Pulseless electrical activity pathophysiology: Difference between revisions

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{{Pulseless electrical activity}}
{{Pulseless electrical activity}}
{{CMG}}
{{CMG}}; {{AE}} {{KGH}}
==Overview==
PEA( pulseless electrical activity) usually occurs when an insult involves the [[cardiovascular]], [[gastrointestinal]] or the [[respiratory system]]<nowiki/>s. Any such event can lead to decrease in [[cardiac contractility]], and the situation gets even worse by potential [[acidosis]], [[hypoxia]], and worsening [[vagal tone]]. A severe initial insult often reduces [[cardiac output]] which may in turn cause [[myocardial ischemia]], [[left ventricular failure]], [[hypoxia]] and [[metabolic acidosis]].  These [[Pathophysiology|pathophysiologic]] disturbances further reduce [[cardiac output]] further exacerbating the downward spiral with loss of [[cardiac output]], [[hypotension]], [[loss of consciousness]] and [[apnea]] rapidly ensue. Other possible mechanisms for pulseless electrical activity include elevated [[afterload]], [[electromechanical dissociation]], reduced [[contractility]], [[parasympathetic]] theory.
 
==Pathophysiology==
==Pathophysiology==
There is often a downward spiral in the pathophysiology of PEA.  A severe initial insult often reduces [[cardiac output]] which may in turn cause [[myocardial ischemia]], [[left ventricular failure]], [[hypoxia]] and [[metabolic acidosis]]. These pathophysiologic disturbances further reduce cardiac output further exacerbating the downward spiral.  With loss of [[cardiac output]]; [[hypotension]], [[loss of consciousness]] and [[apnea]] rapidly ensue.
Pulseless electrical activity is nothing but the loss of [[cardiac muscle]] to generate adequate force in response to electrical depolarization. It usually occurs when an insult involves the cardiovascular, gastrointestinal or the respiratory systems. Any such event can lead to decrease in cardiac contractility, and the situation gets even worse by potential acidosis, hypoxia, and worsening vagal tone. The more and more the inotropic state of the cardiac muscle gets compromised it leads to insufficient mechanical activity, despite the presence of electrical activity. It causes degeneration of cardiac rhythm, and eventually, death followsRespiratory failure leading to hypoxia is one of the most common causes of pulseless electrical activity. The following are other possible mechanisms for pulseless electrical activity:<ref name="pmid30020721">{{cite journal |vauthors=Oliver TI, Sadiq U, Grossman SA |title= |journal= |volume= |issue= |pages= |date= |pmid=30020721 |doi= |url=}}</ref><ref name="pmid30454005">{{cite journal |vauthors=Saarinen S, Salo A, Boyd J, Laukkanen-Nevala P, Silfvast C, Virkkunen I, Silfvast T |title=Factors determining level of hospital care and its association with outcome after resuscitation from pre-hospital pulseless electrical activity |journal=Scand J Trauma Resusc Emerg Med |volume=26 |issue=1 |pages=98 |date=November 2018 |pmid=30454005 |pmc=6245922 |doi=10.1186/s13049-018-0568-0 |url=}}</ref><ref name="pmid30663992">{{cite journal |vauthors=Weber F, Guha R, Weinberg G, Steinbach F, Gitman M |title=Prolonged Pulseless Electrical Activity Cardiac Arrest After Intranasal Injection of Lidocaine With Epinephrine: A Case Report |journal=A A Pract |volume=12 |issue=11 |pages=438–440 |date=June 2019 |pmid=30663992 |doi=10.1213/XAA.0000000000000962 |url=}}</ref><ref name="pmid30352434">{{cite journal |vauthors=Sillers L, Handley SC, James JR, Foglia EE |title=Pulseless Electrical Activity Complicating Neonatal Resuscitation |journal=Neonatology |volume=115 |issue=2 |pages=95–98 |date=2019 |pmid=30352434 |doi=10.1159/000493357 |url=}}</ref><ref name="pmid23949188">{{cite journal |vauthors=Littmann L, Bustin DJ, Haley MW |title=A simplified and structured teaching tool for the evaluation and management of pulseless electrical activity |journal=Med Princ Pract |volume=23 |issue=1 |pages=1–6 |date=2014 |pmid=23949188 |pmc=5586830 |doi=10.1159/000354195 |url=}}</ref><ref name="pmid26044255">{{cite journal |vauthors=Patil KD, Halperin HR, Becker LB |title=Cardiac arrest: resuscitation and reperfusion |journal=Circ. Res. |volume=116 |issue=12 |pages=2041–9 |date=June 2015 |pmid=26044255 |pmc=5920653 |doi=10.1161/CIRCRESAHA.116.304495 |url=}}</ref><ref name="pmid24297818">{{cite journal |vauthors=Myerburg RJ, Halperin H, Egan DA, Boineau R, Chugh SS, Gillis AM, Goldhaber JI, Lathrop DA, Liu P, Niemann JT, Ornato JP, Sopko G, Van Eyk JE, Walcott GP, Weisfeldt ML, Wright JD, Zipes DP |title=Pulseless electric activity: definition, causes, mechanisms, management, and research priorities for the next decade: report from a National Heart, Lung, and Blood Institute workshop |journal=Circulation |volume=128 |issue=23 |pages=2532–41 |date=December 2013 |pmid=24297818 |doi=10.1161/CIRCULATIONAHA.113.004490 |url=}}</ref>


===Reduced Preload and Inadequate Filling of the Left Ventricle or ===
===Reduced Preload and Inadequate Filling Of the Left Ventricle===
PEA may be due to inadequate filling of the [[left ventricle]] with blood to stretch the cardiac sarcomeres adequately to result in a cardiac contraction (i.e. there is inadequate [[preload]]).  Examples include rapid fluid or [[blood loss]] as occurs in major trauma.  [[Cardiac tamponade]], [[pneumothorax]], and [[pulmonary embolism]] are other examples.
PEA may be due to inadequate filling of the [[left ventricle]] with blood to stretch the cardiac sarcomeres adequately to result in a cardiac contraction (i.e. there is inadequate [[preload]]).  Examples include rapid fluid or [[blood loss]] as occurs in major trauma and ruptured [[aortic aneurysm]].  [[Cardiac tamponade]], [[pneumothorax]], and [[pulmonary embolism]] are other conditions associated with decreased preload, predisposing to PEA.


===Elevated Afterload===
===Elevated Afterload===
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===Electromechanical Dissociation===
===Electromechanical Dissociation===
In some cases, PEA may be caused by electromechanical dissociation. The normal condition when electrical activation of muscle cells precedes mechanical contraction is known as [[electromechanical coupling]]. This coupling is lost in some forms of PEA, and this is known as electromechanical dissociation.
In some cases, PEA may be caused by electromechanical dissociation. The normal condition when electrical activation of muscle cells precedes mechanical contraction is known as [[electromechanical coupling]]. This coupling is lost in some forms of PEA, and this is known as electromechanical dissociation.<ref name="pmid6476549">{{cite journal |vauthors=Ewy GA |title=Defining electromechanical dissociation |journal=Ann Emerg Med |volume=13 |issue=9 Pt 2 |pages=830–2 |date=September 1984 |pmid=6476549 |doi=10.1016/s0196-0644(84)80452-7 |url=}}</ref><ref name="pmid2546234">{{cite journal |vauthors=Aufderheide TP, Thakur RK, Stueven HA, Aprahamian C, Zhu YR, Fark D, Hargarten K, Olson D |title=Electrocardiographic characteristics in EMD |journal=Resuscitation |volume=17 |issue=2 |pages=183–93 |date=April 1989 |pmid=2546234 |doi=10.1016/0300-9572(89)90070-1 |url=}}</ref><ref name="pmid2546233">{{cite journal |vauthors=Stueven HA, Aufderheide T, Waite EM, Mateer JR |title=Electromechanical dissociation: six years prehospital experience |journal=Resuscitation |volume=17 |issue=2 |pages=173–82 |date=April 1989 |pmid=2546233 |doi=10.1016/0300-9572(89)90069-5 |url=}}</ref><ref name="pmid2546235">{{cite journal |vauthors=Stueven HA, Aufderheide T, Thakur RK, Hargarten K, Vanags B |title=Defining electromechanical dissociation: morphologic presentation |journal=Resuscitation |volume=17 |issue=2 |pages=195–203 |date=April 1989 |pmid=2546235 |doi=10.1016/0300-9572(89)90071-3 |url=}}</ref>


===Reduced Contractility===
===Reduced Contractility===
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====Reduced Affinity of Troponin for Calcium====
====Reduced Affinity of Troponin for Calcium====
In the setting of [[hypoxia]], calcium binds less avidly to [[troponin]].
In the setting of [[hypoxia]], calcium binds less avidly to [[troponin]].
It is important to differentiate primary from secondary PEA (postshock PEA) to understand physiology of pure PEA. There were several attempts to try to study the pathophysiology of SCA due to PEA. One of them was inducing PEA by asphyxia, which is not the initial mechanism for the onset of PEA, in other than in a clinical induced scenario. In the case of postshock PEA, there is evidence that electrolyte misbalance can explain the presentation of PEA after defibrillation. Whereas on pure PEA, there are several theories that suggest its pathophysiology.


===Parasympathetic Theory===
===Parasympathetic Theory===


There is a theory suggested by DeBehnke in which a vagotomy was performed after PEA provoked by asphyxia <ref name="pmid24297818">{{cite journal| author=Myerburg RJ, Halperin H, Egan DA, Boineau R, Chugh SS, Gillis AM et al.| title=Pulseless electric activity: definition, causes, mechanisms, management, and research priorities for the next decade: report from a national heart, lung, and blood institute workshop. | journal=Circulation | year= 2013 | volume= 128 | issue= 23 | pages= 2532-41 | pmid=24297818 | doi=10.1161/CIRCULATIONAHA.113.004490 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24297818  }} </ref>. 16 canines were induced by asphyxia until PEA presented <ref name="pmid8239096">{{cite journal| author=DeBehnke DJ| title=Effects of vagal tone on resuscitation from experimental electromechanical dissociation. | journal=Ann Emerg Med | year= 1993 | volume= 22 | issue= 12 | pages= 1789-94 | pmid=8239096 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8239096  }} </ref>. Vagotomy was performed in randomized canines. All of them were managed first with CPR and quemical cardioversion with epinephrine (0.02 mg/kg every five minutes). He found that ROSC was achieved in 13% of canines with no vagotomy, versus a 75% in those with vagotomy (P = .02) <ref name="pmid8489681">{{cite journal| author=DeBehnke DJ| title=Atropine use in electromechanical dissociation. | journal=Am J Emerg Med | year= 1993 | volume= 11 | issue= 3 | pages= 312 | pmid=8489681 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8489681  }} </ref>. There were also performed hemodynamic and arterial blood gas values at 5, 10 and 15 minutes after ROSC with no significant differences between the 16 canines.
There is a theory suggested by DeBehnke in which a [[vagotomy]] was performed after PEA provoked by [[asphyxia]]. [[Vagotomy]] was performed in randomized canines. All of them were managed first with [[CPR]] and chemical cardioversion with [[epinephrine]] (0.02 mg/kg every five minutes). He found that ROSC (Return of Spontaneous Circulation) was achieved in 13% of canines with no [[vagotomy]], versus a 75% in those with [[vagotomy]] (P = .02). There were also performed hemodynamic and arterial blood gas values at 5, 10 and 15 minutes after ROSC with no significant differences between the 16 canines. 16 canines were induced by asphyxia until PEA presented <ref name="pmid8239096">{{cite journal| author=DeBehnke DJ| title=Effects of vagal tone on resuscitation from experimental electromechanical dissociation. | journal=Ann Emerg Med | year= 1993 | volume= 22 | issue= 12 | pages= 1789-94 | pmid=8239096 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8239096  }} </ref><ref name="pmid8489681">{{cite journal| author=DeBehnke DJ| title=Atropine use in electromechanical dissociation. | journal=Am J Emerg Med | year= 1993 | volume= 11 | issue= 3 | pages= 312 | pmid=8489681 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=8489681  }} </ref>.<ref name="pmid24297818">{{cite journal| author=Myerburg RJ, Halperin H, Egan DA, Boineau R, Chugh SS, Gillis AM et al.| title=Pulseless electric activity: definition, causes, mechanisms, management, and research priorities for the next decade: report from a national heart, lung, and blood institute workshop. | journal=Circulation | year= 2013 | volume= 128 | issue= 23 | pages= 2532-41 | pmid=24297818 | doi=10.1161/CIRCULATIONAHA.113.004490 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24297818 }} </ref>.
 
===β Blockers===
 
This theory is based on the suspicion that there has been a coincidence in the increased prevalence of SCA due to PEA, and the use of β blockers for cardiac disease <ref name="pmid21060069">{{cite journal| author=Teodorescu C, Reinier K, Dervan C, Uy-Evanado A, Samara M, Mariani R et al.| title=Factors associated with pulseless electric activity versus ventricular fibrillation: the Oregon sudden unexpected death study. | journal=Circulation | year= 2010 | volume= 122 | issue= 21 | pages= 2116-22 | pmid=21060069 | doi=10.1161/CIRCULATIONAHA.110.966333 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21060069 }} </ref>.


==References==
==References==
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[[Category:Emergency medicine]]
[[Category:Emergency medicine]]
[[Category:Intensive care medicine]]
[[Category:Intensive care medicine]]
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Latest revision as of 15:26, 18 June 2020



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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Karol Gema Hernandez, M.D. [2]

Overview

PEA( pulseless electrical activity) usually occurs when an insult involves the cardiovascular, gastrointestinal or the respiratory systems. Any such event can lead to decrease in cardiac contractility, and the situation gets even worse by potential acidosis, hypoxia, and worsening vagal tone. A severe initial insult often reduces cardiac output which may in turn cause myocardial ischemia, left ventricular failure, hypoxia and metabolic acidosis. These pathophysiologic disturbances further reduce cardiac output further exacerbating the downward spiral with loss of cardiac output, hypotension, loss of consciousness and apnea rapidly ensue. Other possible mechanisms for pulseless electrical activity include elevated afterload, electromechanical dissociation, reduced contractility, parasympathetic theory.

Pathophysiology

Pulseless electrical activity is nothing but the loss of cardiac muscle to generate adequate force in response to electrical depolarization. It usually occurs when an insult involves the cardiovascular, gastrointestinal or the respiratory systems. Any such event can lead to decrease in cardiac contractility, and the situation gets even worse by potential acidosis, hypoxia, and worsening vagal tone. The more and more the inotropic state of the cardiac muscle gets compromised it leads to insufficient mechanical activity, despite the presence of electrical activity. It causes degeneration of cardiac rhythm, and eventually, death follows. Respiratory failure leading to hypoxia is one of the most common causes of pulseless electrical activity. The following are other possible mechanisms for pulseless electrical activity:[1][2][3][4][5][6][7]

Reduced Preload and Inadequate Filling Of the Left Ventricle

PEA may be due to inadequate filling of the left ventricle with blood to stretch the cardiac sarcomeres adequately to result in a cardiac contraction (i.e. there is inadequate preload). Examples include rapid fluid or blood loss as occurs in major trauma and ruptured aortic aneurysm. Cardiac tamponade, pneumothorax, and pulmonary embolism are other conditions associated with decreased preload, predisposing to PEA.

Elevated Afterload

Elevated afterload is rarely a cause of PEA.

Electromechanical Dissociation

In some cases, PEA may be caused by electromechanical dissociation. The normal condition when electrical activation of muscle cells precedes mechanical contraction is known as electromechanical coupling. This coupling is lost in some forms of PEA, and this is known as electromechanical dissociation.[8][9][10][11]

Reduced Contractility

Contraction of the myocardium depends upon the integrity of the troponin subunits.

Reduced Calcium Influx

Calcium binding to troponin is required for contractility. This binding can be reduced in calcium channel blocker overdoses.

Reduced Affinity of Troponin for Calcium

In the setting of hypoxia, calcium binds less avidly to troponin.

Parasympathetic Theory

There is a theory suggested by DeBehnke in which a vagotomy was performed after PEA provoked by asphyxia. Vagotomy was performed in randomized canines. All of them were managed first with CPR and chemical cardioversion with epinephrine (0.02 mg/kg every five minutes). He found that ROSC (Return of Spontaneous Circulation) was achieved in 13% of canines with no vagotomy, versus a 75% in those with vagotomy (P = .02). There were also performed hemodynamic and arterial blood gas values at 5, 10 and 15 minutes after ROSC with no significant differences between the 16 canines. 16 canines were induced by asphyxia until PEA presented [12][13].[7].

References

  1. Oliver TI, Sadiq U, Grossman SA. PMID 30020721. Missing or empty |title= (help)
  2. Saarinen S, Salo A, Boyd J, Laukkanen-Nevala P, Silfvast C, Virkkunen I, Silfvast T (November 2018). "Factors determining level of hospital care and its association with outcome after resuscitation from pre-hospital pulseless electrical activity". Scand J Trauma Resusc Emerg Med. 26 (1): 98. doi:10.1186/s13049-018-0568-0. PMC 6245922. PMID 30454005.
  3. Weber F, Guha R, Weinberg G, Steinbach F, Gitman M (June 2019). "Prolonged Pulseless Electrical Activity Cardiac Arrest After Intranasal Injection of Lidocaine With Epinephrine: A Case Report". A A Pract. 12 (11): 438–440. doi:10.1213/XAA.0000000000000962. PMID 30663992.
  4. Sillers L, Handley SC, James JR, Foglia EE (2019). "Pulseless Electrical Activity Complicating Neonatal Resuscitation". Neonatology. 115 (2): 95–98. doi:10.1159/000493357. PMID 30352434.
  5. Littmann L, Bustin DJ, Haley MW (2014). "A simplified and structured teaching tool for the evaluation and management of pulseless electrical activity". Med Princ Pract. 23 (1): 1–6. doi:10.1159/000354195. PMC 5586830. PMID 23949188.
  6. Patil KD, Halperin HR, Becker LB (June 2015). "Cardiac arrest: resuscitation and reperfusion". Circ. Res. 116 (12): 2041–9. doi:10.1161/CIRCRESAHA.116.304495. PMC 5920653. PMID 26044255.
  7. 7.0 7.1 Myerburg RJ, Halperin H, Egan DA, Boineau R, Chugh SS, Gillis AM, Goldhaber JI, Lathrop DA, Liu P, Niemann JT, Ornato JP, Sopko G, Van Eyk JE, Walcott GP, Weisfeldt ML, Wright JD, Zipes DP (December 2013). "Pulseless electric activity: definition, causes, mechanisms, management, and research priorities for the next decade: report from a National Heart, Lung, and Blood Institute workshop". Circulation. 128 (23): 2532–41. doi:10.1161/CIRCULATIONAHA.113.004490. PMID 24297818.
  8. Ewy GA (September 1984). "Defining electromechanical dissociation". Ann Emerg Med. 13 (9 Pt 2): 830–2. doi:10.1016/s0196-0644(84)80452-7. PMID 6476549.
  9. Aufderheide TP, Thakur RK, Stueven HA, Aprahamian C, Zhu YR, Fark D, Hargarten K, Olson D (April 1989). "Electrocardiographic characteristics in EMD". Resuscitation. 17 (2): 183–93. doi:10.1016/0300-9572(89)90070-1. PMID 2546234.
  10. Stueven HA, Aufderheide T, Waite EM, Mateer JR (April 1989). "Electromechanical dissociation: six years prehospital experience". Resuscitation. 17 (2): 173–82. doi:10.1016/0300-9572(89)90069-5. PMID 2546233.
  11. Stueven HA, Aufderheide T, Thakur RK, Hargarten K, Vanags B (April 1989). "Defining electromechanical dissociation: morphologic presentation". Resuscitation. 17 (2): 195–203. doi:10.1016/0300-9572(89)90071-3. PMID 2546235.
  12. DeBehnke DJ (1993). "Effects of vagal tone on resuscitation from experimental electromechanical dissociation". Ann Emerg Med. 22 (12): 1789–94. PMID 8239096.
  13. DeBehnke DJ (1993). "Atropine use in electromechanical dissociation". Am J Emerg Med. 11 (3): 312. PMID 8489681.

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