Background

This post was also featured on REBEL EM.

Administration of a neuromuscular blocker (NMB) is an essential part of Emergency Department  (ED) airway management for facilitating ideal airway conditions and is most commonly performed with either succinylcholine or rocuronium. Despite extensive debates between providers, one agent has not been shown to be superior to other. Limited anesthesia literature has shown that succinylcholine may provider better intubating conditions but it has a number of contraindications (which may not be initially apparent)(Shoenberger 2018). Rocuronium at high doses has a similar onset of action to succinylcholine and may provider longer safe apneic times (Swaminathan 2018). This study seeks to add more information to the clinical discussion.

Clinical Question

Does the first-pass intubation and adverse event rate differ between patients administered succinylcholine versus rocuronium?

Population

Patients older than 14 years of age who were intubated using either succinylcholine or rocuronium in 22 Emergency Departments participating in the National Emergency Airway Registry (NEAR) between January 1st, 2016 and December 31st, 2016.

Intervention

Succinylcholine vs. Rocuronium

Outcomes

Primary: First-pass intubation rate (intubation attempt defined as any placement of the leading edge of the laryngoscope blade into the oral cavity past the alveolar ridge

Secondary: Incidence of any adverse event (cardiac arrest, dental trauma, direct airway injury, dysrhythmias, epistaxis, esophageal intubation, hypotension, hypoxia (sat < 90%), iatrogenic bleeding, laryngoscope failure, laryngospasm, lip laceration, main-stem bronchus intubation, malignant hyperthermia, medication error, pharyngeal laceration, pneumothorax, endotracheal tube cuff failure, vomiting).

Design

Prospective, observational trial

Excluded

Patients with missing or inconsistent data regarding age and patients who did not receive a NMB.

Primary Results

  • Number of intubations
    • n = 5244 with 96.7% captured in data base (n = 5071)
    • Succinylcholine: 2,275
    • Rocuronium: 1800
  • Most common induction medication was etomidate (84.7% of succinylcholine and 79% of rocuronium intubations)
  • Mean dose of succinylcholine: 1.8 mg/kg
  • Mean dose of rocuronium: 1.6 mg/kg

Critical Results

  • First-Pass success rate (primary outcome)
    • No statistically significant difference between agents
    • Succinylcholine: 87.0%
    • Rocuronium: 87.5%
    • Risk difference: 0.5% (95% CI: -1.6% – 2.6%)
    • Multivariate analysis shows no significant difference in first-pass success rate for difficult airway characteristics (OR 0.9 95% CI 0.6 – 1.3)
    • Higher first pass success rate in patients without difficult airways intubated with high dose (> 1.2 mg/kg) vs. standard dose (< 1.2mg/kg) of rocuronium OR 2.2; 95% CI 1.2 – 3.4
  • Overall intubation success rate
    • Succinylcholine: 99.6%
    • Rocuronium: 99.9%
  • Adverse event rate
    • No statistically significant difference between agents
    • Succinylcholine: 14.7%
    • Rocuronium: 14.8%
    • Adjusted OR 1.1 (95% CI 0.9 – 1.3)

Strengths

  • Asks an important, as of yet, unanswered question
  • Multicenter, prospectively collected data
  • Baseline characteristics were similar for most parameters
  • Each participating center in the NEAR registry had a designated site investigator ensuring entry of >90% of all intubations performed in the ED
  • All data was reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement.  This is an international collaborative of epidemiologists, methodologists, statisticians, researchers, and journal editors on the conduct and dissemination of observational studies

Limitations

  • As an observational study, only association can be established, not causality
  • There is no information on why one agent was selected in a particular intubation scenario over the other (i.e. provider preference, or patient contraindications (i.e. hyperkalemia, neurologic conditions))
  • NEAR registry is a registry of academic hospitals, community EDs not included in this registry
  • No data on time from paralytic administration to paralysis onset/offset which could also affect outcomes.  Patients with severe hypoxemia or profound acidosis may benefit from shorter time to paralysis, and therefore faster 1st pass intubation.
  • There were no continuous vital sign measurements reported, therefore an incomplete picture of peri-intubation physiology
  • Data was self-reported by the intubator and subject to recall bias (including intubation attempts, adverse events etc)
  • There were some important baseline differences between the groups
    • Succinylcholine using operators had more overall experience
    • Succinylcholine group more likely to use video laryngoscopy
    • The succinylcholine group was younger and less obese. This difference biases the study in favor of succinylcholine
  • Not all adverse events included in the composite adverse event rate were equivalent.

Discussion

Thoughts from Post-Editor Salim Rezaie

  • The authors of this paper suggest that succinylcholine has a faster onset of action compared to rocuronium, however, Curley et al in Crit Care Med 2011 suggested that at a dose of ≥1.2 mg/kg IV, rocuronium has been shown to have a mean onset time of 55seconds, which is similar to the mean onset time of succinylcholine (50 seconds).
  • There is also a Cochrane review and meta-analysis published in 2015 that concluded that succinylcholine results in superior intubating conditions compared to rocuronium.  This conclusion should not be taken at face value as most of the studies included, were in the OR, not intubations occurring in the ED.  Intubations in the ED differ from intubations in the OR with distinct challenges including noise, more critically ill patients, and limited time to optimize preintubation hemodynamics.  Another key issue with this meta-analysis is the comparison of standard dose succinylcholine compared with 0.6mg/kg rocuronium, which is not the ideal dose of rocuronium for optimal intubating conditions.

Author's Conclusions

“In this large observational series, we did not detect an association between paralytic choice and first-pass rapid sequence intubation success or peri-intubation adverse events.”

Our Conclusions

We agree with the authors conclusions. There was no significant difference in first-pass success between agents in this study.

Potential Impact To Current Practice

We doubt that this data is practice changing. Because of the observational nature of the study, we wouldn’t have been able to crown a victor regardless of the data due to important biases that may have impacted the study. This study appears to be further evidence that dogmatic preaching of the superiority of one agent over another is unwarranted.

Bottom Line

There was no significant difference in first-pass success rate, overall success rate or adverse event rate between succinylcholine and rocuronium. Clinicians should continue to use the NMB agent they are most comfortable with for ED intubation.

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References

Swaminathan A, Mallemat H. Rocuronium Should Be the Default Paralytic in Rapid Sequence Intubation. Ann Emerg Med 2018; 71(3): 397-8. PMID: 28601274

Shoenberger JM, Mallon WK. Rocuronium Versus Succinylcholine Revisited: Succinylcholine Remains the Best Choice. Ann Emerg Med 2018; 71(3): 398-9. PMID: 29458799

Curley GF et al. Rapid Sequence Induction with Rocuronium – A Challenge to the Gold Standard. Crit Care. 2011. PMID: 22112346

Tran DT et al. Rocuronium Versus Succinylcholine for Rapid Sequence Induction Intubation. Cochrane Database Syst Rev 2015. PMID: 26512948