Cardiopulmonary resuscitation in adults

The United Kingdom's guidelines on advanced life support for adults were updated in 1997 and endorsed by the European Resuscitation Council in 1998.¹ During 1999 and 2000 the American Heart Association hosted three meetings of international organisations in Dallas to evaluate the evidence on resuscitation. The sets of guidelines that resulted from the international consensus document have a stronger evidence base than their predecessors but have retained their simplicity.²,³

Experts at the Dallas meetings included representatives from the American Heart Association, the European Resuscitation Council, the Heart and Stroke Foundation of Canada, the Australian Resuscitation Council, the New Zealand Resuscitation Council, the Resuscitation Council of Southern Africa, the Latin American Resuscitation Council, and Japan. All aspects of resuscitation were reviewed, and the quality of the evidence supporting each resuscitation intervention was appraised.²,³ The European Resuscitation Council has accepted most of the recommendations from the international consensus document, and its revised guidelines for adults have been summarised in three papers.^4–6 The Resuscitation Council (UK) has adopted the updated European guidelines in their entirety, and these are incorporated into its latest manual for providers of courses on advanced life support.⁷

Lay people will no longer be trained to check for the carotid pulse to confirm cardiac arrest. Several studies have shown that assessment of the carotid pulse by lay people is time consuming and unreliable: their assessment is wrong in up to 50% of cases.⁸ This change in the guidelines is an example of evidence based practice applied to resuscitation. Healthcare professionals will continue to be taught to check the carotid pulse to confirm cardiac arrest. The ratio of chest compressions to ventilations is now 15:2 for both one person and two person cardiopulmonary resuscitation. A ratio of 15:2 provides more chest compressions per minute than a ratio of 5:1. The external cardiac compression rate remains 100 a minute.

Once the trachea has been intubated, chest compressions, at a rate of 100 a minute, should continue uninterrupted (except for defibrillation or pulse checks when indicated), and ventilation should be continued at roughly 12 breaths a minute. A pause in the chest compressions allows the coronary perfusion pressure to fall substantially. When compressions are resumed there is some delay before the original coronary perfusion pressure is restored. Thus, chest compressions without interruption for ventilation result in a substantially higher mean coronary perfusion pressure.⁹ As an extension of this concept, using only compression in cardiopulmonary resuscitation is now advocated as an option in telephone assisted cardiopulmonary resuscitation.¹⁰ This follows evidence that many lay rescuers are reluctant to perform mouth to mouth ventilation and consequently fail to provide any basic life support.¹¹

The new guidelines include the option to use biphasic shocks. In defibrillation, success rates of repeated biphasic shocks at ⩽200 J are the same as or higher than success rates of monophasic waveforms of escalating energy (200 J, 200 J, 360 J).¹²

A number of changes have been made to the recommendations for drug treatment in advanced life support. An intravenous bolus of amiodarone 300 mg should be considered when the patient has ventricular fibrillation or when pulseless ventricular tachycardia does not respond to three shocks (200 J, 200 J, 360 J). Atropine 3 mg is now indicated for pulseless electrical activity (electromechanical dissociation) with a ventricular rate of less than 60 a minute, as well as for asystole. The international guidelines recommend a single intravenous dose of 40 units of vasopressin as an alternative to adrenaline in cases of ventricular fibrillation or pulseless ventricular tachycardia refractory to three initial shocks.²,³ The European Resuscitation Council and the Resuscitation Council (UK) are awaiting further evidence before adopting this recommendation and will continue to recommend epinephrine (adrenaline) 1 mg every three minutes during cardiopulmonary resuscitation. A recent study of cardiac arrests occurring in hospital failed to detect any advantage for survival of vasopressin over epinephrine.¹³ The administration of “high dose” epinephrine (5 mg) and bretylium is no longer recommended

The advanced life support algorithm, which is relatively simple and universal, remains essentially unchanged. The peri-arrest algorithms of the European Resuscitation Council have been modified, and an algorithm dealing specifically with atrial fibrillation has been added. Difficulty in obtaining the raw material for isoprenaline has driven the recommendation of low dose epinephrine as an alternative treatment for symptomatic bradycardias resistant to atropine. Amiodarone is the preferred drug for treating broad complex tachycardias, although lidocaine (lignocaine) remains an alternative. The narrow complex tachycardia algorithm now includes the recommendation of a synchronised direct current shock if the heart rate exceeds 250 beats a minute and the patient has no pulse. The algorithm for the management of atrial fibrillation is complex. Patients are classed as having high, intermediate, or low risk, and the treatment options depend partly on the duration of the atrial fibrillation. The new guidelines are clearly more evidence based. The challenge is to prove their effectiveness in terms of improved outcome for patients in cardiac arrest.