Electrical Treatment for Cardiac Abnormalities

Advanced Paramedic SkillsMary Osinga

Objectives Defibrillation

Theory What gets defibrillated Safety review Placement AED Introduction

Pacing Overview Transcutaneous

Implanted AED’s

Source: Cummins et al., 1991

The AHA Chain of Survival1. Early access to the emergency medical

services (EMS) system

2. Early CPR either by bystanders or first-responder rescuers

3. Early defibrillation by first responders, emergency medical technicians (EMTs), paramedics, or nurses and physicians if they are on the scene

4. Early ACLS

Chain of Survival- Purpose• EARLY ACCESS

– to 911 system. To get medics moving.

• EARLY CPR– to help circulated oxygen to the patient's heart and

brain.

• EARLY DEFIBRILLATION– May be AED on scene, such as health clubs, fd etc– shocks to restore normal heart rhythm.

• EARLY ADVANCED CARE– provided by als or hospital staff.

Source: Weaver et al., 1986

Most survivors of cardiac arrest are from the group of patients . . .

Whose collapse is witnessed by a bystander,

Who receive cardiopulmonary resuscitation (CPR) within 4 to 5 minutes, and

Who receive advanced cardiac life support (ACLS), e.g., defibrillation, intubation, drug therapy, within the first 10 minutes.

Source: American Heart Association, 1994

No CPR 0%-2%surviveDelayed defibrillation

Early CPR 2%-8%surviveDelayed defibrillation

Early CPR 20%survive Early defibrillation

Early CPR 30%survive Very early defibrillation Early ACLS

Survival Rates

Remember….Time is Muscle!

Defibrillation Statistics Defibrillations chances of restoring

a pulse decrease rapidly with time.

1 2 3 4 5 6 7 8 9 10 11Minutes elapsed

AHA says… Most frequent initial rhythm in SCD

is VF ONLY effective treatment is

defibrillation Probability of successful conversion

diminishes over time Speed at which defib shock is

delivery is MAJOR determining factor

Need for Defibrillation? Only put the unit on someone you would

do CPR on... someone who is Unresponsive Not breathing and has NO signs of circulation

or no pulse. I.e do the LOC, ABC’s first

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Always Start with Basics

First paramedic- Assess responsiveness Airway, no air in and out – oral airway in Breathing – none –start bagging Circulation-none- landmark and start CPR

Second Medic Gets out defibrillator, sets up Attaches big pads Works monitor

Ventricular Fibrillation Ventricular fibrillation (VF) is an abnormal

heart rhythm often seen in sudden cardiac arrest.

This rhythm is caused by an abnormal and very fast electrical activity in the heart.

VF is chaotic and unorganized; the heart just quivers and cannot effectively pump blood.

There IS electrical activity but No mechanical pumping

Ventricular Fibrillation VF will be short lived and will

deteriorate to asystole if not treated promptly.

For each minute that VF persists, the likelihood of successful resuscitation decreases by approximately 10 percent.

Ventricular Fibrillation Ventricular fibrillation (VF) is an

abnormal heart rhythm often seen in sudden cardiac arrest.

This rhythm is caused by an abnormal and very fast electrical activity in the heart.

VF is chaotic and unorganized; the heart just quivers and cannot effectively pump blood.

Ventricular Fibrillation

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This rhythm can be coarse or fine, (close to asystole)

Ventricular Tachycardia

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This rhythm is wide complex (greater than…?)

No discernable P or T waves

Defibrillation Theory Definition-the process of passing a

current through the fibrillating heart to depolarize the cells and allow for repolarization by a pacemaker cell

Need to shock a critical mass of myocardium

Otherwise ectopi foci remain fibrillating

Defib theory continued Defibrillator is a capacitor that stores NRG Consists of capacitor, high voltage power

supply and delivery conduits (pads or paddles)

Various waveforms of NRG, such as monophasic and biphasic (less NRG required)

Use predominately DC NRG=Power x duration Joules =watts (not WHAT’s) x Seconds Resistance to defibrillation success are:

Resistance in Chest Wall to J’s Paddle or pad pressure Pad-skin contact (hair etc) Pad-paddle skin surface area Number of previous countershocks

Concept of transthorasic impedance Time of respiratory cycle (ideally

inspiratory)

Success of defibrillation Time from onset of chaotic rhythm Condition of myocardium Heart size and body weight Impedance Pad size Placement Interface Defibrillator working and delivering

proper energy setting

General Considerations Wet patients (drowning etc) Medication patches Implanted pacemakers Young patients Excessive chest hair

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Patient's Clothing The chest should be exposed to

allow placement of the disposable defibrillation electrodes.

Clothes may need to be cut with shears to facilitate early defibrillation.

Defibrillation = Unsynchronized Cardioversion Used exclusively as the definitive

treatment for ventricular fibrillation and pulseless ventricular tachycardia

A energy used to settle a chaotic heart rhythm temporary into asystole, in the hopes that some pacemaker cell in the heart will start an organized rhythm.

Start with 200J, then 300J and 360J

Steps for Defibrillation Ensure pulselessness (longer pulse checks for hypothermic

patients) Hook up either hands-free pads or paddles to chest with gel pads. Start CPR (May do basic airway and vent, but do not delay

defibrillation for these maneuvers) Press Analyze If vfib or pulseless V tach- machine will say “stand clear” monitor charges to preset voltage( to 200 J) ensure no one touching patient including you Defibrillate at 200Joules with LP 12 or other defibrillator Do not touch patient Reanalyze and repeat at higher J settings 300 Reanalyze – still vfib/vtach charge to 360J and press shock Once at 360, stay at that setting.

Defib Pad Placement Attach anterior pad to R shoulder below the clavicle

R of the sternum

Lateral pad is anterior axillary line at the level of the base or apex of heart -ensure good contact- shave if required

Defibrillation

Must be 25 lbs pressure with paddles to ensure good contact and success of defibrillation

Stacked shocks in beginning 200/300/360J are to decrease transthorasic resistance. If you take too long between shock, this is less effective

Can also defib anterior/posterior but more difficult and cumbersome in the VSA patient

AED Standing Order Review

Shockable rhythms

AED Standing Order Review for Non-shockable rhythms Asystole Anything else with no pulse = PEA

or pulseless elctrical activity

Cardioversion= Synchronized

Used for unstable patients in supraventricular and ventricular fast rhythms with a pulse, in order to slow them down

Rhythms like SVT, rapid Afib/flutter, Vtach, PSVT

Pad placement is the same as for defibrillation

ENSURE THAT WHEN YOU DO THIS, YOU PRESS THE ‘SYNC’ BUTTON ON MONITOR!!

Symptomatic Tachyarrhythmias

Look for these signs/symptoms before aggressively electrically treating a patient

There is no rule on which or how many signs a patient needs to have to be treated electrically, use experience and judgement if no patch available

•Chest pain

•Shortness of breath

•Pulmonary edema

•Altered LOC

•Hypotension

•Syncope

•diaphoresis

What does the ‘SYNC” button do?

This identifies the R waves on the ECG and marks them (will see a ‘tag’ on them)

This tells the machine what timing to use in order to identify the absolute refractory period

Do NOT want to cardiovert at this time! What will happen if you do? (if the

machine failed to sense this or worse, YOU failed to press the ‘sync’ button before you shocked?

Find it on your monitor!

!!! This is bad Yes indeedy….you could put them into vfib you took a organized rhythm and shocked

during the absolute refractory period (R on T ) kind of thing and produced a BADDDD thing!

Always double check before shocking that sync is ‘on’

NOTE: most defibs (LP12 included) have an automatic ‘sync’ shutoff in case patients go into vfib anyway. SO make sure you press it in before EACH cardioversion!

Some info for Paramedic Again, defibrillation may be interfered

with by other equipment Notify partner/other helpers of procedure Watch for skin burns Remove NTG patch Ideally, do not have O2 nearby! Ensure everyone clear when you

defib!

Contraindications

No order for it! Severe hypothermia-reduced

algorithm Code 5 Patient Open chest wounds In a wet environment Rule of thumb: If patients says “what are you doing?”

you do not need to defibrillate!

Transcutaneous Pacing

For symptomatic bradycardias examples are anything from sinus bradycardia

(rare) to 2nd degree type I and II and Third degree block

If it needs speeding up, you could potentially pace it.

May also attempt to pace asystole or slow idioventricular VSA if arrest is new and pacer is quickly available

Standby pacing (pads on but not actually pacing) is indicated for patients in 2nd degree Type II or third degree who are stable

Procedure for Pacing Explain to patient what you are doing IV , O2, ECG (and backup airway equipment) Sedate as indicated from BHP Attach pads to patient. Ideally anterior/posterior

(sandwich) is best for contact and success. Anterior pad over left lower hemithorax. Posterior in the subclavicular area with superior margin just below the clavicles. Good contact is essential

Connect cables to LP 12 Set demand (turn pacer to ‘on” set HR (between 60-80) start increasing mA from O until get capture on screen ensure pulse matches monitor add 10 mA to ensure safe zone Check vitals (pulse, BP and mentation) recheck for capture periodically

Community AED’s More and more people trained to

use AED’s, fully automated versions

Know models of defib and know how to get report (what happened?)

Give rescuers good feedback during transfer of care

Where to place AEDs? In a medical clinic (if available). In a reception or common area. Near a fire extinguisher. With a safety response team member. With a security officer. On board an airline jet. AEDs should be visible and easily

accessible.

For Next Week Please read defibrillation and

cardiac monitoring in book ECG monitoring pgs 1206-1271

(hopefully review) Defibrillation pgs 1297-1305 PLEASE READ ABOVE FOR SURE!