Endotracheal intubation is an essential component of airway management during general anaesthesia. Adequate relaxation of the jaw and laryngeal muscles facilitates laryngoscopy, improves visualization of the glottis and permits atraumatic passage of the endotracheal tube. Rapid-sequence induction and intubation is particularly important in patients at increased risk of pulmonary aspiration, where the interval between loss of protective airway reflexes and securing the airway must be minimized. Although individual rapid-sequence techniques vary, the use of a rapidly acting induction agent followed by an appropriate neuromuscular-blocking drug remains a central component of this approach.[1]

Neuromuscular-blocking agents improve intubating conditions by producing relaxation of the jaw, vocal cords and respiratory muscles. However, their administration requires careful assessment of the depth of blockade and recovery. Current guidelines from the American Society of Anesthesiologists and the European Society of Anaesthesiology and Intensive Care recommend objective neuromuscular monitoring and appropriate antagonism of residual blockade to reduce postoperative respiratory complications. Quantitative monitoring is preferable to clinical assessment alone because apparently adequate muscle strength may coexist with incomplete neuromuscular recovery.[2,3]

Succinylcholine is a depolarizing neuromuscular-blocking agent that has traditionally been used to facilitate rapid tracheal intubation because of its rapid onset and relatively brief duration of action. Despite these favourable pharmacodynamic properties, its administration may be associated with clinically important adverse effects. Of particular concern is the risk of severe hyperkalaemia in patients with burns, denervation injuries, prolonged immobilization, neuromuscular disorders and other conditions associated with upregulation of extrajunctional acetylcholine receptors. These limitations have encouraged the search for a non-depolarizing neuromuscular-blocking agent that can provide similarly rapid and satisfactory intubating conditions.[4]

Rocuronium bromide is an aminosteroidal, non-depolarizing neuromuscular-blocking agent with a more rapid onset than most other non-depolarizing drugs. Its onset and duration are dose dependent. Magorian et al.[7] demonstrated that increasing doses of rocuronium shortened the onset of neuromuscular blockade and that rocuronium at higher doses approached the onset characteristics required for rapid-sequence intubation. Similarly, Schultz et al.[9] found that increasing the rocuronium dose from 0.6 to 0.9 mg/kg shortened the time to maximum blockade and improved intubating conditions, whereas further increasing the dose to 1.2 mg/kg prolonged the duration of profound blockade without providing a clear additional improvement in intubating conditions at 60 seconds.[7,9]

The onset of neuromuscular blockade measured at the adductor pollicis does not necessarily reflect the onset of relaxation at the laryngeal muscles. Meistelmanet al.[5] demonstrated that rocuronium acted more rapidly at the laryngeal adductor muscles than at the adductor pollicis, although the intensity of blockade at the larynx was comparatively lower. Wright et al.[6] subsequently confirmed that rocuronium and succinylcholine showed different onset and recovery profiles at the laryngeal adductors and adductor pollicis. Hemmerling et al.[8], using surface laryngeal electromyography, further demonstrated the importance of evaluating laryngeal neuromuscular function when comparing drugs intended to facilitate endotracheal intubation.[5,6,8]

Consequently, disappearance of the peripheral twitch response alone may not fully describe the clinical conditions encountered during laryngoscopy. A comprehensive comparison should include the measured onset of neuromuscular blockade together with clinically relevant components of intubating conditions, including jaw relaxation, vocal-cord movement and the laryngoscopic view. Haemodynamic changes associated with laryngoscopy and intubation should also be evaluated, because sympathetic stimulation may produce transient increases in heart rate and arterial pressure, particularly when the depth of anaesthesia or neuromuscular blockade is inadequate.

One limitation of high-dose rocuronium is its longer duration of action compared with succinylcholine. The introduction of sugammadex, a selective binding agent capable of reversing rocuronium-induced blockade, has modified the clinical consequences of prolonged paralysis. Sørensen et al.[10] reported that rapid-sequence induction with rocuronium followed by sugammadex allowed spontaneous ventilation to be restored earlier than spontaneous recovery after succinylcholine. Nevertheless, the availability and cost of sugammadex and the need for appropriate dosing and neuromuscular monitoring remain relevant when selecting rocuronium for rapid airway management.[10]

Recent evidence indicates that satisfactory intubating conditions can be obtained with either drug, although succinylcholine may retain an advantage in onset time. In a 2025 randomized study involving patients aged 80 years or older, Vestedet al.[11] observed excellent intubating conditions in 73% of patients receiving rocuronium and 75% receiving succinylcholine, with first-pass success of 98% in both groups. However, the onset of neuromuscular blockade remained significantly shorter with succinylcholine. These findings demonstrate that the quality of intubation and the measured speed of neuromuscular blockade are related but distinct outcomes.[11]

Variations in the dose of neuromuscular-blocking agents, induction technique, timing of laryngoscopy, monitoring site and criteria used to grade intubating conditions have contributed to differences among published studies. Direct comparison under standardized operating-theatre conditions is therefore useful for determining whether rocuronium can provide adequate intubating conditions while avoiding the important contraindications associated with succinylcholine.

The present study was undertaken to compare rocuronium bromide 0.9 mg/kg and succinylcholine chloride 0.9 mg/kg, representing 3 × ED95 doses, for facilitating endotracheal intubation in adult patients undergoing elective surgical procedures under general anaesthesia. The onset of neuromuscular blockade, jaw relaxation, vocal-cord movement and Cormack–Lehane grade were compared between the groups. Haemodynamic responses were evaluated by recording pulse rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure before induction, before intubation and after intubation.

Aim

To compare the efficacy of 3 × ED95 doses of rocuronium bromide and succinylcholine in facilitating endotracheal 

intubation in adult patients undergoing elective surgery under general anaesthesia.

Objectives

1. To compare the onset of neuromuscular blockade and intubating conditions, including jaw relaxation, vocal-cord movement and Cormack–Lehane grade, between patients receiving rocuronium bromide and succinylcholine.
2. To compare the haemodynamic response to endotracheal intubation, including pulse rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure, between the two groups.

Study Design and Setting

This is a randomized, single-blinded, comparative study was conducted in the Department of Anaesthesiology, May 2025 – January 2026, over a period of ten months. The study compared 3 × ED95 doses of rocuronium bromide and succinylcholine chloride for facilitating endotracheal intubation in adult patients undergoing elective surgical procedures under general anaesthesia.

Ethical Considerations

The study protocol was approved by the Institutional Ethics Committee of before commencement of patient recruitment (approval number: )Written informed consent was obtained from all participants after explaining the nature of the study, the anaesthetic procedure and the potential benefits and risks associated with the study drugs. Patient confidentiality was maintained throughout the study.

Study Population

A total of 50 adult patients scheduled for elective surgical procedures under general anaesthesia with endotracheal intubation were included. The patients were randomly allocated in a 1:1 ratio into two groups of 25 patients each.

Patients assigned to Group R received rocuronium bromide, whereas those assigned to Group S received succinylcholine chloride.

Inclusion Criteria

Patients aged 18–60 years of either sex, belonging to American Society of Anesthesiologists physical status I or II and scheduled for elective surgery under general anaesthesia requiring endotracheal intubation were included in the study.

Exclusion Criteria

Patients belonging to ASA physical status III or IV, those with an anticipated difficult airway, renal disease, hepatic failure, major burns, increased intracranial pressure, open-eye injuries, significant cardiovascular or respiratory disease, and patients with any contraindication to the administration of rocuronium or succinylcholine were

Preanaesthetic Evaluation

All patients underwent a detailed preanaesthetic assessment before surgery. Relevant medical and surgical history was obtained, followed by general physical examination, systemic examination and airway evaluation. Airway assessment included Mallampati grading. Age, sex, weight, height and ASA physical status were recorded for every patient. Routine laboratory investigations were performed according to institutional protocol.

Patients were advised to follow standard fasting guidelines before surgery.

Randomization and Group Allocation

Eligible patients were randomly allocated to either Group R or Group S using a computer-generated randomization sequence.

The groups were constituted as follows:

Group R: Twenty-five patients received rocuronium bromide 0.9 mg/kg intravenously.

Group S: Twenty-five patients received succinylcholine chloride 0.9 mg/kg intravenously.

The person designated as blinded in the study protocol was not informed of the group allocation during assessment of the study outcomes.

Anaesthetic Procedure

After the patient was shifted to the operating theatre, an intravenous cannula was secured and an appropriate balanced crystalloid solution was started. Standard monitoring consisting of electrocardiography, pulse oximetry, non-invasive blood pressure monitoring and heart-rate monitoring was established.

Baseline pulse rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were recorded before induction of anaesthesia.

All patients were preoxygenated with 100% oxygen for 3 minutes. Intravenous premedication consisted of glycopyrrolate 3 µg/kg, midazolam 0.02 mg/kg and fentanyl 1 µg/kg. Anaesthesia was induced with titrated intravenous propofol until loss of verbal response.

Following induction, patients received the allocated neuromuscular-blocking agent according to the study group.

Neuromuscular Monitoring

Neuromuscular blockade was assessed using peripheral nerve stimulation. A single-twitch stimulus at a frequency of 0.1 Hz was applied every 10 seconds after administration of the study drug.

The onset time of neuromuscular blockade was measured in seconds from completion of drug administration until disappearance of the elicited twitch response. The same neuromuscular-monitoring technique and endpoint were used in both groups.

Endotracheal Intubation and Assessment

Endotracheal intubation was performed after the predefined neuromuscular-block endpoint had been achieved. During direct laryngoscopy and intubation, jaw relaxation, vocal-cord movement and the Cormack–Lehane laryngoscopic grade were assessed.

Jaw relaxation was categorized as good or poor. Good jaw relaxation was defined as adequate relaxation permitting laryngoscopy without significant resistance, whereas poor relaxation was defined as resistance during mouth opening or laryngoscopy.

Vocal-cord response was recorded as either movement present or no movement. The laryngoscopic view was classified according to the Cormack–Lehane grading system.

Grade I indicated visualization of the entire glottic opening. Grade II indicated visualization of the posterior portion of the glottis or arytenoid cartilages. Grade III indicated visualization of the epiglottis only, and Grade IV indicated that neither the glottis nor the epiglottis was visible.

Haemodynamic Monitoring

The haemodynamic response to induction and endotracheal intubation was assessed by recording pulse rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure at the following time points:

• Pre-induction, before administration of the induction agent.
• Pre-intubation, immediately before laryngoscopy.
• Post-intubation, immediately after successful endotracheal intubation.
• All haemodynamic measurements were obtained using the same standard multiparameter monitor.

Outcome Measures

The primary outcome was the onset time of neuromuscular blockade, measured in seconds.

Secondary outcomes included jaw relaxation, vocal-cord movement, Cormack–Lehane grade and haemodynamic changes associated with endotracheal intubation. Haemodynamic variables included pulse rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure.

Data Collection

Demographic details, airway-assessment findings, group allocation, onset time of neuromuscular blockade, intubating-condition parameters and haemodynamic measurements were entered into a predesigned case-record form.

The collected data were checked for completeness and accuracy before entry into the statistical software.

Statistical Analysis

Data were entered into Microsoft Excel and analysed using IBM SPSS Statistics, version.Continuous variables were expressed as mean ± standard deviation. Categorical variables were presented as frequencies and percentages.Normally distributed continuous variables were compared between the two groups using the independent-samples Student’s t-test. Categorical variables were compared using the Pearson chi-square test or Fisher’s exact test when the expected frequency in any cell was less than 5.Pulse rate, systolic blood pressure, diastolic blood pressure and mean arterial pressure were compared between the two groups at each predefined measurement point.All statistical tests were two-tailed, and a p-value of less than 0.05 was considered statistically significant.

patients were allocated equally into two groups. Group R consisted of 25 patients who received rocuronium bromide, while Group S consisted of 25 patients who received succinylcholine. All 50 enrolled participants completed the study and were included in the final analysis.

Continuous variables were expressed as mean ± standard deviation and compared using the independent-samples Student’s t-test. Categorical variables were expressed as frequencies and percentages and compared using the Pearson chi-square test or Fisher’s exact test, as appropriate. A p-value of less than 0.05 was considered statistically significant.

Table 1. Comparison of baseline characteristics between the study groups

The mean age and weight were comparable between the two groups, with no statistically significant differences. The mean height was significantly greater in Group R than in Group S (154.10 ± 9.60 cm versus 149.00 ± 6.40 cm; p = 0.032).

Table 2. Distribution according to ASA physical status

In Group R, 16 patients (64.0%) were classified as ASA I and 9 patients (36.0%) as ASA II. In Group S, 19 patients (76.0%) were classified as ASA I and 6 patients (24.0%) as ASA II. The difference in ASA physical-status distribution was not statistically significant (p = 0.355).

Table 3. Distribution according to Mallampati grade

Mallampati Grade I was observed in 19 patients (76.0%) in each group, while Grade II was observed in 6 patients (24.0%) in each group. The Mallampati-grade distribution was identical between the two groups (p = 1.000).

Table 4. Comparison of jaw relaxation

Good jaw relaxation was observed in 20 patients (80.0%) in Group R and 23 patients (92.0%) in Group S. Poor jaw relaxation was observed in 5 patients (20.0%) in Group R and 2 patients (8.0%) in Group S. Although good jaw relaxation was numerically more frequent with succinylcholine, the difference was not statistically significant (p = 0.417).

Table 5. Comparison of vocal-cord movement

Vocal-cord movement was present in 4 patients (16.0%) in Group R and 2 patients (8.0%) in Group S. No vocal-cord movement was observed in 21 patients (84.0%) in Group R and 23 patients (92.0%) in Group S. The difference between the groups was not statistically significant (p = 0.667).

Table 6. Distribution according to Cormack–Lehane grade

Cormack–Lehane Grade I was observed in 16 patients (64.0%) in Group R and 18 patients (72.0%) in Group S. Grade II was observed in 9 patients (36.0%) and 7 patients (28.0%), respectively. There was no statistically significant difference in Cormack–Lehane grading between the two groups (p = 0.544).

Table 7. Comparison of onset of neuromuscular blockade

The mean onset of neuromuscular blockade was 72.40 ± 9.00 seconds in Group R compared with 60.20 ± 7.40 seconds in Group S. The onset was approximately 12.20 seconds faster with succinylcholine, and the difference was statistically significant (p < 0.001).

Table 8. Comparison of pulse rate between the study groups

Pre-induction and pre-intubation pulse rates were comparable between the groups. Following intubation, the mean pulse rate was significantly higher in Group R than in Group S (94.80 ± 16.20 versus 82.00 ± 12.00 beats/min; p = 0.003).

Table 9. Comparison of systolic blood pressure

There were no statistically significant differences in systolic blood pressure between the groups at pre-induction, pre-intubation or post-intubation measurements.

Table 10. Comparison of diastolic blood pressure

Mean diastolic blood pressure was comparable between the two groups at all three measurement points. None of the observed differences reached statistical significance.

 Table 11. Comparison of mean arterial pressure

There were no statistically significant differences in mean arterial pressure between the rocuronium and succinylcholine groups at pre-induction, pre-intubation or post-intubation measurements.

Summary of principal results

Both rocuronium and succinylcholine produced broadly comparable intubating conditions. The distributions of ASA physical status, Mallampati grade, jaw relaxation, vocal-cord movement and Cormack–Lehane grade did not differ significantly between the groups.

Succinylcholine produced a significantly faster onset of neuromuscular blockade than rocuronium. Post-intubation pulse rate was significantly higher in the rocuronium group. Systolic blood pressure, diastolic blood pressure and mean arterial pressure remained statistically comparable between the two groups throughout the observed peri-intubation period.

The present study compared rocuronium bromide 0.9 mg/kg and succinylcholine chloride 0.9 mg/kg for facilitating endotracheal intubation in 50 adult patients undergoing elective surgery under general anaesthesia. The principal finding was that succinylcholine produced a significantly faster onset of neuromuscular blockade than rocuronium. However, both drugs provided broadly comparable conditions for endotracheal intubation, as demonstrated by the absence of statistically significant differences in jaw relaxation, vocal-cord movement and Cormack–Lehane grade. Except for a greater post-intubation increase in pulse rate in the rocuronium group, haemodynamic responses were comparable between the groups.

In the present study, the mean onset time was 72.40 ± 9.00 seconds with rocuronium and 60.20 ± 7.40 seconds with succinylcholine, representing a mean difference of 12.20 seconds in favour of succinylcholine. This difference was statistically significant at p<0.001. The result confirms the established rapid-onset profile of succinylcholine and indicates that rocuronium at 0.9 mg/kg, although relatively rapid for a non-depolarizing neuromuscular-blocking agent, does not completely reproduce the onset characteristics of succinylcholine.

This finding is strongly supported by the recent randomized trial conducted by Paul et al.[20] In their study of 135 adult patients, the median time to disappearance of the train-of-four response was 65 seconds with succinylcholine 1 mg/kg, compared with 102 seconds with rocuronium 0.9 mg/kg. Pretreatment with magnesium sulphate shortened the onset of rocuronium to 82 seconds but did not make it as rapid as succinylcholine. The approximately 12-second difference observed in the present study was smaller than the 37-second difference reported by Paul et al. This may be related to differences in neuromuscular-monitoring methods, induction drugs, circulation time, endpoint definition and patient characteristics. Nevertheless, the direction of the association was identical in both studies.

Sluga et al.[23] similarly demonstrated that succinylcholine allowed a more rapid overall endotracheal-intubation sequence than rocuronium in patients requiring emergency surgery. The median total intubation sequence was approximately 95 seconds with succinylcholine compared with 130 seconds with rocuronium. Their findings support the present observation that the pharmacodynamic onset of succinylcholine remains more rapid, particularly when the complete time required to secure the airway is considered.

Although succinylcholine had a faster onset in the present study, the difference in the quality of jaw relaxation was not statistically significant. Good jaw relaxation was observed in 80.0% of patients receiving rocuronium and 92.0% receiving succinylcholine, p=0.417. Therefore, succinylcholine produced a numerically higher rate of good jaw relaxation, but the study lacked evidence of a statistically meaningful difference.

The findings regarding jaw relaxation are compatible with those of Weiss et al.[24], who reported that rocuronium 0.9 mg/kg produced intubating conditions at 60 seconds comparable with those produced by succinylcholine 1.5 mg/kg. In contrast, rocuronium 0.7 mg/kg produced less favourable conditions, suggesting that the ability of rocuronium to approximate succinylcholine is dose dependent. The use of rocuronium 0.9 mg/kg in the present study may therefore explain why the difference in jaw relaxation did not reach statistical significance despite the faster onset observed with succinylcholine.

Andrews et al.[22] conducted a large randomized study using propofol and reported clinically acceptable intubating conditions in 93.2% of patients receiving rocuronium 1 mg/kg and 97.1% receiving succinylcholine 1 mg/kg. The difference of 3.9 percentage points was not considered clinically important. These findings are consistent with the current study, in which acceptable individual components of intubation were common in both groups despite a numerical advantage for succinylcholine. The slightly less favourable result with rocuronium in the present study may be attributable to the lower dose of 0.9 mg/kg and the relatively small sample.

Vocal-cord immobility was observed in 84.0% of the rocuronium group and 92.0% of the succinylcholine group, with no significant difference between the groups. This suggests that both drugs produced satisfactory laryngeal relaxation in most patients. The finding is clinically relevant because vocal-cord position and movement are important components of intubating conditions and may affect resistance to tube passage, coughing and airway trauma.

The Cochrane systematic review by Tran et al.[12], which included 50 studies and 4,151 participants, concluded that succinylcholine was more likely than rocuronium to produce excellent intubating conditions. The pooled relative risk for excellent conditions was 0.86 for rocuronium relative to succinylcholine. However, the difference was substantially smaller when the outcome was broadened to clinically acceptable conditions, with a relative risk of 0.97. These pooled findings help explain the present results: succinylcholine produced numerically better jaw relaxation and vocal-cord immobility, but most patients in both groups still achieved acceptable conditions, resulting in non-significant comparisons within a 50-patient study.

A subsequent systematic review and network meta-analysis by de Carvalho et al.[13] reassessed randomized evidence comparing both agents during rapid-sequence induction. The availability of multiple rocuronium doses and different induction regimens makes interpretation dependent on the exact drug dose, timing of laryngoscopy and definition of successful intubation. Thus, comparisons between studies should not treat all rocuronium or succinylcholine protocols as pharmacologically identical.

Cormack–Lehane Grade I visualization was obtained in 64.0% of the rocuronium group and 72.0% of the succinylcholine group, while Grade II views were observed in 36.0% and 28.0%, respectively. This difference was not statistically significant. These results indicate that the laryngeal view was generally favourable in both groups and that the choice of neuromuscular-blocking agent did not materially alter glottic visualization in patients with a predicted normal airway.

Ramsey et al.[17] reported similar Cormack–Lehane grades following prehospital administration of either drug. Their first-attempt success rates were also nearly identical, at 84% with succinylcholine and 83% with rocuronium. However, the median time from drug administration to the first attempt was shorter with succinylcholine, at 57 seconds compared with 83 seconds with rocuronium. These results closely resemble the present finding that the drugs produced similar laryngoscopic conditions, while succinylcholine achieved those conditions more rapidly.

Tang et al.[18] also found no significant difference in intubating conditions, Cormack–Lehane classification or number of attempts among patients receiving succinylcholine or rocuronium. Their results strengthen the interpretation that high-dose rocuronium may provide clinically satisfactory conditions even when its measured onset remains slower. They additionally found that rocuronium 1.2 mg/kg produced a longer non-hypoxic apnoea period than succinylcholine 1.5 mg/kg, suggesting that evaluation of an RSI agent should extend beyond onset time alone.

The present findings are also supported by studies performed in emergency departments. April et al.[15] analysed more than 4,000 rapid-sequence intubations and reported first-pass success rates of 87.0% with succinylcholine and 87.5% with rocuronium. The occurrence of any peri-intubation adverse event was also almost identical, at 14.7% and 14.8%, respectively. These large registry data suggest that, under routine clinical conditions, operator experience, airway anatomy, laryngoscopy technique and equipment may influence intubation success at least as much as the choice between appropriately dosed rocuronium and succinylcholine.

Patanwalaet al.[21] similarly reported first-attempt success rates of 72.6% with succinylcholine and 72.9% with rocuronium, with p=0.95. Li et al.[16] found no significant difference in first-attempt intubation success among 267 patients, although successful first attempts occurred in 112 patients receiving succinylcholine and 87 receiving rocuronium. These studies support the present conclusion that clinically useful intubating conditions can be obtained with either drug, despite the faster pharmacological onset of succinylcholine.

However, results from emergency and prehospital studies have not been entirely uniform. In the multicentre CURASMUR randomized trial, Guihardet al.[14] reported first-attempt success in 74.6% of patients receiving rocuronium 1.2 mg/kg and 79.4% receiving succinylcholine 1 mg/kg. Rocuronium failed to meet the predefined non-inferiority criterion. Nevertheless, overall Copenhagen intubating-condition scores and mean intubation-difficulty scores were not significantly different. The apparent difference between first-attempt success and intubation-condition scores demonstrates that these outcomes are related but not interchangeable.

The CURASMUR trial involved acutely ill patients undergoing out-of-hospital emergency intubation, whereas the present study included stable ASA physical-status I and II patients undergoing elective surgery with a predicted normal airway. Differences in physiological reserve, airway contamination, cervical immobilization, operator urgency and equipment may account for the differing results. The present findings should therefore primarily be interpreted in the context of controlled operating-theatre intubation and should not be automatically extrapolated to critically ill or trauma patients.

Regarding haemodynamic response, pre-induction and pre-intubation pulse rates were comparable between the groups. Following intubation, pulse rate increased to 94.80 ± 16.20 beats/min in the rocuronium group compared with 82.00 ± 12.00 beats/min in the succinylcholine group, p=0.003. This indicates a greater tachycardic response following rocuronium in the present study. The difference could be related to variations in the depth of neuromuscular block at the time of laryngoscopy, individual sympathetic response or random variation arising from the small sample.

In contrast, systolic blood pressure, diastolic blood pressure and mean arterial pressure did not differ significantly between groups at pre-induction, pre-intubation or post-intubation measurements. Thus, apart from pulse rate, neither drug demonstrated a clear haemodynamic advantage in this relatively healthy population.

Tang et al.[18] found that changes in mean arterial pressure remained within clinically acceptable limits and that the treatment-by-time interaction for MAP was not significant. Although heart-rate patterns differed statistically among their groups, the investigators did not consider the difference clinically important. These observations generally support the haemodynamic stability recorded in the present study, although the significant post-intubation pulse-rate difference in the present series deserves cautious interpretation.

Czarnetzki et al.[19] reported excellent intubating conditions in 46% of patients receiving magnesium pretreatment followed by rocuronium and 45% receiving succinylcholine. Although the magnesium–rocuronium regimen was not superior, it was associated with fewer undesirable effects. Paul et al.[20] subsequently reported that adding magnesium to rocuronium improved intubating conditions and attenuated the haemodynamic response to laryngoscopy, although succinylcholine still produced the most rapid onset. These studies suggest that strategies enhancing rocuronium-induced blockade may improve the balance between rapid onset, intubating conditions and haemodynamic stability.

Collectively, the present findings and published evidence indicate that succinylcholine retains an advantage when the shortest possible onset is the primary requirement. Rocuronium at 0.9–1.2 mg/kg, however, can produce clinically acceptable intubating conditions in most patients and may be particularly useful when succinylcholine is contraindicated. The decision should therefore consider the clinical setting, anticipated airway difficulty, contraindications, desired duration of paralysis, availability of quantitative neuromuscular monitoring and access to sugammadex rather than onset time alone.

The study has several limitations. First, the sample size was limited to 50 patients from a single centre, reducing the power to detect moderate differences in categorical outcomes such as jaw relaxation and vocal-cord movement. Second, only ASA physical-status I and II patients with an apparently normal airway were included, limiting generalizability to emergency, obese, critically ill or difficult-airway populations. Third, neuromuscular blockade was monitored at the adductor pollicis using single-twitch stimulation, whereas the onset of block at the laryngeal muscles may differ. Fourth, intubating conditions were assessed through separate variables rather than a validated composite scoring system. Fifth, the study did not evaluate the duration of paralysis, time to spontaneous recovery, reversal requirements, postoperative myalgia, hyperkalaemia, awareness during paralysis or other adverse effects. Finally, the succinylcholine dose of 0.9 mg/kg was slightly lower than the commonly evaluated 1 mg/kg or 1.5 mg/kg regimens, which should be considered when comparing the findings with previous studies.

Despite these limitations, the study demonstrates a consistent clinically relevant pattern. Succinylcholine produced a significantly faster onset of neuromuscular blockade, whereas rocuronium 0.9 mg/kg provided broadly comparable jaw relaxation, vocal-cord immobility and laryngoscopic grade. Except for a greater post-intubation pulse-rate increase with rocuronium, haemodynamic responses were similar. These findings support the use of rocuronium as an effective alternative when succinylcholine is unsuitable, while confirming that succinylcholine remains faster at the doses evaluated.

In the present study, succinylcholine chloride 0.9 mg/kg produced a significantly faster onset of neuromuscular blockade than rocuronium bromide 0.9 mg/kg. The mean onset time was 60.20 ± 7.40 seconds with succinylcholine compared with 72.40 ± 9.00 seconds with rocuronium.

Although succinylcholine demonstrated a numerical advantage in jaw relaxation, vocal-cord immobility and Cormack–Lehane Grade I visualization, these differences were not statistically significant. Both agents therefore provided broadly comparable clinical conditions for endotracheal intubation in adult patients with an anticipated normal airway.

Pre-induction and pre-intubation haemodynamic parameters were comparable between the groups. Post-intubation pulse rate was significantly higher in the rocuronium group, whereas systolic blood pressure, diastolic blood pressure and mean arterial pressure did not differ significantly.

These findings indicate that succinylcholine remains preferable when the most rapid onset of neuromuscular blockade is required. Rocuronium bromide at a dose of 0.9 mg/kg provides acceptable intubating conditions and may serve as a suitable alternative when succinylcholine is contraindicated or when avoidance of its adverse effects is clinically desirable.

STRENGTHS OF THE STUDY

The study directly compared equal 3 × ED95 doses of rocuronium bromide and succinylcholine under standardized operating-theatre conditions. Both objective onset time and clinically relevant components of intubating conditions were assessed. Haemodynamic measurements were obtained at predefined intervals, permitting evaluation of the cardiovascular response to induction and endotracheal intubation.

Random allocation and equal group sizes reduced allocation imbalance. The use of the same anaesthetic technique and neuromuscular-monitoring method in both groups improved comparability.

LIMITATIONS

The study had several limitations. First, it was conducted at a single centre with a relatively small sample of 50 patients. The study may therefore have lacked sufficient statistical power to identify moderate differences in categorical outcomes such as jaw relaxation, vocal-cord movement and Cormack–Lehane grade.

Second, only ASA physical-status I and II patients aged 18–60 years with an apparently normal airway were included. The findings may not be generalizable to elderly patients, obese patients, critically ill patients, emergency intubations or individuals with a difficult airway.

Third, neuromuscular blockade was assessed at the peripheral muscle using single-twitch stimulation. The onset of blockade at the adductor pollicis may not precisely correspond to relaxation of the laryngeal muscles or diaphragm.

Fourth, jaw relaxation and vocal-cord movement were assessed using relatively simple categorical classifications. A validated composite intubating-condition score could have provided a more comprehensive and reproducible evaluation.

Fifth, the study evaluated only immediate intubation-related outcomes. The duration of neuromuscular blockade, time to recovery, reversal-agent requirement, postoperative residual paralysis and postoperative adverse effects were not evaluated.

Sixth, adverse events specific to succinylcholine, such as fasciculations, postoperative myalgia, hyperkalaemia and bradyarrhythmia, were not systematically compared.

Finally, the succinylcholine dose of 0.9 mg/kg differs slightly from the 1.0–1.5 mg/kg doses commonly evaluated in rapid-sequence-intubation studies, which should be considered when comparing the findings with previous literature.

FUTURE DIRECTIONS

Future multicentric studies with larger sample sizes should evaluate rocuronium and succinylcholine in diverse patient populations, including elderly, obese, critically ill and emergency-surgery patients.

Quantitative train-of-four monitoring and validated intubating-condition scores should be employed to improve the objectivity and reproducibility of outcome assessment. Direct assessment of laryngeal neuromuscular function may also provide a more clinically relevant estimate of readiness for intubation than peripheral twitch monitoring alone.

Further research should compare different rocuronium doses, including 0.9 and 1.2 mg/kg, with standard succinylcholine doses. Studies should additionally evaluate the duration of paralysis, time to spontaneous recovery, reversal requirements, postoperative residual blockade and overall cost-effectiveness.

The role of sugammadex in improving the safety profile of high-dose rocuronium should be examined in settings where immediate reversal may be required. Future studies should also systematically record adverse effects, postoperative myalgia, biochemical changes, airway complications and patient-centred outcomes

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