Pulseless electrical activity
Encyclopedia
Pulseless electrical activity or PEA (also known by the older terms electromechanical dissociation) refers a cardiac arrest
situation in which a heart rhythm is observed on the electrocardiogram
that should be producing a pulse
, but is not. Under normal circumstances, electrical activation of muscle cells precedes mechanical contraction of the heart (known as electromechanical coupling). In PEA, there is electrical activity, but the heart either does not contract or there are other reasons why this results in an insufficient cardiac output
to generate a pulse and supply blood to the major organs.
Cardiopulmonary resuscitation
is the first treatment for PEA, while potential underlying causes are identified and treated. Various drugs may be administered.
is interrupted. As a result, PEA is usually noticed because a person loses consciousness
and stops breathing
spontaneously. This is confirmed by examining the airway
for obstruction, observing the chest for respiratory movement, and feeling the pulse
(usually at the carotid artery
) for a period of 10 seconds.
), but not compatible with either ventricular fibrillation
or ventricular tachycardia
.
is initiated immediately, although this may not take place if there has been a decision not to resuscitate
. The approach in treatment of PEA is to treat the underlying cause, if known (e.g. relieving a tension pneumothorax). Where an underlying cause for PEA cannot be determined and/or reversed, the treatment of pulseless electrical activity is similar to that for asystole
.
The mainstay of drug therapy for PEA is epinephrine
1 mg every 3–5 minutes. Although previously the use of atropine
was recommended in the treatment of PEA/asystole, this recommendation was withdrawn in 2010 by the American Heart Association due to lack of evidence for therapeutic benefit.
Sodium bicarbonate 1meq per kilogram may be considered in this rhythm as well, although there is little evidence to support this practice. Its routine use is not recommended for patients in this context, except in special situations (e.g. preexisting metabolic acidosis, hyperkalemia, tricyclic antidepressants overdose).
All of these drugs should be administered along with appropriate CPR techniques. Defibrillators are not used for this rhythm, as the problem lies in the response of the myocardial tissue to electrical impulses.
Cardiac arrest
Cardiac arrest, is the cessation of normal circulation of the blood due to failure of the heart to contract effectively...
situation in which a heart rhythm is observed on the electrocardiogram
Electrocardiogram
Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...
that should be producing a pulse
Pulse
In medicine, one's pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck , at the wrist , behind the knee , on the inside of the elbow , and near the...
, but is not. Under normal circumstances, electrical activation of muscle cells precedes mechanical contraction of the heart (known as electromechanical coupling). In PEA, there is electrical activity, but the heart either does not contract or there are other reasons why this results in an insufficient cardiac output
Cardiac output
Cardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min...
to generate a pulse and supply blood to the major organs.
Cardiopulmonary resuscitation
Cardiopulmonary resuscitation
Cardiopulmonary resuscitation is an emergency procedure which is performed in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person in cardiac arrest. It is indicated in those who are unresponsive...
is the first treatment for PEA, while potential underlying causes are identified and treated. Various drugs may be administered.
Signs and symptoms
Pulseless electrical activity leads to a loss of cardiac output, and the blood supply to the brainBrain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
is interrupted. As a result, PEA is usually noticed because a person loses consciousness
Unconsciousness
Unconsciousness is the condition of being not conscious—in a mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is a type of unconsciousness. Fainting due to a drop in blood pressure and a...
and stops breathing
Breathing
Breathing is the process that moves air in and out of the lungs. Aerobic organisms require oxygen to release energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose. Breathing is only one process that delivers oxygen to where it is needed in the body and...
spontaneously. This is confirmed by examining the airway
Airway
The pulmonary airway comprises those parts of the respiratory system through which air flows, conceptually beginning at the nose and mouth, and terminating in the alveoli...
for obstruction, observing the chest for respiratory movement, and feeling the pulse
Pulse
In medicine, one's pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck , at the wrist , behind the knee , on the inside of the elbow , and near the...
(usually at the carotid artery
Carotid artery
Carotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...
) for a period of 10 seconds.
Causes
These possible causes are remembered as the 6 Hs and the 6 Ts.- HypovolemiaHypovolemiaIn physiology and medicine, hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma...
- HypoxiaHypoxia (medical)Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
- HydrogenHydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
ions (AcidosisAcidosisAcidosis is an increased acidity in the blood and other body tissue . If not further qualified, it usually refers to acidity of the blood plasma....
) - HyperkalemiaHyperkalemiaHyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...
or HypokalemiaHypokalemiaHypokalemia or hypokalaemia , also hypopotassemia or hypopotassaemia , refers to the condition in which the concentration of potassium in the blood is low... - HypoglycemiaHypoglycemiaHypoglycemia or hypoglycæmia is the medical term for a state produced by a lower than normal level of blood glucose. The term literally means "under-sweet blood"...
- HypothermiaHypothermiaHypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
- Tablets or Toxins (Drug overdoseDrug overdoseThe term drug overdose describes the ingestion or application of a drug or other substance in quantities greater than are recommended or generally practiced...
) - Cardiac TamponadeCardiac tamponadeCardiac tamponade, also known as pericardial tamponade, is an emergency condition in which fluid accumulates in the pericardium ....
- Tension pneumothorax
- ThrombosisThrombosisThrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
(Myocardial infarctionMyocardial infarctionMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
) - ThrombosisThrombosisThrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
(Pulmonary embolismPulmonary embolismPulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...
) - TraumaPhysical traumaTrauma refers to "a body wound or shock produced by sudden physical injury, as from violence or accident." It can also be described as "a physical wound or injury, such as a fracture or blow." Major trauma can result in secondary complications such as circulatory shock, respiratory failure and death...
(HypovolemiaHypovolemiaIn physiology and medicine, hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma...
from blood loss)
Diagnosis
The absence of a pulse confirms cardiac arrest, but PEA can only be distinguished from other causes of cardiac arrest with a device capable of electrocardiography (ECG/EKG). In PEA, there is electrical activity in the heart (as opposed to asystoleAsystole
In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow...
), but not compatible with either ventricular fibrillation
Ventricular fibrillation
Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Ventricular fibrillation is a medical emergency and most commonly identified arrythmia in cardiac arrest...
or ventricular tachycardia
Ventricular tachycardia
Ventricular tachycardia is a tachycardia, or fast heart rhythm, that originates in one of the ventricles of the heart...
.
Treatment
Cardiopulmonary resuscitationCardiopulmonary resuscitation
Cardiopulmonary resuscitation is an emergency procedure which is performed in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person in cardiac arrest. It is indicated in those who are unresponsive...
is initiated immediately, although this may not take place if there has been a decision not to resuscitate
Do not resuscitate
In medicine, a "do not resuscitate" or "DNR" is a legal order written either in the hospital or on a legal form to respect the wishes of a patient to not undergo CPR or advanced cardiac life support if their heart were to stop or they were to stop breathing...
. The approach in treatment of PEA is to treat the underlying cause, if known (e.g. relieving a tension pneumothorax). Where an underlying cause for PEA cannot be determined and/or reversed, the treatment of pulseless electrical activity is similar to that for asystole
Asystole
In medicine, asystole is a state of no cardiac electrical activity, hence no contractions of the myocardium and no cardiac output or blood flow...
.
The mainstay of drug therapy for PEA is epinephrine
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...
1 mg every 3–5 minutes. Although previously the use of atropine
Atropine
Atropine is a naturally occurring tropane alkaloid extracted from deadly nightshade , Jimson weed , mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a drug with a wide variety of effects...
was recommended in the treatment of PEA/asystole, this recommendation was withdrawn in 2010 by the American Heart Association due to lack of evidence for therapeutic benefit.
Sodium bicarbonate 1meq per kilogram may be considered in this rhythm as well, although there is little evidence to support this practice. Its routine use is not recommended for patients in this context, except in special situations (e.g. preexisting metabolic acidosis, hyperkalemia, tricyclic antidepressants overdose).
All of these drugs should be administered along with appropriate CPR techniques. Defibrillators are not used for this rhythm, as the problem lies in the response of the myocardial tissue to electrical impulses.