In Defense of Succinylcholine

OVERVIEW

When it comes to the airway, roc rocks and succ sucks, right? You've heard it more than once. But EMRA*Cast host Peter Lorenz, MD, presents a nuanced argument in defense of succinylcholine, with guests Mike Perza, PharmD, and Patricia Simmer, MD.

Note: The opinions expressed here are the opinions of the individual clinicians in this episode. They do not reflect an expert consensus, as no single consensus exists on this topic. They do not reflect the opinions of their employer.

What You Will Learn in This Episode

1. Efficacy
1. Both agents have very similar first-pass success rates and intubating conditions are essentially equal when rocuronium is used at 1-1.2 mg/kg (1, 8)
2. Side Effects and Contraindications
1. Succinylcholine
1. Hyperkalemia
1. Depolarizing effect results in transient (10 minutes) increase by approximately 0.5-1 meq/L (6, 7, 12)
2. This effect is more pronounced in people who have upregulation of nicotinic acetylcholine receptors including
1. Muscular Dystrophies 
1. This does NOT include myasthenia gravis (3)
1. Myasthenia gravis decreases responsiveness to succinylcholine and increases responsiveness to rocuronium
2. Patients on acetylcholinesterase inhibitors will result in a prolonged effect of succinylcholine
3. Given these, in patients with MG, while succinylcholine is not per se dangerous, it is less predictable and as such a reduced dose of rocuronium is reasonable 
2. Case reports suggest this may include temporary neurologic disorders such as GBS and botulism (5)
2. Prolonged immobilization
3. Patients recovering from severe burns
1. In the convalescent phase there is an upregulation of peripheral acetylcholine receptors and there is a risk of an exaggerated potassium efflux. This phase may persist for months. This risk does not exist in the acute phase and succinylcholine is not contraindicated in the acute burn patient.
4. Patients recovering from denervation injury
2. Malignant hyperthermia
1. The risk of this is vanishingly rare and is primarily seen when used in conjunction with inhaled anesthetics
3. Bradycardia
1. There is a small amount of crossover effect on muscarinic acetylcholine receptors that can result in a transient (30-60s) bradycardia. Heart blocks are not typically seen
4. Increased oxygen consumption
1. There is a theoretical risk that the fasciculations induced by succinylcholine will increase oxygen consumption in a clinically significant way in patients with profound hypoxemia
2. Rocuronium
1. The only adverse effect is prolonged paralysis, the only contraindication is allergy
1. At the recommended RSI doses of 1.2 mg/kg paralysis may persist for 2 hours 
1. The oft cited 30-60 minutes is for the 0.6mg/kg dose (8, 13)
2. The risk of conscious paralysis is much higher with rocuronium (2)
3. Clinical data suggests that the initiation of post intubation sedation is delayed with rocuronium use (1, 14-17)
4. Prolonged paralysis prevents a neurological examination
5. Rocuronium has a very low volume of distribution and should be dosed by ideal body weight
1. At 1.2 mg/kg a 5’9” male would receive 85mg, a 6’3” male would receive 100mg, a 7’0” male would receive 120mg. The doses are approximately 5-10% lower for the same height for females (18, 19)
3. Premise of the episode
1. Every patient is at risk for conscious paralysis with rocuronium. The clinical data suggests that there is an increased risk for conscious paralysis with rocuronium. The clinical data suggests that we are less aggressive with sedation in patients paralyzed with rocuronium when we should be much more aggressive.
2. While succinylcholine does have more side effects, they are rare and tend to occur in predictable patient populations.
3. Given the persistent risk in rocuronium and the predictable risk in succinylcholine, succinylcholine should be the preferred agent unless a specific risk factor for an adverse event is identified.
4. Clinical Cases
1. Found Down
1. At less than 24 hours the risk of upregulation of Ach receptors to the point of causing lethal hyperkalemia is very low (6)
2. In patients who are found down, preservation of a neurologic examination is critical
3. Found down < 24 hours: Succinylcholine
4. Found down > 24 hours: Rocuronium
2. Burn, crush injury, denervation injuries, or major trauma
1. In the acute phase these are not contraindications to succinylcholine administration. It is our opinion that succinylcholine is the preferred agent as all of these are incredibly painful conditions. Preservation of motor function as a visual cue to increase in analgesia has the potential to meaningfully improve patient care. (1)
2. In the post-acute phase of these pathologies, as there is upregulation of Ach receptors, rocuronium is the preferred agent
3. Chronic and Critical Illness
1. Succinylcholine is safe in most patients who are chronically unwell
2. In patients who have been critically ill for a prolonged period (<2 weeks), rocuronium is the preferred agent (4)
4. Muscular dystrophy or acquired neuromuscular disorders
1. Rocuronium
5. Myasthenia gravis
1. Reduced dose of rocuronium (3)
6. Status Epilepticus
1. While convulsive status epilepticus can progress to rhabdomyolysis, renal failure, and hyperkalemia, this is not common (9)
2. I was unable to find a single case report of cardiac arrest after succinylcholine administration to a patient in status epilepticus
3. Many sources state that rocuronium should be preferentially selected in this patient population but fail to offer citations for this (10,11)
4. In the acute phase of status epilepticus, succinylcholine is likely safe and will preserve the neurologic examination. This is important as paralysis does not prevent irreversible brain damage from ongoing seizures.
5. If the duration of seizures is truly unknown and is potentially very long or sugammadex or an EEG is immediately available in the ED, rocuronium is a reasonable choice. 
1. If there is concern for hyperkalemia or very long duration seizures and EEG and sugammadex are not available, consider a lower dose of rocuronium for a shorter duration of action  
6. In most patients, our preferred agent is succinylcholine
7. Dialysis Fistula
1. Many critically ill patients have ESRD.
2. The clinical history and EKG are paramount.
3. In the absence of EKG changes that could be attributed to hyperkalemia, including bradycardia, it is not unreasonable to use succinylcholine. Coadministration with calcium is acceptable. Acute on chronic hyperkalemia is not as dangerous as acute on acute.
4. Utilizing empiric rocuronium is also a reasonable choice and reflects our most common practice pattern
8. EKG with a wide QRS or other abnormalities that could be attributed to hyperkalemia
1. This should be considered an absolute contraindication to succinylcholine
9. Anatomically difficult airway/surgical airway
1. In patients at high risk for conversion to surgical airway our approach is to administer succinylcholine first. If conversion to a surgical airway is required, we then administer rocuronium as succinylcholine demonstrates tachyphylaxis and unexpected movements during cricothyroidotomy is potentially devastating.
10. Profound respiratory failure
1. Critical hypoxemia
1. In patients with intractable critical pre-intubation hypoxemia (<80%) it is not unreasonable to use rocuronium to avoid any additional oxygen consumption as a result of fasciculations
1. T   here are papers to suggest that succinylcholine results in a shorter safe apnea time than rocuronium (24-26)
2. Respiratory failure without intractable hypoxemia
1. In a patient with severe ARDS or asthma who may end up paralyzed for their respiratory failure but has tolerable pre-intubation saturations we utilize succinylcholine followed by aggressive sedative administration prior to the initiation of paralytic infusions.
11. Bradycardia
1. In patients with bradycardia and shock who require intubation rocuronium is the preferred agent
5. Summary
1. Rocuronium
1. Subacute burns, denervation injury, or severe trauma
2. Bradycardia
3. Critical hypoxemia
4. Muscular Dystrophies/Myasthenia Gravis
5. Prolonged (>24 hours) down time
6. Stigmata or concern for critical hyperkalemia
2. Succinylcholine
1. Everyone else
6. Post Intubation Sedation
1. Clinical data suggests we depend more on patient cues than we should (1, 14-17)
2. We should be targeting deep sedation in the immediate post-intubation period
3. Sedation-related vasoplegia/sympatholysis/hypotension should be managed with vasopressors and resuscitation, not a reduction in sedation
1. Peripheral vasopressors are generally safe (20-23)
4. It is our practice to accompany RSI (induction and paralysis) medications with a sizable dose of midazolam (5-10 mg IV push)
1. These larger doses of midazolam are generally very safe (27)
5. Our standard drips are
1. Fentanyl: Bolus 200-400 mcg, infusion 100mcg/hr
2. Propofol: Infusion at 40-80 mcg/kg/min
1. If we start at 80 mcg/kg/min, for a 100 kg adult that is 80 mg over 10 minutes, equivalent to a dose we give as an IV push for conscious sedation
7. Patty and Mikes Paper
1. Single center retrospective cohort of adults seen in the emergency department from 10/2015-7/2024 who had an initial potassium >5.5 who underwent RSI with either rocuronium or succinylcholine
1. Population/Intervention: 434 adults
1. 310: Rocuronium
1. Mean K: 6.4
2. Pre-RSI Ca: 29%
2. 124: Succinylcholine
1. Mean K: 6.2
2. Pre-RSI K: 4%
2. Comparison/Outcome
1. Mortality (24 hours)
1. Rocuronium 10%
2. Succinylcholine 10.5%
2. Arrest w/in 1 hour
1. Rocuronium 1.9%
2. Succinylcholine 0.8%
3. Severe hyperkalemia subgroup
1. Rocuronium
1. 14 patients
2. Mean K 8.5
3. 2 deaths (1 after withdrawal of care, no arrests w/in 1 hour)
2. Succinylcholine
1. 3 patients
2. K = 8.3, 8.6, 8.8
3. 0 deaths, 0 arrests

REFERENCES

1. Acquisto NM, Mosier JM, Bittner EA, et al. Society of Critical Care Medicine Clinical Practice Guidelines for Rapid Sequence Intubation in the Critically Ill Adult Patient. Crit Care Med. 2023;51(10):1411-1430.
2. Pappal RD, Roberts BW, Mohr NM, et al. The ED-AWARENESS Study: A Prospective, Observational Cohort Study of Awareness With Paralysis in Mechanically Ventilated Patients Admitted From the Emergency Department. Ann Emerg Med. 2021;77(5):532-544. 
3. Casarotti P, Mendola C, Cammarota G, Della Corte F. (2014). High-dose rocuronium for rapid-sequence induction and reversal with sugammadex in two myasthenic patients. Acta Anaesthesiol Scand. 2014;58(9):1154–1158. 
4. Blanié A, Ract C, Leblanc PE, et al. The limits of succinylcholine for critically ill patients. Anesth Analg. 2012;115(4):873-9. 
5. Hovgaard HL, Juhl-Olsen P. Suxamethonium-Induced Hyperkalemia: A Short Review of Causes and Recommendations for Clinical Applications. Crit Care Res Pract. 2021;2021:6613118. 
6. Jeevendra Martyn JA, Richtsfeld M. Succinylcholine-induced Hyperkalemia in Acquired Pathologic States: Etiologic Factors and Molecular Mechanisms. Anesthesiology. 2006;104(1):158-169.
7. Sabo D, Jahr J, Pavlin J, et al. The increases in potassium concentrations are greater with succinylcholine than with rocuronium-sugammadex in outpatient surgery: a randomized, multicentre trial. Can J Anaesth. 2014;61(5):423-432. 
8. Tran DTT, Newton EK, Mount VAH, Lee JS, Mansour C, Wells GA, Perry JJ. Rocuronium vs. succinylcholine for rapid sequence intubation: a Cochrane systematic review. Anaesthesia. 2017;72(6):765-777. 
9. Sutter R, Dittrich T, Semmlack S, Ruegg S, Marsch S, Kaplan PW. Acute Systemic Complications of Convulsive Status Epilepticus—A Systematic Review. Crit Care Med. 2018;46(1):138-145.
10. Farkas J. Status Epilepticus. In: Farkas J, ed. Internet Book of Critical Care. EMCrit. Published April 15, 2025.
11. Migdady I, Rosenthal ES, Cock HR. Management of status epilepticus: a narrative review. Anaesthesia. 2022;77(Suppl 1):78-91. 
12. Castillo J, Sierra P, Escolano F, Castaño J. [Succinylcholine induces hyperpotassemia in patients in critically ill patients]. Rev Esp Anestesiol Reanim. 1996;43(10):349-353.
13. Pühringer FK, Rex C, Sielenkamper AW, et al. Reversal of profound, high-dose rocuronium-induced neuromuscular blockade by sugammadex at two different time points: an international, multicenter, randomized, dose-finding, safety assessor-blinded, phase II trial. Anesthesiology. 2008;109(2):188-97. 
14. Johnson EG, Meier A, Shirakbari A, Weant K, Baker Justice S. Impact of Rocuronium and Succinylcholine on Sedation Initiation After Rapid Sequence Intubation. J Emerg Med. 2015;49(1):43-49. 
15. Weingart GS, Carlson JN, Callaway CW, Frank R, Wang HE. Estimates of sedation in patients undergoing endotracheal intubation in US EDs. Am J Emerg Med. 2013;31(1):222-226. 
16. Chong ID, Sandefur BJ, Rimmelin DE, et al. Long-acting neuromuscular paralysis without concurrent sedation in emergency care. Am J Emerg Med. 2014;32(5):452-456. 
17. Korinek JD, Thomas RM, Goddard LA, St John AE, Sakles JC, Patanwala AE. Comparison of rocuronium and succinylcholine on postintubation sedative and analgesic dosing in the emergency department. Eur J Emerg Med. 2014;21(3):206.
18. Meyhoff CS, Lund J, Jenstrup MT, et al. Should dosing of rocuronium in obese patients be based on ideal or corrected body weight? Anesth Analg. 2009;109(3):787-792. 
19. Gaszynski TM, Szewczyk T. Rocuronium for rapid sequence induction in morbidly obese patients: a prospective study for evaluation of intubation conditions after administration 1.2 mg kg−1 ideal body weight of rocuronium. Eur J Anaesthesiol. 2011;28(8):609-610. 
20. Yerke JR, Mireles-Cabodevila E, Chen AY, et al. Peripheral Administration of Norepinephrine: A Prospective Observational Study. Chest. 2024;165(2):348-355. 
21. Tian DH, Smyth C, Keijzers G, Macdonald SP, Peake S, Udy A, Delaney A. Safety of peripheral administration of vasopressor medications: A systematic review. Emerg Med Australas. 2020;32(2):220-227. 
22. Medlej K, Kazzi AA, El Hajj Chehade A, et al. Complications from Administration of Vasopressors Through Peripheral Venous Catheters: An Observational Study. J Emerg Med. 2018;54(1):47-53.
23. Ley Greaves R, Bolot R, Holgate A, Gibbs C. Safety of pre-hospital peripheral vasopressors: The SPOTLESS study (Safety of PrehOspiTaL pEripheral vaSopreSsors). Emerg Med Australas. 2024;36(4):547-553. 
24. Marsch SC, Steiner L, Bucher E, et al. Succinylcholine versus rocuronium for rapid sequence intubation in intensive care: a prospective, randomized controlled trial. Crit Care. 2011;15(4):R199. 
25. Tang L, Li S, Huang S, Ma H, Wang Z. Desaturation following rapid sequence induction using succinylcholine vs. rocuronium in overweight patients. Acta Anaesthesiol Scand. 2011;55(2):203-208. 
26. Tang L, Zhao X, Li S, Huang L, Li J, Chen L, Huang S. Impact of Succinylcholine vs. Rocuronium on Apnea Duration for Rapid Sequence Induction: A Prospective Cohort Study. Front Med (Lausanne). 2022;9:717477.
27. Silbergleit R, Lowenstein D, Durkalski V, Conwit R; Neurological Emergency Treatment Trials (NETT) Investigators. RAMPART (Rapid Anticonvulsant Medication Prior to Arrival Trial): a double-blind randomized clinical trial of the efficacy of intramuscular midazolam versus intravenous lorazepam in the prehospital treatment of status epilepticus by paramedics. Epilepsia. 2011;52(Suppl 8):45-47.