Cardiopulmonary resuscitation and rhythm check

What it is

Cardiac arrest is diagnosed in an adult who is unresponsive with agonal breathing, no pulse or no respirations. CPR is started at once: oxygen is given through a bag valve mask, a defibrillator is attached, and the rhythm is analyzed as soon as possible. Advanced cardiac life support is built around that rhythm check, repeated every 2 minutes for as long as the arrest lasts, because its single question decides the next step.

• Shockable rhythms: ventricular fibrillation and pulseless ventricular tachycardia.
• Nonshockable rhythms: asystole and pulseless electrical activity.

How it is treated

A shockable rhythm is given a shock at an initial dose of 120-200 J: the biphasic dose follows the manufacturer recommendation, and if that is unknown the maximum available is used, with later doses equivalent or higher. Epinephrine follows the second shock and amiodarone or lidocaine the third. For a nonshockable rhythm epinephrine is given as soon as possible instead, then repeated every 3-5 minutes. After either arm CPR is resumed for 2 minutes, then the rhythm is checked again together with signs of ROSC, while IV/IO access is obtained and reversible causes are treated concurrently.

• Epinephrine: 1 mg IV/IO every 3-5 minutes.
• Amiodarone: 300 mg IV/IO once, then 150 mg IV/IO once after 3-5 minutes.
• Lidocaine: 1-1.5 mg/kg IV/IO once, then 0.5-0.75 mg/kg IV/IO once after 3-5 minutes.

Compression quality is itself part of the treatment: push at least 2" at 100-120/min, allow complete chest recoil, minimize interruptions in compressions, avoid excessive ventilation, and rotate the compressor every 2 minutes. Without an advanced airway the compression-ventilation ratio is 30:2; with a supraglottic advanced airway or endotracheal intubation, 10 breaths per minute are given with continuous chest compressions. Quantitative waveform capnography monitors that quality, and a PETCO2 below 10 mm Hg is a call to improve CPR.