chapter 29 - brands delmar - cengage learning 29 cardiac arrest key terms all clear artificial...

C H A P T E R 29

Cardiac Arrest

KEY TERMSall clear

artificial pacemaker

asystole

automated externaldefibrillator (AED)

automatic implantablecardioverter/defibrillator(AICD)

automaticity

cardiac standstill

chain of survival

defibrillation

defibrillator

dysrhythmia

electrocardiogram (ECG)

escape rhythm

hypothermia

motion artifact

normal sinus rhythm (NSR)

premature ventricularcomplex (PVC)

public access defibrillation(PAD)

pulseless electrical activity(PEA)

rhythm

ventricular fibrillation

ventricular tachycardia

O B J E C T I V E SUpon completion of this chapter, the reader should be able to:

1. Describe the assessment of the patient in cardiac arrest.2. Describe the importance of early defibrillation.3. Describe the importance of CPR to cardiac arrest survival.4. List the indications for AED.5. List the contraindications for AED.6. Differentiate between a semiautomated and a fully automated

defibrillator.7. Describe the fundamentals of AED operation.8. Describe the safety considerations for AED use.9. Describe the importance of advanced life support to patient

survival.10. Discuss postresuscitative care of the arrested patient.11. Discuss the function of the physician and AED use.12. Discuss the importance of quality improvement for AED

programs.

O V E R V I E WOne of the most challenging emergency medical services (EMS) callsis for “man down, possible cardiac arrest.” Adrenaline surges throughthe emergency medical technician’s (EMT’s) body, while preparingfor the mental and physical challenges of providing EMS in a life ordeath situation.

In the not too distant past, a cardiac arrest was a death sentence.The introduction of cardiopulmonary resuscitation, or CPR, in the late1960s, improved survival somewhat. CPR, a combination of mouth-to-mouth ventilation and chest compression, gave some hope to anotherwise grim prognosis. Even with CPR, the changes of restoring aheartbeat and ‘reversing’ a cardiac arrest were bleak.

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Advances in medicine and new technology have made prehospitalcardiac arrest reversal more likely. EMTs, carrying special devicescalled defibrillators, are able to provide definitive care to the cardiacarrest victim. This chapter focuses on defibrillation, which is a proce-dure that can enable an EMT to save a life.

THE HISTORY OF DEFIBRILLATIONOne of the most common causes of cardiac arrest is ventricular fibril-lation, a chaotic, unorganized electrical malfunction of the heart thatresults in no useful heartbeat. This chaotic electrical activity can bestopped only by applying an electrical countershock. Once the ven-tricular fibrillation is halted, the heart can then begin normal organ-ized beating.

During open chest surgery, surgeons have successfully been“shocking” fibrillating hearts back to life for many years. Themachines that are used to deliver this shock are called defibrillators,and the process of delivering a shock to the heart is called defibrilla-tion. The difficulty was that early machines were large and wererestricted exclusively to the operating room. Furthermore, defibrilla-tion required that the patient’s chest be opened and the heart exposed.These facts made it impractical for emergency use.

In 1956, Dr. Zoll created the first external defibrillator. Althoughsomewhat cumbersome, it allowed defibrillation outside of the oper-ating room. At about the same time, 1960, Dr. Kouwenhoven pub-lished a paper on closed chest compressions interposed with manualventilations, now known as CPR.

CPR quickly became popular among emergency services personnel,but the defibrillator remained in the hospital. The advent of transistors

636 Section 7 Emergency Medical Care

● What factors are working against this man’s survival?● What factors are working for this man’s survival?● Why is time important to this patient’s survival?● What can an EMT do to reverse the cardiac arrest?

“Unit 24, man down, CPR in progress, Eagle Hills Office, Tower Lobby,time out 16:45.” As he put the ambulance in gear and turned on thelights and siren, Tony thought, “The timing couldn’t be worse, fiveo’clock traffic is a mess and we are at least 15 minutes from the scene.”As Tony passed by stopped cars on the road, he thought of the minutesthat were flying by for the patient.

As he pulled up to the curb in front of the tower building, Tony lookedin the window. Clearly CPR was in progress. One security officer wasusing a pocket mask to ventilate while another was doing compressions.Then he saw it—an AED was attached to the patient. “Maybe the patienthas a chance after all,” he thought. Tony quickly grabbed the quickresponse kit and ran in the front door.

CPR in Progress

and microprocessors brought with them the development of a smallerdefibrillator capable of being used in the prehospital environment.

In 1980, Dr. Eisenberg of Seattle, Washington, started a prehospitaldefibrillation program using these new smaller defibrillators. Hishypothesis was that properly trained EMTs using defibrillators couldsave many lives.

These EMTs used a defibrillator that could “read” the electrocardio-gram (ECG), using a logic algorithm stored in a microprocessor, advisethe EMT to “shock,” or defibrillate the patient, then deliver the shock.These were among the first automated external defibrillators (AEDs).

Chain of SurvivalUsing an AED on the patient in cardiac arrest is only part of the for-mula for a successful cardiac arrest reversal. Because ventricular fibril-lation quickly degenerates from active, yet chaotic, electrical activityto minimal electrical activity and then no activity at all, time is of theessence when treating the cardiac arrest victim. Every minute of delaycalling EMS or getting a defibrillator to the patient decreases thechance that the heart will respond to the shock.

The American Heart Association realized the importance of speedand started to advance the concept of the chain of survival. Simply,the chain of survival links all the elements of a cardiac arrest reversaltogether. The chain of survival depicts the important steps that mustbe taken to improve cardiac arrest survival.

Early AccessQuick notification of EMS is key to getting EMTs trained in the use ofan AED to the patient. Typically, EMS is accessed by calling 9-1-1.Unfortunately, 911 service is still not universally available in theUnited States.

One of the attractions of 911 is that it can provide the communica-tions specialist the location of the call (Figure 29-1). Underlying thisability to locate a call is the assumption that the call is being placedfrom a stationary landline.

Although cellular telephones have made it easier for callers tomake calls from the scene of an incident, location identification hasbeen lost. Future cellular telephones will have this capacity.

Early CPRCPR saves lives. There are some documented cases in which CPR alonereversed a cardiac arrest, although CPR alone is often not sufficient.Once EMS has been called, CPR helps preserve the brain until the EMTand AED are at the patient’s side. Therefore, citizen CPR is still veryimportant to patient survival in a prehospital cardiac arrest (Figure 29-2).

Early DefibrillationThe definitive treatment for cardiac arrest due to ventricular fibrilla-tion is defibrillation. The AED is an easy tool to use and allows rapidapplication of defibrillation to the cardiac arrest victim. EMTs havebeen targeted to learn AED use because they are the largest group ofprehospital care providers (Figure 29-3).

Chapter 29 Cardiac Arrest 637

FIGURE 29-1 Early notification using911, the first link in the chain of survival.

FIGURE 29-2 Early CPR buys time forthe arrival of the AED.

FIGURE 29-3 Early defibrillation saveslives.

Early Advanced Cardiac Life SupportAlthough an AED can reverse the fibrillation that led to the cardiacarrest, it does not address the cause of the fibrillation, and recurrenceof the fibrillation is likely. Advanced life support (ALS) providerstrained in advanced cardiac life support (ACLS) have the skills andknowledge to help protect the patient from further episodes of cardiacarrest. These ALS providers can help to stabilize the patient beforeand during transportation to the hospital.

Survival from Cardiac ArrestAny chain is only as strong as its weakest link. If CPR is provided inless than 4 minutes and defibrillation is provided in less than 8 min-utes, the patient potentially has a 43% chance of survival. For everyminute that defibrillation is delayed to the victim of ventricular fibril-lation, the chances of survival decrease by at least 10%. In the situa-tion of cardiac arrest, every minute counts.

THE AUTOMATED EXTERNALDEFIBRILLATORThe AED consists of two large electrodes (pads that are placed onthe patient’s chest) and cables (leads) that connect the patient to themachine. A battery power source is also necessary to generate theelectricity that is used to perform the defibrillation. Figure 29-4 showsthe components of the AED.

The AED has an internal computer that samples the heart’s electri-cal rhythm through sensors in the electrodes. The computer measuresthe waves in the heart’s electrical activity against a logic formula. Ifthe computer analysis indicates that the rhythm is ventricular fibrilla-tion, or any other rhythm that will potentially respond to defibrilla-tion (which will be discussed later in the chapter), then an audible orvisual warning advises the operator (EMT).

The single largest advantage of an AED is that it does not requirethe EMT or operator to learn the complex rules of ECG interpretation.The ECG is the record of the heart’s electrical activity. There are manydifferent patterns of electrical activity the heart can exhibit, each ofwhich requires a different management strategy. Some of these differ-ent patterns are discussed briefly later in this chapter, although theEMT is not expected to interpret the rhythms after reading this chap-ter. Much more training is required to learn the technique of ECGinterpretation. The EMT can allow the AED to interpret the rhythmand advise him to shock if appropriate.

Use of the AEDAt the beginning of every shift, the EMT must ensure that the AED isproperly prepared for use. An overall inspection should be per-formed. The case should be intact. Cases may be broken when anAED is accidentally dropped. A broken case is a potential electricalhazard, and the AED should be taken out of service. Next, check the


Do not be surprised if an AEDhas already been used beforeEMS is on the scene. AEDs haveso improved in simplicity anddependability that certain seg-ments of the public are beingtrained in the use of an AED.Airlines now routinely train flightattendants in the use of the AED.

Public access defibrilla-

tion (PAD), the availability of adefibrillator to the lay public, israpidly becoming commonplacein the shopping mall, on the fac-tory floor, and in the businessoffice. CPR courses now rou-tinely include AED training forrescuers.

StreetSmartStreetSmart

Large public gatherings, such ascounty fairs or sporting events,are often scenes of cardiacarrests. EMTs assigned to standby at these events should havean AED readily available. TheAED left in the ambulance is ofno value to the patient who is inthe middle of the bleachers incardiac arrest.


FIGURE 29-4 The automated externaldefibrillator, or AED.

cables. Like the case, the cables should be intact. Frayed cables andbare wires are dangerous and should be replaced. Finally, check theelectrodes. All electrodes should be sealed within a protective wrap-per. Check the expiration date on the electrode package. Old elec-trodes become dried out and useless.

BatteriesThe AED uses a battery for its power source. Batteries have a ten-dency to stop working when they are needed most. Every AEDshould be equipped with a backup battery. The EMT should alwaysensure that the primary battery and backup battery are adequatelycharged.

Some types of batteries require regular recharging; others have acharge that lasts for years without a need for a recharge (Figure 29-5).The EMT should familiarize himself with the type of battery hisagency uses in its AED.

SuppliesIn every routine equipment check, the EMT should ensure that theproper accessory supplies are with the AED. Most AEDs used byEMTs are equipped with a case that has several pockets used to holdadditional supplies that may be needed.

It is always advisable to have a spare set of electrode pads as wellas a spare battery on hand. Because an AED is used in life or death sit-uations, it is important to have redundancy in critical supplies.Families of patients have successfully sued EMS providers thatresponded with an AED that had dead batteries.

The electrode pads must tightly adhere to the chest wall for optimaldelivery of the electrical energy. Moisture prevents proper adhesion.A gauze 4-by-4 pad or a towel should be immediately available towipe down the chest before applying the electrodes.

Excessive chest hair can also interfere with adhesion of electrodes.A pair of bandage scissors may be used to quickly shear hair. A razormay also be used to shave hair from the chest for ideal electrode adhe-sion; however, it is often not necessary and may waste precious time.A safety razor should, however, be available so that if it is necessaryto shave a portion of the patient’s chest, it can be done quickly.

After completing an AED equipment check, always document theinspection and testing of the AED (Figure 29-6). Failure to documentan inspection leaves the EMT vulnerable should a lawsuit occurowing to equipment failure. Be sure to report malfunctions and takethe faulty AED out of service until it can be serviced by a qualifiedbiomedical engineer.

CARDIAC ARRESTA common consequence of acute myocardial infarction (AMI) is car-diac arrest and clinical death. This event, defined as the unexpectedcessation of heartbeat within 2 hours of the onset of chest pain, iscalled sudden cardiac death (SCD).


EMTs who interact with ALSproviders frequently purchasean AED that has an ECG displayscreen and a paper ECG print-out. These enable the ALSprovider to interpret the ECG.Then the ALS providers canoverride and manually operatethe AED. Usually a key or acode is required to override theAED control.

An EMT should not overridethe AED. Without proper training,the EMT may jeopardize thepatient’s life and risk his own abil-ity to practice. For most EMTs,the more commonly used AEDwithout a printout is satisfactory.


FIGURE 29-5 The rechargeable bat-tery is the power source for the AED.

Profuse sweating often occursduring an AMI just before car-diac arrest. To improve electrodeadhesion, many EMTs will wipethe chest down with a towel,then spray the chest with anantiperspirant. Be sure to use adry spray that says antiperspi-rant and not a deodorant.


More than 50% of the cases of sudden cardiac death occur outsideof the hospital. Therefore, it is imperative for the EMT to understandwhy cardiac arrest occurs and how to respond to it.

Signs and SymptomsWhen a patient experiences chest pain or any of the other cardiac-related symptoms described in Chapter 28, she may be experiencingan AMI. Without prompt treatment, the AMI can lead to complica-tions such as congestive heart failure (Chapter 27), cardiogenic shock(Chapter 9), or SCD. Why does SCD occur? To understand the causeof SCD, the EMT must first understand the heart’s normal electricalactivity.


FIGURE 29-6 A precall AED checklist. (Reproduced with permission, © 2004, American Heart Association, www.americanheart.org)

Normal Sinus RhythmTo review, the heart is a pump. Pumps essentially have two interre-lated components; an electrical system triggers the mechanical por-tion to do its job. The human heart is such a pump. It has an electricalsystem that triggers the ventricles, the mechanical portion, to pumpblood.

The electrical impulse begins at the sinoatrial node (SA node), a groupof specialized cells located high in the right atrium. The impulse thenproceeds through the atria to the atrioventricular node (AV node),another specialized group of cells that is situated between the atriaand the ventricles. From the AV node, the spark travels through adefined bundle of muscle fibers, called the bundle of His. This bundleof conductive fibers then splits into several branches known as bundlebranches. These bundle branches carry the electrical impulse to theventricular muscle. Within the ventricular muscle are additional spe-cialized conductive fibers called Purkinje fibers, which will then stim-ulate the remainder of the ventricular muscle. For a review of thesestructures, see Chapter 5.

As the electrical impulse is carried in this organized fashionthrough the heart, the muscle is stimulated to contract in a coordi-nated fashion. Because the atria are stimulated by the electricalimpulse first, they will contract first, moving blood into the ventricles.

The ventricles will contract after they have been stimulated by theelectrical impulses received by the bundle branches and Purkinjefibers. When the ventricles contract in an organized fashion, the effectis for blood to be ejected out through the aorta. Figure 29-7 depicts thepath of the heart’s electrical stimulation.

Every heartbeat has an electrical event that precedes the mechanicalevent. The normal electrical event within the heart is the propagation ofelectrical impulses from the SA node to the ventricles as outlined. This


FIGURE 29-7 An electrical impulse from the SA node travels to the AV node and the ventricle, causing the ventricle to contractand creating a pulse.

electrical activity from the heart can be detected by an electrocardiogram(ECG) machine and graphically displayed on an oscilloscope or printedon paper. This display is called an electrocardiogram.

An ECG normally displays a pattern of grouped waves, called com-plexes. These regularly repeating complexes are seen as a rhythm (aregularly reccurring or repeating pattern) on the ECG. The naturalsource of a normal cardiac complex is the SA node. Therefore, theelectrical rhythm that is seen when the heart’s electrical system isfunctioning properly is called a normal sinus rhythm (NSR). An NSRis the predominant natural rhythm of the heart.

Although it is not important for an EMT to be able to interpret anECG, the concept is helpful in understanding the physiology of car-diac arrest. Figure 29-8 shows an example of an NSR.

Escape PacemakersThe normal source of a heartbeat is the SA node. The SA node is there-fore referred to as the heart’s pacemaker because it establishes the rateof stimulation and, therefore, contraction.

Heart muscle, or myocardium, has a unique ability to be its ownpacemaker. If for some reason the SA node or AV node fails to func-tion properly, the ventricles have the ability to pace themselves,although not as efficiently as the normal conduction system. This abil-ity of the myocardium to self-pace is called automaticity.

The special ability of the myocardium to function independently isvaluable when the electrical system fails. The resulting rhythm, calledan escape rhythm, may provide the patient with enough blood flow tostay alive until a physician can insert an artificial pacemaker (a man-made electronic device that will create an electrical impulse signalingthe heart to beat). An escape rhythm is slower and less efficient than anNSR. Pacemakers are discussed later in the chapter.

DysrhythmiaWhen the heart’s muscle is injured during an AMI, the musclebecomes irritable, firing chaotically. This irritability can lead to disruptions in the NSR. Any disruption of the NSR is called a dysrhythmia.

Occasionally, a small group of irritated cells in the ventricles willstart to fire earlier than expected. This unnatural pacemaker creates apremature ventricular complex (PVC) (Figure 29-9). A PVC inter-


FIGURE 29-8 Normal sinus rhythm.

Normally when a patient’s bloodpressure drops, for whateverreason, the heart races to com-pensate for the loss. This reflex-ive tachycardia is a hallmark ofshock.

When an EMT determinesthat the patient has a low bloodpressure, he naturally assumesthat the heart will be tachycar-diac. This is not always thecase. If the electrical system ofthe heart is damaged by an AMI,then an escape pacemaker willtake over and the result will be abradycardiac escape rhythm.

When an EMT sees bothhypotension and bradycardia ina medical patient, he should bethinking about a possible AMI.


rupts the regular sinus rhythm and is therefore a dysrhythmia. PVCscan disturb blood flow and are felt as an irregular pulse. PVCs can bean indication of ventricular irritability.

If the signal from this small group of cells in the ventricles is fastenough and strong enough, it can take over the heart’s own inherentpacemaker. The ventricles often race at rates from 100 to 250 beats perminute. The resulting ECG rhythm is called ventricular tachycardia.Ventricular tachycardia creates a distinctive ECG, similar to a sinewave pattern (Figure 29-10).


FIGURE 29-9 Unnatural pacemakers, created by an AMI, interrupt the NSR.

PVC PVC

FIGURE 29-10 Ventricular tachycardia robs the heart’s coronary arteries of life-giving blood.

Infarct

Racing ventricles with a heart rate over 150 bpm do not haveenough time to fill with blood and then empty. The result is little or noblood flow to the body, particularly to the coronary arteries. Pulses arequickly lost, and the patient loses consciousness. If a normal heartbeatdoes not resume quickly, the patient eventually dies. Defibrillationcan help to halt this rapid firing of irritable ventricular cells.

If the area of damage from an AMI is extensive, a large group ofcells in the ventricle becomes irritable. These irritable cells misfire andcan lead to sudden cardiac death. This process can be compared to anuclear explosion. A pound of uranium is dangerous and potentiallylethal. Several pounds of uranium are enough to create a spontaneousnuclear reaction and even a nuclear explosion. Similarly, if enoughirritable ventricular myocardial cells fire prematurely, they can resultin ventricular fibrillation, a chaotic firing of multiple ventricular cellsresulting in no organized rhythm. During ventricular fibrillation, theheart simply quivers and does not create any forward blood flow. TheECG looks like a chaotic collection of waves that have no discerniblerhythm (Figure 29-11).

Without a coordinated rhythmic contraction, blood flow stops andpulses are lost. The patient is in cardiac arrest. Without any bloodpressure, the coronary arteries are not filled and the heart muscle goeswithout oxygen. Defibrillation can halt this chaotic firing of cells.

Eventually, the damage is so extensive, and the cells so damaged,that all cardiac activity stops. The heart, in cardiac standstill, will lieflaccid and unable to respond to any stimulus. The inert heart is in asys-tole. Because there is no electrical activity, it would not help to defibril-late the patient in asystole. CPR and rapid transport are indicated.

Asystole is a true arrhythmia (meaning “without rhythm”). Withoutany electrical activity in the ventricles, the patient’s ECG will be flat-line, or asystolic (Figure 29-12).


FIGURE 29-11 Lethal ventricular fibrillation has no discernible rhythm.

Chaotic ventriculardepolarization

Pulseless Electrical ActivityThere are certain conditions, such as severe blood loss, that will resultin no forward blood flow from the heart despite adequate electricalactivity. This is called pulseless electrical activity (PEA). It is importantfor the EMT to realize that despite normal-appearing electrical activityon an ECG, the patient may have cardiac compromise. The best bet is topay close attention to the patient and not to the monitor. If the patienthas no pulse, CPR should be begun, despite the ECG findings.

PEA is not treated with a shock, because there is nothing wrongwith the electrical activity. The proper course of action is CPR, 100%oxygen, and rapid transport to the closest appropriate hospital wherethe cause can be determined and treated.

AssessmentThe assessment of the cardiac arrest victim is done similarly to theassessment of any other unresponsive medical patient. Beginningwith a scene size-up, the EMT moves through the initial assessmentquickly, providing airway, breathing, and circulatory (ABC) support,in that order. Because cardiac arrest requires significant work beforethe completion of even the initial assessment, the EMT may never getto a focused history and physical exam. It is, however, important thatthe EMT gather any known history from the patient’s family whilecare is being provided to the patient. Such historical information willbe useful to both advanced providers and hospital personnel.

Scene Size-UpAs discussed in Chapter 12, scene safety must always be addressed.Fluids present a hazard to the EMT using an AED. Fluids can transmitthe electrical energy to the EMT instead of to the patient, resulting in


FIGURE 29-12 Asystole, a true arrhythmia, occurs in cardiac standstill.

Cardiac standstill Doctors, nurses, paramedics, andEMTs use the terms arrhythmiaand dysrhythmia interchangeably.Although not strictly correct, it isaccepted practice.


Ventricular fibrillation is an inter-pretation of the ECG. For theAED to make an accurate inter-pretation of the ECG, the AEDmust be properly functioning.Examples of problems includefailure to firmly connect the ECGcables to the machine, driedelectrode gel on the pads (verycommon), and cold skin.

Always check the patientfirst. If the patient is awake, howcan she be in v-fib? Then checkthe machine to see whether it isfunctioning properly. Start at thechest wall. Check the elec-trodes, then check the cableconnections, and finally checkthe AED. The patient who isawake does not have ventricularfibrillation and should not beshocked by an AED.

Safety TipSafety Tip

injury to the EMT. Examples of fluids that can potentially transmitelectricity include snow, vomit, rain, urine, and pooled water. If thepatient is wet, she should be immediately moved to a dry place. Thenthe patient should be toweled dry before proceeding. Never defibril-late a patient who is still lying in a puddle of liquid.

The patient’s body should also not be in contact with any metalobjects. Again, the metal can transmit the energy to the EMT insteadof to the patient. Examples of metal objects include sidewalk grates,catwalks, and aluminum flooring. The patient should be movedimmediately, in an emergency carry, to a safe location before an AEDis used (Figure 29-13).

General ImpressionThe initial dispatch information may have been for a cardiac arrest.CPR may already be in progress when the EMT arrives. In those cases,the EMT enters the scene prepared.

In some cases, the dispatch information does not match thepatient’s situation. The call may have been received for a “personpassed out” or, commonly, for a “person seizing.” The EMT walksinto those calls unaware of the situation.

Stop and look around the scene first. Get the global picture. Tablesor lamps that are knocked over indicate a sudden collapse. If the tele-phone is off the hook, the patient may have been calling for help.Medications, both over-the-counter and prescription, left out maygive a clue to the patient’s condition.

Gather a quick impression from the patient’s overall appearance.Whether the patient is on the ground, sitting in a chair, or lying in abed, she will be unconscious if in cardiac arrest. Without blood circu-lating, the patient will be grossly cyanotic.

Try to obtain a chief complaint from any available family memberor bystanders. Ask whether anybody witnessed the patient’s collapse.If the patient fell, ask whether the head struck anything on the waydown. If no one is available, or the answers are questionable, assumespinal trauma.

Position the patient for further assessment. If the patient is uncon-scious, and CPR is likely to be needed, then the patient needs to be ona firm surface. Move the patient out of the bed or chair and onto thefloor. If the room is small, such as a bathroom or a cramped bedroom,consider quickly moving the patient to a larger room, such as the hall-way or living room (Figure 29-14).

If the patient is unconscious, or is in cardiac arrest, the assistance ofALS personnel is required. If ALS is available, then request assistanceto the scene right away.

Initial AssessmentAfter completing the scene size-up, the EMT should immediatelydetermine the patient’s level of consciousness. If trauma is suspected,an EMT should take manual stabilization of the head and spine first.If the patient is unconscious and unresponsive to pain, the EMTshould immediately open the airway. After the airway has beenopened, the EMT should assess for the presence of breathing. If thepatient is not breathing, the EMT should deliver two rescue breaths


FIGURE 29-13 Before using the AED,make sure the scene is safe.

The AED should be a part of thestandard first-in gear for all med-ical calls. It is of no use in theambulance when it is neededimmediately on scene. The fewminutes lost retrieving the AEDfrom the ambulance might costthe patient her life.


FIGURE 29-14 Quickly move thepatient to a large enough area for CPR.

using an appropriate ventilation device. After these breaths have beengiven, the EMT should check for a carotid pulse, taking no more than10 seconds for the pulse check.

If the patient is pulseless, the AED must be immediately prepared.If sufficient personnel are available, or if there is a delay in getting theAED to the patient’s side, CPR should be begun. Think of the assess-ment priorities as changing from ABC to ABCD: airway, breathing,circulation, and defibrillation.

A detailed description of CPR can be reviewed in Appendix B.

ManagementIf an AED is immediately available, the EMT should quickly attachthe electrodes on the patient’s chest. First, attach the electrode pads tothe cables. Then place one pad under the patient’s right clavicle andthe other pad on the patient’s lower left rib cage. Alternatively, onepad may be placed on the anterior chest and one on the posteriorchest as indicated in Figure 29-15.

A diagram for electrode pad placement is often found either on theelectrodes or on the AED. The cables are also color coded. The whitecable and pad are attached under the clavicle on the right. The redcable and pad are attached to the lower left rib cage (see Figure 29-15).

Once the AED has been attached to the patient, the power shouldbe turned on. Usually the “power on” switch is prominently dis-played. Every EMT should take a moment before the call to review theoperational features of the AED before using it.

Once the AED is operational, press the analyze button to activatethe AED. Often a voice prompt will advise the EMT or operator thatthe AED is analyzing.

If CPR is in progress, the EMT or operator should instruct everyoneto stop. The usual command to the rest of the team is “all clear.” Allclear means that nothing, not even the bag-valve-mask, should touchthe patient. Motion from CPR can create motion artifact (a false ECGreading created by vibration), causing the AED to mistakenly identifythe ECG as ventricular fibrillation (Figure 29-16).


The definition of the term deadweight is never clearer thanwhen an EMT has to move apatient to the floor. If a back-board is available, consider slid-ing the seated patient onto thebackboard. Place the backboardunder the patient’s feet and thenslide the patient down the ramp.Once the patient is on the back-board, move the backboard tothe floor. If the patient is in bed,consider logrolling the patientonto the backboard and then lift-ing the board onto the floor.


FIGURE 29-15 There are two acceptable positions for the AED pads: A. anterior-anterior or B. anterior-posterior.

A useful way to remember wherethe colored electrodes are placedis to say “white-right, red-ribs.”The rhyme and letter coordina-tion may make placement easierto recall.

In some cases it may not bepractical or possible to place theself-adhesive defibrillation padsin the anterior-anterior position;for example, if the person beingresuscitated has a very smallframe. The anterior-posteriorposition is an acceptable alter-native in those cases.

Similarly, it may be difficult toplace the apical pad or the defibril-lator paddle in place on largebreasted patients. In those cases itis acceptable to place theleft/apical self-adhesive defibrilla-tion pad or paddle just lateral to thebreast or underneath the breast.


If the patient is already aboard the ambulance when she arrests,and the ambulance is moving, instruct the driver to stop the vehicle.Road vibrations can also create motion artifact that the AED couldmisinterpret as ventricular fibrillation.

The AED may take a few seconds, after the analyze button has beenpressed, to determine whether the ECG is a shockable rhythm, a rhythmthat will respond to defibrillation. If a shockable rhythm is identified,the AED will start to automatically charge. Most machines create anaudible warning or a verbal prompt or both. The audible warningindicates that the AED is energizing. The verbal prompt typicallystates “shock advised” or a similar statement.

While the AED is charging, call all clear again. Be sure that nothingis touching the patient. The danger of an accidental shock, and thesafety of the team, cannot be overstressed. An EMT accidentallyshocked could potentially go into ventricular fibrillation, making abad situation worse by creating a second patient.

For the third and final time, the EMT or operator should call allclear. Some EMTs use the mantra “I’m clear, you’re clear, we’re allclear” while making a visual sweep of the patient before actuallydefibrillating the patient.

Always perform a head-to-toe visual sweep with every defibrilla-tion. Make a habit of looking at the patient’s nose, then looking at hertoes, and looking again at her nose, before pressing the button to acti-vate the defibrillator. Defibrillation should never become so routinethat the EMT becomes complacent about safety.

Once all team members are physically clear of the patient, the EMTor operator then presses the shock button. The shock button willdeliver the defibrillation from the AED to the patient.

The EMT or operator should immediately press the analyze button,again stating all clear. The AED will analyze the ECG to see whetherthe defibrillation was effective. If the shock was not effective, then theprocess is repeated.

The goal of the EMT or operator is to deliver the shock in less thanone minute from arrival on-scene. It is not necessary to check for apulse between shocks.

Some EMTs may be taught to use a manual defibrillator. Inthose cases, the first shock should be at maximum joules, usually360 joules or the biphasic equivalent energy setting. Always fol-low the manufacturer’s recommendations regarding the use of amanual defibrillator.

Once the defibrillation sequence has ended, the EMT shouldagain check for pulse and breathing. If none is present, CPR shouldbe resumed. The AED can be used again after five cycles of CPR, orapproximately two minutes, to analyze the heart’s rhythm to seewhether a shockable rhythm is present. Remember that there areseveral rhythms that will result in cardiac arrest yet are notamenable to defibrillation; therefore, the machine will say “noshock advised.” If the patient does not have a pulse, however, CPRmust be done and the patient should be transported quickly to theclosest appropriate hospital. Skill 29-1 describes the operation ofan AED.


There is little time during a car-diac arrest to stop and read theelectrode packaging for instruc-tions. Many EMTs have learnedthis simple mnemonic: Smokeover Fire. The white cable,smoke, is placed higher on thebody than the red cable, fire.


Older defibrillators had manualdefibrillation paddles. Thesepaddles consisted of handlesand large metal electrodes. Aconductive medium, or defibrilla-tion gel, had to be applied to thepaddles before use.

Paddles had many safetyissues. For one, the gel wouldget all over the chest wall, andsometimes all over the EMT.The result was that the chargewas ineffective at best or couldshock the EMT.

It also took 20 pounds (8kg)of pressure on the paddles toget acceptable contact on thechest wall. While applying thispressure, many EMTs would slipoff the chest wall.

Newer electrode padspermit hands-off defibrillation.The distance of several feetincreases the margin of safetyfor the EMT as well as improvesAED efficiency.

These newer self-adhesivedefibrillation pads are a safe andoften preferrable alternative tostandard defibrillation paddlesfor the reasons stated earlier.


Defibrillation EnergyOriginal defibrillators delivered the electrical charge in what is calleda monophasic waveform; more specifically the monophasic truncatedexponential or MTE waveform.

Subsequent research and development created the more effectivebiphasic waveforms. These energy waveforms require less energy toeffectively perform the same defibrillation, as does the monophasicwaveform.

Most newer models of defibrillators take advantage of this newtechnology, using either the biphasic truncated exponential (BTE)waveform at 150 joules to 200 joules or the rectilinear biphasicwaveform at 120 joules.

As most AED are self-calibrating and programmed to deliver theoptimal energy, the EMT does not have worry about which energysetting to choose.

If the EMT is still using the older model monophasic defibrillator,the program should be adjusted to deliver the maximum joules (usu-ally 360) with each defibrillation.

The obvious problem in a cardiac arrest is that no blood flows fromthe heart to the body. Although CPR provides some blood flow, CPRcannot sustain the body for a long period. The best CPR provides onlyabout 30% of the normal cardiac output. The preferred option wouldbe to have the heart beat naturally.

If an electrical current is passed through the fibrillating heart mus-cle, the electrical current will stun, or shock, the heart. All uncoordi-nated contractions of the heart will immediately stop simultaneously.Then natural sinus pacemakers can assume dominance over the heartand an NSR can begin again.

For defibrillation to work, there must be some muscular activity inthe heart. Ventricular tachycardia and ventricular fibrillation are twoexamples of shockable rhythms.

Asystole is an example of a nonshockable rhythm. Without any mus-cular activity, the heart will not respond to the defibrillation. In thosecases, CPR should be continued until ventricular fibrillation appears.

Prolonged Down Time In some cases the EMT may come across the patient with a prolongeddowntime, i.e. someone who has been in cardiac arrest for over fourto five minutes. In those cases it may be reasonable to start with around of CPR first; a round of CPR being five cycles of compressionsto ventilations at a ratio of 30:2.

Special SituationsThere will be several situations that may require slight deviation fromthe usual protocol in assessing and managing the patient in cardiacarrest. The EMT should be familiar with these few situations.

Artificial PacemakersWhen the electrical system of the heart fails, causing bradycardia, acardiologist will place an artificial pacemaker into the patient. The


If the patient is on the gurney, besure that no one’s foot is touch-ing the metal undercarriage. It iscommon for an EMT to rest hisfeet on the lower bar of the gur-ney, out of sight of the EMT oroperator handling the AED.Because the hard rubber wheelsof the gurney electrically isolatethe gurney, the EMT’s foot cre-ates a new electrical pathway,and the EMT will get shocked.


FIGURE 29-16 Motion, from roadvibrations or CPR, creates ECG motionartifact.

During an emotionally intenseevent such as a cardiac arrest,some new team members maybecome so focused on what theyare doing that they mentallyblock out extraneous noise,including the command all clear.

Some EMTs or operatorswill physically sweep above thebody with one hand, in a circularmotion. This action will breakanother team member’s concen-tration and redirect his attentionto the EMT or operator. Thistechnique is very useful in noisyenvironments as well.



The EMT applies the electrode pads to the ante-rior chest wall, one to the apex of the heart at thelower left rib cage and the other to the right sternalborder below the clavicle.

2The EMT must confirm that the patient is in car-diac arrest.1

SKILL 29-1 Operation of an AutomatedExternal Defibrillator

PURPOSE: To perform an external defibrillation,when indicated, on a patient in cardiac arrest.STANDARD PRECAUTIONS:

� Automated external

defibrillator

� Personal protective

clothing

The EMT then turns the power on the AED whilecalling “all clear.” The EMT must ensure that no one istouching the patient.

3

(continues)

artificial pacemaker will create the impulse that signals the heart tobeat, ensuring a heart rate that will support a normal blood pressure.

An artificial pacemaker has a pulse generator and a set of wires thatlead to the heart. The pulse generator is usually placed in a pocket underthe skin, usually below the right clavicle, and the pocket is sewn shut.

The AED electrode pad is placed in about the same location as thepacemaker. If a pacemaker is located under the skin, as indicated by abulge about the size of a silver dollar, then the AED pads should bemoved slightly to the left and down several inches toward the feet sothat the electrode is not over the pacemaker.

If the AED electrode is placed immediately over the pacemaker, theAED may sense the pacer’s impulse, seen as a spike on the ECG, andthink the heart is beating regularly. Even more important, if the AEDfunctions correctly, detects the ventricular fibrillation, and a defibril-lation is delivered, the pacer will absorb some of the defibrillationenergy and may not work properly afterward.

Automatic Implantable Cardioverter/DefibrillatorUsing state-of-the-art microelectronics and more powerful micro-processors, physicians and biomedical engineers have created anAED that can be placed within the body. The automatic implantablecardioverter/defibrillator (AICD) is used for patients who are at riskfor developing recurrent ventricular tachycardia or fibrillation.

Often the patient’s family will tell the EMT that the patient hasan AICD. Many patients also carry an instruction card in their wal-let or purse.

Similar to a pacemaker, the AICD has a generator/defibrillator anda set of wires that leads to the heart. When the AICD senses an event,


After the shock has been performed, the EMTmust perform CPR for five duty cycles of ventilationand compression (30:2). Then the EMT should checkfor the presence or absence of a pulse. If the pulse isabsent, then another shock may be advised. If thepatient’s pulse returns, then the EMT checks forbreathing.

5The EMT then presses the analyze button andpresses the shock button, as advised. Again, the EMTmust ensure that no one is touching the patient.

4

SKILL 29-1 (continued)

Many defibrillators use a tech-nology called “biphasic defibrilla-tion,” which allows use of alower overall energy settingwhile still providing effectiveenergy to the heart muscle. TheEMT should be familiar with themachine and technology usedby his agency.


such as ventricular fibrillation, it signals the defibrillator, which inturn shocks the heart.

Because the AICD is internal and the wires are attached directly tothe heart, it takes very little energy to defibrillate the heart, 5–15joules. The energy is so low, and the shock so small, that if the AICDshould function, or fire, while the EMT is doing CPR, he may feel amild tingling in the arms. This is not dangerous to the EMT yet can bediminished by use of gloves, which act as an insulator.

The most common type of AICD looks very similar to an artificial pace-maker and is typically located in the same location under the right clavi-cle (Figure 29-17). When an AICD is detected, the AED electrode padsshould be moved slightly to the left of normal and several inches towardthe feet, in the same placement as used for a patient with a pacemaker.

Medication PatchesThe use of transdermal patches has become increasingly popular. Theseself-adhesive patches contain medication that is slowly absorbed throughthe skin of the patient. Patches are an easy and convenient way of admin-istering a medication that must have a steady level in the bloodstream.Alternatively, the patient would have to take a pill several times a day.

Examples of transdermal patches include nitroglycerin patches,used for cardiac patients; nicotine patches, used for cigarette cessationprograms; and hormone replacement patches, used in cancer preven-tion or treatment.

These transdermal patches often have an aluminum backing or thedrug’s paste medium is reactive to the defibrillation. Consequently,when the patient is shocked, the patch either ignites, making a pop-ping sound, or heats up, burning the patient.

Patches are generally worn on the upper chest, on the upper back,or on the shoulders. Before operating the AED, the EMT must com-pletely expose the patient’s chest wall and look for patches.

Gloves should always be worn when removing a patch. Lift the cornerof the patch by the tab and pull. The patch should come off easily. If med-ication is still visible on the patient’s skin, use a 4-by-4 pad and wipe it off.

HypothermiaHypothermia is a condition in which the body temperature dropsbelow 95°F (normal body temperature is 98.6°F). When the body tem-perature drops even further, to 90°F, the heart becomes quite irritableand the patient is at risk for ventricular fibrillation.

Examples of patients who could suffer hypothermia include winterhikers, persons immersed in cold water for a long time, and homelesspersons. Whenever a patient has been outdoors for a prolongedperiod, consider the possibility of hypothermia.

The cold heart is resistant to attempts at defibrillation. Most medicalprotocols and the American Heart Association’s Advanced Cardiac LifeSupport (ACLS) course advocate delivering one shock only. If the heartdoes not respond to these initial attempts, continue CPR and immedi-ately transport the patient to the most appropriate emergency facility.

TransportThe patient in cardiac arrest, or having been reversed from cardiacarrest, is a critically ill patient. Transport should be accomplished


FIGURE 29-17 An automaticimplantable cardioverter/defibrillator is aninternal AED.

There have been several reportedcases of sparks produced by thedefibrillator leading to fire. In those cases poorly attached self-adhesive defibrillator pads orloose defibrillation paddles, alongwith an oxygen enriched environ-ment, lead to the fires. Careshould be taken to firmly apply the defibrillator pads or paddlesand to remove oxygen sources(i.e. oxygen masks or mask-bagdevices) from close proximity ofthe patient during defibrillation.


quickly, and the patient should be brought to the closest appropriatehospital. Local protocols often govern the destination of particularpatients on the basis of hospital capability.

ALS should always be requested early in the resuscitation of a car-diac arrest victim. ALS providers can offer additional medicationsand other procedures to the patient. If no ALS provider has arrived onthe scene by the time the patient is packaged and ready to go, an inter-cept should be attempted while en route to a hospital.

Postarrest CareAfter the first shock, CPR should be resumed immediately. Pulsechecks, taking no longer than 10 seconds should proceed the nextshock. During a pulse check the EMT should perform a reverse CPRcheck. Start by checking the carotid pulse. If a pulse is detected, thenthe EMT should proceed to checking for breathing.

It is common that for several minutes after a successful defibrilla-tion, and cardiac arrest reversal, the patient will need manual ventila-tion, using a bag-mask-device.

If the patient is breathing adequately, then place the patient on ahigh-concentration oxygen mask and proceed to check the patient’slevel of consciousness.

If the patient remains unconscious and has no evidence of trauma,turn the patient over onto her side in the recovery position. The recoveryposition facilitates drainage of secretions from the mouth and decreasesthe risk of aspiration. The electrodes should be left in place so that defib-rillation may be quickly performed if cardiac arrest should recur.

Ongoing AssessmentDuring transport, the patient should be closely monitored. The ongo-ing assessment should involve continuous monitoring of the breath-ing and pulse. Recurrence of cardiac arrest is not uncommon. Thesooner it is discovered, the more likely the EMT will be successful inreversing it again.

Should pulse and breathing be lost, the patient should again beplaced on her back; everyone should be clear of the patient; and theAED should be allowed to analyze the rhythm.

Field TerminationThere are some circumstances in which resuscitative efforts will notbe indicated. Circumstances in which death is obviously irreversibleare discussed in Chapter 3 and should be reviewed.

In some areas, ALS personnel may have a protocol to terminateresuscitative efforts once they have become futile. Termination isoften done with direct contact with a physician.

Despite the death of the patient, it is important for the EMT tooffer support to the family or friends who are present. Family onscene will need support when the decision is made that the patientis dead.

After death has been declared, the EMT must remember to showrespect for the deceased. Speak to the family, calling the patient by hisor her common name. Use direct language, including the word dead.Do not use terms such as “gone to a better place,” as these leave roomfor misinterpretation.


It is recommended that patientswho weigh less than 25 kilograms(kg) or are under 9 years of agebe defibrillated with a machinethat is specifically designed foruse on children. Typically, asmaller amount of electricity isused and the machine might beprogrammed to respond to elec-trical patterns more commonlyseen in pediatric patients.

While these pediatric-capabledefibrillators are intuitively pre-ferred, recommendations basedupon the available literature con-clude that an adult AED may beused on children older than 1 yearof age if that is the only machine athand. Nonetheless, services thatrespond to a large number of pedi-atric patients might consider main-taining an AED that is specificallyrecommended for this age group.

The AED may be used on chil-dren, starting at age 1 to adult.Pediatric defibrillation pads are pre-ferred, but adult pads may be usedif those are all that are available.

PediatricConsiderations

PediatricConsiderations

This is not the time for morbid humor but a time for reverence.Though humorous situations do sometimes occur at death, leave thelaughter until later.

Be prepared for the family’s reactions to death. Any reaction is pos-sible, from denial to anger and rage to bargaining. These normalbehaviors represent either some way of fleeing the message or fight-ing the messenger. Do not take any behaviors personally.

Senior EMTs or clergy, or both, should be on hand, if possible, todeal with grieving family members. Any death notification is a timefor high emotions and can lead to surprising reactions.

POSTCALLAfter a cardiac arrest call, the EMT needs to document all actions accu-rately on the Patient Care Report (PCR). If CPR was not initiated, therationale for no CPR must be explained. If CPR and the AED were used,then all care surrounding the event must be documented. A readout ofthe AED’s memory or a copy of the tape should be attached to the PCR.

This documentation is generally reviewed by the quality improve-ment committee. A physician is often a part of this committee whencardiac arrest calls are reviewed (Figure 29-18). The committee willreview the call for adherence to protocols as well as for comparisonwith EMS standards. Nationally, EMS strives to have CPR beginwithin 4 minutes, and defibrillation within 8 minutes.

All supplies used during cardiac arrest resuscitation should bereplenished immediately. Supplies typically used include defibrilla-tion electrode pads (with cables) and the cassette tape or module. Thebatteries should be rotated out of service, for recharging, and replacedwith fresh batteries. Use of a checklist can make this process easier.

Competency AssuranceMany EMTs do not have an opportunity to use an AED regularly.However, EMTs are expected to be proficient with the use of an AEDat all times. Therefore, it is important that EMTs practice AED use reg-ularly. A semiannual refresher course in the use of an AED is a mini-mum expectation for many EMTs.

Physician oversight is a very important component to any defibril-lation program. The involvement of a physician in the refreshercourses as well as call reviews can help improve the medical caregiven by the EMT. Physicians are also involved in protocol develop-ment regarding the use of AEDs and resuscitation situations. TheEMT should be familiar with all relevant protocols in his area.

DebriefingA cardiac arrest can be one of the most stressful calls to which an EMTwill respond. In some cases, the EMT may know the patient or thepatient’s family. This personal involvement creates some special stress forthe EMT.

Whenever a patient dies, an EMT will reflect on the care that wasgiven. Concerns about errors that may have been made and questions


It is often useful to the family tohave one person on the crewexplain everything that is goingon with their loved one from thevery beginning of the resuscita-tion. It is not difficult for an EMTto tell the family that their lovedone’s heart is not beating andthat she is not breathing, butwhat they need to hear is thatyou are trying to get the heartrestarted and are providingbreaths for the patient.

These explanations mayhelp the family come to termswith the fact that everything isbeing done, and may also helpthem accept the death, if that isthe outcome.


FIGURE 29-18 Medical control willwant to review the Patient Care Reportwhenever an AED is used by EMTs.

about personal competency surface. It is important that the EMTexplore these questions and resolve them.

A postcall debriefing may help the EMT work through the prob-lems and, more important, improves performance for the next call.

C O N C L U S I O NThe advent of AED technology has improved the chances of survival from pre-hospital cardiac arrest. An EMT, armed with an AED, can provide definitivecare in this critical situation. Combining assessment, AED, and CPR, theEMT can contribute to the successful resuscitation of a victim of cardiac arrest.

T E S T YO U R K N O W L E D G E1. List, in order, the steps of assessment for a patient in cardiac

arrest.2. Why is early defibrillation important?3. What are the indications for the AED?4. Which ECG rhythms are “shockable” and which are

“nonshockable”?5. What is the difference between a fully automatic and a

semiautomatic defibrillator?6. List several safety considerations for the AED.7. List several special conditions when the AED may have

limited use.8. What is the importance of ALS to the care of the cardiac arrest

patient?9. What is the function of the physician in AED practice?

10. What is a debriefing useful for?

I N T E R N E T R E S O U R C E SFor additional resources on cardiac arrest and defibrillation, check outthese Web sites:

• American Heart Association, http://www.americanheart.org• Heart Center Online, http://www.heartcenteronline.com• National Center for Early Defibrillation, http://www.early-

defib.org

F U R T H E R S T U DYThe critical moment. (1997). Journal of Emergency Medical Services,

22(1), supplement.Newman, M. (1998). The chain of survival revisited. Journal of

Emergency Medical Services, 23(5), 46–52.


chapter 29 - brands delmar - cengage learning 29 cardiac arrest key terms all clear artificial...

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