardial, and esophageal.

Emergency cardiac pacing options

The question one has to ask oneself is, "are they going to feel worse if I have to pace them transcutaneously, or place a jugular sheath for wires?" The answer may be "yes". Apart from doing nothing, which is the opposite of a plan, one may instead choose to correct electrolytes that may be contributing, to rewarm the cold patient, reawaken the profoundly sedated patient, return to them their forgotten thyroxine, and wait.

Emergency Physicians Discuss Emergent Use of Pacemakers for Patients with Bradycardia

Nothing gets your heart racing like bradycardia. Wait, that sounds backwards. How about, “Nothing makes you as dia­phoretic as your patient like unstable bradycardia does.” That’s better.

Emergent Cardiac Pacing

Slowly increase output until capture is acquired. Electrical capture can be judged on the cardiac monitor. (Every pacer spike should be followed by a wide complex QRS complex.) However, assessing for mechanical capture is more important. Classically, this was done by feeling for a pulse and correlating the cardiac monitor with the pulse oximeter tracing. However, I prefer to watch for mechanical capture using bedside ultrasound.

External Pacing

The indication for external pacing is simply symptomatic bradycardia that has not responded to initial medical treatment. This may be atropine or even adrenaline in some cases.

Identifying Complete Heart Block and the use of Temporary Cardiac Pacing in the Emergency Department

Human studies have shown that the average current necessary to achieve capture is between 65-100 mA in unstable bradycardias and about 50-70 mA in hemodynamically stable patients.

Temporary Cardiac Pacing Complications

There are many advantages to transcutaneous pacing such as wide availability, ease of use, quick deployment and decreased risk of serious complications in comparison to invasive techniques such as transvenous pacing, however, pain secondary to electrical induced muscular contraction is a big drawback to this method. Other complications include failure to capture and skin burns. The pain that occurs from transcutaneous pacing primarily is the result of muscle contractions from the high current output levels. Proper sedation with benzodiazepine and analgesia with opiates are essential for patient undergoing transcutaneous pacing to lessen discomfort and pain until transvenous pacing can be initiated.

The permanent decline of temporary pacing

Emergency transvenous temporary pacing is a potentially lifesaving procedure that can be associated with significant complications. Historically, this procedure was performed by relatively inexperienced doctors. In recent years, there have been moves to improve the delivery of emergency pacing in UK hospitals.

Transcutaneous & Temporary Transvenous Pacing

Temporary cardiac pacemakers are only bridges to definitive care. Patients with hemodynamic unstable bradycardia often require cardiac catheterization, advanced cardiac electrophysiologic studies, and potentially permanent pacemaker placement. Джерело: https://tccc.org.ua/en/guide/transcutaneous-and-temporary-transvenous-pacing-enroute

Transcutaneous and Transvenous Cardiac Pacing

Symptomatic bradydysrhythmias represent the primary indication for the use of transcutaneous pacing. The pathophysiology that results in a slowed ventricular rate may be subdivided into two main etiologic classifications: disorders of impulse formation (such as sinus arrest or sinus bradycardia) and disorders of impulse conduction (such as second- or third-degree AV blocks).

Transcutaneous Pacing

if pacing rate not captured at a current of 120-130mA -> resite electrodes... once pacing captured, set current at 5-10mA above threshold