Defibrillation and Defibrillation and Cardioversion Cardioversion EMS Professions EMS Professions Temple College Temple College
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Defibrillation andDefibrillation and
CardioversionCardioversion
EMS Professions EMS ProfessionsTemple CollegeTemple College
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DefibrillationDefibrillation
MechanismMechanism
Current depolarizes myocardiumCurrent depolarizes myocardium
Induces asystole temporarilyInduces asystole temporarily
Allows one pacemaker to regainAllows one pacemaker to regain
controlcontrol
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DefibrillationDefibrillation
Factors to considerFactors to consider
Duration of VFDuration of VF
The longer VF lasts, the harder it isThe longer VF lasts, the harder it isto cureto cure
The quicker the betterThe quicker the better
Shock earlyShock early--Shock oftenShock oftenLikelihood of resuscitation decreasesLikelihood of resuscitation decreases
77--10% with each passing minute10% with each passing minute
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DefibrillationDefibrillation
Factors to considerFactors to consider
Myocardial environment/conditionMyocardial environment/conditionHypoxia, acidosis, hypothermia,Hypoxia, acidosis, hypothermia,
electrolyte imbalance, drug toxicityelectrolyte imbalance, drug toxicity
impede conversionimpede conversion
DoDo NOTNOT delay shock trying todelay shock trying to
correct problemscorrect problems
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DefibrillationDefibrillation
Factors to considerFactors to consider
Heart size/body weightHeart size/body weight
Pedi requirement lower than adultPedi requirement lower than adult
± ± 2 J/kg initial shock 2 J/kg initial shock
± ± 4 J/kg repeat shocks4 J/kg repeat shocks
Direct size/energy relationship inDirect size/energy relationship in
adults unknownadults unknown
²² 200 to 360 J200 to 360 J
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DefibrillationDefibrillationPrevious countershock Previous countershock
Repeated shocks lower resistanceRepeated shocks lower resistance
Give three initial shocks in 30Give three initial shocks in 30--45 sec45 sec²² One quickly after another with little time betweenOne quickly after another with little time between
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DefibrillationDefibrillation
Factors to considerFactors to consider
Paddle sizePaddle size
Adults (large paddles)Adults (large paddles)²² 1010--13 cm diameter13 cm diameter
Pediatric (small paddles usually < 1 yr)Pediatric (small paddles usually < 1 yr)
± ± Children 8 cmChildren 8 cm
± ± Infants 4.5 cmInfants 4.5 cm
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DefibrillationDefibrillationUse largest size that completelyUse largest size that completely
contacts chest without paddlescontacts chest without paddles
touchingtouching
Small paddles: concentrate current,Small paddles: concentrate current,
burn heartburn heart
Large paddles: reduce currentLarge paddles: reduce currentdensitydensity
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DefibrillationDefibrillation
Paddle placementPaddle placement
One to right of sternum below clavicle;One to right of sternum below clavicle;
Other to left of left nipple in anteriorOther to left of left nipple in anterior
axillary lineaxillary line
Reversing paddles marked ³apexReversing paddles marked ³apex----
sternum´ does NOT affectsternum´ does NOT affect
defibrillationdefibrillationAP placement can be used to defibAP placement can be used to defib
small children with adult paddlessmall children with adult paddles
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DefibrillationDefibrillation
PaddlePaddle--skin interfaceskin interface
Cream, paste, saline pads, gelled padsCream, paste, saline pads, gelled padsDecreases resistance to current flowDecreases resistance to current flow
Avoid smearing or running: ³bridges´Avoid smearing or running: ³bridges´
chargechargeNEVER use alcohol!!!NEVER use alcohol!!!
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DefibrillationDefibrillation
Paddle contact pressurePaddle contact pressure
Firm pressure of 25 poundsFirm pressure of 25 pounds
Deflates lungs; Shortens current pathDeflates lungs; Shortens current path
Do not lean on paddles; They slipDo not lean on paddles; They slip
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CardioversionCardioversion
DefinitionsDefinitions
CardioversionCardioversion
Use of electrical shock to interruptUse of electrical shock to interrupttachycardiatachycardia
²² Used in NonUsed in Non--Arrest patients onlyArrest patients only
²² Only VF/VT (pulseless) can beOnly VF/VT (pulseless) can bedefibrillateddefibrillated
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CardioversionCardioversion
DefinitionsDefinitions
Synchronized cardioversionSynchronized cardioversion
Timing of shock to avoid peak of TTiming of shock to avoid peak of T--
wavewave
Prevents VF caused by deliveringPrevents VF caused by delivering
shock during vulnerable periodshock during vulnerable period
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CardioversionCardioversionIndicationsIndications
Tachyarrhythmias which:Tachyarrhythmias which:
Cause or worsen hemodynamicCause or worsen hemodynamic
compromisecompromise
Cause or worsen ischemic heartCause or worsen ischemic heart
diseasedisease
Are resistant to drug therapyAre resistant to drug therapy
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CardioversionCardioversion
ProcedureProcedure
Oxygen, ECG monitor, IVOxygen, ECG monitor, IVPatient must be on leads to cardiovertPatient must be on leads to cardiovert
Sedate with Valium or VersedSedate with Valium or Versed
Do NOT make patient unresponsiveDo NOT make patient unresponsive
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CardioversionCardioversion
ProcedureProcedure
Activate synchronizerActivate synchronizer
Observe marking of complexesObserve marking of complexesMay need to unsynchronize if:May need to unsynchronize if:
Random synching occursRandom synching occurs
DoubleDouble--synching occurssynching occurs
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CardioversionCardioversion
ProcedureProcedure
Charge to desired energy settingCharge to desired energy setting
Depress buttons; Hold until dischargeDepress buttons; Hold until dischargeoccursoccurs
If VF occurs, unsynchronize beforeIf VF occurs, unsynchronize before
defibrillatingdefibrillating
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CardioversionCardioversion
If a patient is in VF, why might theIf a patient is in VF, why might the
defibrillator not discharge if thedefibrillator not discharge if the
synchronizer is on?synchronizer is on?