ACEP News - June 2008 - (Page 6)

CARDIOVASCULAR DISORDERS ACEP NEWS • J U N E 2 0 0 8 As prescriptions for β-blockers grow, more patients are presenting with pulseless electrical activity. B Y M I C H E L E G. S U L L I VA N β-Blockers Linked to ‘Pulseless’ Cardiac Arrest tion,” Dr. Youngquist said in an interview. “But patients who have [ventricular fibrillation] as a presenting rhythm in cardiac arrest can often be shocked back into a normal rhythm. Unfortunately, there’s often not much you can do for someone in PEA. The outcome is usually very poor. Furthermore, β-blockade may thwart the one medication we have: epinephrine.” Both β-blocker use and presenting PEA in cardiac arrest have increased over the past 20 years, said Dr. Youngquist, now at the University of Utah, Salt Lake City. β-Blockers are now the fourth most-commonly prescribed medication for hypertension, and about 60% of post-MI patients at all hospitals are discharged on β-blockers. Else vier Global Medical Ne ws S A N F R A N C I S C O — The increased use of β-blockers may be contributing to a proportionate increase in pulseless electrical activity in cardiac arrest, Dr. Scott Youngquist reported in a poster presented at the 12th International Conference on Emergency Medicine. His retrospective study concluded that patients whose presenting rhythm was pulseless electrical activity (PEA) were five times as likely to be taking a β-blocker as those presenting with ventricular fibrillation—a finding that raises questions about the presumed causes and treatment of PEA arrest. “We know that β-blockers prevent patients from going into ventricular fibrilla- At the same time, however, PEA has gone up as well. In the decades of the 1980s and 1990s, ventricular fibrillation (VF) accounted for up to 60% of all outof-hospital cardiac arrests in the United States. Now, VF accounts for only about 25% of arrests, Dr. Youngquist said, and the reason is unclear. Dr. Youngquist and his colleagues theorized that the temporal association between the two trends might be more than coincidental. They performed a chart review of 478 out-of-hospital cardiac arrests that presented to Harbor-UCLA Medical Center, Los Angeles, during the period from 2001 to 2006. Most of the patients (59%) in the review were male; their median age was 70 years. The researchers excluded the records of patients for whom β-blocker status was unknown and for those who arrived in asystole, leaving them with a final cohort of 179; 100 (56%) of these presented with PEA and 79 (44%) with VF. Overall, 65 (36%) were taking β-blockers and 114 (64%) were not. Significantly more patients presenting with PEA than VF were on β-blockers at the time of their cardiac arrest (49% vs. 20%). A univariate analysis revealed that patients taking a β-blocker were almost four times as likely to present with PEA as they were to present with ventricular fibrillation. After adjustment for misclassification of β-blocker use, confounding, and random error, the odds ratio increased to 5. While the results are interesting, they raise as many questions as they answer. However, “If larger studies confirm this, they may suggest that we need to change the way we treat the patient in PEA,” Dr. Youngquist said. For example, glucagon is typically used to reverse a β-blocker overdose, he added, and there are some animal studies that suggest glucagon also may be useful in treating PEA. ■ What to Do When a Pacemaker Delivers Repeated Shocks That high index of suspicion is terribly important, Dr. Although they’re not usually in medical trouble, patients who receive only a single shock might still show up Mattu said, because treatment delay can be deadly. Morat the emergency department, usually because they’re tality is more than 60% if the infections are not treated promptly. S A N F R A N C I S C O — A single shock from an im- scared and in pain. Whether early or late, site infections are usually treat“Most patients say that getting a shock is very painful, plantable cardioverter defibrillator is usually nothing to ed with vancomycin, which covers the usual staph and worry about—but when a patient presents to the emer- like getting kicked in the chest,” he said. Current guidelines recommend a screening exam that strep culprits, as well as any infections caused by methigency department with multiple shocks, it’s time to rev focuses on the history preceding the shock. “If there cillin-resistant Staphylococcus aureus. up the response. Dr. Mattu also offered some pearls for more unusual “If you have a patient presenting with two or more weren’t any other concerning signs or symptoms—like repetitive shocks, it’s considered a medical emergency, syncope, shortness of breath, or chest pain—you proba- situations: bly don’t even need to check cardiac enzymes and this patient needs a formal device interAn ICD patient who presents with sudden right heart or electrolytes,” he noted. “Just tell them to failure might have tricuspid valve damage from the pacrogation” to determine whether the shocks follow up with their cardiologist.” were appropriate, said Dr. Amal Mattu of the ing wire, which can perforate the leaflets. Such patients The most common causes of inappropriate need immediate tricuspid valve repair. University of Maryland in Baltimore. shock are supraventricular tachycardia (espe“Get the patient on a cardiac monitor with The subclavian is no place for a central venous line in cially in the presence of aberrant conduc- those patients. an external defibrillator nearby; do a work-up tion), atrial fibrillation, and atrial flutter. But for reversible causes of shocks, like electrolyte Instead, the femoral vein is the safest access site. The device failures, including fractured leads, in- second choice for venous access would be the contralatabnormalities; get the cardiac enzymes and an sulation damage, and misconnections, can eral subclavian or the internal jugular. Use the magnet to electrocardiogram; and take a good history of also cause shocks. Most of the time, these will deactivate the ICD when the wires go in, Dr. Mattu recany symptoms that preceded the shocks, like be obvious on a plain chest x-ray, Dr. Mattu ommended. If possible, insert the line under fluoroscopy palpitations, syncope, or chest pain,” Dr. MatIf the ECG sinus said. tu said at the 12th International Conference to prevent coiling. rhythm is normal The lead can even perforate the myocardion Emergency Medicine. and the device is If an ICD patient presents with cardiac arrest, put the um. When that happens, unusual symptoms defibrillator paddles or pads in the anterior-posterior poBe aware, however, that the shocks will still delivering probably cause transient changes in some of shocks, deactivate might develop. Dr. Mattu said he had seen such sition to avoid damaging the pacemaker. If you have to these diagnostic measurements, Dr. Mattu the shock function. a condition in a patient with intractable hic- put both pads on the chest, Dr. Mattu noted, try to stay cups. The lead was up against the diaphragm at least 10 cm away from the device. said. ■ DR. MATTU and was pacing it, causing After shocks, most patients will have ST elevations or depressions. The changes tend to be low and the hiccups. Pectoral muscles can be DATA WATCH transient, however, and resolve within 15-20 minutes, he similarly affected, resulting in insaid. If the ECG shows persistent ST changes, the patient tractable spasms. Such patients need Top 10 Most Expensive Health Conditions has true ischemia that can’t be attributed to the shock. to be admitted for replacement of the (in billions of dollars) Cardiac enzymes are often slightly elevated after a shock device, he said. About 8% of patients with an ICD but usually subside within 24 hours, he added. Heart conditions $76 An electrophysiologist or industry technician will have eventually develop a site infection. Trauma disorders $72 to be called in to interrogate the device; that is the only Early infections occur within 60 days Cancer $70 way to determine whether the shocks were appropriate. of implantation and are easily recogMental disorders, including depression $56 A history won’t be sensitive or specific enough to make nized by their classic symptoms: fever, Asthma and COPD $54 as well as pain and erythema at the that determination, Dr. Mattu said. High blood pressure $42 If the ECG shows normal sinus rhythm and the device site. Type 2 diabetes $34 Late infections are more subtle and is still delivering shocks, it’s appropriate to deactivate the Joint diseases* $34 because of that, more dangerous. Ofshock function. Back problems $32 Place a large magnet over the device, and the shock ten, the only complaint is gradually infunction will be disabled. That can be permanent or tem- creasing pain. If the ICD has been in $32 Normal childbirth porary, depending on the model. Consider keeping the place more than a couple of months *Includes osteoarthritis. magnet there until a definitive management is applied, and the only complaint is gradually inNote: Based on 2005 data for visits to doctors’ offices, clinics, and emergency departments, and for hospital stays, home health care, and Dr. Mattu added. Two magnets might be necessary to de- creasing pain, “that is an ICD infection prescription drugs. activate an implantable cardioverter defibrillator (ICD) in until otherwise proven,” Dr. Mattu Source: Agency for Healthcare Research and Quality said. a very obese patient. B Y M I C H E L E G. S U L L I VA N Else vier Global Medical Ne ws ELSEVIER GLOBAL MEDICAL NEWS

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ACEP News - June 2008 Contents News - Time to Move Tricks of the Trade - Revealing Tips Focus On - Dengue Fever Practice Trends - EMTALA Results

ACEP News - June 2008

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