What is the recommended joule setting for three stacked shocks in a Cardiac Arrest Life Support (CALS) scenario?

Recommended Joule Settings for Three Stacked Shocks in CALS

For three stacked shocks in Cardiac Arrest Life Support (CALS), the recommended energy levels are 200 J, 200 J, and 360 J when using a monophasic defibrillator. 1

Energy Recommendations by Defibrillator Type

Monophasic Defibrillators

• Initial three-shock sequence should use 200 J, 200 J, and 360 J 2, 1
• Subsequent shocks after the initial three-shock sequence should continue at 360 J 2, 1
• If a coordinated rhythm appears briefly but then deteriorates, either continuing with 360 J or reverting to 200 J is acceptable 2, 1

Biphasic Defibrillators

• For biphasic truncated exponential (BTE) waveforms, use 150-200 J for initial shock 1
• For rectilinear biphasic (RLB) waveforms, use 120 J or greater for initial shock 1
• For subsequent biphasic shocks, either maintain the same energy level or increase it if possible 1

Implementation of Stacked Shocks

• Modern defibrillators have sufficiently short charging times to deliver three shocks within one minute 2
• Pulse checks should only be performed after a shock if the waveform changes to one compatible with cardiac output 2
• If ventricular fibrillation (VF) or ventricular tachycardia (VT) persists with identical waveform after the first shock, proceed immediately to the second shock without checking for a pulse 2, 1

Technical Considerations for Effective Defibrillation

• Proper paddle placement is crucial: one paddle below the right clavicle in the mid-clavicular line and the other over the lower left ribs in the mid-anterior axillary line 2
• Ensure adequate contact with the chest wall and proper use of conductive gel to maximize current delivery 2
• In female patients, place the second paddle firmly on the chest wall just outside the position of the normal cardiac apex, avoiding breast tissue 2

Evolution of Defibrillation Protocols

• It's important to note that modern guidelines have evolved from the three stacked shocks approach to a single shock strategy followed by immediate CPR resumption 2, 1
• This change was made to minimize interruptions to chest compressions and because of the greater efficacy of biphasic shocks (>90% first-shock success) 2
• The 2005 AHA guidelines marked this shift from the 3-shock sequence to a single shock protocol 2

Research Insights

• Studies show that impedance changes between consecutive shocks are minimal and inconsistent, which is why increasing energy settings is necessary for subsequent shocks 3
• First shock defibrillation failure often predicts low efficacy for subsequent shocks 3
• Some research suggests that stacked shock strategies may be superior to single shock strategies for successful defibrillation and better resuscitation outcomes in treating ventricular fibrillation 4
• Biphasic shocks at 200 J have demonstrated better first-shock defibrillation efficacy for short-duration VF than 200 J monophasic shocks 5

Potential Complications

• Myocardial injury, both functionally and morphologically, may increase with higher energy levels 2
• Repeated high-energy shocks may result in a higher incidence of atrioventricular block after defibrillation 6

While modern protocols have moved toward single shock strategies, the traditional three stacked shocks approach using 200 J, 200 J, and 360 J for monophasic defibrillators remains the historical standard when specifically implementing a three-shock protocol.