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UPDATE ON EMERGENCY CARDIAC CARE GUIDELINES Mark L. Greenberg, MD Associate Professor of Medicine Director, Clinical Electrophysiology and Pacing BLS and ACLS-Historical Perspective 1956: External defibrillation (Zoll) 1958: Mouth-to-mouth ventilation (Safar, Elam) 1960: Chest compressions (Kouwenhoven) 1979: Automatic External Defibrillator (AED) (Diack) 1996: Biphasic waveform approved for AED use in USA 2000: First international evidence-based resuscitation guidelines 1 The Chain of Survival of Cardiopulmonary Resuscitation Interdependence of Early CPR and Early Defibrillation Valenzuela, et al. Circulation. 1997;96:330813. The physiologic mechanism of chest compressions: cardiac pump (A) or thoracic pump (B)? What’s New in BLS New Chest Compression Rate and CompressionVentilation Ratio for Adults Interposed Abdominal Compression CPR (IACCPR) INTERRUPTIONS IN CHEST COMPRESSIONS ARE DETRIMENTAL Lay rescuers: 16 seconds to administer 2 breaths (cf 3-4 sec. for professionals). Compression: ventilation ratio of 5:1 yields higher PaO2 but lower oxygen delivery than 15:2 (64 compressions, 8 ventilations per minute). New Chest Compression Rate and Compression-Ventilation Ratio for Adults Compression rate approx. 100/min for adults and children over age one Compression-ventilation ratio 15:2 for both one and two-rescuer CPR (5:1 after trachea intubated) Interposed Abdominal Compression CPR (IACCPR) An alternative for in-hospital resuscitation Abdomen compressed between xiphoid and umbilicus during relaxation phase of chest compression Increases forward blood flow during CPR and appears to improve survival IAC-CPR Seesaw-like Function of the Lifestick ResQPump™ Metronome Force Gauge Suction Cup Handle Inspiratory Impedance Threshold Valve (ITV) Concept: Lower intrathoracic pressure in the chest during the decompression phase of CPR enhances venous return to the thorax. Design: Each time the chest wall recoils following a compression, the ITV transiently blocks air/oxygen from entering the lungs, creating a small vacuum in the chest. ResQValve (CPRx) Disposable, oneway valve that fits into the respiratory circuit and impedes inspiratory gas exchange during decompression ResQValve Placement Blood Flow During CPR (Porcine VF Model) Blood Flow (ml/min/gm) 1.0 STD CPR 0.8 STD CPR + ITV 0.6 ACD CPR ACD CPR + ITV 0.4 0.2 0.0 Left Ventricle Brain Lurie et al. Improving ACD CPR with an inspiratory impedance valve. Circulation 1995;91:1629-32. Blood Pressure During CPR in Humans 120 mmHg 100 80 STD CPR 60 ACD + ITV 40 20 Baseline (Normal) 0 Systolic Diastolic Cohen et al, JAMA 1992 and Plaisance et al, Circulation 2000 RCT of ACD/ITV CPR vs. STANDARD CPR 220 patients, 157 with witnessed events (Mainz, Germany) 24 hr. survival 37% with ACD/ITV CPR vs. 22% with standard CPR (p=0.03) Wolcke et. al. Circulation.2002;106:II-538. What’s New in External Defibrillation More emphasis on early defibrillation Automatic External Defibrillation (AED) and Public Access Defibrillation (PAD) Defibrillation with a biphasic waveform Defibrillation The Time Factor* * Non-linear Guidelines 2000 for Cardiovascular Resuscitation and Emergency Cardiovascular Care.Circulation. 2000;102(suppl I)8. August 22,2000 90 80 70 Percent of Survival Survival rates after VF cardiac arrest decrease approximately 7% to 10% with every minute that defibrillation is delayed. 100 60 50 40 30 20 10 0 1 2 3 4 5 6 Time (min) 7 8 9 10 13 year old boy struck by a pitch Commotio Cordis Goals For Early Defibrillation In hospital: defibrillation within 3 minutes Out of hospital: defibrillation within 5 minutes of activation of the EMS (value of AED and PAD) Unconscious patient, no pulse Shock advised Unconscious patient, no pulse No shock advised? “It is time for the national government to help bring AED’s to public places all over America. . . I am working with Congress to complete a vital piece of legislation that would not only encourage the installation of AED’s in federal buildings, but also grant legal immunity to good Samaritans who use them. .. It is now our responsibility to bring this technology , this modern miracle, to every community in America.” President Bill Clinton, 5/20/00 radio address. Prevalence of AED’s National Registry of CPR Hospitals: 31% VA Hospitals: 14% Commerical Airliners: 100% O’Hare International Airport: 60-90 Second Walk To An AED Caffrey et. al. N Engl J Med 2002;347:1242-7. CHICAGO AIRPORT AED STUDY Three airports, serving >100 million passengers/yr. 21 cardiac arrests over 2 yrs; 18 had VF, 11 of whom were resuscitated (10 alive & well one yr. later) Caffrey et. al. N Engl J Med 2002;347:1242-7. Incidence of Unexpected Cardiac Arrest AEDs: UNANSWERED QUESTIONS Does formal training improve performance? How are they best deployed? Are they cost effective? DEFIBRILLATOR WAVEFORMS Defibrillation Current Flow Biphasic defibrillation—current flows in two phases, first in one direction from one electrode, and then current flows the other way from the other electrode Biphasic Defibrillation Risk of Damage 40 Monophasic Peak Current Current (amps) 30 40% Difference Biphasic Peak Current 20 10 0 -10 -20 0 5 10 15 20 Time (msec) Much less peak current and better efficacy than monophasic Source: SL Higgins, Prehospital Emergency Care 2000; 4:305-313 Transthoracic Impedance Measured by the defibrillator Higher impedance • • • • • Skin surface—especially dry Hair Fat Bone Air in chest Impedance 60 Current variance due to impedance, energy held constant Peak Current (amps) 50 40 30 20 10 0 25 50 75 100 125 150 Patient Impedance (ohms) The current a heart receives from a 200J shock depends on the patient’s impedance Impedance Distribution Histogram of patient impedances Percentage of Patients 16 14 12 10 8 6 4 2 0 30 40 50 60 70 80 90 100 110 120 Impedance (ohms) Medtronic Physio-Control: Impedance data on 723 SCA patients. 130 140 150 More Biphasic Defibrillators Are NOT All the Same Waveforms vary (with regard to voltage or pulse duration) in their response to transthoracic impedance measurements. Energy settings may be fixed, lowdose escalating, or “standard” dose escalating. No clear superiority among manufacturers. IMPEDANCE ADJUSTMENT WITH PHILIPS FR2 50 SMART Biphasic 40 50, 150 J 30 75, 150 J Current (A) 20 125, 150 J 10 0 -10 -20 0 5 10 15 20 25 30 Time (msec) 35 150-150-150 J Current adjusted for impedance Customized waveform shape for each patient and each shock 40 Why Will Biphasic Defibrillators Replace Standard Monophasic Models? Impedance compensating, lower shock strength biphasic waveforms have less potential to damage cells. Biphasic waveforms have superior efficacy for treating atrial fibrillation and ventricular fibrillation. Randomized, controlled trial of 150 J biphasic shocks with 200-360 J monophasic shocks in 115 patients with out-of-hospital VF; time to first shock 8.9+/-3.0 min. 96% (52/54) p <0.0001 98% (53/54) p < 0.0001 69% (42/61) 59%(36/61)B % Biphasic Monophasic 1st shock Biphasic Monophasic 3 shocks Schneider T, et al, Circulation 2000;102:1780-1787. What’s New in ACLS? Airway Management Vasopressin IV amiodarone as a first-line drug What’s New in Airway Management Emphasis on skilled bag-mask ventilation with continuous cricoid pressure Validation of airway adjuncts like the laryngeal mask and Combitube Recommendation for secondary confirmation techniques to verify ETT placement (e.g.end-tidal CO2) Cricoid Pressure Can Minimize Gastric Inflation Advanced Airway Devices Esophagealtracheal combitube Advanced Airway Devices Laryngeal mask airway (LMA) Superior to ETT for BLS-level personnel Equal to ETT for ACLS-level personnel Laryngeal Mask Confirming Tracheal Tube Placement Esophageal detector devices Vasopressin 40 U IV Before Epinephrine 1 mg IV? Vasopressin appears at least as effective as epinephrine (large RCT underway in Europe). Vasopressin is non-beta-adrenergic and does not increase myocardial 02 consumption. Longer half-life (10-20 min. vs. 3-5 min.) simplifies administration. Amiodarone 300 mg IV Should Be Given Before Lidocaine Advantage lidocaine: rapid onset of action, no hypotension Game, set, and match amiodarone: minimal proarrhythmia, much stronger evidence for efficacy Amiodarone vs. Placebo in 504 Pts. with Shock Refractory Outof-Hospital VT/VF Kudenchuk et. al. NEJM 1999;341:871-8. Amiodarone vs. Lidocaine for Shock-Resistant VF Dorian et al. N Engl J Med 2002;346:884-90. Stable Ventricular Tachycardia Monomorphic VT Is cardiac function impaired? Reasonable LV function Medications: * Procainamide Others acceptable * Amiodarone * Lidocaine Poor LV function Amiodarone * 150 mg IV over 10 minutes or Lidocaine * 0.5 to 0.75 mg/kg IV push Then use Synchronized cardioversion Polymorphic Ventricular Tachycardia Polymorphic VT * Is QT baseline interval prolonged? Normal baseline QT Interval Normal baseline QT Interval * Treat ischemia * Correct electrolytes Medications: * Beta Blockers or * Lidocaine or * Amiodarone or * Procainamide or * Sotalol Prolonged baseline QT Interval (suggests Torsades) Long baseline QT Interval * Correct abnormal electrolytes Interventions: * Magnesium * Overdrive pacing * Isoproterenol * Lidocaine