Cardiac Arrest Flashcards
What is a cardiac arrest?
Arrest in the activity of the heart - stood beating
No contraction of the heart muscle, BUT there may still be electrical activity in the heart
What is PEA?
Most common cause?
Pulseless electrical activity
No contraction, but still electrical activity in the heart
any electrical activity that appears on an ECG like it should be producing a pulse, but it is not
Most common cause is hypovolemia
What is an irreversible consequence of cardiac arrest?
Irreversible brain damage can occur after <5 minutes of cardiac arrest
What are the reversible causes of cardiac arrest?
5 H’s and 4 T’s
H’s:
- Hypoxia
- Hypovolemia
- Hypokalaemia, (Hypoglycemia, Hypocalcemia, Acidemia and other metabolic disorders)
- Hyperkalaemia
- Hypothermia
T’s:
- Tension pneumothorax
- Tamponade (cardiac)
- Toxins
- Thrombosis (coronary or pulmonary)
What are reversible causes added to the list for pregnant patients?
Eclampsia
Intracranial haemorrhage
What is the prognosis of a cardiac arrest?
Medical emergency, poor prognosis
Out of hospital arrest has a survival rate of 2-8%
In hospital cardiac arrest has a 1-year survival rate of about 15%.
How does defibrillation work?
When you pass a large current through the heart, you can completely depolarise it. After this time, there will be a period of asystole, hopefully after which normal sinus mechanisms will restore sinus rhythm to the heart.
Defibrillators deliver a high-voltage, short duration DC shock, via two metal pads (coated in conducting gel or jelly) placed on the chest.
Where should the defibrillator pads be placed?
upper right sternal edge and the apex.
What is the difference between defibrillation vs cardioversion?
Defibrillation - unsynchronised shock given to the heart
Cardioversion - synchronised shock given to the heart (at a specific time in the ECG)
What can happen if you give a shock around the peak of the T wave?
You can induce unusual and dangerous rhythms eg. AF or VTach
When is a synchronised shock usually given?
Around 0.02s after the peak of the R wave
What can be said about shocks given in ventricular fibrillation?
Timing of the impulse/shock is not important
What is the initial management of cardiac arrest?
- On finding an unconscious individual - three SSS’s
- Safety - safe to approach?
- Shake - “are you alright?” while shaking their shoulder
- Shout - if pt responds, do ABCDE assessment. If doesn’t respond, shout for help and put out a cardiac arrest call. - Open airway with head tilt/chin lift manoeuvre (jaw thrust if risk of c-spine injury), palpate carotid, listen and feel for breathing for 10 seconds
- No pulse or no signs of life - begin CPR, 30:2 compressions:ventilation, to lower half of sternum to depth of 5-6cm at a rate of 100 per minute
Ventilation applied via bag-valve-mask (BVM)
- Attach defibrillator pads and pause CRP to analyse the rhythm - further management depends on whether rhythm is shockable or not
What are shockable rhythms?
Ventricular fibrillation
Pulseless Ventricular Tachycardia
What are Non-shockable rhythms?
PEA - pulseless electrical activity
Asystole - no rhythm present
How are shockable rhythms managed?
VF or Pulseless VT
- As individuals to stand clear and remove any oxygen delivery devices. After charged, deliver 1 shock with defibrillator
- Immediately resume CPR for 2 mins
- Assess rhythm - if shockable, resume compressions immediately. charge defibrillator again and deliver second shock. then do CPR for 2 mins.
Repeat until third shock
- After third shock, give adrenaline 1mg IV (10 ml of 1:10,000) and Amiodarone 300mg IV
Continue giving adrenaline after alternate shocks ie fifth, seventh, ninth, eleventh etc
- If organised electrical activity seen during rhythm check (step 3) - seek evidence of return of spontaneous circulation (ROSC)
- If present, commence post-resuscitation care
- If absent, resume CPR immediately and switch to non-shockable rhythm algorithm - If systole noticed at any point, switch to non-shockable algorithm
How are non-shockable rhythms managed?
Systole or PEA
- On recognition - resume chest compressions immediately for 2 mins
- On recognising organised electrical activity, seek evidence of ROSC and if absent (PEA), resume chest compressions immediately for 2 minutes
- After first rhythm check, give adrenaline 1 mg IV (10 ml of 1:10,000)
- After two minutes, pause CPR to check the rhythm; on recognising asystole, resume chest compressions immediately and continue for 2 minutes; on recognising organised electrical activity, seek evidence of ROSC and if absent (PEA), resume chest compressions immediately and continue for 2 minutes
Repeat until third rhythm check
- After 3rd rhythm check, given adrenaline 1 mg IV (10 ml of 1:10,000); continue giving adrenaline after alternate rhythm checks i.e. 5th, 7th, 9th etc
- If shockable rhythm is identified during a rhythm check, switch to the shockable algorithm but continue giving adrenaline after alternate rhythm checks: do not withhold until after the third shock
What is the defibrillator usually charged to?
150J
When is cardioversion usually used?
Often pre-planned
Used to treat significant, but not immediately life-threatening arrhythmias eg. narrow complex tachycardias, AF, Atrial flutter
Do patients receive sedation in cardioversion?
Emergency - pt usually unconscious due to cariogenic shock, so no anaesthesia given
Awake / planned - pt may get sedation to make tx more tolerable
What are contraindications and complications?
Digoxin - increases risk of arrhythmias after cardioversion, so in elective cases this is withheld for 24hrs before tx
Systemic embolus risk increased in pts with longstanding atrial arrhythmias who get elective cardioversion – these pts given 4 weeks anticoagulant therapy either before/after cardioversion
What are the main points of ALS?
Chest compressions
Defibrillation
Drug delivery
Adrenaline
Amiodarone
Thrombolytic Drugs
Chest compressions as part of ALS
- Ratio of chest compressions to ventilation is 30:2
- Chest compressions are continued while defibrillator is charged
Defibrillation in ALS
- Single shock for VF/pulseless VT followed by 2 minutes of CPR
- If cardiac arrest is witnessed in a monitored patients (eg. in a coronary care unit), give up to 3 successive (stacked) shocks (rather than 1 shock) followed by CPR
Drug delivery in ALS
1st line - attempt IV access
If IV access can’t be obtained - Intraosseous route (IO)
What is no longer recommended in terms of delivery of drugs?
Delivery via tracheal tube