Cardiac Arrest with Anoxic Brain Injury

Cardiac Arrest with Anoxic Brain Injury

Research Paper

        The majority of deaths throughout the world are caused from cardiac arrest. It also plays a huge role in the amount of disability cases worldwide.  An estimated 420, 000 people fall victims of cardiac arrest every year in the United States and eighty percent of those individuals die before receiving hospital care (Bin, Dao-Jie, et al., 2017).

The heart muscle contracts in a certain rhythm which pumps blood throughout the body.  Cardiac arrest can be explained as an electrical problem within the heart which causes an unexpected loss of predicted heart rhythm, or heartbeat. This lack of normal heart rhythm keeps the heart from being able to adequately perfuse the brain, lungs, and other organs.  Cardiac output is the rate at which the heart pumps blood, therefore without a heartbeat, there is no blood flow.  When there is an interference in the rhythm of the heart, a decrease in cardiac output results.  Cardiac arrest quickly results in respiratory arrest and resuscitation includes regaining stable circulation as well as maintaining adequate ventilation and establishing an airway.  It also interferes with perfusion to the brain, which cuts off the brain’s oxygen supply rapidly leading to an unconscious state (WANG, 2016).

Cardiac arrest can result from heart attack, drowning or drug overdose, but it is most commonly the result of arrhythmias.  It usually follows ventricular fibrillation (V-fib), which occurs when nerve impulses used to regulate heartbeat fire in a disorganized manner causing the heart to quiver.  More commonly, V-fib and CA are due to the progressive blockage of the heart arteries, which eventually causes an impedance of blood flow to the heart muscle.  Another underlying cause of CA is ventricular tachycardia (V-tach), which can possibly result in an absent pulse, leading to an unconscious state as well.

        Cardiac arrest is generally easy to recognize and assess.  Signs of cardiac arrest include the sudden collapse of a patient, the absence of a palpable pulse, unresponsiveness, and apnea or abnormal breathing patterns may also be present.  Cardiac arrest generally is more common in the elderly. African Americans are at a higher risk than any other race.  The risk is even further increased if they have other health problems such as, diabetes, hypertension, congestive heart failure (CHF), chronic kidney disease, or any other underlying heart conditions.  Most people that experience cardiac arrest have some degree of coronary artery disease (CAD), but this underlying condition may not be determined until after cardiac arrest occurs.  Patients who have a history of arrhythmias, heart attack, and heart failure have a greater chance of experiencing cardiac arrest.  

        Cardiac arrest is a medical emergency and usually occurs suddenly without warning, therefore doctors diagnose patients with cardiac arrest after it has taken place by eliminating any other possible causes of a person’s sudden collapse.  Doctors eliminate other possible causes by collecting necessary data from certain diagnostic tests given.  A blood test is usually recommended post CA to evaluate electrolyte balance such as, potassium and magnesium, which affect the heart’s electrical signals.  An electrocardiogram (EKG) is always performed after cardiac arrest occurs.  EKGs detect and record the heart’s strength and electrical activity, as well as determining the heart rate and rhythm.  An EKG can also show signs of previous or current heart attack, and also reveal any heart damage due to CAD.  An echocardiography (echo) is an examination that uses sound waves to create pictures of the heart, which identifies the size and shape.   An echo has the ability to assess the function of the heart’s chambers and valves, identifying areas of poor perfusion, decreased contractility, and previous injury to heart muscle. A cardiac MRI can obtain more detailed pictures of the heart actively beating.  It creates both still and moving pictures of the heart and the major vessels to evaluate their structure and function.

        When managing cardiac arrest, the primary goal is reestablishing and maintaining heart and lung function.  Rapid return of circulation is necessary for adequate oxygen delivery to organs and tissues.  Cardiopulmonary resuscitation (CPR) is a vital factor in restoring circulation, and can be attained with prompt, continuous chest compressions. Defibrillation is necessary for survival in cardiac arrest patients due to VF or pulseless VT.  It helps achieve normal heart rhythm by delivering electrical shocks to the heart. Vasopressors and antiarrhythmic drugs are administered during cardiac arrest to assist in restoring circulation.  One of the goals in managing cardiac arrest is to promote systemic vasoconstriction, directing blood flow to the coronary and cerebral circulations.  This can be accomplished by administering vasopressors, such as epinephrine and vasopressin.  Vasopressors are recommended for most cases of pulseless cardiac arrest, including those due to asystole, pulseless electrical activity, and V-fib or V-tach that is not corrected with an initial defibrillation attempt.  Amiodarone, lidocaine, magnesium and atropine are common antiarrhythmic drugs necessary in certain cases that are refractory to defibrillation and vasopressors.