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Philips SMART Biphasic therapy Application note Philips SMART Biphasic therapy Since Philips introduced the first biphasic waveform for an external defibrillator in 1996, biphasic therapy has gained acceptance and is now recognized as the standard of care. However, the various defibrillator manufacturers recommend a wide range of energy (joules) dosages. This is because defibrillator manufacturers have created distinct biphasic waveform "formulations." So each manufacturer recommends energy doses appropriate for their shock formulation. While energy (joules) remains entrenched in defibrillator vocabulary as a descriptor of shock strength, current (amperes) has been shown to be a better predictor. For meaningful shock strength comparisons of biphasic waveforms, it's necessary to look beyond energy levels and compare the current delivered to the patient.
All presently available Philips HeartStart defibrillators incorporate a proprietary biphasic truncated exponential (BTE) waveform formulation employing high current delivered in a low energy dosage. Further, Philips uses real-time impedance compensation to automatical y adjust the waveform to deliver shock strength personalized to the needs of each patient, starting with the first shock. Philips therapy has been rigorously studied and is backed by a substantial body of peer-reviewed, published data demonstrating effectiveness across the full spectrum of patients, including those considered "difficult-to-treat." While biphasic waveforms effectively terminate arrhythmias, meaningful clinical differences between defibrillators may lie in the amount of energy needed for successful defibrillation and its negative impact on post-resuscitation myocardial function. While high current defibrillates, high energy is associated with negative side effects. So the optimal waveform formulation delivers high current at lower energy doses to help reduce the total energy delivered. Meaningful clinical differences may also lie in how quickly a shock is delivered fol owing the CPR pause, as this may substantial y influence shock success. Only Philips AEDs and the Philips MRx Monitor/Defibrillator in AED mode offer Quick Shock technology, which helps shorten time-to-shock after CPR and increase the chance a shock will successful y return circulation, which may improve survival. Philips SMART Biphasic therapy Biphasic waveforms use distinct formulations
Not all biphasic waveforms are the same. Manufacturers
American Heart Association and European Resuscitation Council use distinct shock formulations, making their individual positions on current energy dosages an invalid comparison tool for evaluating their relative shock strength. This can be likened to " Because it is accepted that defibril ation is accomplished by the passage of sufficient Although different drugs within a class may all be current through the heart, the concept of considered safe and effective, each requires its own current-based defibril ation is appealing. dosage due to its distinctive molecular structure. For example, statins are proven to lower LDL cholesterol.
Energy is a non-physiologic descriptor of Yet, the maximum 80mg dose of Lipitor® (atorvastatin defibril ation despite its entrenchment in calcium) is not necessarily more therapeutic than traditional jargon…Transition to current- the 40mg maximum dose of Crestor® (rosuvastatin calcium) based description is timely and should be 3 simply because it is twice the dose. Because each drug in a class has a unique formulation, the number of mil igrams of one drug in a class is not – American Heart Association2 necessarily indicative of therapeutic strength relative to another, and does not lend itself to "apples to apples" comparisons.
" Although energy levels are selected for defibril ation, it is the transmyocardial current Biphasic waveforms as a class have been proven to flow that achieves defibril ation. Current effectively terminate arrhythmias. They deliver "electric medicine" and, similar to pharmaceutical medications, correlates well with successful defibril ation use distinctive waveform formulations. For biphasic and cardioversion…Future technology may waveforms, the formulation is driven by different device enable defibril ators to discharge according components, waveform shape, and duration, which produce current. According to the American Heart to transthoracic current: a strategy that Association and European Resuscitation Council, it's may lead to greater consistency in shock current that defibril ates, not the amount of energy success…manufacturers are encouraged to (joules).2,3 Due to varying waveform formulations, it is possible for the recommended first shock dosage of 150J explore further this move from energy-based from one defibril ator manufacturer to deliver higher to current-based defibril ation." current levels than a 200J first shock from another – European Resuscitation Council3 defibril ator manufacturer, even though the latter delivers a larger energy dosage.

A 5-second jolt from Theoretical y, when the typical 1200V taser used by law enforcement would incapacitate a person, conductive surface, but the person would such as a person's only absorb a 1/4J tongue, the person would eventual y absorb 360J.
Current, not energy, determines shock strength
Waveform formulation key terms
If the connectors of a common 9V battery were placed on a person's tongue, the person would eventual y Capacitor – A key component of the defibril ator design that stores electrons.
absorb 360J. Of course, no one would consider using a Manufacturers have created distinct waveform formulations that use various 9V battery to defibril ate a patient as it lacks sufficient size capacitors to generate voltage and current for defibril ation. The size voltage and current. of the capacitor impacts the amount of energy (joules) needed to produce voltage and current. Smal er capacitors typical y use fewer joules to pack the On the other hand, a person incapacitated by the typical necessary voltage and current punch for effective defibril ation. Whereas, 1200V taser used by law enforcement for 5 seconds would larger capacitors usual y use more joules to achieve comparable levels.
only absorb a ¼J shock. After one excruciating minute, Voltage – The force that pushes the electrons through the patient. The
just 3J would be absorbed. With sufficient voltage and amount of voltage stored on the capacitor drives the amount of current current, a ¼J shock can be quite strong indeed.
available for defibril ation. The higher the voltage level, the greater the force and amount of current that can be delivered for defibril ation.
The point of these examples is that while energy (joules) Current – The movement of electrons, measured in amperes, which achieves
remains entrenched in defibril ator vocabulary as a defibril ation. For biphasic waveforms, distinctive formulations driven by descriptor of shock strength, published studies have different device components, waveform shape, and duration produce current.
shown that current (amperes) is a better predictor.4,5 The American Heart Association and the European Impedance – The resistance of the body to the flow of current, which is
Resuscitation Council are both advocating a shift to measured in ohms. Human impedance levels typical y range from 25 ohms to current-based defibril ation.
180 ohms.
Voltage gradient – Reflects the actual intensity of a defibril ation shock in
For effective defibril ation, a defibril ator must generate terms of the electric field it generates within the myocardium itself. Accurate high voltage in order to drive a sufficiently high current measurement of intracardiac voltage gradients requires instrumenting the over the duration when the heart cel s are physiological y heart with electrodes to capture the data.
most receptive to defibril ation (See Table 1 for
Duration – The period over which the current is delivered to the heart. The
Waveform formulation key terms). Therefore, for goal is to deliver therapy over an optimal time period to increase the chance meaningful shock strength comparisons of biphasic of defibril ation.
waveforms, it is necessary to look beyond energy and compare the current delivered to the patient.
Philips SMART Biphasic therapy The Philips SMART Biphasic waveform formulation to the heart – when comparing each manufacturer's
When Philips set out to design the first biphasic
recommended first shock energy setting. The authors waveform for an external defibril ator, the engineers concluded that energy descriptors correlate poorly chose a smal er 100 microfarad (μF) capacitor that to actual shock intensities and provide an inaccurate used fewer joules to pack the necessary voltage and measure of relative shock strength among different current punch for effective defibril ation. Philips external defibril ators. The authors also concluded that patented the use of a smal er capacitor for external peak current is a better measure of shock strength.
defibril ation, which led other manufacturers to select larger (200 μF) capacitors for their The Philips SMART Biphasic waveform formulation formulations. Larger capacitors typical y use more delivers high voltage to drive high current and generate joules to achieve voltage and current, meaning shock high voltage gradients at the heart with fewer joules.
strength, comparable to Philips. Using standard protocols, this means that Philips delivers higher Voltage levels by recommended first shock energy setting shock strength starting with the first shock than other typical biphasic waveforms that escalate their energy levels to reach equivalent shock strength. Escalating potential y wastes time and shocks during Voltage levels by recommended first shock energy setting Philips (100 µF capacitor) Another biphasic waveform (200 µF capacitor) The amount of voltage stored on the defibril ator's capacitor determines the amount of current delivered to the patient, which is responsible for defibril ating the heart and considered a more accurate measure of shock Philips (100 µF capacitor) Another biphasic waveform (200 µF capacitor) strength. Figure 1 shows that the Philips waveform
Measurements based on a resistive load of 80 ohms.
(using a 100 μF capacitor) at its recommended first shock energy setting can produce significantly higher voltage than another common biphasic waveform (using Delivered current by recommended first shock energy setting a 200 μF capacitor) at its recommended first shock setting.6 Philips distinct waveform formulation uses fewer joules to achieve higher voltage levels. Delivered current by recommended first shock energy setting Higher voltage drives higher current to the patient. Applying basic physics, namely Ohm's Law, Figure 2 shows
Philips (100 µF capacitor) Another biphasic waveform (200 µF capacitor) how the Philips formulation is able to generate higher current with fewer joules at its recommended first shock Assumes an average patient impeda 30 nce of 80 ohms.
energy setting than that of another common biphasic waveform (using a 200 μF capacitor).
Philips (100 µF capacitor) Another biphasic waveform (200 µF capacitor) waveform requires more energy to deliver current Measures of shock strength:
equivalent to the Philips waveform.
First shock (simulated human impedance at 75 ohms )
A swine study by Niemann, et al.8 * measured whether energy or peak current measured at the body surface is a better predictor of the actual shock electric- field strength to which the heart is exposed. Porcine hearts were instrumented with electrodes to measure voltage gradients within the heart achieved by various defibril ator brands. Figure 3 demonstrates that Philips
delivers the highest observed peak current and voltage
Peak voltage gradient (V/cm) Peak current (Amps) gradients – meaning more defibrillation therapy right Philips SMART Biphasic therapy Evidence-based therapy with consistently
With no head-to-head comparison data available, two peer-reviewed, published clinical trials using different As the first biphasic waveform in an external biphasic waveforms in out-of-hospital, long-downtime VF defibril ator, the performance of Philips therapy has patients were of similar size, design, and purpose.25,28* been rigorously studied and reported in numerous The observed response conditions for these studies peer-reviewed, published manuscripts. They reflect were largely similar in terms of average patient weight, waveform performance in both animals9–12 and humans, cal -to-shock time, percent of witnessed arrest, and including the chal enging long-duration VF relevant to percent of bystander CPR. The first study by Schneider, hospital code teams and responders in out-of-hospital et al. using Philips biphasic therapy (150J fixed-energy settings.13–26 These data demonstrate consistently high protocol) showed a 96% first shock efficacy. Seventy- efficacy, regardless of factors such as: patient size, age, six (76) percent of patients experienced return of impedance, incidence of refibril ation, or underlying spontaneous circulation (ROSC). Of surviving patients, cause of cardiac arrest, including myocardial infarction. 94% showed good/moderate neurological function. Survival to discharge was 28%. The second study by van Philips therapy was the first biphasic therapy Alem et al. using Physio-Control's high-energy biphasic with sufficient evidence to receive a Class IIa therapy (200-360J escalating energy protocol) also recommendation from the American Heart Association: reported a high first shock efficacy of 98%. Sixty-one "Standard of care", "Intervention of choice".27 percent of patients experienced ROSC and 14% survived In contrast, some biphasic therapies on the market to discharge. (Figure 4)
today have limited or no published out-of-hospital clinical data. With no published, peer-reviewed Another study by Stiel , et al.29 * using Physio-Control's studies in humans directly comparing the performance high-energy biphasic therapy (200-360J escalating of various biphasic waveforms in treating VF, the energy protocol) reported first shock efficacy of 89%. American Heart Association (AHA) advises, "The Forty nine (49) percent of patients experienced ROSC safety and efficacy data related to specific biphasic and 82% of surviving patients showed good/moderate waveforms must be evaluated on an individual basis."27 neurological function. Survival to discharge was 16%. Accordingly, clinicians are cautioned about generalizing This study also included a low-energy (150J non- conclusions about one manufacturer's biphasic therapy's escalating energy protocol) arm that used a low-current performance to other manufacturer's therapy. design not comparable to the Philips high-current 150J waveform. Rather, the study compared a manufacturer's standard adult high energy/high current protocol with the same manufacturer's non-standard adult low energy/ Two out-of-hospital defibrillation trials
low current protocol. (Physio-Control not Philips therapy 150J Physio-Control therapy 200-360J Philips SMART Biphasic therapy Proven across the full spectrum of patients
Philips therapy has been proven highly effective across the full spectrum of patients, even those considered "difficult-to-treat." 23-26,30,31
The results of some of these published, peer-reviewed studies are summarized in Table 2.
patient group
Overweight and obese
White RD, et al. Critical Care Medicine. First shock efficacy and subsequent shock success, resuscitation, (BMI > 25) patients and survival were not related to patient body weight. Philips 150J fixed-energy protocol appears effective and appropriate. High/low impedance patients White RD, et al. Resuscitation. 2005.* 24 With the Philips 150J fixed-energy protocol, efficacy was high. Impedance had no bearing on defibril ation, ROSC, or survival at discharge.
Refibril ating patients Hess EP, et al. Resuscitation. 2008.* 26 No significant difference in the frequency of shock success between initial and recurrent episodes of VF using a Philips 150J fixed-energy protocol was observed. VF recurrence is common and does not adversely affect shock success, ROSC or survival.
Myocardial infarction patients Schneider T, et al. Over half the patients in this study were diagnosed with acute Circulation. 2000.* 25 myocardial infarction, but VF was successful y terminated for all patients using a Philips 150J fixed-energy protocol, with a 96% first shock efficacy. Atrial fibril ation patients Santomauro M, et al. Italian Heart Only the Philips biphasic waveform demonstrated 100% Journal. 2004.* 30 cardioversion success for AF compared with patients treated with a monophasic or the Zoll Rectilinear Biphasic™ waveform. The Philips biphasic waveform required less total energy (statistical y significant) and fewer shocks per patient (not significant). The Philips waveform appears to achieve a higher success rate at lower energy levels. Philips real-time impedance compensation delivers optimized therapy One major contributor to Philips biphasic therapy's effectiveness across the full spectrum of patients is real-time impedance-compensation technology, which optimizes every shock. Philips defibril ators automatical y measure patient impedance and in real- time dynamical y vary the waveform. Personalized therapy is delivered to each patient, including the difficult-to-treat ones, starting with the first shock for the best chance of success. Figure 5 shows how the
Philips waveform is adjusted to compensate for varying impedance levels.32 Philips SMART Biphasic therapy Meaningful clinical differences among
Tang, et al.33 *compared the impact of various defibril ation waveforms delivered at different energy Dysfunction from high energy settings on post-resuscitation myocardial function using When responding to a sudden cardiac arrest emergency, an animal model, which effectively isolated the impact of terminating VF quickly is the only priority. However, in just the defibril ation shocks. The study showed that for the calm of the defibril ator selection process, there is swine in long-duration VF, higher current/lower energy the opportunity to consider the side effects of waveform and a higher current/higher energy waveform were design, particularly in resuscitation situations that require equal y effective at defibril ating. However, the higher multiple shocks. Animal studies suggest that electric shocks energy waveform was associated with significantly higher
can have a negative inotropic influence on cardiac function levels of harmful cardiac dysfunction.
depending on the clinical circumstances, the energy dosage,
the number of shocks delivered, and the underlying cardiac Table 3 demonstrates that the high energy waveform
function.10,32,33 Too many shocks can cause transient
(200 μF capacitor at 360J) required up to nine times the cardiac injury, such as decreased contractility and reduced total energy delivered as the low energy waveform (100 cardiac output during the critical period immediately after μF capacitor at 150J) to achieve equivalent results. severe cardiac compromise.10,33,34 While this type of injury is not permanent, clinical data suggest that during a code Table 3 also shows the negative impact of the total
this stunning may be significant, complicating subsequent delivered energy on ejection fraction, considered a interventions in the emergency department or intensive representative measure of dysfunction. Conversely, care unit and potential y impacting patient outcomes.10,33,35 high peak current was the only positive predictor of increased survival, which reinforces the importance of Higher-energy defibril ation waveforms, whether current in the defibril ation equation. monophasic or biphasic, are associated with increased post-shock cardiac dysfunction. Experimental33,34 and clinical35 Tang, et al.33 concluded that maximizing survival while studies suggest that in typical out-of-hospital multi-shock minimizing myocardial dysfunction may be achieved resuscitations, total energy delivered is a negative predictor with a waveform formulation that delivers higher peak of myocardial function. An animal study noted a correlation current while minimizing total energy delivered. between post-resuscitation myocardial dysfunction and early death after initial successful resuscitation.33 Philips distinct biphasic waveform formulation is able to deliver high peak current at low energy levels. This type of lower energy shock has been shown to have fewer negative inotropic consequences than higher energy shocks. This clinical difference could be particularly meaningful for the long downtime SCA patients, both in and out-of-hospital, who typical y require multiple Median peak current shocks and could help make post-resuscitation interventions in the ED or ICU more successful. Survival (to 72 hours) Median number of shocks to Philips biphasic therapy delivers its strongest therapy from the first shock to maximize effectiveness, Median CPR duration (seconds) yet minimize total energy delivered. In contrast, Median total energy required defibril ators that employ high energy formulations typical y start with weaker shocks (lower current Median ejection fraction at delivered at lower energy settings) and escalate 30 minutes (% of baseline)** to higher energy settings in the event of failure, Table 333
** A representative measure of dysfunction. A lower number compared to baseline means more dysfunction. presumably to balance the trade off between shock Philips SMART Biphasic therapy Time-to-shock after CPR and shock success
Shock success 20% Pre-shock pause (seconds) Figure 641
strength and potential post-shock dysfunction. Philips HeartStart AEDs and the MRx Monitor/ Assuming the Guidelines 2005-recommended Defibril ator in AED mode shock as fast as 8-10 seconds protocol2, it could take up to 6 minutes (including (typical) after CPR pause using a technology cal ed CPR intervals) to reach such an escalating, high- "Quick Shock." This unique feature shortens time-to- energy biphasic waveform's maximum shock strength. shock after CPR, thereby increasing the chance that a Philips does not face this trade off.
shock will successful y return circulation and, in turn, improve survival. Time-to-shock fol owing CPR pause impacts shock successAnimal and clinical studies show that in longer downtime situations (>4 minutes), CPR immediately prior to defibril ation can help restore normal heartbeats in more patients.36,37 Yet, the beneficial effects of CPR disappear in seconds, making time-to-shock fol owing CPR critical.38,39 Thus, another key therapy attribute is how quickly the defibril ator delivers a shock fol owing a CPR pause. In fact, a formulation that includes shorter time-to-shock fol owing CPR may substantial y influence shock success.40 A clinical study evaluating the impact of pre-shock
CPR interruptions on shock effectiveness reported
that, "…a 5 second decrease in pre-shock pause was
associated with an 86% increase in the odds of shock
success (p=0.02)." The study concluded that, "…
consideration should be given to the use of newer-
generation AEDs with shorter (<10 seconds) analysis
times."41 * (Figure 6)
Philips SMART Biphasic therapy Biphasic waveforms have become the standard of care for external defibril ation. Manufacturers have created distinctive formulations and recommend energy (joule) dosages appropriate for their waveforms. While energy remains entrenched in defibril ator vocabulary as a descriptor of shock strength, current has been shown to be a better predictor. For meaningful shock strength comparisons of biphasic waveforms, it's necessary to look beyond energy levels and compare the current delivered to the patient. Philips distinct waveform formulation is able to generate high voltage and deliver high current, which produces high voltage gradients using fewer joules. It's common for other defibril ator manufacturers to use larger capacitors for their formulations and deliver significantly more energy to achieve voltage and current, meaning shock strength, comparable to Philips. Philips evidence-based therapy has been rigorously studied and is supported by a substantial body of peer-reviewed, published data. It has been clinical y proven to deliver high first shock efficacy for long-downtime SCA patients and effectively defibrillate across the full spectrum of patients, including those labeled "difficult-to-treat." In contrast, some biphasic therapies on the market today have limited or no published out-of-hospital clinical data. Philips success across such a broad patient population is due in part to its real-time impedance-compensation technology, which automatical y optimizes every shock to deliver personalized therapy to each patient starting with the first shock. Key waveform design attributes may result in meaningful clinical dif erences among waveforms. Total delivered energy is a negative predictor of myocardial function and survival. Philips approach reduces the total energy delivered, which minimizes the risk of post-shock myocardial dysfunction. This means Philips can deliver its strongest shock from the outset, without the need to consider tradeof s with dysfunction. In addition, clinical data demonstrate that the sooner a shock is delivered after CPR, the higher the chances of shock success. Only Philips HeartStart AEDs and the MRx Monitor/Defibril ator in AED mode of er Quick Shock technology, which helps shorten time-to-shock after CPR and increase the chance a shock wil successful y return circulation, which may improve survival.
Philips SMART Biphasic therapy 1 Physicians' Desk Reference. 2008. 62nd Edition.
23 White RD, Blackwel TH, Russel JK, Jorgenson DB. Body weight does 2 American Heart Association Guidelines 2005 for Cardiopulmonary not af ect defibril ation, resuscitation or survival in patients with out-of- Resuscitation and Emergency Cardiovascular Care. Circulation. hospital biphasic waveform defibril ator. Critical Care Medicine. 2004; 32(9) Supplement: S387-S392. 3 European Resuscitation Council Guidelines 2005. Resuscitation. 2005; Vol 24 White RD, Blackwel TH, Russel JK, Snyder DE, Jorgenson DB. 67, Supplement 1.
Transthoracic impedance does not af ect defibril ation, resuscitation or 4 Dorian P, Wang MJ. Defibril ation and impedance are determinants of survival in patients with out-of-hospital cardiac arrest treated with defibril ation energy requirements. Pacing and Clinical Electrophysiology. a non-escalating biphasic waveform defibril ator. Resuscitation. 2005 Jan; 64(1):63-69.
5 Kerber RE, Martins JB, Kienzle MG, et al. Energy, current, and 25 Schneider T, Martens PR, Paschen H, et al. Multicenter, randomized, success in defibril ation and cardioversion: clinical studies using an control ed trial of 150-J biphasic shocks compared with 200- to 360-J automated impedance-based method of energy adjustment. Circulation. monophasic shocks in the resuscitation of out-of-hospital cardiac arrest victims. Circulation. 2000;102:1780-7 6 Measurements were made by discharging a standard Philips HeartStart 26 Hess EP, Russel JK, Liu PY, et al. A high peak current 150-J fixed-energy MRx ALS Monitor/Defibril ator and Physio-Control LIFEPAK® 20 defibril ation protocol treats recurrent ventricular fibril ation (VF) as defibril ator/monitor with pads into resistive load of 80 ohms. The effectively as initial VF. Resuscitation. 2008 Oct;79(1):28- 33.
measurement of Peak Voltage was made using a Tektronix P5210 HV 27 Cummins RO, et al. Guidelines 2000 for cardiopulmonary resuscitation Differential probe and Agilent MSO8104A oscil oscope, as measured and emergency cardiovascular care. Supplement to Circulation. 2000;102:I- directly across the resistive load. The voltages shown are the average of 28 van Alem AP, Chapman FW, Lank P, et al. A prospective, randomized and 7 Current levels were derived using the voltage levels from the stored blinded comparison of first shock success of monophasic and biphasic capacitance equation above and applying Ohm's Law V = IR; V = volts, waveforms in out-of-hospital cardiac arrest. Resuscitation. 2003;58:17-24.
I = current, R = resistance (patient impedance). An average patient 29 Stiel IG, Walker RG, Nesbitt LP, et al. BIPHASIC Trial: a randomized impedance of 80 ohms was used as R.
comparison of fixed lower versus escalating higher energy levels for 8 Niemann JT, Walker RG, Rosborough JP. Intracardiac voltage gradients defibril ation in out-of-hospital cardiac arrest. Circulation. 2007 Mar 27; during transthoracic defibril ation: Implications for post-shock myocardial injury. Academic Emergency Medicine. 2005;12(2).
30 Santomauro M, Borrel i A, Ottaviano L, et al. Transthoracic cardioversion 9 Gliner BE, Lyster TE, Dil ion SM, et al. Transthoracic defibril ation of in patients with atrial fibril ation: comparison of three dif erent waveforms. swine with monophasic and biphasic waveforms. Circulation 1995;92:1634- Italian Heart Journal. Suppl. 2004 Jan; 5(1 Suppl):36-43.
31 Page RL, Kerber RE, Russel JK, et al. Biphasic versus monophasic 10 Tang W, Weil MH, Sun S, et al. The effects of biphasic and conventional shock waveform for conversion of atrial fibril ation. The results of an monophasic defibril ation on post resuscitation myocardial function. international randomized, double-blind multicenter trial. Journal American College Cardiology. 1999;34(3):815-822. Journal American College of Cardiology. 2002;39:1956-1963. 11 Tang W, Weil MH, Sun S, et al. A comparison of biphasic and monophasic 32 Waveforms based on actual timing of a Philips HeartStart MRx Monitor/ waveform defibril ation after prolonged ventricular fibril ation. Chest. Defibril ator (M3535A).
33 Tang W, Weil MH, Sun S, et al. The effects of biphasic waveform design 12 Tang W, Weil MH, Jorgenson DB, et al. Fixed energy biphasic waveform on post-resuscitation myocardial function. Journal American College of defibril ation in a pediatric model of cardiac arrest and resuscitation. Critical Care Medicine. 2002;30(12):2736-2741.
34 Xie J, Weil MH, Sun S, et al. High-energy defibril ation increases the 13 Page RL, Joglar JA, Kowal RC, et al. Use of automated external severity of post resuscitation myocardial function. Circulation. 1997;96:683- defibril ators by a U.S. airline. New England Journal of Medicine. 2000;343:1210-1216. 35 Weaver WD, Cobb LA, Copass MK, et al. Ventricular defibril ation-A 14 Capucci A, Aschieri D, Piepoli MF, et al. Tripling survival from sudden comparative trial using 175J and 320J shocks. New England Journal of cardiac arrest via early defibril ation without traditional education in Medicine. 1982;307:1101-1106. 36 Cobb LA, Fahrenbruch CE, Walsh TR, et al. Influence of cardiopulmonary 15 White RD, Atkinson EJ. Patient outcomes fol owing defibril ation with a resuscitation prior to defibril ation in patients with out-of-hospital low energy biphasic truncated exponential waveform in out-of-hospital ventricular fibril ation. JAMA. 1999; 281(13):1182-1188.
cardiac arrest. Resuscitation. 2001;49:9-14. 37 Wik L, Hansen TB, Fyl ing F, et al. Delaying defibril ation to give basic 16 Gliner BE, Jorgenson DB, Poole JE, et al. Treatment of out-of-hospital cardiopulmonary resuscitation to patients with out-of-hospital ventricular cardiac arrest with a low-energy impedance-compensating biphasic fibril ation. JAMA. 2003; 289(11):1389-1395.
waveform automatic external defibril ation. Biomedical Instrumentation & 38 Yu T, Weil MH, Tang W, et al. Adverse outcomes of interrupted Technology. 1998;32:631-644. precordial compression during automated defibril ation. Circulation. 2002; 17 White RD, Russel JK. Refibril ation, resuscitation and survival in out-of- hospital sudden cardiac arrest victims treated with biphasic automated 39 Eftestol T, Sunde K, Steen PA. Ef ects of interrupting precordial external defibril ators. Resuscitation. 2002; 55(1):17-23. compressions on the calculated probability of defibril ation success during 18 Gliner BE, White RD. Electrocardiographic evaluation of defibril ation out-of-hospital cardiac arrest. Circulation. 2002;105:2270-2273.
shocks delivered to out-of-hospital sudden cardiac arrest patients. 40 Snyder D, Morgan C. Wide variation in cardiopulmonary resuscitation Resuscitation. 1999;41(2):133- 144. interruption intervals among commercial y available automated external 19 Poole JE, White RD, Kanz KG. et al. Low-energy impedance- defibril ators may af ect survival despite high defibril ation efficacy. Critical compensating biphasic waveforms terminate ventricular fibril ation at high Care Medicine. 2004;32(9 Suppl):S421-424.
rates in victims of out-of-hospital cardiac arrest. Journal of Cardiovascular 41 Edelson D, Abel a B, Kramer-Johansen J, et al. Ef ects of compression Electrophysiology. 1997;8:1373-1385. depth and pre-shock pauses predict defibril ation failure during cardiac 20 Caf rey SL, Wil oughby PJ, Pepe PF, et al. Public use of automated external arrest. Resuscitation. 2006;71(2):137-145. defibril ators. New England Journal of Medicine. * Ask your Philips sales rep for a research summary of this article.
21 Gurnett CA, Atkins DL. Successful use of a biphasic waveform automated Lipitor® is a registered trademark of Parke-Davis, A Division of external defibril ator in a high-risk child. American Journal Warner-Lambert Company LLC, A Pfizer Company.
of Cardiology. 2000;86:1051- 1053.
Crestor® is a registered trademark of AstraZeneca Pharmaceuticals LP.
22 Martens PR, Russel JK, Wolcke B, et al. Optimal response to cardiac Physio-Control® is a registered trademark of Physio-Control, Inc., arrest study: defibril ation waveform effects. a Division of Medtronic.
ZOLL® is a registered trademark of ZOLL Medical Corporation.
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