Ventricular Fibrillation, Basic Life Support (BLS) and Advanced Cardiac Life Support (ACLS)

In this article, we will discuss the Ventricular Fibrillation, Basic Life Support (BLS) and Advanced Cardiac Life Support (ACLS). So, let’s get started.

Ventricular Fibrillation

It is a catastrophic arrhythmia characterized by a rapid, irregular, disorganised, ventricular rhythm resulting in lack of cardiac output, absent pulses and unrecordable BP. In the absence of ECG monitoring ventricular fibrillation cannot be distinguished from ventricular asystole because both rhythm disturbances result in clinical cardiac arrest.

Causes

Causes of Ventricular Fibrillation

Diagnosis and Management

On ECG ventricular fibrillation is characterized by very fast (>300/bpm) heart rate with no identifiable waveform of pattern with undulating wavy baseline. Technically it is indistinguishable from cardiac arrest, hence, management is like cardiac arrest with unsynchronized DC shock called defibrillation stock (see below)

Basic Life Support

Basic life support (BLS), popularly known as cardio pulmonary resuscitation (CPR) is meant to maintain organ perfusion until definite interventions can be instituted. The initial and primary element of CPR is to maintain circulation (C), airway (A) and breathing (B).

Circulation (C) is maintained by closed chest compressions by placing one palm of one hand over the lower sternum while other palm resting on the dorsum of lower hand. The sternum is depressed with the arms remaining straight at a rate of 100/min. Sufficient force to depress the sternum (4-5 cm) is used and then released abruptly. Airway (A) is kept patent by tilting the head back and lifting the chin and clearing the respiratory passage. Breathing (B) is maintain either by mouth to mouth or by oropharyngeal airways or masked ambu bag.

Advanced Cardiac Life Support (ACLS)

Advanced Cardiac Life Support aims at:

  • To restore normal cardiac rhythm by different relation when the cause of cardiac arrest is tachyarrhythmias.
  • To restore cardiac output by correcting other reversible causes of cardiac arrest (4Hs and 4Ts).
  • To provide additional support to basic life saving measures by administering intravenous drugs.
  • Intubation with an endotracheal tube to administer positive pressure ventilation.
  • Insertion of intravenous line.

Measures/Actions

If cardiac arrest is witnessed at thumpversion (precordial thump) may sometime convert VF / VT to normal sinus rhythm. It is of no use if the cardiac arrest has lasted longer than few seconds. Start CAB also called ABC of basic life support.

The priority of Advanced Cardiovascular Life Support (ACLS) is to assess basic cardiac rhythm by attaching a defibrillator / monitor. Defibrillation is indicated if VF or pulseless VT is observed on monitor. Defibrillation is started first with 200 Joules, if normal sinus rhythm is not restored within few seconds, then CPR is done at a rate of 100/min for 2 minutes followed by shock of 200 Joules; if unsuccessful, chest compressions continued followed by a third shock of 360 Joules. If all the three shocks remain unsuccessful, then 1mg of adrenaline intravenously plus CPR is continued for full one minute to prepare the patient for next cycle of three shocks each at 360 Joules. If the patient is less than fully conscious on reversion or if 2-3 attempts fail, prompt intubation, ventilation and arterial blood gas analysis should be carried out. Ventilation with oxygen may promptly reverse hypoxemia and acidosis. For acidosis, NaHCO3 may be used. If electro-mechanical dissociation is the cause of cardiac arrest, than it is treated without defibrillation by only maintaining the CPR and treating or correcting the reversible causes of cardiac arrest (4Hs and 4Ts).

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