Previous lessons dealt with Brady and Tachy arrythmias. Now let’s learn about cardiac arrest.
Cardiac arrest Vs Heart attack
Heart attack and cardiac arrest are different things. A heart attack can lead to cardiac arrest but not all heart attacks will end up in cardiac arrest (Stoppage of heart).
In heart attack, a part of the heart is unable to receive blood supply due to a block in the vessel. This results in weakened heart muscle and pumping goes down. If the area of muscle involved is huge, this can lead to cardiac arrest ultimately if immediate help is not available.
In cardiac arrest, the heart stops pumping blood and as a result you will not be able to feel a pulse on such cardiac arrest victims. If CPR/treatment is not given, the victim will be declared dead soon.
Cardiac arrest rhythms
As part of ACLS course, there are 4 kinds of rhythms that are considered as cardiac arrest. Shockable and non-shockable rhythms differ in the mode of management. Click on the rhythm name to learn about them. Keep reading to learn how to manage cardiac arrest.
- Non-shockable rhythms
- Shockable rhythms
Initial assessment
You should be aware of team dynamics before you learn about the resuscitation part to ensure the team performs well.
First, verify if it’s a cardiac arrest (no pulse) or the victim/patient is just unconscious (has pulse).
If it’s a cardiac arrest, start high quality CPR immediately.
Apply Oxygen from the head end.
Attach a monitor/defibrillator to check the rhythm, which will help you identify it it’s a Shockable or Non-shockable cardiac arrest. For the initial rhythm check, you may stop CPR as soon as monitor is attached. Subsequent rhythm checks occur at 2 minute intervals (5 cycles of compressions + breaths) after stopping CPR. Rhythm check should not be done during active CPR.
Shockable rhythms
If the initial rhythm check reveals a Ventricular Fibrillation (VF) or Pulseless Ventricular Tachycardia (VT), it must be shocked immediately. Don’t wait for the CPR cycle to be over. Shock has a higher priority. If defibrillator or AED is being arranged or being charged, during that period, CPR should go on.
How to deliver a safe shock
- Step1 – Choose maximum energy or device specified energy
- Step2 – Charge the defibrillator
- Step3 – Announce CLEAR, check no one is in contact with the patient and deliver the shock (Not everyone may understand what you mean by CLEAR).
Resume CPR for 2 minutes and establish an IV cannula in the mean time. If you can’t get an IV, try IO line (intra-osseous).
At the end of every 2 minutes, 3 things should occur – Stop Switch Analyze.
- STOP – CPR
- SWITCH – the compressors to avoid fatigue
- ANALYZE – the rhythm on the monitor to see if another shockable rhythm is seen
If monitor shows shockable rhythm, Deliver another shock as done before and resume CPR.
Give 1mg of epinephrine and continue giving Epinephrine every 3-5 minutes as long as you continue CPR (Alternate rhythm check cycle).
At the end of 2 min, repeat Stop – Switch – Analyze.
If a shockable rhythm is seen, deliver another shock and resume CPR.
Give 300mg of Amiodarone the first time and give 150mg for next doses that are given during every alternate rhythm check cycles if shockable rhythm persists.
Instead of Amiodarone, Lidocaine is an alternative drug – First dose 1-1.5mg/kg and next doses 0.5-0.75mg/kg.
Reversible causes
Now is the time to consider reversible causes of cardiac arrest and treat if a cause is found. If you do not treat such causes, you are unlikely to achieve a pulse. Considering reversible cause is not a one time thing. You have to be checking them consistently throughout the resuscitation / code. These are known as 5Hs and 5Ts.
Five Hs
- Hypoxia – Apply oxygen to treat hypoxia. ABG can help find it out.
- Hypo / Hyperkalemia – Measure via a quick ABG and correct potassium as needed.
- Hypovolemia – If it’s a possibility (dehydrated or blood loss cases), connect IV fluids / blood.
- Hydrogen ion excess (Acidosis) – Drugs may not work in acidic environment, correct it as per ABG reading by giving Sodium bicarbonate.
- Hypothermia – Check temperature and correct it. You may need prolonged CPR in hypothermia and Shocks may be ineffective till temperature is corrected.
Five Ts
- Toxins – Ask the attendants for possible intoxication and give the antidote ASAP.
- Tension pneumothorax – Check if one side of chest is over-inflated and air-entry is minimal with AMBU bag ventilation. A quick Ultrasound while bagging can help diagnose (Barcode sign – positive for Pneumo and Sea-shore sign – Negative).
Relieve with a needle (IV cannula) or ICD (Chest tube) placement in the 5th intercostal space just anterior to the mid axillary line. - Tamponade – Cardiac tamponade can prevent the heart refilling and pumping becomes ineffective. 2D Echo can help diagnose (Muffled heart sounds on Stethoscope are difficult to listen in noisy emergency room. The blood from pericardium must be drained to treat it.
- Thrombosis coronary – A blockage in heart blood supply needs to be removed by thrombolysis.
- Thrombosis pulmonary – A massive pulmonary embolism is possible if there was a history of sudden onset shortness of breath before the arrest and the victim has some risk factors like recent prolonged travel, bed ridden status (recent surgeries etc) are present. This also needs thrombolysis.
Non-shockable rhythms
If on rhythm check, if it turns out to be either Asystole or Pulseless electrical activity (PEA), only high quality CPR is needed. No shock is indicated. Just give epinephrine 1mg every alternate cycle (3-5min) and correct any reversible causes (5Hs and 5Ts) as explained above.
A non shockable rhythm can turn into shockable rhythm and vice-versa. Check the rhythm carefully at every 2 minute mark ( STOP SWICTH ANALYZE).
In Asystole, think of flatline protocol
ROSC
Once a pulse is achieved, we call it ROSC – return of spontaneous circulation. You may stop CPR and take measures to avoid re-arrest in the victim by considering reversible causes again. More on this in Post ROSC chapter.