Cardiac Arrest

Definition

Definition of Cardiac Arrest
Cardiac arrest, also known as cardiopulmonary arrest or circulatory arrest, is the abrupt cessation of normal circulation of the blood due to failure of the heart to contract effectively during systole.

Cardiac arrest is different from (but may be caused by) a heart attack (myocardial infarction), where blood flow to the still-beating heart is interrupted (as in cardiogenic shock).

Arrested blood circulation prevents delivery of oxygen to ''all'' parts of the body. Cerebral hypoxia, or lack of oxygen supply to the brain, causes victims to lose consciousness and to stop normal breathing, although agonal breathing may still occur. Brain injury is likely if cardiac arrest is untreated for more than five minutes, although new treatments such as induced hypothermia have begun to extend this time. To improve survival and neurological recovery immediate response is paramount.

Symptoms

Symptoms of Cardiac Arrest
Cardiac arrest is an abrupt cessation of pump function in the heart (as evidenced by the absence of a palpable pulse). Prompt intervention can usually reverse a cardiac arrest, but without such intervention it will almost always lead to death. In certain cases, it is an expected outcome to a serious illness.

However, due to inadequate cerebral perfusion, the patient will be unconscious and will have stopped breathing. The main diagnostic criterion to diagnose a cardiac arrest, (as opposed to respiratory arrest which shares many of the same features), is lack of circulation, however there are a number of ways of determining this. Near death experiences are reported by 10-20% of people who survived cardiac arrest.

Causes

Causes of Cardiac Arrest
Coronary heart disease is the leading cause of sudden cardiac arrest. Many other cardiac and non-cardiac conditions also increase ones risk.

"Hs and Ts" is the name for a mnemonic used to aid in remembering the possible treatable or reversible causes of cardiac arrest.

Hs
Hypovolemia - A lack of blood volume
Hypoxia - A lack of oxygen
Hydrogen ions (Acidosis) - An abnormal pH in the body
Hyperkalemia or Hypokalemia - Both excess and inadequate potassium can be life-threatening.
Hypothermia - A low core body temperature
Hypoglycemia or Hyperglycemia - Low or high blood glucose

Ts
Tablets or Toxins
Cardiac Tamponade - Fluid building around the heart
Tension pneumothorax - A collapsed lung
Thrombosis (Myocardial infarction) - Heart attack
Thromboembolism (Pulmonary embolism) - A blood clot in the lung
Trauma

Diagnosis

Diagnosis of Cardiac Arrest
A cardiac arrest is usually diagnosed clinically by the absence of a pulse. In many cases lack of carotid pulse is the gold standard for diagnosing cardiac arrest, but lack of a pulse (particularly in the peripheral pulses) may be a result of other conditions (e.g. shock), or simply an error on the part of the rescuer. Studies have shown that rescuers often make a mistake when checking the carotid pulse in an emergency, whether they are healthcare professionals or lay persons.

Owing to the inaccuracy in this method of diagnosis, some bodies such as the European Resuscitation Council (ERC) have de-emphasised its importance. The Resuscitation Council (UK), in line with the ERC's recommendations and those of the American Heart Association, have suggested that the technique should be used only by healthcare professionals with specific training and expertise, and even then that it should be viewed in conjunction with other indicators such as agonal respiration.

Treatment

Treatment of Cardiac Arrest
Sudden cardiac arrest may be treated via attempts at resuscitation. This is usually carried out based upon basic life support (BLS) / advanced cardiac life support (ACLS), pediatric advanced life support (PALS) or neonatal resuscitation program (NRP) guidelines. Several organisations promote the idea of a "chain of survival". The chain consists of the following "links":

Early recognition - If possible, recognition of illness before the patient develops a cardiac arrest will allow the rescuer to prevent its occurrence. Early recognition that a cardiac arrest has occurred is key to survival - for every minute a patient stays in cardiac arrest, their chances of survival drop by roughly 10%.
Early CPR - improves the flow of blood and of oxygen to vital organs - an essential component of treating a cardiac arrest. In particular, by keeping the brain supplied with oxygenated blood, chances of neurological damage are decreased.
Early defibrillation - is effective for the management of ventricular fibrillation and pulseless ventricular tachycardia If defibrillation is delayed the rhythm is likely to degenerate into asystole for which outcomes are worse.
Early advanced care - Early Advanced Cardiac Life Support is the final link in the chain of survival.

Prognosis

Prognosis of Cardiac Arrest
With positive outcomes following cardiac arrest unlikely, an effort has been spent in finding effective strategies to prevent cardiac arrest. With the prime causes of cardiac arrest being ischemic heart disease, efforts to promote a healthy diet, exercise, and smoking cessation are important. For people at risk of heart disease, measures such as blood pressure control, cholesterol lowering, and other medico-therapeutic interventions are used.

Prevention

Prevention of Cardiac Arrest
Consult with your doctor.