AMP 18: Defibrillation Flashcards
Name 8 reported extra-cardiac causes for Vfib in dogs and cats
- shock
- hypoxemia
- electrolyte disorders
- acid-base disorders
- electrical shock
- excessive sympathetic tone
- hypothermia
- drug reactions
List factors within or outside of the clinicians control that affect impedance to current during defibrillation
Within clinician’s control:
* paddle size
* quality of contact between tissue and paddles
* amount of air inchest (give shock and end-exhalation!)
Outside of clinician’s control:
* absolute amount of air and tissue in the chest
* chest width
Do defibrillators use a direct (DC) or alternating current (AC(?
- direct current
List safety precautions that should be taken to prevent accidental shocking of personnel during defibrillation
- patient should be on a nonconducting surface (E.g., rubber mat)
- no one is touching the patient
- contact gel should not extend beyond the surface of the pad
- warning shout “clear” with sufficient time for personnel to step away
- operator must visually verify that everyone is clear before giving shock
What are risk factors for accidental patient burning during defibrillation
- poor contact –> arcing of electrical current
- isopropyl alcohol used
How commonly does a shockable rhythm occur in in-hospital CPA in dogs and cats?
28% in dogs, 16% in cats (Kass, Haskins, Survival following CPR in dogs and cats, 1992 JVECC)
Fill the gaps:
Survival rates decrease by ——- for each minute the ventricles fibrillate and thus survival approaches zero after —— min of ventricular fibrillation
Survival rates decrease by 7-10% for each minute the ventricles fibrillate and thus survival approaches zero after 10-12 min of ventricular fibrillation
What is “fine ventricular fibrillation”?
form of ventricular fibrillation where the undulations of the baseline are so small that it appears similar to asystole on the ECG
List the steps of internal defibrillation
When attempting cardioversion of VT or SVT, at what phase of the cardiac cycle should the shock occur?
R or S wave
At what phase during the cardiac cycle could attempted cardioversion cause ventricular fibrillation?
during the repolarization process, i.e., during the T wave
When attempting cardioversion of SVT or VT, what energy setting should be used?
for VT half of the energy setting used for defibrillation (i.e., 1-2 J/kg)
for SVT less energy is usually required for successful cardioversion (0.5-1 J/kg)
At what energy dose has defibrillation shown to injury dogs or be lethal in dogs
- injury starts as low as 10 J/kg (median dose required for injury 30 J/kg)
- median lethal dose 470 J/kg
Data from experiments using monophasic defibrillators march 19 9.50am
What energy dose should be used for internal defibrillation in veterinary patients?
10% of the external dose - about 0.2 -0.5J/kg
List drugs that have been shown to increase the defibrillation threshold (i.e., lead to requirement of higher dose for successful defibrillation)
- amiodarone
- lidocaine
- mexiletine
Sotalol and beta-blockers decrease the threshold
less important in biphasic defibrillators though