Transcript No Slide Title

Defibrillation and
Cardioversion
Terry White, RN
Defibrillation
Mechanism
 Current
depolarizes myocardium
 Induces asystole temporarily
 Allows one pacemaker to regain
control
Defibrillation
Factors
to consider
 Duration
of VF
The longer VF lasts, the harder it is
to cure
The quicker the better
Shock early-Shock often
Likelihood of resuscitation decreases
7-10% with each passing minute
Defibrillation
Factors
to consider
 Myocardial
environment/condition
Hypoxia, acidosis, hypothermia,
electrolyte imbalance, drug toxicity
impede conversion
Do NOT delay shock trying to
correct problems
Defibrillation
Factors
to consider
 Heart
size/body weight
Pedi requirement lower than adult
– 2 J/kg initial shock
– 4 J/kg repeat shocks
Direct
size/energy relationship in
adults unknown
– 200J bi-phasic or 360 J mono phasic
Defibrillation
 Previous
countershock
Repeated shocks lower resistance
Give one initial shocks in 30-45 sec
Defibrillation
Factors
to consider
 Paddle
size
Adults
(large paddles)
– 10-13 cm diameter
Pediatric
(small paddles usually < 1 yr)
– Children 8 cm
– Infants 4.5 cm
Defibrillation
Use
largest size that completely
contacts chest without paddles
touching
Small
paddles: concentrate current,
burn heart
Large paddles: reduce current
density
Defibrillation
Paddle
 One
placement
to right of sternum below clavicle;
Other to left of left nipple in anterior
axillary line
 Reversing paddles marked “apex-sternum” does NOT affect
defibrillation
 AP placement can be used to defib
small children with adult paddles
Defibrillation
Paddle-skin
 Cream,
interface
paste, saline pads, gelled pads
 Decreases resistance to current flow
 Avoid smearing or running: “bridges”
charge
NEVER use alcohol!!!
Defibrillation
Paddle
 Firm
contact pressure
pressure of 25 pounds
 Deflates lungs; Shortens current path
 Do not lean on paddles; They slip
Cardioversion
Definitions
 Cardioversion
Use
of electrical shock to interrupt
tachycardia
– Used in Non-Arrest patients only
– Only VF/VT (pulseless) can be
defibrillated
Cardioversion
Definitions
 Synchronized
cardioversion
Timing of shock to avoid peak of Twave
Prevents VF caused by delivering
shock during vulnerable period
Cardioversion
Indications
 Tachyarrhythmias
which:
Cause or worsen hemodynamic
compromise
Cause or worsen ischemic heart
disease
Are resistant to drug therapy
Cardioversion
Procedure
 Oxygen,
ECG monitor, IV
 Patient must be on leads to cardiovert
 Sedate with Valium or Versed
Do NOT make patient unresponsive
Cardioversion
Procedure
 Activate
synchronizer
 Observe marking of complexes
 May need to unsynchronize if:
Random synching occurs
Double-synching occurs
Cardioversion
Procedure
 Charge
to desired energy setting
 Depress buttons; Hold until discharge
occurs
 If VF occurs, unsynchronize before
defibrillating
Cardioversion
If a patient is in VF, why might the
defibrillator not discharge if the
synchronizer is on?