Advanced cardiac life support

In emergency medicine, advanced cardiac life support is "the use of sophisticated methods and equipment to treat full or impending cardiopulmonary arrest. Advanced Cardiac Life Support (ACLS) includes the use of specialized equipment to maintain the airway, early defibrillation and pharmacological therapy." It is sufficiently resource-intensive that it will not be attempted under most triage systems for mass casualty incidents.

Diagnosis

Basic life support (BLS) recognizes the cessation of heartbeat, but ACLS goes further into differentiating life-threatening cardiac conditions that may not involve a complete stoppage of mechanical or electrical heart activity.

When there is no electrical or mechanical activity, a distinction is made between metabolic and trauma-induced arrest. The treatment of trauma-related arrest is surgical, with possible extension of survival time through fluid replacement. Trauma surgeons often consider arrest caused by blunt damage to be irreversible; it is often associated with cardiac rupture.

Severe bradycardia or tachycardia do not necessarily cause cessation of heartbeat, but remain emergencies requiring intervention that only ACLS can provide.

Pulseless electrical activity is indistinguishable from cardiac arrest in terms of physical signs, but an electrical rhythm is present. In this situation, the problem involves the contractile efficiency of the heart.

Initial treatment

ACLS goes beyond the manual chest compressions and ventilation of basic life support (BLS). BLS increasingly is being extended to include the use of automated external defibrillators, in contrast to ACLS, where defibrillation, along with other external and internal electrical methods, is done based on clinical judgment. There is an increasing consensus that CPR buys time to defibrillate, but, for many cardiac emergencies, defibrillation is a way to buy time for more definitive treatment of the underlying pathology.

A mnemonic for priorities has long been "ABCD":

• Airway
• Breathing
• Circulation
• Defibrillation (or "drugs" or "definitive")

Nevertheless, once the airway is established, circulation receives a higher priority than ventilation, at the basic life support level.

In ACLS, additional techniques, not available to BLS, are used.

Clinical practice guidelines for advanced cardiovascular life support by the American Heart Association provide treatment algorithms. The current guidelines state "Checklists or cognitive aids, such as the AHA algorithms, may be considered for use during actual resuscitation (Class IIb, LOE C)."

• Adult BLS Healthcare Provider Algorithm
• Pulseless Arrest Algorithm
• Bradycardia Algorithm.
• ACLS Tachycardia Algorithm.
  • For regular, wide complex (≥0.12 seconds), adenosine will
    • help if the underlying rhythm is supraventricular tachycardia with aberrant conduction
    • neither help nor hurt if the underlying rhythm is ventricular trachycardia

Airway

In ACLS, the airway is secured using, if necessary, invasive methods such as tracheal intubation or cricothyrotomy.

Ventilation

Artificial respiration may be needed, although, in an ACLS context, this is usually provided by an automatic ventilator or at least a bag-mask manual ventilator rather than mouth-to-mouth resuscitation.

Chest compression

While there are recommendations that BLS which should include chest compressions done for at least 60% of the duration of the period without pulse. The effect of chest compressions may be helped by active compression-decompression with a device such as ResQPOD.

Definitive treatment

Clinical practice guidelines for advanced cardiovascular life support by the American Heart Association provide treatment algorithms:

Pulseless arrest

The first step is determining if there is electrical activity, and, if so, if defibrillation will be beneficial.

• Ventricular fibrillation and ventricular tachycardia: give one shock and resume CPR
• Asystole or pulseless electrical activity: defibrillation will not help; when access is available, administer epinephrine and continue CPR.

Bradycardia

• Bradycardia Algorithm.

Tachycardia

• ACLS Tachycardia Algorithm.

To treat atrial tachycardia, both electrical cardioversion and drug therapy are used. While cardioversion may physically be done with the same machine used for ventricular tachycardia and ventricular fibrillation, the technique is quite different. Where defibrillation overpowers the electrical activity of the heart and "restarts" it, cardioversion detects a signal and fires the electrical impulse to "resynchronize" it.

• For regular, wide complex (≥0.12 seconds), adenosine will
  • help if the underlying rhythm is supraventricular tachycardia with aberrant conduction
  • neither help nor hurt if the underlying rhythm is ventricular trachycardia

Ethical issues

When not to start ACLS

In a particular jurisdiction, this may have legal constraints, or operational ones such as standing orders from the medical director of an emergency medical system (EMS). This kind of emotionally draining decision is apt to be most straightforward when a patien's medical records are readily available and contain an explicit "Do Not Resuscitate" (DNR) or "Do Not Attempt Resuscitation" request from the patient or a surrogate with the appropriate authority.

This can be much more difficult in the field. Most EMS systems have rules for the obvious cases when any life support would be futile, such as decapitation or decomposition. A current controversy deals with certain kinds of trauma, where, variously,

1. With reasonable medical certainty, there is no possibility of resuscitation with all possible resources. Finding a victim who is pulseless and has sustained major blunt chest trauma is the usual example where death is not obvious
2. Studies are ongoing about when ACLS is futile for out-of-hospital arrests.
3. Situations where ACLS will not help, but immediate surgical intervention has some chance. Current thinking is that the appropriate treatment for exsanguinating hemorrhage is not fluids, not ACLS, but immediately opening the chest for manual heart compression and, perhaps, emergency repair or control of a vascular injury. In such a situation, if there is minimal but not absent cardiac activity, and there is a facility nearby prepared for emergency thoracotomy, the ACLS "treat until stable" is less appropriate than "scoop and run".

When to terminate ACLS

A clinical prediction rule suggests advice about stopping ACLS that is in progress.

The Ontario Prehospital Advanced Life Support (OPALS) recommendation is "termination of resuscitation when there was no return of spontaneous circulation prior to transport, no shock was given and the arrest was not witnessed by Emergency Medical Services personnel."