Comparison of Succinylcholine and Rocuronium for First-attempt Intubation Success in the Emergency Department
Presented at the American College of Clinical Pharmacy annual meeting, Anaheim, CA, October 2009.
Disclosures: No funding or support was received for this research.
Supervising Editor: Robert Reardon, MD.
Abstract
ACADEMIC EMERGENCY MEDICINE 2011; 18:11–14 © 2011 by the Society for Academic Emergency Medicine
Objectives: The objective was to determine the effect of paralytic type and dose on first-attempt rapid sequence intubation (RSI) success in the emergency department (ED).
Methods: This was a retrospective evaluation of information collected prospectively in a quality improvement database between July 1, 2007, and October 31, 2008. Information regarding all intubations performed in a tertiary care ED was recorded in this database. All RSI performed using succinylcholine or rocuronium were included. Logistic regression was used to analyze the effect of paralytic type and dosing, as well as age, sex, body mass index, physician experience, device type, and presence of difficult airway predictors on first attempt RSI success.
Results: A total of 327 RSI were included in the final analyses. All patients received etomidate as the induction sedative and were successfully intubated. Of these, 113 and 214 intubations were performed using succinylcholine and rocuronium, respectively. The rate of first-attempt intubation success was similar between the succinylcholine and rocuronium groups (72.6% vs. 72.9%, p = 0.95). Median doses used for succinylcholine and rocuronium were 1.65 mg/kg (interquartile range [IQR] = 1.26–1.95 mg/kg) and 1.19 mg/kg (IQR = 1–1.45 mg/kg), respectively. In the univariate logistic regression analyses, variables predictive of first-attempt intubation success were laryngeal view (more success if Grade 1 or 2 compared to Grade 3 or 4 of the Cormack-Lehane classification, odds ratio [OR] = 55.18, 95% confidence interval [CI] = 18.87 to 161.39), intubation device (less success if direct laryngoscopy, OR = 0.57, 95% CI = 0.34 to 0.96), and presence of a difficult airway predictor (OR = 0.55, 95% CI = 0.31 to 0.99). In the multivariate analysis, the only variable predictive of first-attempt intubation success was laryngeal view.
Conclusions: Succinylcholine and rocuronium are equivalent with regard to first-attempt intubation success in the ED when dosed according to the ranges used in this study.
Succinylcholine and rocuronium are the most common paralytic agents used for rapid sequence intubation (RSI) in the emergency department (ED).1,2 Studies comparing these agents for RSI have primarily evaluated their effect on intubation conditions, which may vary in a dose-dependent manner. Current evidence suggests that succinylcholine provides superior intubation conditions to rocuronium.1,3 However, this advantage of succinylcholine may be due to the underdosing of rocuronium in comparative studies. Studies evaluating higher doses of rocuronium have produced intubation conditions similar to those of succinylcholine.1 Also, intubation conditions may not necessarily translate into intubation success or the number of intubation attempts required in the ED. Therefore, the effect of paralytic type and dose on first-attempt intubation success in the ED needs further evaluation.
In addition to its effect on intubation conditions, succinylcholine is considered to be the paralytic of choice for RSI due to its short duration of action. Duration of paralysis after rocuronium can be greater than 45 minutes, which is much longer than the effect of succinylcholine, which typically lasts less than 6 minutes.4,5 This is one of the primary reasons why use of rocuronium is avoided, as intubation failure after the use of rocuronium may require prolonged bag-mask ventilation. However, the potential of using new reversal agents, such as sugammadex for nondepolarizing neuromuscular blockers, has renewed enthusiasm for the use of rocuronium.2,6 Theoretically, the use of rocuronium followed by sugammadex after intubation could reduce the duration of paralysis to less than that with succinylcholine, thereby addressing the concerns about the long duration of effect. However, this drug is currently not available in the United States. More importantly, succinylcholine may be contraindicated in certain patient populations in the ED, and potential adverse effects such as hyperkalemia and increased intracranial pressure limit its use. If higher doses of rocuronium produce similar intubation success rates to succinylcholine, then rocuronium could replace succinylcholine as the paralytic agent of choice for RSI in the ED.
The primary purpose of this investigation was to determine the effect of paralytic type and dose on first-attempt intubation success in the ED. Additionally, other factors that may be associated with first-attempt intubation success were evaluated. The number of intubation attempts required for successful intubation was also compared between the succinylcholine and rocuronium groups.
Methods
Study Design
This was a retrospective evaluation of information collected prospectively in a quality improvement database between July 1, 2007, and October 31, 2008. Approval was obtained from the human subjects committee prior to conducting this study.
Study Setting and Population
The study was performed in a 40-bed academic, tertiary care ED with an annual census of approximately 70,000 patients. The ED is designated as a Level I trauma center. The ED is the site of a 3-year emergency medicine (EM) residency program. Intubations are primarily performed by EM residents or attending emergency physicians (EPs). During each RSI, the physicians have access to a RSI medication box at the bedside that contains etomidate for induction of sedation and succinylcholine or rocuronium for paralysis. Physicians also have access to other sedatives that are stored in controlled access cabinets (Pyxis, CareFusion Corp., San Diego, CA) in the ED. Medications used for RSI are based on physician preference.
Data were prospectively recorded for all consecutive patients who were intubated in the ED during the study period. Patients were excluded from the analyses if they were younger than 18 years of age, did not receive RSI, received medications other than etomidate for induction or succinylcholine or rocuronium for paralysis, or had missing documentation in the database or medical record.
Study Protocol
Outcomes measured were success of endotracheal intubation, first-attempt intubation success, and number of attempts required. A successful intubation was defined as proper placement of the endotracheal tube without requirement for a surgical airway. An intubation attempt was defined as introduction of the laryngoscope into the patient’s mouth and its removal regardless of whether an endotracheal tube was inserted. This definition was similar to that used in previous investigations.7
Data were collected prospectively by the EP performing the intubation and were recorded immediately after the intubation using a paper data collection form. The information was subsequently entered into an electronic database by an EP who manages the database. Data collected included patient age, sex, reason for intubation (and if intubation was related to a traumatic injury), medications used for RSI, presence of difficult airway predictors, device used, EP experience categorized by year of residency training, and laryngeal view using the Cormack-Lehane classification system (Table 1).8 Outcomes were also recorded such as success of the intubation and number of intubation attempts. Some data required for our analyses such as patient height, weight, and drug doses were not available in the database and were subsequently obtained by the investigators from medical records.
| Succinylcholine (n = 113) | Rocuronium (n = 214) | |
|---|---|---|
| Patient demographics | ||
| Age, yr (mean ± SD) | 47.4 ± 20.6 | 46.7 ± 21 |
| Weight, kg (mean ± sd) | 82.5 ± 24.3 | 78.5 ± 19 |
| Body mass index (mean ± SD) | 27.4 ± 8.1 | 26.2 ± 5.9 |
| Trauma patient, n (%) | 60 (53) | 118 (55) |
| Intubation data | ||
| Reason for intubation, n (%) | ||
| Airway protection | 79 (70) | 158 (73.8) |
| Patient control | 8 (7.1) | 24 (11.2) |
| Respiratory failure | 23 (20.4) | 28 (13.1) |
| Hypoxia | 2 (1.8) | 3 (1.4) |
| Cardiac arrest | 1 (0.9) | 1 (0.4) |
| Laryngeal view,*n (%) | ||
| Grade 1 | 58 (51.3) | 139 (65) |
| Grade 2 | 34 (30.1) | 45 (21) |
| Grade 3 | 13 (11.5) | 21 (9.8) |
| Grade 4 | 8 (7.1) | 5 (2.3) |
| Difficult airway predictors,†n (%) | ||
| ≥1 present | 81 (71.7) | 153 (71.5) |
| Device, n (%) | ||
| Direct laryngoscopy | 72 (63.7) | 121 (56.5) |
| GlideScope | 37 (32.7) | 76 (35.5) |
| Other | 4 (3.5) | 17 (7.9) |
| Physician experience, n (%) | ||
| First-year resident | 18 (15.9) | 36 (16.8) |
| Second-year resident | 41 (36.3) | 84 (39.3) |
| Third-year resident or attending | 51 (45.1) | 88 (41.1) |
| Number of intubation attempts, n (%) | ||
| 1 | 82 (72.6) | 156 (72.9) |
| 2 | 25 (22.1) | 37 (17.3) |
| ≥3 | 6 (5.3) | 21 (9.8) |
- *Cormack-Lehane classification.
- †Blood in airway, vomit in airway, facial trauma, cervical immobility, obesity, airway edema, small mandible, short neck, large tongue, other.
For this study, the only data collected retrospectively were patient height, weight, and drug doses. This was obtained by a single abstractor who was trained to obtain this information from specific locations in the electronic medical record. The training session consisted of a 1-hour period where the abstractor was familiarized with the electronic record and locations from where this information could be obtained. This was then directly entered into the database. Information abstracted was double-checked by a second investigator to identify any potential errors during abstraction. No errors were identified.
Outcome Measures
The primary outcome measures were the effect of paralytic type and dose on first-attempt intubation success. The succinylcholine and rocuronium groups were compared with regard to this outcome. Other factors predictive of first-attempt intubation success such as patient age, sex, body mass index, physician experience, presence of difficult airway predictors, device used, and laryngeal view were evaluated.
Data Analysis
The rocuronium and succinylcholine groups were compared descriptively with regard to patient demographics. Categorical variables were analyzed using the Fisher’s exact test. Nonparametric data were analyzed using the Wilcoxon rank-sum test. Univariate logistic regression analyses were performed to evaluate the effect of paralytic type and dosing, as well as other factors on first-attempt intubation success (Table 1). A multivariate logistic regression was performed with variables included in the final model if they were significant at a 0.05 level or they altered the coefficient of the main variable by more than 10% in cases in which the main association was significant. Significance for all analyses were defined as p < 0.05. Analyses were performed using Stata, version 11 (StataCorp, College Station, TX).
Results
A total of 621 patients were intubated during the study period. Of these, 93 patients had missing or partial documentation in the database or medical record with regard to patient weight or medication doses used, 83 patients were less than 18 years of age, 71 patients did not undergo RSI, and 47 patients either did not receive etomidate for induction of sedation or did not receive succinylcholine or rocuronium for paralysis. Therefore, 327 patients were included in the final analyses. There were 113 (35%) patients in the succinylcholine group and 214 (65%) patients in the rocuronium group. The groups were similar demographically and with regard to intubation parameters such as reason for intubation, presence of difficult airway predictors, laryngeal view, intubating device, and physician experience (Table 1).
All patients were successfully intubated, with none requiring a surgical airway. First-attempt intubation success was similar between the succinylcholine and rocuronium groups (72.6% vs. 72.9%, p = 1.00). The median number of intubation attempts was also similar between the succinylcholine and rocuronium groups (1, interquartile range [IQR] = 1–2 vs. 1, IQR = 1–2, p = 0.87). Median doses used for succinylcholine and rocuronium were 1.65 mg/kg (IQR = 1.26–1.95 mg/kg) and 1.19 mg/kg (IQR = 1–1.45 mg/kg), respectively. The median dose of etomidate was 0.25 mg/kg in both groups. Unadjusted odds ratios (OR) of variable predictive of first-attempt intubation success with regression analysis are reported in Table 2. In the multivariate regression analysis, the only variable predictive of first attempt intubation success was laryngeal view, with more success with Grade 1 or 2 compared to Grade 3 or 4 using the Cormack-Lehane classification (OR = 55.18, 95% confidence interval [CI] = 18.87 to 161.39). Paralytic type and dose, as well as patient age, sex, body mass index, physician experience, presence of difficult airway predictors, and device, used were not predictive of first-attempt intubation success. GlideScope video layngoscopy (Verathon Medical Inc., Bothell, WA) was used in 84% of the cases when direct laryngoscopy was not used.
| OR | 95% CI | p-value | |
|---|---|---|---|
| Age, yr | 1 | 0.99–1.02 | 0.54 |
| Body mass index | 1 | 0.96–1.04 | 1 |
| Male* | 0.6 | 0.35–1.04 | 0.07 |
| Rocuronium† | 1.02 | 0.61–1.7 | 0.95 |
| Paralytic dose | |||
| Succinylcholine | 0.58 | 0.29–1.13 | 0.11 |
| Rocuronium | 1.1 | 0.51–2.4 | 0.81 |
| Laryngeal view‡ | 55.18 | 18.87–161.39 | <0.001 |
| Difficult airway predictor§ | 0.55 | 0.31–0.99 | 0.05 |
| Device|| | 0.57 | 0.34–0.96 | 0.03 |
| Physician experience¶ | |||
| Second-year resident | 1.15 | 0.58–2.26 | 0.7 |
| Third-year resident or attending | 1.74 | 0.87–3.48 | 0.12 |
- *Likelihood due to male.
- †Likelihood due to rocuronium.
- ‡Likelihood due to Grade 1 or 2 Cormack-Lehane classification.
- §Blood in airway, vomit in airway, facial trauma, cervical immobility, obesity, airway edema, small mandible, short neck, large tongue, other.
- ||Likelihood due to direct laryngoscopy compared to GlideScope or other devices.
- ¶Compared to first-year residents.
Discussion
The most important finding in this study was that there was no difference in success rate for first intubation attempt or number of attempts regardless of the type of paralytic used or the dose administered. Based on these results, the superior intubation conditions with succinylcholine found in previous investigations may not translate into superior intubation success. However, it is important to note that the median dose of rocuronium used in this study was 1.19 mg/kg (IQR = 1–1.45 mg/kg), which is higher than what is commonly recommended. This finding is consistent with previous investigations that used doses between 0.9 and 1.2 mg/kg and found similar intubating conditions to succinylcholine.1 Subgroup analyses of studies using a lower rocuronium dose of 0.6 to 0.7 mg/kg had a relative risk favoring succinylcholine for excellent intubating conditions.1 Very few patients in this study received this lower dose of rocuronium, so we could not address this facet due to the routine use of higher doses in our study. Another interesting finding is that a greater proportion of patients in our study received rocuronium. This is reflective of current practice at our institution, since clinicians often avoid the use of succinylcholine due to the potential for adverse effects.
In a previous investigation in an operating room setting, patients undergoing elective surgical procedures were randomly allocated to receive 0.3, 0.5, 1, 1.5, or 2 mg/kg of succinylcholine.9 Intubation conditions were considered to be excellent in 43.3, 60, 63.3, 80, and 86.7% of the patients, respectively. The authors concluded that the optimal dose was 1.5 mg/kg, although some have advocated using 2 mg/kg based on these data.10 The median succinylcholine dose in our study was 1.65 mg/kg (IQR = 1.26–1.95 mg/kg). Therefore, the median doses used were adequate to make an appropriate comparison with rocuronium. Overall, the dosing of the paralytics did not influence our primary outcomes within the ranges used in this study.
We only included patients who were given etomidate for induction of sedation. This was done to eliminate the potential for confounding due to different sedatives. However, etomidate is one of the most commonly used sedatives for RSI in the ED. This is due to its favorable pharmacokinetic profile and the relative lack of hemodynamic or respiratory effects. Since most patients in our ED are sedated with etomidate for RSI, we decided to exclude patients given other sedatives in an effort to recruit a homogenous patient population for analyses.
Limitations
Information was not collected regarding intubating conditions and satisfaction of the providers with the paralytics used. However, the strength of this study is that we looked beyond intubation conditions and evaluated outcomes from a more practical perspective. The success rate of first intubation attempt and the number of attempts gives us additional information regarding the effect of intubation conditions. We did not have information regarding complications or drug-related adverse effects. However, the doses used in this study were within the recommended dosing range for the agents used. Information regarding the type of laryngoscope blade, approach used, adjunctive devices, or reason for device selection was not recorded. It is possible that device selection was influenced by assessment of a difficult airway. However, the presence of difficult airway predictors was similar between groups. Finally, most protocols in randomized controlled studies have evaluated intubation conditions at a specific time after drug administration (e.g., 60 seconds). Data were not available with regard to time between drug administration and intubation attempts. This could be an issue with regard to rocuronium due to a slower onset of effect. In this case intubation success would be expected to be lower if the attempt occurred too soon after drug administration. However, since we did not find any difference in our primary outcomes, it is likely that intubation attempts were performed after the drugs had taken effect.
Conclusions
Succinylcholine and rocuronium are equivalent with regard to first attempt intubation success in the ED when dosed according to the ranges used in this study.
