Rapid Sequence Intubation (RSI): Succinylcholine For RSI

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Mechanism of Action

• Succinylcholine is a depolarizing neuromuscular blocker (NMBA) that resembles the structure of 2 molecules of acetylcholine.
  • Only depolarizing NMBA in the United States

Succinylcholine binds to nicotinic acetylcholine receptors at the motor endplate and causes depolarizations and continuous stimulation to the endplate which inhibits repolarization

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Dose

1 to 2 (commonly 1.5) mg/ kg total body weight IV

Lower doses have been studied (0.3-0.6 mg/kg), however, the onset of action with lower dosages isn’t ideal for emergent intubations such as RSI

3-4 mg/kg IM 

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Onset

IV: 10-50 seconds

IM: 3-4 minutes

Duration

• 3-10 minutes

Metabolism:

• Rapidly hydrolyzed by plasma pseudocholinesterase to inactive metabolites
  • Plasma cholinesterase activity may be diminished in patients with genetic abnormalities of plasma cholinesterase, malignant tumors, infections, burns, anemia, and decompensated heart disease.
    • This is insignificant clinically as duration is extended by 15-20 minutes.

Elimination

• Renal Excretion: 10%

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Adverse effects

• Bradycardia
• Hyperkalemia
• Fasciculations
• ↑ intraocular pressure
• Transient ↑ ICP ~5-10 mmHg
• Malignant hyperthermia (rare)

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Contraindications

• History of malignant hyperthermia in the patient or family
• Patients at high risk of severe hyperkalemia
  • Burns, crush injuries, spinal cord injuries, strokes, and intraabdominal sepsis >5 days old
• Neuromuscular diseases, e.g., multiple sclerosis, amyotrophic lateral sclerosis, myasthenia gravis myopathies
• Allergy to class/drug
• spinal cord damage (1 week – 3 months old)

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Pearls

Cholinesterase inhibitors (neostigmine) don’t reverse depolarization NMBAs and may prolong the duration of action of succinylcholine by promoting higher acetylcholine concentration at the nerve terminal.

Succinylcholine-induced depolarization could lead to an increase in serum potassium by 0.5 mEq/L.

While Succinylcholine leads to a transient increase in intraocular pressure and intracranial pressure, data has not confirmed that this leads to worse patient outcomes.

In theory, subsequent dosing of succinylcholine could lead to secondary block which could lead to SA nodal blockade and resultant bradycardia.

Bradycardia is more common in the pediatric population due to the vagal predominance in the autonomic nervous system.

Literature Review

Author, year	Design/ sample size	Intervention & Comparison	Outcome
Guihard, 2019	Noninferiority randomized clinical trial n=1248	Succinylcholine ≥ 1.5 mg/kg vs Rocuronium ≥ 1.2 mg/kg	Successful first-attempt intubation was 455 of 610 (74.6%) in the rocuronium group vs 489 of 616 (79.4%) in the succinylcholine group, with a between-group difference of -4.8%, which did not meet criteria for noninferiority.
April 2018	Prospective cohort study n= 4,275	Succinylcholine ≥ 1 mg/kg vs Rocuronium ≥ 1.2 mg/kg	The first-pass intubation success rate was no difference between the agents with 87.0% with succinylcholine versus 87.5% with rocuronium (adjusted OR 0.9; 95% CI 0.6- 1.3
Patanwala, 2016	Retrospective cohort study n=233	Succinylcholine (dosing not reported) vs Rocuronium (dosing not reported)	In the high-severity TBI patients, succinylcholine was associated with increased mortality compared with rocuronium (OR 4.10, 95% CI 1.18–14.12).
Watt, 2012	Retrospective cohort study n=200	Succinylcholine 1.7 ± 0.7 mg/kg vs Rocuronium 1.3 ± 0.4 mg/kg	After intubation, 77.5% (n=155) of patients were initiated on a sedative infusion of propofol (n=148) or midazolam (n=7). Mean time to post-intubation sedation was significantly greater with rocuronium compared to succinylcholine (27 min vs 15; p <0.001)

Comments by ED Physician Attendings

Pro’s	Con’s
” I like the shorter duration of paralysis”	” Can see hyper-K with CNS/spinal cord injury (>3 days), myopathies, burns (few days late), sepsis, critical illness, and occasionally with severe traumatic injury acutely due to succinic acid mechanism. Avoid sux when possible in pediatric populations (<8) “

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References

• Guihard B, Chollet-Xémard C, Lakhnati P, et al. Effect of Rocuronium vs Succinylcholine on Endotracheal Intubation Success Rate Among Patients Undergoing Out-of-Hospital Rapid Sequence Intubation: A Randomized Clinical Trial. JAMA. 2019;322(23):2303-2312. doi:10.1001/jama.2019.18254
• April MD, Arana A, Pallin DJ, Schauer SG, Fantegrossi A, Fernandez J, Maddry JK, Summers SM, Antonacci MA, Brown CA 3rd; NEAR Investigators. Emergency Department Intubation Success With Succinylcholine Versus Rocuronium: A National Emergency Airway Registry Study. Ann Emerg Med. 2018 Dec;72(6):645-653. doi: 10.1016/j.annemergmed.2018.03.042. Epub 2018 May 7. PMID: 29747958.
• 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 Jun;72(6):765-777. doi: 10.1111/anae.13903. PMID: 28654173.
• Patanwala AE, Erstad BL, Roe DJ, Sakles JC. Succinylcholine Is Associated with Increased Mortality When Used for Rapid Sequence Intubation of Severely Brain Injured Patients in the Emergency Department. Pharmacotherapy. 2016 Jan;36(1):57-63. doi: 10.1002/phar.1683. PMID: 26799349.
• Patanwala AE, Stahle SA, Sakles JC, Erstad BL. Comparison of succinylcholine and rocuronium for first-attempt intubation success in the emergency department. Acad Emerg Med. 2011 Jan;18(1):10-4. doi: 10.1111/j.1553-2712.2010.00954.x. Epub 2010 Dec 23. PMID: 21182564.
• Weiss JH, Gratz I, Goldberg ME, Afshar M, Insinga F, Larijani G. Double-blind comparison of two doses of rocuronium and succinylcholine for rapid-sequence intubation. J Clin Anesth. 1997 Aug;9(5):379-82. doi: 10.1016/s0952-8180(97)00065-2. PMID: 9257203.
• Smith CE, Kovach B, Polk JD, Hagen JF, Fallon WF Jr. Prehospital tracheal intubating conditions during rapid sequence intubation: rocuronium versus vecuronium. Air Med J. 2002 Jan-Feb;21(1):26-32. doi: 10.1067/mmj.2002.121713. PMID: 11805764.
• Magorian T, Flannery KB, Miller RD. Comparison of rocuronium, succinylcholine, and vecuronium for rapid-sequence induction of anesthesia in adult patients. Anesthesiology. 1993 Nov;79(5):913-8. doi: 10.1097/00000542-199311000-00007. PMID: 7902034.
• Micromedex [Electronic version].Greenwood Village, CO: Truven Health Analytics. Retrieved September 6, 2018, from http://www.micromedexsolutions.com/