The rhythm of life

In the  spirit of the groovin 70s  let's talk about the rhythm of life daddy-o, or to be more honest and accurate fatal and non fatal cardiac rhythms!


 Heart rhythms associated with cardiac arrest are divided into two groups:

 shockable rhythms (ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT)) and non-shockable rhythms (asystole and pulseless electrical activity (PEA). 

The main difference in the treatment of these two groups is the need for attempted defibrillation in patients with VF/pVT

Drugs and advanced airways are still included among ALS interventions, but are of secondary importance to early defibrillation and high quality, uninterrupted chest compressions.

Shockable rhythms (VF/pVT)

The first monitored rhythm is VF/pVT in approximately 20% of both in-hospital and out-of-hospital cardiac arrests (OHCAs).

Ventricular fibrillation/pulseless ventricular tachycardia will also occur at some stage during resuscitation in about 25% of cardiac arrests with an initial documented rhythm of asystole or PEA.

Non-shockable rhythms (PEA and asystole)

Pulseless electrical activity (PEA) is defined as cardiac arrest in the presence of electrical activity (other than ventricular tachyarrhythmia) that would normally be associated with a palpable pulse. 

These patients often have some mechanical myocardial contractions, but these are too weak to produce a detectable pulse or blood pressure – this is sometimes described as ‘pseudo-PEA’

. PEA can be caused by reversible conditions that can be treated if they are identified and corrected. Survival following cardiac arrest with asystole or PEA is unlikely unless a reversible cause can be found and treated effectively.


Treatment of shockable rhythms (VF/VT)

  1. Confirm cardiac arrest –  check for signs of life and normal breathing, and if trained to do so check for breathing and a pulse simultaneously.
  2. Call resuscitation team.
  3. Perform uninterrupted chest compressions while applying self-adhesive defibrillation/monitoring pads – one below the right clavicle and the other in the V6 position in the midaxillary line.
  4. Plan actions before pausing CPR for rhythm analysis and communicate these to the team.
  5. Stop chest compressions; confirm VF/pVT from the ECG. This pause in chest compressions should be brief and no longer than 5 seconds.
  6. Resume chest compressions immediately; warn all rescuers other than the individual performing the chest compressions to “stand clear” and remove any oxygen delivery device as appropriate.
  7. The designated person selects the appropriate energy on the defibrillator and presses the charge button. Choose an energy setting of at least 150 J for the first shock, the same or a higher energy for subsequent shocks, or follow the manufacturer’s guidance for the particular defibrillator. If unsure of the correct energy level for a defibrillator choose the highest available energy.
  8. Ensure that the rescuer giving the compressions is the only person touching the patient.
  9. Once the defibrillator is charged and the safety check is complete, tell the rescuer doing the chest compressions to “stand clear”; when clear, give the shock.
  10. After shock delivery immediately restart CPR using a ratio of 30:2, starting with chest compressions. Do not pause to reassess the rhythm or feel for a pulse. The total pause in chest compressions should be brief and no longer than 5 seconds.
  11. Continue CPR for 2 min; the team leader prepares the team for the next pause in CPR.
  12. Pause briefly to check the monitor.
  13. If VF/pVT, repeat steps 6–12 above and deliver a second shock.
  14. If VF/pVT persists, repeat steps 6–8 above and deliver a third shock. Resume chest compressions immediately. Give adrenaline 1 mg IV and amiodarone 300 mg IV while performing a further 2 min CPR. Withhold adrenaline if there are signs of return of spontaneous circulation (ROSC) during CPR.
  15. Repeat this 2 min CPR – rhythm/pulse check – defibrillation sequence if VF/pVT persists.
  16. Give further adrenaline 1 mg IV after alternate shocks (i.e. approximately every 3–5 min).
  17. If organised electrical activity compatible with a cardiac output is seen during a rhythm check, seek evidence of ROSC (check for signs of life, a central pulse and end-tidal CO2 if available).
    1. If there is ROSC, start post-resuscitation care.
    2. If there are no signs of ROSC, continue CPR and switch to the non-shockable algorithm.
  18. If asystole is seen, continue CPR and switch to the nonshockable algorithm.


Treatment of PEA and asystole

  1. Start CPR 30:2
  2. Give adrenaline 1 mg IV as soon as intravascular access is achieved
  3. Continue CPR 30:2 until the airway is secured – then continue chest compressions without pausing during ventilation
  4. Recheck the rhythm after 2 min:
a.    If electrical activity compatible with a pulse is seen, check for a pulse and/or signs of life
i.    If a pulse and/or signs of life are present, start post resuscitation care
ii.    If no pulse and/or no signs of life are present (PEA OR asystole):
  1. Continue CPR
  2. Recheck the rhythm after 2 min and proceed accordingly
  3. Give further adrenaline 1 mg IV every 3–5 min (during alternate 2-min loops of CPR)
b.    If VF/pVT at rhythm check, change to shockable side of algorithm.
Whenever a diagnosis of asystole is made, check the ECG carefully for the presence of P waves because the patient may respond to cardiac pacing when there is ventricular standstill with continuing P waves. There is no value in attempting to pace true asystole.



 Reference:  Resuscitation Council (UK) 2019

Resus Council Adult ALS


 

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