chapter 4 Flashcards by Stephanie Santoro

What are the three electrical therapies that can be used for the management of a cardiac emergency?

Defibrillation, synchronized cardioversion, transcutaneous pacing

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what are the two ways to perform defibrillation?

Automated external defibrillator (AED) or a manual defibrillator

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what are the indications for defibrillation?

pulseless monomorphic VT, sustained polymorphic VT and VF

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What is the term for the delivery of an electrical current across the heart muscle over a very brief period to terminate and abnormal heart rhythm and which the current has no relationship to the cardiac cycle?

Defibrillation

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what are the benefits of combination pads?

combination pads can be used for defibrillation, synchronized cardioversion and in some cases pacing. they also physically separate the operator from the patient

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what’s the equation for energy?

Energy (joules) = current (amperes) x voltage (volts) x time (s)

it’s the current that delivers the energy to the patient and depolarize the myocardium

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what is transthoracic impedance?

Impedance is the resistance to the flow of current so transthoracic is the natural resistance of the chest wall to the flow of current
measured in ohms

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What are some of the factors known to affect transthoracic impedance?

body tissue and hair

note that when biphasic waveform defibrillation is used, the body weight of the patient does NOT influence the energy delivered

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what patients should use adult paddles or pads?

Patients that weigh more than 10 kg (22 lb) - generally older than 1 year

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how much space should be separating the pads?

1 inch in between the pads (3 cm)

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T or F: you should use alcohol, tincture of benzoin or antiperspirant when preparing the skin for paddle or pad placement

FALSE!

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What is the typical paddle or pad position used during resuscitation for the sternum-apex position?

Sternum-apex position

also called: anteriolateral or apex-anterior position

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Where do the L and R paddles get placed?

Right paddle - placed lateral tot he right side of the patient’s sternum, just below the clavicle

left paddle - left midaxillary line, lateral to the patient’s left nipple

do NOT put the paddle directly on the breast as it results in higher transthoracic impedance and will reduce current flow

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What energy level should you use with a monophasic defibrillator?

360 J

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If you are using hand help paddles for adult defibrillation, how much pressure should you use?

firm downward pressure about 25 pounds

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if defibrillation successfully terminates pulseless VT/VF but the rhythm recurs, what energy level should you defibrillate at?

Defibrillate at the last energy level used that resulted in successful defibrillation

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Where should you place the pads if a patient has an ICD or pacemaker?

At least 3 inches (8 cm) from the pulse generator

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What is an external defibrillator with a computerized cardiac rhythm analysis system called?

Automated External Defibrillator

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What is the preferred defibrillation method for infants?

Manual defibrillator is preferred for infants. if a manual defibrillator isn’t available an AED with a pediatric attenuator is desirable

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what should you do while the AED is analyzing the patient’s cardiac rhythm?

All movement (including chest compressions, artificial ventilations and the movement associated with patient transport) must stop

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what’s the general operation for an AED?

turn on the power
attach the device
analyze the rhythm
deliver a shock if indicated and safe

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What’s up with precipitation and using an AED?

If a patient is lying on snow or ice the AED can be used.

If a patient is lying in water or is covered with water it may be reasonable to remove them from the water and dry the chest before attempting defibrillation

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what is the type of electrical therapy during which a shock is timed or programmed for delivery during ventricular depolarization?

synchronized cardioversion

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When does synchronized cardioversion deliver its shock?

a few milliseconds after the R wave deflection or the QS deflection

This is why synchronized cardioversion isn’t used for rhythms that are disorganized or don’t have a clearly identifiable QRS complex

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What are the indications for synchronized cardioversion?

- unstable atrial fibrillation - unstable atrial flutter - unstable monomorphic VT - unstable narrow-QRS tachycardia

If a synchronized cardioversion produces a VF and the patient has no pulse, what should you do?

Defibrillate!

How far away should oxygen sources be placed before you cardiovert or defibrillate a patient?

At least 3.5 to 4 feet away from the patients chest examples: masks, nasal cannulae, resuscitation bags and ventilator tubing

What is transcutaneous pacing?

TCP is the use of electrical stimulation through pacing pads positioned on a patient's torso to stimulate contraction of the heart.

What is the stimulating current selected for TCP measured in?

milliamperes

what are the indications for TCP?

symptomatic bradycardias unresponsive to atropine therapy or when atropine is not immediately available or indicated

what should you set the initial rate at in an adult when using a TCP?

60-80 bpm

what is mechanical capture when using a TCP?

Mechanical capture occurs when pacing produces a response that can be measured, like a palpable pulse and blood pressure Assess this by assessing the patients right upper extremity or right femoral pulses AVOID using the neck pulses or the patients left side

what is electrical capture when using a TCP?

usually seen in the form of a wide QRS and a broad T wave

What is the main limitation of TCP?

Patient discomfort Discomfort is proportional to the intensity of skeletal muscle contraction and the direct electrical stimulation of cutaneous nerves

What is failure to capture that can occur with TCP?

the inability of a pacemaker stimulus to depolarize the myocardium it's recognized on the EKC by visible pacemaker spikes that are not followed by P waves or QRS complexes

what is failure to sense that can occur with TCP?

Failure to sense occurs when the pacemaker fails to recognize spontaneous myocardial depolarization can result in "R-on-T phenomenon" which can precipitate VF or VT

With what rhythms do use defibrillation and what are the recommended energy levels?

Rhythms: Pulseless VT/VF, Sustained polymorphic VT Energy levels: varies depending on the device used the biphasic defibrillator effective dose is typically 120-200 J - if the effective dose is unknown consider using the maximal dose If using a monophasic defibrillator use 360 J for all shocks

What electrical therapy do you use with unstable narrow-QRS tachycardia and what is the recommended energy levels?

The biphasic dose is typically 50 J to 100J initially, increase in a stepwise fashion if the initial shock fails

What electrical therapy do you use with unstable atrial flutter and what is the recommended energy levels?

The biphasic dose is typically 50 J to 100J initially, increase in a stepwise fashion if the initial shock fails

What electrical therapy do you use with unstable atrial fibrillation and what is the recommended energy levels?

The biphasic dose is typically 120 J to 200 J initially, increase in a stepwise fashion if the initial shock fails begin with 200 J if using monophasic energy and increase if unsuccessful

What electrical therapy do you use with unstable monomorphic VT and what is the recommended energy levels?

The biphasic dose is typically 100 J initially, it's reasonable to increase in a stepwise fashion if the initial shock fails

What type of electrical therapy should you use with symptomatic bradycardia and what are the recommended energy levels?

Transcutaneous pacing Set the initial rate between 60 and 80 bpm increased currten (output/mA) until pacer spires are visible before each QRS complex. verify electrical and mechanical capture Final mA setting should be slightly above (about 2 mA) where capture is obtained to help prevent loss of capture

What is the purpose of defibrillation?

The purpose is to deliver a uniform electrical current of sufficient intensity to depolarize myocardial cells (including fibrillating cells) a the same time briefly stunning the heart. this provides an opportunity for the hearts natural pacemakers to resume normal activity

List three indications for defibrillation

Sustained polymorphic VT pulseless VT VF

Explain the difference between manual defibrillation and automated external defibrillation?

Manual defibrillation refers to the placement of paddles or pads on a patients chest, interpretation of the patients cardiac rhythm by a trained healthcare professional and the healthcare professionals decision to deliver a shock Automated external defibrillation refers tot he placement of paddles or pads on a patient's chest and interpretation of the patient's cardiac rhythm by the defibrillators computerized analysis system the machine will then either deliver a shock or tell you to !

Name four possibilities to consider if the cardiac monitor displays a flat line

no power, loose leads, true asystole, unplugged cables, no connection to the patient, and no connection to the defibrillator/monitor

Where is the pulse generator of an implantable cardioverter defibrillator typically located?

an ICD is usually located subcutaneously in the LUQ of the patients abdomen or left pectoral region.

An 80 yo M experienced a cardiac arrest. The monitor displays VF. you have exposed the patients chest and are preparing to defibrillate when you notice the patient has a permanent pacemaker in place. what distance from the pacemaker generator should the defibrillator paddles or pads be placed?

Be careful not to place the defibrillator paddles or combination pads directly over the device. Ideally place them at least 3 inches (8 cm) from the pulse generator

What are the four main steps in the operation of an AED?

Turn on the power attach the device analyze the rhythm deliver a shock if indicated and safe

you just delivered a synchronized shock with 50 J to an unstable patient whose cardiac monitor shows AV nodal reentrant tachycardia. THe cardiac monitor now shows VF. what course of action should be taken at this time?

If the rhythm changes to VF after synchronized cardioversion, confirm that the patient has no pulse while another team member quickly verifies that all electrodes and cable connections are secure, turn off the sync control, and defibrillate

when does synchronized cardioversion deliver a shock?

during the QRS complex

A 68 yo m is complaining of chest pain. his level of responsiveness if rapidly decreasing. BP 50/P, P 188 amd R 6. the cardiac monitor reveals a narrow QRS tachycardia at 320 bpm whats the best course of action?

Sedate and perform synchronized cardioversion with 120 J

A 49 yo M is found unresponsive, not breathing and pulseless, the cardiac monitor reveals monomorphic VT. the most important actions in the management of this patient are what?

CPR and defibrillation

A 75 yo M is on the telemetry floor recovering from an inferior wall MI. the nursing staff arrive in the patients room in response to an alarm from his cardiac monitor which reveals a sinus bradycardia at 40 bpm. patient is unresponsive, apneic and pulseless. an IV is in place you should now...

Begin CPR, ventilate with a bag mask and give epinephrine IV

A 73 yo W is complaining of palpitations and chest pain. her BP is 72/50, P 188, R 16. the cardiac monitor reveals a wide-QRS tachycardia. your best course of action?

Perform synchronized cardioversion with 100 J

recommended initial biphasic energy for monomorphic VT with pulses

synchronized cardioversion with 100 J

When a ____ waveform is used for defibrillation, current passes through the heart in one direction

Monophasic

resistance tot he flow of current

Impedance

Another name for sternum-apex paddle or pad position

anterolateral

During pacing, assessment of ____ capture requires assessment of the patients pulse

mechanical capture

Unstable polymorphic ventricular tachycardia (with or without pulses) should be treated with?

Defibrillation

The energy selected for defibrillation or cardioversion is indicated in?

Joules

The recommended monophasic energy for ventricular fibrillation?

defibrillation with 360 J

Failure to ____ is the inability of a pacemaker stimulus to depolarize the myocardium

capture

Recommended initial biphasic energy for atrial fibrillation?

synchronized cardioversion with 120 J to 200 J

failure to ____ is a pacemaker malfunction that occurs when the pacemaker fails to deliver an electrical stimulus or when it fails to deliver the correct number of electrical stimulations per minute

Pace

when a ____ waveform is used for defibrillation, current passes through the heart in two phases

biphasic

during pacing, assessment of ____ capture requires observation of the cardiac monitor

electrical

The energy selected for transcutaneous pacing is indicated in?

milliamperes

Recommended initial biphasic energy for unstable narrow-QRS tachycardia?

synchronized cardioversion with 50 J to 100 J

Failure to ____ occurs when the pacemaker fails to recognize spontaneous myocardial depolarization

sense