Medical personnel checking the carotid pulse of a patient Cardiac arrest is synonymous with clinical death. Historical information and a physical exam can diagnose cardiac arrest and provide information regarding the potential cause and the prognosis. The provider taking taking the person's clinical history should aim to determine if the episode was observed by anyone else, what time the episode took place, what the person was doing (in particular if there was any trauma), and if there were involvement of drugs. The physical examination portion of diagnosing cardiac arrest focuses on the absence of a pulse. In many cases, lack of a carotid pulse is the gold standard for diagnosing cardiac arrest. Lack of a pulse in the periphery (radial/pedal) may also result from other conditions (e.g. shock), or simply an error on the part of the rescuer. Studies have shown that rescuers may often make a mistake when checking the carotid pulse in an emergency, whether they are healthcare professionals or lay persons. 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 person experiencing cardiac arrest's bedside. POCUS can accurately diagnose cardiac arrest in hospital settings, overcoming some of the shortcomings of diagnosis through checking the central pulse (carotid arteries or subclavian arteries), as well as detecting movement and contractions of the heart. Using POCUS, clinicians can have limited, two-dimensional views of different parts of the heart during arrest. 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 reversible causes of an arrest. 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 guidelines, have recognized the potential benefits of using POCUS in diagnosing and managing cardiac arrest. Owing to the inaccuracy in this method of diagnosis, some bodies such as the European Resuscitation Council (ERC) have de-emphasised its importance. Instead, the current guidelines prompt individuals to begin CPR on any unconscious person who has absent or abnormal breathing. The Resuscitation Council in the United Kingdom stand in line with the ERC's recommendations and those of the American Heart Association. 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 such as agonal respiration. Various other methods for detecting circulation, and therefore diagnosing cardiac arrest have been proposed. Guidelines following the 2000 International Liaison Committee on Resuscitation (ILCOR) recommendations were for rescuers to look for "signs of circulation", but not specifically the pulse. These signs included coughing, gasping, colour, twitching, and movement. However, in face of evidence that these guidelines were ineffective, the current recommendation of ILCOR is that cardiac arrest should be diagnosed in all casualties who are unconscious and not breathing normally, a similar protocol that of which the European Resuscitation Council has adopted. 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. 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. Below is a chart of the clinical findings and signs/symptoms a person may have and a potential cause associated with it. +Physical findings related to potential causes Location Findings Possible Causes General Pale skin Hemorrhage Decreased body temperature Hypothermia Airway Presence of secretions, vomit, blood Aspiration Inability to provide positive pressure ventilation Tension pneumothorax Airway obstruction Neck Distension of the neck veins Tension pneumothorax Cardiac tamponade Pulmonary embolism Trachea shifted to one side Tension pneumothorax Chest Scar in the middle of the sternum Cardiac disease Lungs Breath sounds only on one side Tension pneumothorax Right mainstem intubation Aspiration No breath sounds or distant breath sounds Esophageal intubation Airway obstruction Wheezing Aspiration Bronchospasm Pulmonary edema Rales Aspiration Pulmonary edema Pneumonia Heart Decreased heart sounds Hypovolemia Cardiac tamponade Tension pneumothorax Pulmonary embolus Abdomen Distended and dull Ruptured abdominal aortic aneurysm Ruptured ectopic pregnancy Distended and tympanic Esophageal intubation Rectal Blood present Gastrointestinal hemorrhage Extremities Asymmetrical pulses Aortic dissection Skin Needle tracks Drug abuse Classifications Clinicians classify cardiac arrest into "shockable" versus "non-shockable", as determined by the EKG rhythm. This refers to whether a particular class of cardiac dysrhythmia is treatable using defibrillation. The two "shockable" rhythms are ventricular fibrillation and pulseless ventricular tachycardia while the two "non-shockable" rhythms are asystole and pulseless electrical activity.
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medical cause of Ventricular fibrillation