Diagnosing Cardiac Arrest

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Acute coronary syndrome is due to cardiac arrest in adults; however, respiratory failure or shock is generally the cause of cardiac arrest in pediatric patients. Because of this, if shock or respiratory failure is successfully managed, cardiac arrest can often be avoided. Ventricular arrhythmia (which occurs suddenly) is the cause of cardiac arrest less than 10 percent of the time.

It is possible to identify and quickly treat a reversible cause of cardiac arrest. Children and infants generally have the same reversible causes as adults.

Reversible Causes of Cardiac Arrest
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 (VFiB)
PULSELESS VENTRICULAR TACHYCARDIA (VTach)

Table 23

Pulseless Electrical Activity and Asystotle

Both pulseless electrical activity (PEA) and asystole are life-threatening and unshockable, making them both related to cardiac rhythm. Represented by a flat-line ECG, the absence of electrical or mechanical cardiac activity is known as asystole. No cardiac electrical activity is perceptible, despite a subtle movement away from baseline (drifting flat-line). Be sure that no technical error is causing a reading of asystole. Ensure that the ECG’s power is on, gain is appropriately set, and that cardiac leads are properly connected. Confirm with two different leads. PEA—thought without a detectable pulse—is one of any number of ECG waveforms (even sinus rhythm). Any pulseless waveform besides asystole, VT, or VF may be included in PEA. Roughly similar to a normal waveform, an agonal rhythm is a waveform that occurs without a pulse, intermittently, and slowly.

Take Note

Asystole and PEA are unshockable rhythms.

Ventricular Fibrillation and Pulseless Ventricular Tachycardia

Life-threatening cardiac rhythms that cause ineffective ventricular contractions are ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT). Instead of a forceful contraction, VF causes a rapid quivering of the ventricles. Atrial contractions are not synchronized with VF’s ventricular motion. Pulseless VT occurs when there is not enough blood being pumped to create a palpable pulse by the rapidly contracting ventricles. Persons are not receiving adequate perfusion in both VF and pulseless VT. Both VF and pulseless VT are shockable rhythms.

Take Note

VF and pulseless VT are shockable rhythms.

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