History

Fact Explanation
Sudden loss of consciousness Cardiac arrest is the sudden and complete cessation of cardiac output which is a medical emergency.[1] Loss of consciousness is due to disrupted blood supply to the brain. The most common causes are catastrophic arrhythmias or mechanical causes such as cardiac rupture or aortic dissection. Ventricular fibrillation, ventricular tachycardia and asystole are arrhythmias that can lead to cardiac arrest. Pulse-less electrical activity is the absence of cardiac output in spite of normal electrical activity in the heart.[2] Causes include cardiac tamponade, pulmonary thrombosis, hypovolaemia etc.
Cessation of normal breathing Breathing usually continues for sometime after cessation of cardiac function. Agonal breathing describes the labored breathing or gasping associated with cardiac arrest.[3]
History of previous cardiac disease. Various cardiac diseases such as coronary artery disease, cardiomyopathies, valvular heart disease etc can lead to cardiac arrest and sudden cardiac death. Coronary heart disease is a common cause of cardiac arrest and the patient may have a history of chest pain, previous myocardial infarction and previous cardiac arrest. Risk factors for cardiac disease such as diabetes mellitus, smoking, hypertension, hyperlipidaemia etc may also be present.[4]
References
  1. COLLEDGE N.R, WALKER B.R, RALSTON S.H ed. Davidson's principles and practice of medicine. 21st ed. London, CHURCHILL LIVINGSTONE, 2010. ch 18, pg 1034.
  2. KUMAR P, CLARK M ed. Kumar and Clark's Clinical medicine. 7th ed. Edinburgh, Saunders Elsevier, 2009. ch 13, pg 759-760.
  3. REA TD. Agonal respirations during cardiac arrest. Curr Opin Crit Care [online] 2005 Jun, 11(3):188-91 [viewed 16 September 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/15928464
  4. HODGETTS TJ, KENWARD G, VLACHONIKOLIS IG, PAYNE S, CASTLE N. The identification of risk factors for cardiac arrest and formulation of activation criteria to alert a medical emergency team. Resuscitation [online] 2002 Aug, 54(2):125-31 [viewed 16 September 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/12161291

Examination

Fact Explanation
Examination should be meticulous and rapid. Initiation of patient resuscitation is the main priority in cardiac arrest. Resuscitation should be prompt and started inn the out-hospital setting.[1] Maintaining adequate cerebral perfusion prevents cerebral ischemia and damage. Use the A- airway, B- breathing, C- circulation approach when examining the patient.
Cardiovascular examination – Inability to feel the pulse, No blood pressure recording Lack of cardiac output will lead to absence of pulse and unrecordable blood pressure. It is important to note that examination of patient and investigations should not delay the initiation of emergency resuscitation.[1]
Respiratory examination - Absence of spontaneous breathing Look, listen and feel for spontaneous breathing.[1]
References
  1. KELLUM MJ, KENNEDY KW, EWY GA. Cardiocerebral resuscitation improves survival of patients with out-of-hospital cardiac arrest. Am J Med [online] 2006 Apr, 119(4):335-40 [viewed 16 September 2014] Available from: doi:10.1016/j.amjmed.2005.11.014

Differential Diagnoses

Fact Explanation
Hypovolaemic shock Hypovolaemic shock is the generalized state of low tissue perfusion due to reduced circulating volume. The cause may be due to profound hemorrhage or non-hemorrhagic causes such as severe dehydration, prolonged vomiting, third spacing of body fluids etc.[1] The patient presentation depends on the degree of fluid loss which is graded into 4 grades. Patients with a 40-50% reduction in blood volume(grade 4 shock) present with reduced level of consciousness/ coma, cold pale peripheries, tachypnea, low blood pressure, prolonged capillary refilling time and profound tachycardia. The diagnosis is clinical and requires immediate fluid resuscitation.
Cardiogenic shock Cardiogenic shock is the occurrence of low cardiac output due to primary failure of the heart to pump out blood. Causes include massive myocardial infarction, cardiac arrhythmia, myocardial injury etc.[2] Myocardial depression due to drugs, infective agents may also cause cardiogenic shock. The presentation is similar with hypovolaemic shock with the addition of features of venous hypertension.
Cardiac arrhythmia Cardiac arrhythmia are a common cause of cardiac arrest. The most commonly associated arrhythmia are ventricular fibrillation and ventricular tachycardia. In ventricular fibrillation ventricular contractions are in-coordinated with no mechanical gain. In ventricular tachycardia the rapid ventricular rate will lead to reduced ventricular filling.[3] Diagnosis is by assessing the cardiac rhythm.
Cardiac tamponade/ Tension pneumothorax In these conditions the preload of the ventricles is reduced due to obstruction to blood flow. Cardiac tamponade will result when there is accumulation of blood with the pericardial space. Kinking of the great vessels will result in tension pneumothorax due to mediastenal shift.[4] Both these conditions can develop after thoracic trauma. Tension pneumothorax is a clinical diagnosis which needs immediate decompression by needle thoracocentesis. Diagnosis of tamponade is difficult since other typical features are masked by the cardiac arrest. Transthoracic echocardiography may aid in diagnosis. Management is usually with thoracotomy.
Massive pulmonary thrombus A thrombus lodged in the main pulmonary trunk will obstruct blood flow to the lungs leading to reduced preload to the left ventricle. Pulmonary thrombosis is usually an embolus from the lower limbs. Look for risk factors for deep vein thrombosis. The patient may complain of leg pain and swelling. Diagnosis can be arrrived at using a ventilation-perfusion graph of the lungs.[5]
References
  1. KUMAR P, CLARK M ed. Kumar and Clark's Clinical medicine. 7th ed. Edinburgh, Saunders Elsevier, 2009. ch 13, pg 759-760.
  2. WILLIAMS N.S, BULSTRODE C.J.K, O'CONNELL P.R ed. Bailey and Love's short practice of surgery. 25th ed. London, Edward arnold, 2008. ch 2, pg 14-15.
  3. KOPLAN BA, STEVENSON WG. Ventricular Tachycardia and Sudden Cardiac Death Mayo Clin Proc [online] 2009 Mar, 84(3):289-297 [viewed 16 September 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2664600
  4. BARTON ED. Tension pneumothorax. Curr Opin Pulm Med [online] 1999 Jul, 5(4):269-74 [viewed 13 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/10407699
  5. British Thoracic Society guidelines for the management of suspected acute pulmonary embolism Thorax [online] 2003 Jun, 58(6):470-483 [viewed 13 June 2014] Available from: doi:10.1136/thorax.58.6.470

Investigations - for Diagnosis

Fact Explanation
The diagnosis is clinical Make a quick assessment of the unresponsive patient to check the pulse and breathing. Once suspected quickly start cardiopulmonary resuscitation (CPR) without delaying for other investigations.[1]
Serum electrolytes Metabolic changes such as hyper/hypo-kalaemia may lead to cardiac arrest.[2]
Arterial blood gas analysis (ABG) Cardiac arrest will lead to the development of metabolic acidosis due to lactic acidosis. Degree of ventilation may causes changes in this. ABG can also be used to monitor the pH and PaCO2 which correlate with coronary perfusion pressure and cardiac output.[3]
References
  1. Adult advanced life support. Resuscitation Council (UK). 2010 [Viewed on 11 June 2014]. Available from : https://www.resus.org.uk/pages/als.pdf
  2. SOAR JASMEET, PERKINS GAVIN D., ABBAS GAMAL, ALFONZO ANNETTE, BARELLI ALESSANDRO, BIERENS JOOST J.L.M., BRUGGER HERMANN, DEAKIN CHARLES D., DUNNING JOEL, GEORGIOU MARIOS, HANDLEY ANTHONY J., LOCKEY DAVID J., PAAL PETER, SANDRONI CLAUDIO, THIES KARL-CHRISTIAN, ZIDEMAN DAVID A., NOLAN JERRY P.. European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution. Resuscitation [online] 2010 October, 81(10):1400-1433 [viewed 12 June 2014] Available from: doi:10.1016/j.resuscitation.2010.08.015
  3. ANGELOS MG, DEBEHNKE DJ, LEASURE JE. Arterial blood gases during cardiac arrest: markers of blood flow in a canine model. Resuscitation [online] 1992 Apr-May, 23(2):101-11 [viewed 12 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/1321470

Investigations - Followup

Fact Explanation
Post resuscitation care Continue monitoring the patient after successful resuscitation. Monitor vital parameters. Observe for features of cerebral injury or myocardial dysfunction. ECG, echocardiography can be used to assess cardiac function. Monitor blood glucose levels to prevent either hyper/ hypoglycemia.[1]
Rehabilitation Patients who survive the acute episode should investigated for an aetiology. ECG, echocardiography, caridac enzyme levels can be used to identify cardiac diseases. Risk factors for coronary heart disease can be investigated with blood glucose level, HbA1c level, lipid profile etc. Coronary angiography may be required to visualize the coronary vessels.[2]
References
  1. Adult advanced life support. Resuscitation Council (UK). 2010 [Viewed on 11 June 2014]. Available from : https://www.resus.org.uk/pages/als.pdf
  2. THOMPSON D, LEWIN R. Management of the post-myocardial infarction patient: rehabilitation and cardiac neurosis Heart [online] 2000 Jul, 84(1):101-105 [viewed 13 June 2014] Available from: doi:10.1136/heart.84.1.101

Management - General Measures

Fact Explanation
Call for help Call out for help. Management of cardiac arrest should ideally be done by a specific team of professionals with each member of the team designated with a specific task.[1]
Set up monitors Monitors/ defibrillator should be quickly attached to the patient with minimum interference to CPR. the use of the capnography - end-tidal CO2 trace is currently recommended.[1]
References
  1. Adult advanced life support. Resuscitation Council (UK). 2010 [Viewed on 11 June 2014]. Available from : https://www.resus.org.uk/pages/als.pdf

Management - Specific Treatments

Fact Explanation
Management of cardiac arrest The latest guidelines used for management of cardiac arrest are the American Heart Association (AHA) guidelines for Cardiopulmonary resuscitation and emergency cardiovascular care science published in 2010. Algorithms have being developed for basic life support and advanced life support.[1]
Basic life support (BLS) Basic life support is recommended in the out of hospital setting where one rescuer is present. First ensure safety for the rescuer before approaching the victim. Check for responsiveness and if the patient is not responding shout out for help. Proceed to open the airway with the head tilt and chin lift. Look, listen and feel for breathing for no more than 10 seconds. If the patient's breathing has ceased or is labored proceed to administering cardiopulmonary resuscitation.[2][3]
Cardiopulmonary resuscitation (CPR) CPR is used to maintain the circulation as much as possible until definitive care administered. Chest compressions with intermittent rescue breaths are administered repeatedly. Chest compressions are administered at the lower sternum with interlocked hands. A rate of 100-120 compressions per minute and a depth of 5 - 6 cm is used. After completion of 30 compressions, correct the airway before administering 2 rescue breaths. Continue with chest compressions and rescue breaths in a ratio of 30:2.[4]
Advanced life support As with BLS start CPR after calling for help. Connect the patient to the monitor/ defibrillator. Assess the cardiac rhythm. Ventricular fibrillation/ pulseless ventricular tachycardia are considered shockable rhythms while asystole, pulse-less electrical activity are non-shockable rhythms. Management defers depending on the type of rhythm identified.[4]
Management of Ventricular fibrillation/ pulseless ventricular tachycardia These rhythms are managed with defibrillation. The charge used is a 150-200 J biphasic for the first shock and followed by 150-360 J biphasic shocks for subsequent attempts. CPR is continued with minimum interruption. After the shock, the rhythm is assessed and up to 3 shocks are given initially. After the 3rd shock adrenaline 1 mg IV and amiodarone 300 mg IV is administered. If VF/VT persists continue administering shocks while giving further adrenaline 1 mg IV after each alternate shock (approximately every 3-5 min).[4]
Management of asystole and pulse-less electrical activity These are considered non-shockable rhythms. Management includes continued cardiopulmonary resuscitation while adrenaline IV is administered at intervals of 3-5 minutes.[4]
Rule out reversible causes of cardiac arrest. Hypothermia, hypovolaemia, hypoxia, metabolic changes(hyperkalaemia), toxins, tension pneumothorax, thrombosis etc are reversible causes of cardiac arrest. Exclusion of these should be carried out during the resuscitation process with minimum interference to administration of cardiopulmonary resuscitation.[5]
Precordial thump Precordial thump has a low success rate and is effective only when administered close to the onset of the cardiac arrest.[3] Currently the use of precordial thump is de-emphasised. It may be used under medical supervision in the setting of emergency department resuscitation room, ICU etc.
Post-resuscitation care Following return of spontaneous circulation it is important to ensure continued care to the patient. Avoid hyperoxaemia by maintaining a SaO2 of 94-98%. Monitor and control blood glucose level of the patient. It is also recommended to use primary percutaneous coronary intervention in appropriate patients.[6] Post cardiac arrest syndrome developing following cardiac arrest comprises of cerebral injury, myocardial dysfunction, ischaemia/reperfusion response.
Use of therapeutic hypothermia Hypothermia has shown to be neuroprotective.[7] Cooling suppresses neural pathway transmission and lowers brain metabolic rate. Currently hypothermia is used in patients who are comatose.[8]
Rehabilitation Patients who survive cardiac arrest need thorough investigation for the aetiology. Management should be tailored according to the cause. Patients with coronary heart disease need proper evaluation of disease extent, pharmacological management, optimization of cardiac risk factors. Further evaluation is required to routinely recommend an intensive early intervention service.[9]
References
  1. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. American Heart Association. 2010. [Viewed on 10 June 2014]. Available from : http://www.heart.org/idc/groups/heart-public/@wcm/@ecc/documents/downloadable/ucm_318152.pdf
  2. Adult basic life support. Resuscitation Council (UK). 2010 [Viewed on 11 June 2014]. Available from :https://www.resus.org.uk/pages/bls.pdf
  3. HENLIN T, MICHALEK P, TYLL T, HINDS JD, DOBIAS M. Oxygenation, Ventilation, and Airway Management in Out-of-Hospital Cardiac Arrest: A Review. Biomed Res Int [online] 2014:376871 [viewed 12 June 2014] Available from: doi:10.1155/2014/376871
  4. Adult advanced life support. Resuscitation Council (UK). 2010 [Viewed on 11 June 2014]. Available from : https://www.resus.org.uk/pages/als.pdf
  5. SOAR JASMEET, PERKINS GAVIN D., ABBAS GAMAL, ALFONZO ANNETTE, BARELLI ALESSANDRO, BIERENS JOOST J.L.M., BRUGGER HERMANN, DEAKIN CHARLES D., DUNNING JOEL, GEORGIOU MARIOS, HANDLEY ANTHONY J., LOCKEY DAVID J., PAAL PETER, SANDRONI CLAUDIO, THIES KARL-CHRISTIAN, ZIDEMAN DAVID A., NOLAN JERRY P.. European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution. Resuscitation [online] 2010 October, 81(10):1400-1433 [viewed 12 June 2014] Available from: doi:10.1016/j.resuscitation.2010.08.015
  6. PEBERDY M. A., CALLAWAY C. W., NEUMAR R. W., GEOCADIN R. G., ZIMMERMAN J. L., DONNINO M., GABRIELLI A., SILVERS S. M., ZARITSKY A. L., MERCHANT R., VANDEN HOEK T. L., KRONICK S. L.. Part 9: Post-Cardiac Arrest Care: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation [online] December, 122(18_suppl_3):S768-S786 [viewed 12 June 2014] Available from: doi:10.1161/CIRCULATIONAHA.110.971002
  7. HOLZER M, BERNARD SA, HACHIMI-IDRISSI S, ROINE RO, STERZ F, MüLLNER M, COLLABORATIVE GROUP ON INDUCED HYPOTHERMIA FOR NEUROPROTECTION AFTER CARDIAC ARREST. Hypothermia for neuroprotection after cardiac arrest: systematic review and individual patient data meta-analysis. Crit Care Med [online] 2005 Feb, 33(2):414-8 [viewed 12 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/15699847
  8. NIELSEN N, WETTERSLEV J, FRIBERG H, TTM TRIAL STEERING GROUP. Targeted temperature management after cardiac arrest. N Engl J Med [online] 2014 Apr 3, 370(14):1360 [viewed 12 June 2014] Available from: doi:10.1056/NEJMc1401250
  9. MOULAERT VéRONIQUE RMP, VERBUNT JEANINE A, VAN HEUGTEN CAROLINE M, BAKX WILBERT GM, GORGELS ANTON PM, BEKKERS SEBASTIAAN CAM, DE KROM MARC CFTM, WADE DERICK T. Activity and Life After Survival of a Cardiac Arrest (ALASCA) and the effectiveness of an early intervention service: design of a randomised controlled trial. BMC Cardiovasc Disord [online] 2007 December [viewed 16 September 2014] Available from: doi:10.1186/1471-2261-7-26