Sussan K. Sutphen, MD,Medscape Pulmonary Medicine.2007; ©2007 MedscapePosted 01/16/2007

Introduction

Heart disease remains the leading cause of mortality in the United States. According to the National Center for Health Statistics, ~685,000 individuals died in 2003 from cardiac causes.^[1] In 2006, the American Heart Association (AHA) published updates to the “American Heart Association 2005 Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.” The guidelines are evidence-based with a rating system applied to the evidence and the treatments, procedures, or testing.^[2]

This review highlights the changes in the advanced cardiovascular life support (ACLS) guidelines for healthcare providers (HCPs) with a brief overview of basic life support. A comprehensive review of the guidelines is beyond the scope of this article; however, the complete guidelines are available at the AHA Web site at http://circ.ahajournals.org/content/vol112/24_suppl/. Additional Webcasts and audio discussions are available at http://www.americanheart.org/presenter.jhtml?identifier=3037720.

Basic Life Support

Airway, breathing, circulation, and defibrillation — the ABCDs — remain the cornerstones of cardiopulmonary resuscitation (CPR). The new guidelines emphasize effective CPR because it improves the victim’s chances of survival from sudden cardiac arrest (SCA) by 3- to 4-fold.^[3] Effective CPR prolongs the presence of ventricular fibrillation (VF), improving the chances that a shock will terminate the rhythm.^[3] HCPs are advised to “push hard, push fast” (30:2 compressions to ventilations or 100/minute) and provide rescue breaths over 1 second with visible chest rise.^[2-4]

Deep breaths and hyperventilation should be avoided. Hyperventilation increases intrathoracic pressure, reducing the amount of blood returned to the heart during cardiac refill, and obstructs cardiac outflow during chest compressions.^[3,5] Bag valve mask is best if provided by 2 persons, one to seal the mask and the other to squeeze the bag while aiming for a tidal volume of 500-600 mL with supplemental oxygen.^[5,6] If an advanced airway is placed, HCPs should provide the airway with which they are most familiar and avoid interrupting compressions for more than 10 seconds. Once an advanced airway is in place, maintain a respiratory rate of 8-10 breaths per minute.^[5,6]

VF is the most common cause of cardiac arrest, and victims defibrillated within 5 minutes of SCA have a greater chance of survival.^[3] Victims should receive a single shock by defibrillator or automated external defibrillator (AED) as soon as possible preceded and followed by CPR. AEDs with appropriate dose mitigation systems may be used in children over age 1 year.^[2,4] A single shock instead of 3 stacked shocks is advised on the basis of the finding that AEDs can have delays of up to 37 seconds between shocks.^[7] Current defibrillators have a higher rate of shock success — up to 85%. Energy levels are 150-200 J if a biphasic defibrillator is used. If a monophasic defibrillator is used, then 360 J may be used. HCPs should be familiar with the defibrillators available in their institution.^[4,5,7]

After the shock, CPR provides some perfusion while an organized rhythm develops. One study demonstrated that only 25% to 40% of SCA victims had an organized rhythm after defibrillation.^[5] CPR provides blood flow and increases the chance that an effective rhythm will return. Once the shock has been delivered, resume CPR for 2 minutes or 5 cycles. Continued CPR enhances the chance that a second shock will work if the first did not.^[4,5,7]

ACLS

The greatest change in ACLS is a reduced emphasis on additional modalities, such as medications, rhythm checks, and central line placement, that interrupt compressions for more than 10 seconds and an increased emphasis on searching for and correcting any cause for SCA.^[2,4]

Shockable Pulseless Arrest Rhythms

Pulseless arrest rhythms are divided into shockable and nonshockable. Shockable rhythms are VF or ventricular tachycardia (VT). If VT/VF persists after the first shock and 5 cycles or 2 minutes, then give another shock, resume CPR, and obtain intravenous (IV) access.

The IV access should be obtained and should be peripheral or interosseous (IO) and not interfere with chest compressions. Central lines do provide better peak drug concentrations and shorter circulation times, but also are more difficult to obtain and result in longer interruptions in CPR. Drugs may also be given endotracheally but should be diluted with 5-10 cc of water or normal saline.^[4,8]

If VT/VF persists, give a vasopressor. Drugs may be given immediately before or after the shock. Epinephrine 1 mg may be given IV or IO and repeated every 3-5 minutes. Vasopressin 40 IU may be given as an alternate to the first or second dose of epinephrine. Resume CPR for 5 cycles or 2 minutes; check the rhythm; shock; and resume CPR. Should VT/VF persist, then give an antiarrhythmic. Amiodarone 300 mg IV/IO followed by 150 mg IV/IO is first-choice. Lidocaine 1-1.5 mg/kg IV/IO first dose followed by 0.5-0.75 mg/kg IV/IO up to a total of 3 doses or 3 mg/kg may also be given. If torsades de pointes is present, then give magnesium 1-2 g diluted in 10 mL D₅W IV/IO push, typically over 5-20 minutes (Class IIa for torsades). Continue CPR followed by 1 shock and additional CPR/medications for 5 cycles or 2 minutes. If the rhythm becomes nonshockable, then practitioners should follow the algorithm for nonshockable rhythms.^[8]

Nonshockable Pulseless Arrest Rhythms

Nonshockable rhythms include asystole and pulseless electrical activity. If these rhythms result after a shock, give a vasopressor. Epinephrine 1 mg IV/IO every 3-5 minutes or vasopressin 40 IU IV/IO instead of the first or second dose of epinephrine may be given. If there is no response and pulseless electrical activity or asystole persists, give atropine 1 mg IV/IO, which may be repeated every 3-5 minutes. HCPs should search for and treat possible reversible causes for cardiac arrest ( Table 1 ).^[4,8]

Symptomatic Bradycardia

Bradycardia is defined as a heart rate < 60 beats/minute, which may be normal for some individuals. However, if the individual has symptoms, such as hypotension, altered mental status, chest pain, syncope, or other signs of shock, then treatment is warranted.^[9] Practitioners should provide basic treatment, including oxygen, airway maintenance and breathing assistance, electrocardiographic (ECG) monitoring, and IV access, and prepare for transcutaneous pacing. If there is a high-degree atrioventricular (AV) block, such as Mobitz II or third-degree AV bock, consider giving medications as a bridge to pacing. Atropine 0.5 mg IV (up to 3 mg maximum), an epinephrine infusion 2-10 micrograms (mcg)/minute, or a dopamine infusion 2-10 mcg/minute may be given. Begin transcutaneous pacing if these medications are ineffective and prepare for transvenous pacing with expert consultation.^[4,9]

Symptomatic Tachycardia

Although tachycardia is defined as a heart rate > 100 beats/minute, patients are usually symptomatic with rates > 150 beats/minute. Patients with symptoms of shock should be treated. Basic treatment is the same as for symptomatic bradycardia; however, sedation may be considered. Immediate synchronized cardioversion is performed for unstable supraventricular tachycardia (SVT) due to reentry, unstable atrial fibrillation, unstable flutter, and unstable monomorphic VT. An unstable patient with polymorphic VT should receive immediate high-energy unsynchronized shock ( Table 2 ).^[9]

Further treatment for stable patients is based on classification of the rhythm into narrow-complex or wide-complex tachycardia and regular or irregular. Regular narrow-complex tachycardias (QRS < 0.12 seconds) include sinus tachycardia and SVT. There is no specific drug treatment for sinus tachycardia. HCPs should search for and treat the underlying cause, such as fever, anemia, or shock. Initial treatment for SVT is vagal maneuvers, which terminate 20% to 25% of reentry SVT, and adenosine.^[9] Give adenosine 6 mg IV over 1-3 seconds followed by 20 mL of saline flush and arm elevation. If the rhythm persists after 1-2 minutes, give 12 mg IV. If the rhythm doesn’t convert, give a second 12-mg bolus 1-2 minutes later. Side effects are transient and include flushing, shortness of breath, and chest pain.^[9]

If the rhythm persists after adenosine, then second-line drugs, such as a calcium channel blocker (verapamil or diltiazem) or a beta blocker, may be used. Verapamil 2.5-5 mg IV over 2 minutes and repeat doses of 5-10 mg may be given at 15-minute intervals to a total dose of 20 mg. For diltiazem, the dose is 15-20 mg IV over 2 minutes, and if there is no response in 15 minutes, then 20-25 mg may be given followed by a maintenance infusion of 5-15 mg/hour. These drugs should not be used for Wolff-Parkinson-White syndrome. HCPs should use the beta blocker with which they are most familiar. Side effects include bradycardias, hypotension, and AV conduction delays.^[9]

Regular wide-complex tachycardias (QRS ≥ 0.12 seconds) include VT, SVT with aberrancy, and those associated or mediated by accessory pathways. Adenosine is recommended for wide-complex tachycardias that are believed to be SVT. If VT and the patient are stable, then an antiarrhythmic drug may be given. Amiodarone 150 mg IV may be given over 10 minutes and may be repeated to a maximum dose of 2.2 g IV every 24 hours. Other drugs include procainamide 20 mg/minute as an infusion until the rhythm is converted, the QRS is widened by 50%, or a total of 17 mg/kg has been given. Maintenance is 1-4 mg/minute. Sotalol 1-1.5 mg/kg may be given at a rate of 10 mg/minute.^[9]

If the rhythm is wide or narrow and irregular, then it may be atrial fibrillation with an uncontrolled ventricular response. Expert consultation is advised. Consultation is also advised for polymorphic VT or torsades de pointes; however, if the patient is unstable, then provide high-energy unsynchronized shock and begin CPR following the steps for a pulseless cardiac arrest.^[9]

Postresuscitation Care

Return of spontaneous circulation (ROSC) does not mean full recovery for the victim or even survival. Postresuscitation deaths are highest in the first 24 hours after ROSC; therefore, postresuscitation care is critical for survival.^[10]

The HCP should verify the airway, make sure that it is maintained and adequate, monitor vital signs, provide supplemental oxygen, and establish additional IV access as needed. Serial ECGs and an echocardiogram help guide subsequent therapy. Medications, including vasoactive drugs and inodilators, should be titrated to support perfusion and blood pressure. The victim should be evaluated again for any factors that may have led to the arrest and correct any factors identified.^[10]

Postresuscitation patients can develop a mild hypothermia, which may improve neurologic outcome. Patients should not be actively rewarmed if stable (temperature, > 33°C or 91.5°F). However, elevated temperatures should be avoided because these can cause an imbalance in oxygen supply and demand, which can lead to poor neurologic outcome. Seizures should be aggressively treated for the same reasons.^[4,10] Use of neuromuscular blocking agents should be minimized because use of these drugs prevents an accurate neurologic assessment, although patients may require sedation. Evidence has suggested that strict glucose control improves outcomes for many patients; however, further study is warranted.^[10] Appropriate postresuscitation care is critical. Hemodynamic and cardiac instability must be treated to support organ function and improve the chances of survival for victims of SCA.

Summary

Deaths from heart disease remain a public health issue, although the numbers have improved. The new “American Heart Association 2005 Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care” emphasize effective CPR and rapid defibrillation to improve the chances of survival for victims of SCA.

US Centers for Disease Control and Prevention (CDC). Deaths and mortality. Fast stats A to Z. National Center for Health Statistics. October 6, 2006. Available at: http://www.cdc.gov/nchs/fastats/deaths.htm Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112: IV-1-IV-5. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112(suppl):IV-12-IV-18. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006. American Heart Association. Highlights of the 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Currents in ECC. 2005;16:1-27. Available at: http://www.americanheart.org/presenter.jhtml?identifier=3035674 Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112(suppl):IV-19-IV-34. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112(suppl):IV-51-IV-57. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112(suppl):IV-35-IV-36. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112(suppl):IV-58-IV-66. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112(suppl):IV-67-IV-77. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006. American Heart Association. 2005 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. International Consensus on Science. Circulation. 2005;112(suppl):IV-84-IV-88. Available at: http://circ.ahajournals.org/content/vol112/24_suppl/ Accessed August 22, 2006.

Sussan K. Sutphen, MD, MEd, Member, American Medical Writers Association, American College of Physician Executives; Diplomat, American Board of Emergency Medicine