CPR AED Advanced 1 — Questions and Answers

Question 1: What is the main advantage of a biphasic waveform AED over older monophasic devices?

It delivers more total energy
It is more effective at lower energy levels, reducing myocardial damage (Correct answer)
It can shock asystole
It does not require electrode pads

Correct answer: It is more effective at lower energy levels, reducing myocardial damage

Biphasic AEDs are as effective or more effective at lower energies than monophasic devices, causing less myocardial damage.

Biphasic defibrillators deliver current that flows in one direction for a specified duration and then reverses direction for the remainder of the discharge. This allows effective defibrillation at significantly lower energy levels (120-200 joules) compared to monophasic devices (360 joules). The lower energy requirements reduce myocardial injury while maintaining equivalent or superior defibrillation efficacy. Biphasic truncated exponential (BTE) and rectilinear biphasic (RLB) are the two most common waveforms. Modern AEDs and defibrillators are almost exclusively biphasic, though monophasic devices are still found in some older hospital and EMS settings.

Question 2: When should pediatric AED electrode pads or attenuation keys be used?

For all patients under 18 years old
For children aged 1-8 years (or under 25 kg) when available (Correct answer)
Only for infants under 6 months old
Pediatric pads are not necessary; adult pads can always be used

Correct answer: For children aged 1-8 years (or under 25 kg) when available

Pediatric pads or attenuation keys should be used for children under 8 years or under 25 kg when available, as they reduce delivered energy to safe levels.

Pediatric AED attenuator systems (special pads or adapters) reduce the energy delivered by the AED to approximately 50-75 joules, which is appropriate for children aged 1-8 years or weighing less than 25 kg. Adult electrode pads and energy levels (150-360 joules) may cause myocardial injury in small children. For infants under 1 year, manual defibrillation with a manual defibrillator is preferred, but if an AED is the only available device, it can be used with pediatric attenuators (or adult pads as a last resort). For children over 8 years or >25 kg, adult AED pads and energy can be used.

Question 3: What is the correct anteroposterior (front-to-back) electrode pad placement for AED use?

One pad on the right upper chest, one pad on the left lower chest
One pad on the front center of the chest, one pad on the back between the shoulder blades (Correct answer)
Both pads on the anterior chest wall
One pad on the right lower chest, one on the left upper chest

Correct answer: One pad on the front center of the chest, one pad on the back between the shoulder blades

Anteroposterior placement puts one pad on the front center of the chest and one on the back, which is used in special situations like a pacemaker or breast tissue.

The standard AED electrode placement is anterior-lateral: one pad on the right upper chest below the clavicle, and one on the left lateral chest below the armpit. The anteroposterior (AP) placement—one pad on the front left side of the chest over the precordium and one on the back to the left of the spine—is an acceptable alternative used when standard placement is contraindicated (e.g., implanted pacemaker/ICD in the right chest) or when the patient is very thin. Both placements allow effective defibrillation by ensuring the electrical vector passes through the cardiac muscle mass. Pads should never touch each other.

Question 4: What should be done if a patient has a hairy chest when applying AED electrode pads?

Apply pads directly over the hair without concern
Firmly press and rip off the first set of pads to remove hair, then apply a new set (Correct answer)
Wet the chest to improve conductivity
Use gel to compensate for poor contact

Correct answer: Firmly press and rip off the first set of pads to remove hair, then apply a new set

Pressing and removing the first set of pads removes chest hair, allowing the second set to adhere properly and deliver current effectively.

Excessive chest hair prevents proper adhesion of AED electrode pads and creates resistance that may cause arcing and skin burns during shock delivery, while reducing the energy reaching the myocardium. If a razor is available, quickly shave the pad placement area. If no razor is available, apply the first set of pads firmly and quickly remove them—this removes the hair in that area like a wax strip. Then apply fresh pads to the now-hair-free skin. Most AED kits include a razor or shaving prep materials for this purpose. The entire process should be completed as quickly as possible to minimize time to defibrillation.

Question 5: What is the significance of an AED's rhythm analysis algorithm in the context of shock delivery?

It can identify all cardiac rhythms and recommend treatment
It detects VF and pVT patterns and advises shock, while detecting non-shockable rhythms and advising no shock (Correct answer)
It delivers multiple shocks automatically without user input
It monitors the patient's blood pressure to determine shock timing

Correct answer: It detects VF and pVT patterns and advises shock, while detecting non-shockable rhythms and advising no shock

AED algorithms analyze the ECG signal to identify shockable (VF/pVT) vs. non-shockable (asystole/PEA) rhythms and advise the rescuer accordingly.

AED rhythm analysis algorithms use sophisticated pattern recognition to analyze the electrical waveform characteristics of the cardiac rhythm and differentiate shockable from non-shockable rhythms. VF is identified by chaotic, irregular waves with no discernible pattern, while pVT is identified by rapid, repetitive, wide complexes. The algorithm has high sensitivity (ability to detect shockable rhythms) and specificity (ability to correctly identify non-shockable rhythms). Motion artifact can interfere with analysis—rescuers must stop CPR and ensure no one is touching the patient during analysis. The device then advises shock or no shock, but the rescuer is responsible for pressing the shock button.

Question 6: A patient is found to have an implanted cardioverter-defibrillator (ICD). How does this affect AED pad placement?

An ICD means an AED should never be used on the patient
Place AED pads at least 1 inch away from the ICD device and in a standard or alternate position (Correct answer)
Place one pad directly over the ICD to synchronize shock delivery
Remove the ICD before applying AED pads

Correct answer: Place AED pads at least 1 inch away from the ICD device and in a standard or alternate position

AED pads should be placed at least 1 inch (2.5 cm) away from an ICD or pacemaker to avoid device damage and ensure effective shock delivery.

Implanted cardiac devices (pacemakers and ICDs) can interfere with AED shock delivery and be damaged if an AED pad is placed directly over them. The implanted device is typically located in the upper chest, usually under the left or right clavicle, and creates a visible bulge under the skin. AED pads should be placed at least 1 inch (2.5 cm) from the device. If standard pad placement would overlap the device, use anteroposterior placement instead. The AED should still be used if the patient is in cardiac arrest—the benefits far outweigh the small risk of device damage. An ICD may also deliver internal shocks, which are safe for rescuers to feel.

Question 7: What should a rescuer do if the patient is lying in water when using an AED?

Apply pads and shock immediately while in water
Move the patient to a dry surface before applying pads and using the AED (Correct answer)
Use the AED in water only if both rescuers are wearing rubber gloves
Delay AED use until the patient is completely dry

Correct answer: Move the patient to a dry surface before applying pads and using the AED

The patient must be moved from standing water to a dry surface before AED use to prevent current conduction through water to rescuers and to ensure effective shock delivery.

Water on the chest can conduct electricity across the chest surface rather than through the myocardium, reducing shock effectiveness. Standing water also poses a serious electrocution risk to the rescuer. If the patient is in water, quickly move them to a dry surface before applying AED pads. If the chest is wet, dry it quickly before applying pads. Sweat alone is generally not enough to impair AED function significantly. If the patient is on snow or ice, the AED can still be used—the main concern is standing water that would bridge the two electrode pads electrically. Never delay defibrillation unnecessarily, but a few seconds to move from water is warranted.

Question 8: In an automated external defibrillator with a 'manual override' feature, when might a trained healthcare provider choose to use this mode?

To shock any rhythm including non-shockable ones
To perform synchronized cardioversion for a patient with a pulse in an unstable tachyarrhythmia (Correct answer)
To bypass the charging phase and shock faster
To reduce shock energy below manufacturer settings

Correct answer: To perform synchronized cardioversion for a patient with a pulse in an unstable tachyarrhythmia

Manual override enables synchronized cardioversion for unstable tachyarrhythmias in patients with a pulse, where unsynchronized shock risks causing VF.

Some AEDs and semi-automated defibrillators have a manual override mode that allows trained healthcare providers to use the device like a manual defibrillator. This mode enables synchronized cardioversion—delivering a shock timed to the R-wave of the QRS complex—for hemodynamically unstable patients with a pulse in tachyarrhythmias like atrial fibrillation, atrial flutter, SVT, or stable VT that are not responding to medication. Unsynchronized shock in a patient with a pulse risks delivering the shock during the vulnerable period (T-wave), potentially inducing VF. Manual mode also allows the provider to select energy levels and deliver defibrillation without waiting for the algorithm.

Question 9: What is the recommended energy for the first defibrillation attempt with a biphasic AED when treating adult VF/pVT?

50-100 joules
120-200 joules (manufacturer specified) or 200 joules if unknown (Correct answer)
300 joules
360 joules

Correct answer: 120-200 joules (manufacturer specified) or 200 joules if unknown

Biphasic AEDs should use the manufacturer's recommended energy (120-200 J); if unknown, use 200 J for the first shock.

Biphasic AEDs are programmed to deliver their manufacturer-specified optimal energy for defibrillation, typically between 120-200 joules. If the rescuer is using a device where the optimal energy is not known, 200 joules is recommended for the initial shock. For subsequent shocks, the same or higher energy may be used. For monophasic defibrillators (older equipment), 360 joules should be used for all shocks. Studies have demonstrated that first-shock efficacy for terminating VF with biphasic devices is 85-94%, compared to approximately 60% with monophasic devices. After each unsuccessful shock, CPR should be immediately resumed without interruption.

Question 10: How often should AED electrode pads be replaced in a maintenance program?

Every 6 months regardless of use
According to manufacturer's expiration date, typically every 2-5 years (Correct answer)
Only when they appear damaged
Every year without exception

Correct answer: According to manufacturer's expiration date, typically every 2-5 years

AED pads should be replaced according to the manufacturer's expiration date (typically 2-5 years) and after each use.

AED electrode pads have a gel layer that can dry out over time, reducing adhesion and conductivity. Manufacturers specify expiration dates (typically 2-5 years for sealed pads) that must be respected. Pads must also be replaced after every use since they cannot be re-used. Regular AED maintenance checks should include verifying pad expiration dates, ensuring pads are properly sealed in their packaging (to prevent gel desiccation), checking battery charge/expiration, and verifying device readiness indicators (ready light or similar). AED maintenance logs should be kept to document checks. Most AEDs include self-testing features that indicate when pads or batteries need replacement.

Question 11: What is a 'waveform analysis artifact' in the context of AED use during CPR?

An additional shock delivered by the AED without prompting
Electrical interference from CPR compressions that can confuse the AED's rhythm analysis (Correct answer)
A display on the AED showing the patient's ECG continuously
A safety warning when pads are improperly placed

Correct answer: Electrical interference from CPR compressions that can confuse the AED's rhythm analysis

Motion artifact from chest compressions creates electrical noise that can confuse AED algorithms, which is why compressions must pause during analysis.

Waveform analysis artifact (also called CPR artifact) occurs when the mechanical motion from chest compressions, patient movement, or electrical interference from resuscitation equipment creates noise in the ECG signal that can confuse the AED's analysis algorithm. This is why all rescuers must stop touching the patient and no movement should occur during AED rhythm analysis. Research is ongoing to develop 'CPR-on' analysis systems that can filter out compression artifact and analyze rhythm during ongoing compressions, which would eliminate the need for analysis pauses. Some advanced defibrillators have this capability, but most AEDs still require a hands-off period for analysis.

Question 12: For which of the following situations is AED use contraindicated or should be used with caution?

In a patient with dentures
In a patient with a transdermal medication patch in the pad placement area (Correct answer)
In a patient with a pacemaker in the abdomen
In a child over 8 years of age

Correct answer: In a patient with a transdermal medication patch in the pad placement area

Transdermal medication patches should be removed and wiped clean before AED pad placement, as patches can cause arcing, burns, and reduce shock effectiveness.

Transdermal medication patches (nitroglycerin, nicotine, analgesics, hormones) must be removed before placing AED electrode pads. If a pad is placed over a patch, the current can cause burns, arcing between the patch and pad, and the patch may absorb some of the shock energy, reducing its effectiveness. The patch area should be wiped clean after removal. This applies to any medication patch or thick gel product in the pad placement area. Dentures do not interfere with AED use and are generally left in place (they help maintain a mask seal for ventilations). Pacemakers and ICDs require pad relocation, not AED avoidance.

Question 13: What is the purpose of the 'analyze' phase in AED operation?

To deliver a test shock to determine proper pad placement
To analyze the patient's heart rhythm and determine whether a shock is indicated (Correct answer)
To calculate the patient's blood pressure and oxygen saturation
To notify the emergency medical services automatically

Correct answer: To analyze the patient's heart rhythm and determine whether a shock is indicated

The analyze phase uses the AED's algorithm to evaluate the cardiac rhythm and determine whether defibrillation (shock) is indicated.

During the analyze phase, the AED samples and evaluates the electrical signal from the electrode pads over several seconds (typically 5-13 seconds depending on the device). The algorithm processes the signal to identify characteristics of the cardiac rhythm—specifically looking for patterns consistent with VF or pVT (shockable rhythms) versus organized rhythms or asystole (non-shockable). The analysis must occur without motion artifact—all rescuers must stop compressions and avoid touching the patient. If the AED determines a shockable rhythm, it charges the capacitor and advises shock delivery. If non-shockable, it advises 'no shock indicated' and prompts CPR resumption.

Question 14: What is 'defibrillation threshold' (DFT) and its clinical significance?

The minimum energy level at which defibrillation is reliably successful for a given patient (Correct answer)
The maximum energy an AED is allowed to deliver
The time between shocks in a multi-shock protocol
The depth of compressions required before using an AED

Correct answer: The minimum energy level at which defibrillation is reliably successful for a given patient

Defibrillation threshold is the minimum energy needed to successfully terminate VF/pVT for a given patient, which varies among individuals.

The defibrillation threshold (DFT) is the minimum energy level at which defibrillation can be reliably achieved in a given patient and is typically measured in joules. DFT varies significantly among patients due to differences in body size, chest impedance, metabolic state, and other factors. Clinically, this is why some patients require multiple shocks or escalating energy levels for successful defibrillation. In ICD implantation, DFT testing was historically performed to ensure the device could reliably defibrillate the patient. High DFT is a risk factor for ICD failure and may require device programming adjustments or drug therapy (e.g., amiodarone can lower DFT). AEDs use algorithms that consider impedance to optimize delivered energy.

Question 15: How does transthoracic impedance affect AED shock delivery, and how do modern AEDs compensate?

Higher impedance increases shock effectiveness; AEDs decrease energy in high-impedance patients
Higher impedance reduces current flow to the heart; biphasic AEDs adjust waveform characteristics to compensate (Correct answer)
Impedance has no effect on shock delivery
AEDs always deliver fixed energy regardless of impedance

Correct answer: Higher impedance reduces current flow to the heart; biphasic AEDs adjust waveform characteristics to compensate

Biphasic AEDs measure transthoracic impedance and automatically adjust shock waveform characteristics to maintain effective current delivery despite variation.

Transthoracic impedance (the electrical resistance of the chest wall, lungs, and cardiac tissue) varies significantly between patients (typical range: 25-180 ohms). High impedance reduces the amount of current that reaches the myocardium, potentially resulting in an ineffective shock. Modern biphasic AEDs use impedance compensation—they measure chest impedance through the pads before and during shock delivery and automatically adjust the waveform shape, duration, and characteristics to maintain optimal current delivery across the range of impedance values. This makes biphasic AEDs more reliable across diverse patient populations. Factors that affect impedance include chest size, lung inflation, pad contact quality, and the time since last shock.

Question 16: What should a rescuer do while the AED is charging in preparation for a shock?

Continue chest compressions until the shock is ready, then clear (Correct answer)
Stop CPR and wait for the AED to charge before doing anything
Deliver rescue breaths only while waiting
Begin calling family members to notify them

Correct answer: Continue chest compressions until the shock is ready, then clear

Continue compressions while the AED charges to minimize the pre-shock pause, then clear just before the shock is delivered.

The peri-shock pause (total pause in compressions from before the shock to after the shock) is a major determinant of defibrillation success. To minimize pre-shock pauses, high-performing teams continue CPR while the AED charges, stopping compressions only in the moment before the shock is delivered (clearing the patient). This can reduce the pre-shock pause from a typical 5-10 seconds to 2-3 seconds. The shock should be delivered as quickly as possible after stopping compressions. Immediately after the shock, compressions should resume without waiting for a rhythm check. This 'charge and continue' strategy requires practice and teamwork but significantly improves outcomes.

Question 17: What are the two main types of electrode placement for AED use?

Anterior-posterior (AP) and anterior-lateral (AL) (Correct answer)
Bilateral anterior and bilateral posterior
Right chest only and left chest only
Upper chest bilateral

Correct answer: Anterior-posterior (AP) and anterior-lateral (AL)

Anterior-lateral (standard) and anterior-posterior (alternative) placements are the two main configurations for AED pads.

The two main electrode pad configurations for AED use are: (1) Anterior-lateral (AL): one pad on the right upper chest below the clavicle (sternal position) and one on the left lateral chest below the armpit (apex position). This is the standard, most commonly used placement and is pre-marked on AED pads with diagrams. (2) Anterior-posterior (AP): one pad on the left anterior chest (precordium) and one on the posterior chest to the left of the spine. This is used when the standard placement is unsuitable (e.g., implanted device in the right chest) or in some pediatric situations. Both placements are considered equally effective by current evidence.

Question 18: What is the role of an AED's 'ready' indicator or status display?

It shows the patient's heart rate in real time
It indicates that the AED is in working order and ready for use (battery and pads are functional) (Correct answer)
It counts down to the next scheduled shock
It monitors the rescuer's compression rate

Correct answer: It indicates that the AED is in working order and ready for use (battery and pads are functional)

The ready indicator confirms the AED is functional and ready for deployment—battery is charged and pads/accessories are present and connected.

AED ready indicators (typically a green light, checkmark display, or 'ready' text) confirm that the device has completed its automated self-test and is prepared for use. Most AEDs perform daily or periodic self-tests that check battery charge level, pad connection (if pre-connected), internal circuitry, and software integrity. A steady ready indicator means the device is functional; a flashing or absent indicator signals a problem requiring attention. Regular visual inspection of the ready indicator is the most basic element of an AED maintenance program. Rescuers should check the indicator before every scheduled inspection and immediately report any failure signals to the appropriate maintenance personnel.

Question 19: Following unsuccessful defibrillation of VF, what is the correct post-shock action?

Increase energy and immediately shock again
Immediately resume CPR starting with chest compressions for 2 minutes (Correct answer)
Check the pulse before resuming CPR
Apply additional pads to improve conductivity

Correct answer: Immediately resume CPR starting with chest compressions for 2 minutes

After any shock (successful or not), immediately resume CPR starting with chest compressions for 2 minutes before re-analyzing rhythm.

Regardless of whether defibrillation appeared successful, CPR should be immediately resumed starting with compressions after every shock delivery. This is because even if defibrillation terminates VF, the heart typically needs time to generate an effective coordinated contraction and perfusing rhythm. Immediately after defibrillation, the myocardium is stunned and requires ongoing perfusion support from CPR. A pulse check should NOT be performed immediately post-shock as it delays compressions and is unreliable in the immediate post-shock period. After 2 minutes of CPR, the AED will analyze again and the team may check the pulse at that time. Minimizing the post-shock pause is as important as minimizing the pre-shock pause.

Question 20: What information should be documented when an AED is used in a cardiac arrest event?

Only the final outcome (survived or died)
Time of collapse, time of CPR start, time of AED use, number of shocks, energy used, and patient outcome (Correct answer)
The brand name of the AED used
The names of all bystanders present

Correct answer: Time of collapse, time of CPR start, time of AED use, number of shocks, energy used, and patient outcome

Comprehensive documentation of all resuscitation timelines, interventions, and outcomes is required for quality improvement and legal purposes.

Documentation of an AED-assisted cardiac arrest should be thorough and include: (1) Time of patient collapse or last known normal, (2) Time bystander CPR started, (3) Time AED was applied and first analysis performed, (4) Time and number of shocks delivered with energy levels, (5) Time advanced life support arrived, (6) Medications administered (if applicable), (7) ROSC time if achieved, (8) Patient disposition and outcome. Many modern AEDs automatically record event data, ECG strips, and timestamps that can be downloaded for quality review. This data is critical for quality improvement programs (like cardiac arrest registries) and may be required for legal documentation.

Question 21: What is the purpose of 'AED feedback technology' integrated into newer AED models?

To automatically adjust shock energy based on rhythm detection
To provide real-time audio or visual cues to guide rescuers on compression rate, depth, and technique (Correct answer)
To communicate with hospital dispatch systems
To measure the patient's blood pressure between compressions

Correct answer: To provide real-time audio or visual cues to guide rescuers on compression rate, depth, and technique

AED feedback technology provides real-time guidance on compression rate, depth, and other CPR quality metrics to improve rescuer performance.

Modern AEDs and defibrillators increasingly incorporate CPR feedback technology using accelerometers and force sensors in the pads or a separate sensor placed on the chest. These devices measure compression rate, depth, recoil, and fraction in real time, providing audio and visual feedback such as 'push harder,' 'push faster,' or metronome tones for rate guidance. Studies demonstrate that CPR feedback significantly improves compression quality among both trained and untrained rescuers. Some devices integrate with hospital quality dashboards to provide post-event reports. The AHA recommends using CPR feedback devices when available to maintain high-quality compressions throughout resuscitation.

Question 22: How should an AED be applied to a patient with a large amount of water on their chest?

Apply pads directly; water does not affect AED function
Quickly dry the chest area where pads will be placed, then apply pads (Correct answer)
Submerge the AED pads in water to improve conductivity
Delay AED use until the patient is transported to a dry facility

Correct answer: Quickly dry the chest area where pads will be placed, then apply pads

The chest must be dried quickly before pad application to ensure adequate adhesion and prevent current from traveling across the wet skin surface.

Water on the chest creates several problems for AED use: (1) Poor pad adhesion, leading to a high-impedance connection and potential arc burns, (2) Electrical current may preferentially follow the water film across the chest surface rather than passing through the myocardium, reducing shock effectiveness, (3) Risk of electrical shock to rescuers if they are in contact with the water. The chest should be quickly dried with a towel or clothing before applying pads—this takes only seconds and significantly improves shock effectiveness. The AED should not be used until the patient is out of standing water, but brief drying of the chest is appropriate and should not cause undue delay in defibrillation.

Question 23: What is the clinical significance of 'first-shock success rate' for AED/defibrillator performance?

It measures how fast the AED charges
It indicates the percentage of VF/pVT episodes terminated by the first shock, with higher rates correlating with better patient outcomes (Correct answer)
It measures how many patients survive to hospital discharge
It reflects the AED's battery life under normal usage

Correct answer: It indicates the percentage of VF/pVT episodes terminated by the first shock, with higher rates correlating with better patient outcomes

First-shock success rate reflects defibrillation efficacy; higher first-shock success rates are associated with improved ROSC rates and survival.

First-shock efficacy (the percentage of VF/pVT episodes that are successfully terminated by the first shock) is a key performance metric for defibrillators. Biphasic devices achieve first-shock success rates of 85-94% for VF, compared to 60% for monophasic devices. Every unsuccessful shock requires additional CPR time before the next analysis, increasing the total duration of cardiac arrest. Studies show that early defibrillation (especially within 3-5 minutes of witnessed VF onset) combined with high first-shock efficacy are among the strongest predictors of survival with good neurological outcome. This underscores the importance of both rapid AED deployment and using optimal defibrillation technology.

Question 24: What does a fully automated external defibrillator (FAED) do differently from a standard semi-automated AED?

It delivers a higher energy shock
It automatically delivers the shock without requiring the rescuer to press a shock button (Correct answer)
It can be used on infants only
It connects to hospital systems automatically

Correct answer: It automatically delivers the shock without requiring the rescuer to press a shock button

A fully automated AED delivers the shock automatically after analysis without requiring the operator to press a button, reducing potential operator hesitation.

Fully automated external defibrillators (FAEDs) analyze the rhythm and, if a shockable rhythm is detected, charge and deliver the shock automatically without requiring the operator to press a shock button. This reduces the chance of operator hesitation delaying defibrillation and may be particularly beneficial in lay-responder settings where individuals may be reluctant to press the shock button. Standard semi-automated AEDs require the operator to press a shock button after the device advises 'shock indicated.' In both types, the rescuer must ensure no one is touching the patient before shock delivery. FAEDs are increasingly used in public-access defibrillation programs.

Question 25: What is the recommended approach if an AED is applied and the rhythm is analyzed as 'asystole' (flat line)?

Deliver a shock to attempt to restart the heart
Resume CPR immediately and search for reversible causes (Correct answer)
Turn off the AED and wait for advanced help
Deliver three rapid shocks in succession

Correct answer: Resume CPR immediately and search for reversible causes

Asystole is not shockable; immediate CPR resumption with identification and treatment of reversible causes (H's and T's) is the appropriate response.

Asystole represents a complete absence of cardiac electrical activity and is not a shockable rhythm. Defibrillation has no therapeutic value in asystole because there is no disorganized electrical activity to terminate. When asystole is identified, CPR should be resumed immediately with high-quality chest compressions while the team systematically evaluates for reversible causes (H's: hypovolemia, hypoxia, acidosis, electrolyte imbalance, hypothermia; T's: tension pneumothorax, tamponade, toxins, thrombosis). Epinephrine 1 mg IV/IO every 3-5 minutes is the only recommended medication. Survival from asystole is poor, particularly without an identified reversible cause.

Question 26: In public access defibrillation (PAD) programs, what is the target time from collapse to first shock?

Within 10 minutes
Within 3-5 minutes (Correct answer)
Within 1 minute
Within 8 minutes

Correct answer: Within 3-5 minutes

PAD programs aim to deliver the first shock within 3-5 minutes of collapse, with each minute of delay reducing survival rates by 7-10%.

For witnessed VF cardiac arrest, survival rates decrease by approximately 7-10% for every minute without defibrillation. Public access defibrillation (PAD) programs strategically place AEDs in high-traffic locations to enable defibrillation within 3-5 minutes of collapse, before EMS arrives. Studies in airports, casinos, and other public venues have demonstrated survival rates exceeding 50% when AEDs are used within 3-5 minutes. Dispatcher-assisted CPR and bystander AED use are critical components of PAD programs. AED placement should prioritize locations where a cardiac arrest is likely within 5 years and where EMS response time exceeds 5 minutes.

Question 27: What safety precaution must always be taken immediately before delivering an AED shock?

Apply oxygen at high flow
Ensure no one is touching the patient by loudly announcing 'Clear!' and visually confirming all are clear (Correct answer)
Verify the patient's identity and next of kin
Check the patient's blood pressure

Correct answer: Ensure no one is touching the patient by loudly announcing 'Clear!' and visually confirming all are clear

Before shock delivery, announce 'Clear!' and visually confirm no one is in contact with the patient to prevent accidental electrocution.

Before delivering any defibrillation shock, the rescuer operating the AED must: (1) Loudly announce 'Clear!' (or 'Shocking in 3-2-1, clear!'), (2) Visually scan the patient from head to toe to ensure no one is touching the patient or conductive surfaces (metal stretcher rails, wet floors), (3) Visually confirm their own hands and body are clear of the patient, (4) Deliver the shock. Direct contact with the patient during shock delivery can cause the electrical current to pass through the bystander's heart, potentially inducing VF. This safety check must be performed every time, including in highly trained teams, to prevent accidental harm to rescuers.

Question 28: What type of cardiac arrest rhythms are specifically targeted by AEDs for shock delivery?

Atrial fibrillation and atrial flutter
Ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT) (Correct answer)
Asystole and PEA
Sinus tachycardia and SVT

Correct answer: Ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT)

AEDs are designed to detect and treat only ventricular fibrillation and pulseless ventricular tachycardia—both shockable arrest rhythms.

AEDs are specifically designed and programmed to detect and treat two shockable cardiac arrest rhythms: ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT). VF produces chaotic, disorganized electrical activity with no organized contractions, while pVT produces rapid, organized ventricular complexes too fast for effective cardiac output. Both lack a palpable pulse. AED algorithms are trained on thousands of rhythm examples to achieve high sensitivity and specificity for these patterns. Other rhythms—atrial fibrillation, asystole, PEA, sinus rhythms—will not trigger an AED shock recommendation. Synchronized cardioversion (for patients with a pulse) requires manual override mode, not the standard AED function.

Question 29: What is the recommended first step when encountering a person in apparent cardiac arrest who has an AED already attached?

Remove the AED and reposition pads
Turn on or follow the AED's prompts, and resume CPR if the device prompts you to do so (Correct answer)
Immediately deliver a shock regardless of the AED's status
Wait for EMS to arrive before touching the patient

Correct answer: Turn on or follow the AED's prompts, and resume CPR if the device prompts you to do so

Follow the AED's prompts and resume CPR as indicated—if pads are already in place, the AED may be mid-cycle and you should take over according to its guidance.

If you arrive to find a patient in cardiac arrest with an AED already applied, the appropriate approach is to: (1) Ensure the AED is turned on and follow its voice and visual prompts, (2) Take over chest compressions if someone is not currently performing them, (3) Coordinate with the AED's rhythm analysis cycle—resume CPR as the device directs, and (4) Clear the patient for shock delivery as prompted. If the pads appear properly placed and adherent, there is no need to remove and reapply them. Assess pad placement visually for any obvious issues. The AED's guidance system is designed to work with incoming rescuers and will walk through the entire algorithm.

Question 30: What does 'AED electrode impedance check' mean during device self-test?

The AED measures battery voltage
The device checks electrical resistance through the pads to ensure proper pad-to-skin contact and circuit integrity (Correct answer)
The AED tests its shock delivery mechanism with a dummy load
The device checks for radio frequency interference

Correct answer: The device checks electrical resistance through the pads to ensure proper pad-to-skin contact and circuit integrity

Self-test impedance checks verify the electrical circuit between pads and the device is intact and ready for use.

Modern AEDs perform periodic automated self-tests that include an impedance check—measuring the electrical resistance through the connected electrode circuit. If the pads are properly stored (sealed packaging preserving gel moisture) and connected, impedance falls within normal range, confirming circuit integrity. Elevated impedance may indicate dry or expired pads, a loose connector, or damaged leads, triggering a service alert. This self-test ensures the device can deliver an effective shock when needed. Most AEDs display a ready indicator (green light or check mark) when all self-tests pass, including the impedance check.

Question 31: What is the maximum recommended interval between CPR and defibrillation during resuscitation?

30 seconds
No CPR is needed before shock
10 seconds—compressions should continue until the last possible moment before shock (Correct answer)
5 minutes of CPR always before shock

Correct answer: 10 seconds—compressions should continue until the last possible moment before shock

The hands-off period before shock should be ≤10 seconds; the compressor continues until the AED is charged and ready.

The peri-shock pause—the total time from stopping compressions to restarting them after a shock—should be minimized to under 10 seconds. Continuing compressions while the AED charges, then pausing only for the 2-3 seconds needed to clear the patient and press shock, achieves pre-shock pauses of 3-5 seconds. Immediately after the shock, compressions must resume without a pulse check. Studies show each 5-second increase in pre-shock pause reduces defibrillation success by about 18%. High-performing teams practice 'charge-and-continue CPR' to minimize this pause.

Question 32: In an AED-equipped workplace, who bears responsibility for ensuring the AED is maintained and ready for use?

The device manufacturer is solely responsible
The designated AED program coordinator and the organization deploying the device (Correct answer)
Only certified EMTs on staff
The nearest hospital's emergency department

Correct answer: The designated AED program coordinator and the organization deploying the device

Organizations deploying AEDs must designate a coordinator responsible for maintenance, training, and regulatory compliance.

Workplace AED programs require formal management including: a designated AED program coordinator (typically a safety officer or nurse manager), a maintenance schedule (regular inspection of battery, pads, and device status), documentation of monthly/quarterly checks, staff training records, a medical director to provide physician oversight and a standing order, and post-use protocols including event review and restocking. Regulatory requirements vary by jurisdiction—many states mandate AED programs in specific venues (schools, gyms, government buildings). Failure to maintain a deployed AED (e.g., expired pads, dead battery) creates legal liability if the device fails to function during a real arrest.

Question 33: What is the purpose of the AED's 'CPR coaching' audio prompts?

They provide legal documentation of the resuscitation
They guide untrained bystanders through compression rate, depth cues, and breath delivery in real time (Correct answer)
They transmit data to the hospital
They record the victim's vital signs

Correct answer: They guide untrained bystanders through compression rate, depth cues, and breath delivery in real time

CPR coaching audio prompts guide lay rescuers through the steps of CPR with timed cues for compressions and ventilations.

Most modern AEDs include built-in CPR coaching that provides step-by-step audio guidance: instructions to start compressions, metronome tones (typically at 100-110 bpm) to guide rate, prompts to 'push harder' if a feedback sensor detects shallow compressions, countdown to ventilations, and instructions to clear the patient during analysis. This coaching was specifically designed to support untrained bystanders who may never have performed CPR, dramatically lowering the barrier to effective response. Studies show that AED coaching increases bystander CPR rates and improves compression quality in lay users. The coaching system also helps trained responders maintain proper pacing, especially when fatigued.

Question 34: What is the role of 'hands-free' defibrillation pads compared to hand-held paddles in AED use?

Paddles deliver a stronger shock than hands-free pads
Hands-free pads allow the operator to stand clear of the patient without maintaining physical contact, enabling safer shock delivery and continuous CPR between shocks (Correct answer)
Paddles are more accurate for rhythm analysis
Hands-free pads cannot deliver shocks, only monitor rhythm

Correct answer: Hands-free pads allow the operator to stand clear of the patient without maintaining physical contact, enabling safer shock delivery and continuous CPR between shocks

Hands-free adhesive pads eliminate the need for direct patient contact during analysis and shock, improving safety and enabling continued CPR up to the moment of shock.

All modern AEDs and most defibrillators use self-adhesive hands-free electrode pads rather than hand-held paddles. Advantages of hands-free pads: (1) The operator does not need to maintain contact with the patient during analysis or shock delivery, reducing the risk of accidental shock to the rescuer, (2) Pads can remain attached throughout resuscitation, enabling rapid cycling between CPR and shock without repositioning electrodes, (3) Continuous ECG monitoring between shocks, (4) Automatic impedance compensation, (5) Enables one rescuer to manage defibrillation while another continues CPR. Gel-coated paddles required the operator to hold them firmly against the chest during discharge, creating electrocution risk and requiring two-handed operation by a trained provider.

Question 35: What determines whether an AED rhythm analysis result is reliable and should be acted upon?

The time of day and environmental temperature
The quality of electrode contact, absence of motion artifact, and proper placement of pads on a dry chest (Correct answer)
The brand of AED being used
The patient's age and weight entered into the device

Correct answer: The quality of electrode contact, absence of motion artifact, and proper placement of pads on a dry chest

Reliable rhythm analysis requires good pad contact, no motion artifact, and proper placement—any of these issues can cause false results.

AED rhythm analysis reliability depends on: (1) Electrode-to-skin contact quality—proper adhesion with sufficient gel contact ensures the signal is not distorted by high impedance or air gaps, (2) Absence of motion artifact—all movement (CPR, patient movement, vehicle motion) must cease during analysis, (3) Correct pad placement—pads in non-standard positions may produce atypical waveforms the algorithm was not trained to interpret, (4) Absence of electromagnetic interference from nearby equipment. If analysis seems inconsistent with the clinical situation (e.g., AED says 'no shock' in witnessed collapse with no pulse), reassess pad placement, ensure no motion, and re-analyze. Trust clinical assessment over device prompts when there is clear discordance.

Question 36: What is the recommended response when an AED's ready indicator is not illuminated or shows an error?

Use the device anyway—the indicator may be malfunctioning
Do not use the device; report the malfunction, retrieve a backup AED if available, and begin manual CPR (Correct answer)
Shake the device to reset it
Replace only the battery and immediately use the AED

Correct answer: Do not use the device; report the malfunction, retrieve a backup AED if available, and begin manual CPR

A failed AED should not be used—begin CPR, retrieve a backup device, and report the malfunction immediately.

If an AED's ready indicator is not illuminated, shows an error message, or the device fails to turn on, the device should not be used in a cardiac arrest as it may not function properly. Immediate actions: (1) Begin or continue manual CPR, (2) Call for a backup AED from another location, (3) Follow the AED's error instructions if displayed—some errors (e.g., battery low) may still allow limited function, but this should not delay getting a functional backup, (4) Report the malfunction to the AED program coordinator for immediate repair or replacement, (5) Document the malfunction. This underscores the importance of regular AED maintenance checks—discovering a failed device during an arrest is preventable with routine monthly inspections and daily visual checks of the ready indicator.

CPR AED Advanced 1

What is the main advantage of a biphasic waveform AED over older monophasic devices?

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