Editing Cardiac arrest (section)

==Diagnosis==
[[File:Carotidian pulse and recovery position.jpg|thumb|Medical personnel checking the carotid pulse of a simulated patient]]
Cardiac arrest is synonymous with [[clinical death]].<ref name="AHA-2005" /> The physical examination to diagnose cardiac arrest focuses on the absence of a pulse.<ref name="Walls-2017" /> In many cases, lack of a [[pulse|central pulse]] ([[carotid arteries]] or [[subclavian arteries]]) is the [[gold standard (test)|gold standard]]. Lack of a pulse in the periphery (radial/pedal) may also result from other conditions (e.g. [[Shock (circulatory)|shock]]) or be the rescuer's misinterpretation.

Obtaining a thorough history can help inform the potential cause and prognosis.<ref name="Walls-2017" /> The provider taking the person's clinical history should try to learn whether the episode was observed by anyone else, when it happened, what the patient was doing (in particular whether there was any trauma), and whether drugs were involved.<ref name="Walls-2017" />

During resuscitation efforts, continuous monitoring equipment including EKG leads should be attached to the patient so that providers can analyze the electrical activity of the cardiac cycle and use this information to guide the management efforts. EKG readings will help to identify the arrhythmia present and allow the team to monitor any changes that occur with the administration of CPR and defibrillation. Clinicians classify cardiac arrest into "shockable" versus "non-shockable", as determined by the [[Electrocardiogram|EKG]] rhythm. This refers to whether a particular class of [[cardiac dysrhythmia]] is treatable using [[defibrillation]].<ref name="Resuscitation Council" /> The two "shockable" rhythms are [[ventricular fibrillation]] and [[pulseless ventricular tachycardia]], while the two "non-shockable" rhythms are [[asystole]] and [[pulseless electrical activity]].<ref>{{cite book |url=https://books.google.com/books?id=vNgrOsHjIKEC&pg=PA43 |title=ABC of resuscitation |publisher=Wiley-Blackwell |year=2012 |isbn=9781118474853 |veditors=Soar J, Perkins JD, Nolan J |edition=6th |location=Chichester, West Sussex |page=43 |archive-url=https://web.archive.org/web/20170905133735/https://books.google.com/books?id=vNgrOsHjIKEC&pg=PA43 |archive-date=2017-09-05 |url-status=live}}</ref> Moreover, in the post-resuscitation patient, a 12-lead EKG can help identify some causes of cardiac arrest, such as STEMI which may require specific treatments.

[[Emergency ultrasound|Point-of-care ultrasound (POCUS)]] is a tool that can be used to examine the movement of the heart and its force of contraction at the patient's bedside.<ref name="Long-2018">{{cite journal | vauthors = Long B, Alerhand S, Maliel K, Koyfman A | title = Echocardiography in cardiac arrest: An emergency medicine review | journal = The American Journal of Emergency Medicine | volume = 36 | issue = 3 | pages = 488–493 | date = March 2018 | pmid = 29269162 | doi = 10.1016/j.ajem.2017.12.031 | s2cid = 3874849 | doi-access = free }}</ref> POCUS can accurately diagnose cardiac arrest in hospital settings, as well as visualize cardiac wall motion contractions.<ref name="Long-2018" /> Using POCUS, clinicians can have limited, two-dimensional views of different parts of the heart during arrest.<ref name="Paul-2021">{{cite journal | vauthors = Paul JA, Panzer OP | title = Point-of-care Ultrasound in Cardiac Arrest | journal = Anesthesiology | volume = 135 | issue = 3 | pages = 508–519 | date = September 2021 | pmid = 33979442 | doi = 10.1097/ALN.0000000000003811 | s2cid = 234486749 | doi-access = free }}</ref> These images can help clinicians determine whether electrical activity within the heart is pulseless or pseudo-pulseless, as well as help them diagnose the potentially [[#Mnemonic for reversible causes|reversible causes of an arrest]].<ref name="Paul-2021" /> Published guidelines from the [[American Society of Echocardiography]], [[American College of Emergency Physicians]], [[European Resuscitation Council]], and the [[American Heart Association]], as well as the 2018 preoperative [[Advanced cardiac life support|Advanced Cardiac Life Support]] guidelines, have recognized the potential benefits of using POCUS in diagnosing and managing cardiac arrest.<ref name="Paul-2021" />

POCUS can help predict outcomes in resuscitation efforts. Specifically, use of transthoracic ultrasound can be a helpful tool in predicting mortality in cases of cardiac arrest, with a systematic review from 2020 finding that there is a significant positive correlation between presence of cardiac motion and short term survival with CPR.<ref>{{cite journal | vauthors = Kedan I, Ciozda W, Palatinus JA, Palatinus HN, Kimchi A | title = Prognostic value of point-of-care ultrasound during cardiac arrest: a systematic review | journal = Cardiovascular Ultrasound | volume = 18 | issue = 1 | pages = 1 | date = January 2020 | pmid = 31931808 | pmc = 6958750 | doi = 10.1186/s12947-020-0185-8 | doi-access = free }}</ref>

Owing to the inaccuracy diagnosis solely based on central pulse detection, some bodies like the European Resuscitation Council have de-emphasized its importance. Instead, the current guidelines prompt individuals to begin CPR on any unconscious person with absent or abnormal breathing.<ref name="Resuscitation Council" /> The Resuscitation Council in the United Kingdom stands in line with the European Resuscitation Council's recommendations and those of the American Heart Association.<ref name="AHA-2005" /> They have suggested that the technique to check carotid pulses 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 like [[agonal respiration]].<ref name="Resuscitation Council">{{cite web |url=http://www.resus.org.uk/pages/guide.htm |title=Resuscitation Council (UK) Guidelines 2005 |url-status=live |archive-url=https://web.archive.org/web/20091215230632/http://www.resus.org.uk/pages/guide.htm |archive-date=2009-12-15 }}</ref>

Various other methods for detecting circulation and therefore diagnosing cardiac arrest have been proposed. Guidelines following the 2000 International Liaison Committee on Resuscitation recommendations were for rescuers to look for "signs of circulation" but not specifically the pulse.<ref name="AHA-2005" /> These signs included coughing, gasping, color, twitching, and movement.<ref>{{cite book |author=British Red Cross |author2=St Andrew's Ambulance Association |author3=St John Ambulance |title=First Aid Manual: The Authorised Manual of St. John Ambulance, St. Andrew's Ambulance Association, and the British Red Cross |publisher=Dorling Kindersley |year=2006 |isbn=978-1-4053-1573-9 |url-access=registration |url=https://archive.org/details/firstaidmanualau0000unse }}</ref> Per evidence that these guidelines were ineffective, the current International Liaison Committee on Resuscitation recommendation is that cardiac arrest should be diagnosed in all casualties who are unconscious and not breathing normally, a similar protocol to that which the European Resuscitation Council has adopted.<ref name="AHA-2005" /> In a non-acute setting where the patient is expired, diagnosis of cardiac arrest can be done via [[molecular autopsy]] or postmortem molecular testing, which uses a set of molecular techniques to find the ion channels that are cardiac defective.<ref>{{Citation| vauthors = Glatter KA, Chiamvimonvat N, He Y, Chevalier P, Turillazzi E |title=Postmortem Analysis for Inherited Ion Channelopathies|date=2006|work=Essentials of Autopsy Practice: Current Methods and Modern Trends|pages=15–37| veditors = Rutty GN |publisher=Springer|language=en|doi=10.1007/1-84628-026-5_2|isbn=978-1-84628-026-9 }}</ref> This could help elucidate the cause of death in the patient.

Other physical signs or symptoms can help determine the potential cause of the cardiac arrest.<ref name="Walls-2017" /> Below is a chart of the clinical findings and signs/symptoms a person may have and potential causes associated with them.
{| class="wikitable"
|+Physical findings related to potential causes<ref name="Walls-2017" />
!Location
!Findings
!Possible Causes
|-
|General
|[[Pallor|Pale skin]]
|[[Bleeding|Hemorrhage]]
|-
|
|Decreased body temperature
|[[Hypothermia]]
|-
|Airway
|Presence of secretions, vomit, blood
|[[Pulmonary aspiration|Aspiration]]
|-
|
|Inability to provide [[Modes of mechanical ventilation|positive pressure ventilation]]
|[[Pneumothorax|Tension pneumothorax]]
[[Airway obstruction]]
|-
|Neck
|[[Jugular venous pressure|Distension of the neck veins]]
|Tension pneumothorax
[[Cardiac tamponade]]

[[Pulmonary embolism]]
|-
|
|[[Tracheal deviation|Trachea shifted to one side]]
|Tension pneumothorax
|-
|Chest
|[[Median sternotomy|Scar in the middle of the sternum]]
|Cardiac disease
|-
|Lungs
|[[Respiratory sounds|Breath sounds only on one side]]
|Tension pneumothorax
[[Tracheal intubation|Right mainstem intubation]]

Aspiration
|-
|
|No breath sounds or distant breath sounds
|Esophageal intubation

Airway obstruction
|-
|
|[[Wheeze|Wheezing]]
|Aspiration

[[Bronchospasm]]

[[Pulmonary edema]]
|-
|
|[[Crackles|Rales]]
|Aspiration

Pulmonary edema

Pneumonia
|-
|Heart
|Decreased heart sounds
|[[Hypovolemia]]

Cardiac tamponade

Tension pneumothorax

Pulmonary embolus
|-
|Abdomen
|[[Abdominal distension|Distended]] and dull
|Ruptured [[abdominal aortic aneurysm]]

Ruptured [[ectopic pregnancy]]
|-
|
|Distended and [[wikt:tympanic|tympanic]]
|Esophageal intubation
|-
|Rectal
|Blood present
|[[Gastrointestinal bleeding|Gastrointestinal hemorrhage]]
|-
|Extremities
|Asymmetrical pulses
|[[Aortic dissection]]
|-
|Skin
|Needle tracks
|Drug abuse
|}