- Author: Sandy N Shah, DO, MBA, FACC, FACP, FACOI; Chief Editor: Barry E Brenner, MD, PhD, FACEP more...
Asystole is generally a diagnosis made via ongoing cardiac monitoring or electrocardiogram (ECG) and physical examination with pulselessness. Pulse oximetry may be used during resuscitation to monitor the effectiveness of forward flow or cardiopulmonary resuscitation (CPR); however, usually flow is too inadequate for the sensor to register results.
The "H's and T's of advanced cardiac life support" (ACLS) is a pneumonic that is used to help clinicians recall the major contributing factors of asystole and are as follows:
Hydrogen ion (acidosis)
Thrombosis (coronary and pulmonary)
Potassium level and ABG
A potassium level may be useful if deemed appropriate and results are immediately available.
Arterial blood gas (ABG) analysis may be used to obtain rapid reporting of potassium level in many institution's laboratories. In addition, ABG results may also help to evaluate the ventilatory and acid-base status of the patient as well as the hemoglobin level. Note that if the patient is in full arrest, a blood gas level does not accurately reflect the overall pH status of the tissues.
For documentation purposes, in addition to including rhythm strips from 2 separate leads identifying asystole, bedside ultrasonography may be useful to confirm cardiac standstill. The heart may be viewed via either a subxiphoid view or an intercostal view wall motion, or lack thereof is observed. An image of 2-dimensional echocardiography taken over time in M-mode may be taken, saved, and included in the medical record. This will further document the lack of heart wall motion.
Continuous Cardiac Monitoring
Isoelectric flat line is interpreted as asystole. Immediately rule out the following as causes of isoelectric flat line not due to asystole:
Loose or disconnected leads
Loss of power to the electrocardiographic (ECG) monitor
Low signals gain on the ECG monitor
Asystole is best determined in 2 separate cardiac leads. This helps protect against reading a flat line due to lead malfunction incorrectly as asystole, as well as helps in differentiating fine ventricular fibrillation (VF), particularly in an isoelectric lead, from asystole (see the following images).
Eliminate a possible diagnosis of VF, which may masquerade as asystole, by checking 2 leads perpendicular to each other. In spite of this caveat, Cummins et al found that using a flat-line protocol based on a 3-lead check, occult VF was documented in only 3 (2.5%) of 118 asystolic patients, indicating that VF masquerading as asystole is uncommon. Technical problems were much more common, observed in 10 patients (8%).
Exclude the possibility of lead misplacement by always checking for the presence of a pulse.
Spurious asystole can be seen when using manual defibrillator paddles to monitor the rhythm. This is usually very brief, but nevertheless, can be avoided by switching to monitoring leads, especially after several successive shocks.
Gold RS, Pollard Z, Buchwald IP. Asystole due to the oculocardiac reflex during strabismus surgery: a report of two cases. Ann Ophthalmol. 1988 Dec. 20(12):473-5, 477. [Medline].
Moonie GT, Rees DL, Elton D. The oculocardiac reflex during strabismus surgery. Can Anaesth Soc J. 1964 Nov. 11:621-32. [Medline].
Locatelli ER, Varghese JP, Shuaib A, Potolicchio SJ. Cardiac asystole and bradycardia as a manifestation of left temporal lobe complex partial seizure. Ann Intern Med. 1999 Apr 6. 130(7):581-3. [Medline].
van der Lende M, Surges R, Sander JW, Thijs RD. Cardiac arrhythmias during or after epileptic seizures. J Neurol Neurosurg Psychiatry. 2016 Jan. 87 (1):69-74. [Medline].
Bognolo DA, Rabow FI, Vijayanagar RR, Eckstein PF. Traumatic sinus node dysfunction. Ann Emerg Med. 1982 Jun. 11(6):319-21. [Medline].
Gray WA, Capone RJ, Most AS. Unsuccessful emergency medical resuscitation--are continued efforts in the emergency department justified?. N Engl J Med. 1991 Nov 14. 325(20):1393-8. [Medline].
Engdahl J, Bang A, Lindqvist J, Herlitz J. Can we define patients with no and those with some chance of survival when found in asystole out of hospital?. Am J Cardiol. 2000 Sep 15. 86(6):610-4. [Medline].
Richman PB, Nashed AH. The etiology of cardiac arrest in children and young adults: special considerations for ED management. Am J Emerg Med. 1999 May. 17(3):264-70. [Medline].
Atkins DL, Everson-Stewart S, Sears GK, Daya M, Osmond MH, Warden CR, et al. Epidemiology and outcomes from out-of-hospital cardiac arrest in children: the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest. Circulation. 2009 Mar 24. 119(11):1484-91. [Medline]. [Full Text].
Niemann JT, Cairns CB. Hyperkalemia and ionized hypocalcemia during cardiac arrest and resuscitation: possible culprits for postcountershock arrhythmias?. Ann Emerg Med. 1999 Jul. 34(1):1-7. [Medline].
Niemann JT, Stratton SJ, Cruz B, Lewis RJ. Outcome of out-of-hospital postcountershock asystole and pulseless electrical activity versus primary asystole and pulseless electrical activity. Crit Care Med. 2001 Dec. 29(12):2366-70. [Medline].
Ewy GA. Cardiac resuscitation--when is enough enough?. N Engl J Med. 2006 Aug 3. 355(5):510-2. [Medline].
Barthell E, Troiano P, Olson D, et al. Prehospital external cardiac pacing: a prospective, controlled clinical trial. Ann Emerg Med. 1988 Nov. 17(11):1221-6. [Medline].
Mosier J, Itty A, Sanders A, Mohler J, Wendel C, Poulsen J. Cardiocerebral resuscitation is associated with improved survival and neurologic outcome from out-of-hospital cardiac arrest in elders. Acad Emerg Med. 2010 Mar. 17(3):269-75. [Medline].
Cummins RO, Austin D Jr. The frequency of 'occult' ventricular fibrillation masquerading as a flat line in prehospital cardiac arrest. Ann Emerg Med. 1988 Aug. 17(8):813-7. [Medline].
Resuscitation Council [UK]. Spurious asystole when using manual defibrillators and monitoring through the defibrillator paddled. Resusitation Council [UK]. 2002. 1-2.
Lin JL, Lim PS, Leu ML, Huang CC. Outcomes of severe hyperkalemia in cardiopulmonary resuscitation with concomitant hemodialysis. Intensive Care Med. 1994. 20 (4):287-90. [Medline].
Bernard SA, Gray TW, Buist MD, Jones BM, Silvester W, Gutteridge G, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med. 2002 Feb 21. 346(8):557-63. [Medline].
Testori C, Stertz F, Behringer W, et al. Mild therapeutic hypothermia is associated with favourable outcome in patients with cardiac arrest with non-shockable rhythms. Resuscitation. 82 :1162-1167.
Wenzel V, Krismer AC, Arntz HR, et al. A comparison of vasopressin and epinephrine for out-of-hospital cardiopulmonary resuscitation. N Engl J Med. 2004 Jan 8. 350(2):105-13. [Medline].
Gueugniaud PY, David JS, Chanzy E, Hubert H, et al. Vasopressin and epinephrine vs. epinephrine alone in cardiopulmonary resuscitation. N Engl J Med. 2008 Jul 3. 359(1):21-30. [Medline].
Vukov LF, White RD. External transcutaneous pacemakers in prehospital cardiac arrest. Ann Emerg Med. 1988 May. 17(5):554-5. [Medline].
Mader TJ, Smithline HA, Gibson P. Aminophylline in undifferentiated out-of-hospital asystolic cardiac arrest. Resuscitation. 1999 Jun. 41(1):39-45. [Medline].
Billi JE, Zideman DA, Eigel B, et al. Conflict of interest management before, during, and after the 2005 International Consensus Conference on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations. Resuscitation. 2005 Nov-Dec. 67(2-3):171-3. [Medline].
ECC Committee. 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2005 Dec 13. 112(24 Suppl):IV1-203. [Medline].
Field JM, Hazinski MF, Sayre MR, et al. Part 1: executive summary: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010 Nov 2. 122(18 Suppl 3):S640-56. [Medline].
Hazinski MF, Nolan JP, Billi JE, et al. Part 1: Executive summary: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. Circulation. 2010 Oct 19. 122(16 Suppl 2):S250-75. [Medline].
Morrison LJ, Visentin LM, Kiss A, Theriault R, Eby D, Vermeulen M, et al. Validation of a rule for termination of resuscitation in out-of-hospital cardiac arrest. N Engl J Med. 2006 Aug 3. 355(5):478-87. [Medline].
Sau A, Mereu R, Taraborrelli P, et al. A long-term follow-up of patients with prolonged asystole of greater than 15s on head-up tilt testing. Int J Cardiol. 2016 Jan 15. 203:482-5. [Medline].
Pokorney SD, Radder C, Schulte PJ, et al. High-degree atrioventricular block, asystole, and electro-mechanical dissociation complicating non-ST-segment elevation myocardial infarction. Am Heart J. 2016 Jan. 171 (1):25-32. [Medline].
Estock JL, Curinga HK, Li A, Grieve LB, Brackney CR. Comparison of chest compression interruption times across 2 automated devices: a randomized, crossover simulation study. Am J Emerg Med. 2016 Jan. 34 (1):57-62. [Medline].
Attin M, Wang L, Soroushmehr SM, et al. Digitization of electrocardiogram from telemetry prior to in-hospital cardiac arrest: a pilot study. Biol Res Nurs. 2015 Aug 27. [Medline].
Ewy GA, Bobrow BJ, Chikani V, et al. The time dependent association of adrenaline administration and survival from out-of-hospital cardiac arrest. Resuscitation. 2015 Nov. 96:180-5. [Medline].