Recognizing Cardiac Arrest

Unlike cardiac arrest in adults, which is very common due to acute coronary syndrome, cardiac arrest in pediatrics is more commonly the consequence of respiratory failure or shock. Thus, cardiac arrest can often be avoided if respiratory failure or shock is successfully managed. Less than 10% of the time, cardiac arrest is the consequence of ventricular arrhythmia and occurs suddenly. It may be possible to identify a reversible cause of cardiac arrest and treat it quickly. The reversible causes are essentially the same in children and infants as they are in adults.

RECOGNIZE CARDIOPULMONARY FAILURE
THE H’S	THE T’S
Hypovolemia	Tension pneumothorax
Hypoxia	Tamponade
H+ (acidosis)	Toxins
Hypo/Hyperkalemia	Thrombosis (coronary)
Hypoglycemia	Thrombosis (pulmonary)
Hypothermia	Trauma (unrecognized)

Table 21

REVERSIBLE CAUSES OF CARDIAC ARREST
AIRWAY	• May or may not be patent
BREATHING	• Slow breathing • Ineffective breathing
CIRCULATION	• Bradycardia and hypotension • Slow capillary refill • Weak central pulses (carotid) • No peripheral pulses (radial) • Skin mottling/cyanosis/coolness
DISABILITY	• Decreased level of consciousness
EXPOSURE	• Bleeding? • Hypothermia? • Trauma?

Table 22

RECOGNIZE ARREST RHYTHMS
ASYSTOLE
PULSELESS ELECTRICAL ACTIVITY (PEA)
VENTRICULAR FIBRILLATION (V FiB)
PULSELESS VENTRICULAR TACHYCARDIA (VTach)

Table 23

PULSELESS ELECTRICAL ACTIVITY AND ASYSTOTLE

Pulseless electrical activity (PEA) and asystole are related cardiac rhythms in that they are both life-threatening and unshockable. Asystole is the absence of electrical or mechanical cardiac activity and is represented by a flat-line ECG. There may be subtle movement away from baseline (drifting flat-line), but there is no perceptible cardiac electrical activity. Make sure that a reading of asystole is not a technical error. Ensure that the cardiac leads are connected, gain is set appropriately, and the power is on. Check two different leads to confirm. PEA is one of any number of ECG waveforms (even sinus rhythm) but without a detectable pulse. PEA may include any pulseless waveform except VF, VT, or asystole. Asystole may be preceded by an agonal rhythm. An agonal rhythm is a waveform that is roughly similar to a normal waveform but occurs intermittently, slowly, and without a pulse.

PEA and asystole are unshockable rhythms.

VENTRICULAR FIBRILLATION AND PULSELESS VENTRICULAR TACHYCARDIA

Ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) are life-threatening cardiac rhythms that result in ineffective ventricular contractions. VF is a rapid quivering of the ventricles instead of a forceful contraction. The ventricular motion of VF is not synchronized with atrial contractions. Pulseless VT occurs when the rapidly contracting ventricles are not pumping blood sufficiently to create a palpable pulse. In both VF and pulseless VT, victims are not receiving adequate perfusion. VF and pulseless VT are shockable rhythms.