Asystole

Asystole is a cardiac arrest accompanied by the disappearance of its electrical activity.

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What causes asystole?

• Operations with increased stimulation of the vagus nerve (eg, gynecological/ophthalmological).
• Initially present complete heart block, second-degree block or trifascicular block.

How does asystole manifest itself?

• There is no electrical activity on the ECG - as a rule, there is a slowly undulating isoline on the monitor.
• The pulse in the main arteries (carotid and femoral) is not palpable.
• Sometimes there is electrical activity in the atria but no electrical activity in the ventricles. This "P-wave asystole" may respond to pacing.

How is asystole recognized?

Electrolytes and urea, blood gases, chest x-ray, ECG.

Differential diagnosis

• Disconnecting the ECG electrode will result in a straight line appearing on the monitor.
• Very low ECG voltage - however, some signs of electrical complexes are usually preserved on the monitor.
• Hypoxia - airway obstruction, esophageal or bronchial intubation, cessation of oxygen supply.
• Hypovolemia - hemorrhagic shock (especially during induction of anesthesia), anaphylaxis.
• Hypo/hyperkalemia and metabolic disorders - renal failure, suxamethonium-induced hyperkalemia in burns.
• Hypothermia - unlikely.
• Tension pneumothorax - especially in patients with trauma or after central venous catheterization.
• Cardiac tamponade - after penetrating trauma.
• Intoxication/therapeutic disorders - following drug overdose (self-inflicted or iatrogenic).
• Thromboembolism is a massive thrombus in the pulmonary artery.

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What to do if there is asystole?

• Stop any surgical procedures that may cause excessive stimulation of the vagus nerve (eg, peritoneal traction).
• Restore airway patency, begin ventilation with 100% oxygen. Intubate - but this should not delay the start of indirect cardiac massage.
• Perform indirect cardiac massage at a rate of 100 per minute, without interrupting it for ventilation.
• Administer atropine intravenously - according to the universal algorithm of extended resuscitation, once in a dose of 3 mg. If asystole was caused by vagus stimulation during surgical intervention, it is advisable to administer atropine fractionally at 0.5 mg.
• If asystole is not resolved immediately after cessation of surgical manipulation or injection of atropine, administer 1 mg of adrenaline. Repeat this dose of adrenaline every 3 minutes until spontaneous circulation is restored.

Further management

• Rule out or treat potentially reversible causes of asystole.
• Rapid infusion of fluids (including blood in case of severe blood loss).
• Complete heart block or Mobitz II second-degree block require pacing. Transvenous pacing may be performed percutaneously until trained personnel with experience in transvenous pacing are available.
• If resuscitation is successful, complete the life-saving portion of the procedure (e.g., stop bleeding). Unless CPR was very brief (say, less than 3 minutes), the patient should remain intubated and transferred to the ICU.
• Perform chest X-ray, 12-lead ECG, blood gas and plasma electrolyte analysis.

Pediatric Features

• In case of asystole in children, resuscitation is based on the same principles.
• Hypoxia is more likely as the underlying cause.

Special considerations

• Asystole associated with excessive vagal stimulation or suxamethonium administration usually resolves spontaneously after the underlying cause has been eliminated. However, atropine (0.5-1 mg) or glycopyrrulate (200-500 mcg) should be administered, and brief cardiac massage may sometimes be required.
• In such cases, follow-up studies are usually not necessary.
• In other cases, the prognosis is poor, with the exception of asystalia caused by a cause that is potentially reversible with immediate intervention.