Dangers of defibrillation to patient & operator

1. Patient

a) Paddle burn to skin

i) Gel may form arc on skin

ii) Poor electrode contact with reduced surface area & increased current density

b) Myocardial cell damage

i) Too much current can cause damage to the myocardium that is not thermal in nature

ii) Damage to cell membrane & contractile structure may lead to depressed function, necrosis, persistent arrest or single cell fibrillation

iii) Reflected by persistent ST-T segment changes, elevated cardiac enzymes,

iv) Therefore overdose of current may result in failure to defibrillate

v) There exists a therapeutic window for effective defibrillation

c) Pulmonary oedema

i) Secondary to electrical depression of left ventricular function

d) Arrhythmia (better than norrhythmia!)

e) Internal paddles

i) Should be wet with saline

ii) Electrodes with non insulated backs should be positioned so not to contact other tissue

2. Operator

a) Shock

i) Gel on hands contacting electrode

ii) Touching electrode[paddle]

iii) Contact with patient

iv) Standing on water, reduced resistance to ground (in older defibrillatory devices)

3. Environment

a) Fire & explosion if used in presence of oxygen

4. Equipment

a) Certain electromedical equipment may be damaged if not disconnected from patient prior to defibrillation

b) Manufactures generally have protected internal pacemaker circuits however charge may be shunted to myocardium via pacing electrodes resulting in endocardial burns & loss of effective pacing

i) Place paddles away from pacemaker

ii) Disconnect external pacemaker

c) Disconnect diathermy

5. Prevention of tissue damage

a) Use minimum energy levels

b) Enough gel or saline to cover paddles but not too much to cause arcing

c) Multiple low-energy shocks cause less cardiac damage than a few high-energy shocks