Editing Pulseless electrical activity

{{Infobox medical condition (new)
| name = Pulseless electrical activity
| synonyms = '''Electromechanical dissociation'''
| image = Pulseless electrical activity EKG.svg
| caption = A drawing of what a rhythm strip showing PEA could look like
| pronounce = 
| field = [[Emergency Medicine]], [[Cardiology]]
| symptoms = Loss of Consciousness, Respiratory Arrest, Sudden death
| complications = [[Death]]
| onset = 
| duration = 
| types = 
| causes = 
| risks = Certain drug overdoses, [[Heart attack]], Chest trauma, [[Pulmonary Embolism]], Hypoxia, [[Hypothermia]], [[Hypokalemia]], [[Hyperkalemia]], [[Hypovolemia]]
| diagnosis = [[Electrocardiogram]]
| differential = [[Cardiac arrest]]
| prevention = 
| treatment = [[Cardiopulmonary Resuscitation]]
| medication = [[Epinephrine]]
| prognosis = Poor (2-5% outside of the hospital)
| frequency = Incidence out-of-hospital: 22% to 30% of cardiac arrest events 
Incidence in-hospital: 35% to 40% of cardiac arrest events
| deaths = 
}}
'''Pulseless electrical activity''' ('''PEA''') is a form of [[cardiac arrest]] in which the [[electrocardiogram]] shows a heart rhythm that should produce a [[pulse]], but does not. Pulseless electrical activity is found initially in about 20% of out-of-hospital cardiac arrests<ref>{{Cite journal |last1=Bergström |first1=Mattias |last2=Schmidbauer |first2=Simon |last3=Herlitz |first3=Johan |last4=Rawshani |first4=Araz |last5=Friberg |first5=Hans |date=December 2018 |title=Pulseless electrical activity is associated with improved survival in out-of-hospital cardiac arrest with initial non-shockable rhythm |url=https://pubmed.ncbi.nlm.nih.gov/30352246/ |journal=Resuscitation |volume=133 |pages=147–152 |doi=10.1016/j.resuscitation.2018.10.018 |issn=1873-1570 |pmid=30352246|s2cid=53025153 }}</ref> and about 50% of in-hospital cardiac arrests.<ref>{{Cite journal |last1=Norvik |first1=A. |last2=Unneland |first2=E. |last3=Bergum |first3=D. |last4=Buckler |first4=D. G. |last5=Bhardwaj |first5=A. |last6=Eftestøl |first6=T. |last7=Aramendi |first7=E. |last8=Nordseth |first8=T. |last9=Abella |first9=B. S. |last10=Kvaløy |first10=J. T. |last11=Skogvoll |first11=E. |date=2022-07-01 |title=Pulseless electrical activity in in-hospital cardiac arrest – A crossroad for decisions |url=https://www.sciencedirect.com/science/article/pii/S0300957222001423 |journal=Resuscitation |language=en |volume=176 |pages=117–124 |doi=10.1016/j.resuscitation.2022.04.024 |pmid=35490937 |hdl=10810/57896 |issn=0300-9572|hdl-access=free }}</ref>

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 insufficient [[cardiac output]] to generate a pulse and supply blood to the organs, whether the heart itself is failing to contract or otherwise.<ref name="2010AHA" /> While PEA is classified as a form of cardiac arrest, significant cardiac output may still be present, which may be determined and best visualized by bedside ultrasound ([[echocardiography]]).

<!-- Treatment and prognosis -->
[[Cardiopulmonary resuscitation]] (CPR) is the first treatment for PEA, while potential underlying causes are identified and treated. The medication [[epinephrine]] (aka adrenaline) may be administered.<ref name="2010AHA" /> Survival is about 20% if the event occurred while the patient was already in the hospital setting.<ref name=Bal2016>{{cite journal|last1=Baldzizhar|first1=A|last2=Manuylova|first2=E|last3=Marchenko|first3=R|last4=Kryvalap|first4=Y|last5=Carey|first5=MG|title=Ventricular Tachycardias: Characteristics and Management.|journal=Critical Care Nursing Clinics of North America|date=September 2016|volume=28|issue=3|pages=317–29|pmid=27484660|doi=10.1016/j.cnc.2016.04.004}}</ref>

==Signs and symptoms==
Pulseless electrical activity leads to a loss of cardiac output, and the blood supply to the [[brain]] is interrupted. As a result, PEA is usually noticed when a person [[Unconsciousness|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.<ref name="2010AHA" />

==Causes==
These possible causes are remembered as the 6 Hs and the 6 Ts.<ref name=ACLS_2003_H_T>{{cite book |author=Mazur, Glen |title=Acls: Principles And Practice |publisher=Amer Heart Assn |location=[Dallas, TX] |year=2003 |pages=71–87 |isbn=0-87493-341-2 }}</ref><ref name=ACLS_2003_EP_HT>{{cite book |author1=Barnes, Thomas Garden |author2=Cummins, Richard O. |author3=Field, John |author4=Hazinski, Mary Fran |title=ACLS for experienced providers |publisher=American Heart Association |location=[Dallas, TX] |year=2003 |pages=[https://archive.org/details/aclsforexperienc00amer_0/page/3 3–5] |isbn=0-87493-424-9 |url-access=registration |url=https://archive.org/details/aclsforexperienc00amer_0/page/3 }}</ref><ref name="ECC_2005_7.2">{{cite journal |author=2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care |title=Part 7.2: Management of Cardiac Arrest |journal=Circulation  |date=December 2005 |volume=112 |issue=24 Suppl |pages=IV 58–66 |doi=10.1161/CIRCULATIONAHA.105.166557 |doi-access=free }}</ref> See [[Hs and Ts]]
* [[Hypovolemia|'''H'''ypovolemia]]
* [[hypoxia (medical)|'''H'''ypoxia]]
* [[Hydrogen|'''H'''ydrogen]] ions ([[Acidosis]])
* [[Hyperkalemia|'''H'''yperkalemia]] or [[Hypokalemia|'''H'''ypokalemia]]
* [[Hypoglycemia|'''H'''ypoglycemia]]
* [[Hypothermia|'''H'''ypothermia]]
* [[Tablet (pharmacy)|'''T'''ablets]] or [[Toxins|'''T'''oxins]]<!--Either-or; no need for {{which}}.-->
* [[Cardiac tamponade|Cardiac '''T'''amponade]]
* [[Tension pneumothorax|'''T'''ension pneumothorax]]
* [[Thrombosis|'''T'''hrombosis]] (e.g., [[myocardial infarction]], [[pulmonary embolism]])
* [[Tachycardia|'''T'''achycardia]]
* [[Physical trauma|'''T'''rauma]] (e.g., [[hypovolemia]] from blood loss)

The possible mechanisms by which the above conditions can cause pulseless in PEA are the same as those recognized as producing circulatory shock states. These are (1) impairment of cardiac filling, (2) impaired pumping effectiveness of the heart, (3) circulatory obstruction and (4) pathological vasodilation causing loss of vascular resistance and excess capacitance. More than one mechanism may be involved in any given case.{{citation needed|date=October 2014}}

==Diagnosis==
[[File:Dissociazione elettromeccanica (PEA).svg|thumb|upright=1.6|Pulseless electrical activity, it is possible to observe by invasive blood pressure (red) the transition from a normal mechanical activity of the heart, which progressively changes in rhythm and contractile quality to [[asystole]], even in the presence of normal electrical activity (green), also confirmed by the pulse oximeter detection even if with artifacts (blue)]]
The absence of a pulse confirms a clinical diagnosis of 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 organised or semi-organised electrical activity in the heart as opposed to asystole (flatline) or to the disorganised  electrical activity of either [[ventricular fibrillation]] or [[ventricular tachycardia]].<ref name="2010AHA" />

==Treatment==
Cardiac resuscitation guidelines (ACLS/BCLS) advise that [[cardiopulmonary resuscitation]] should be initiated promptly to maintain [[cardiac output]] until the PEA can be corrected. 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]].<ref name="2010AHA" /> There is no evidence that external cardiac compression can increase cardiac output in any of the many scenarios of PEA, such as hemorrhage, in which impairment of cardiac filling is the underlying mechanism producing loss of a detectable pulse.{{citation needed|date=October 2014}}

A priority in resuscitation is placement of an intravenous or [[Intraosseous infusion|intraosseous line]] for administration of medications. The mainstay of drug therapy for PEA is [[epinephrine]] (adrenaline) 1&nbsp;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.<ref name="2010AHA">{{cite journal |author=2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care |title=Part 8: Adult Advanced Cardiovascular Life Support|journal=Circulation  |date=November 2010 |volume=122 |issue=18 Suppl |pages=S729–S767 | doi=10.1161/CIRCULATIONAHA.110.970988|pmid=20956224|doi-access=free }}</ref> Epinephrine too has a limited evidence base, and it is recommended on the basis of its mechanism of action.{{citation needed|date=February 2021}}

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 antidepressant overdose]]).<ref name="2010AHA" />

All of these drugs should be administered along with appropriate CPR techniques. [[Defibrillator]]s cannot be used to correct this rhythm, as the problem lies in the response of the myocardial tissue to electrical impulses.{{citation needed|date=February 2021}}

==References==
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== External links ==
{{Medical resources
|  DiseasesDB     = 4166
|  ICD10          = {{ICD10|I|46|9|I|30}}
|  ICD9           = {{ICD9|427.9}}
|  eMedicineSubj  = med
|  eMedicineTopic = 2963
}}
{{Heart diseases}}

[[Category:Cardiac arrhythmia]]
[[Category:Diagnostic emergency medicine]]
[[Category:Medical emergencies]]
[[Category:Medical aspects of death]]
[[Category:Causes of death]]