Ease of intubation: A randomized, double-blind study to compare two doses of rocuronium bromide for endotracheal intubation

Abstract

Context:

Clinical need for a nondepolarizing agent with a rapid onset time and a brief duration of action has led to the development of rocuronium bromide.

Aims:

The aim of this study was to evaluate optimal dose of rocuronium bromide for intubation and to compare the onset time, duration of action, intubating conditions, and hemodynamic effects of two doses of rocuronium bromide.

Settings and Design:

A prospective, randomized, double-blind study.

Materials and Methods:

All the patients were divided in a randomized, double-blind fashion into two groups of twenty patients each. Group I patients received rocuronium bromide 0.6 mg/kg intravenously and intubated at 60 s, Group II patients received rocuronium bromide 0.9 mg/kg and intubated at 60 s. The neuromuscular block was assessed using single twitch stimulation of 0.1 Hz at adductor pollicis muscle of hand at every 10 s.

Statistical Analysis Used:

The results were compiled and analyzed statistically using Chi-square test for qualitative data and Student's t-test for quantitative data.

Results:

Time of onset was significantly shorter (P < 0.01) and duration of action was prolonged (P < 0.001) for Group II as compared to Group I. The intubating conditions were (excellent + good) in 100% patients of Group II and (excellent + good) in 80% of Group I. There was no significant change in pulse rate and mean arterial pressure from the baseline value after the administration of muscle relaxants in either of the two groups.

Conclusions:

Rocuronium bromide 0.9 mg/kg is a safer alternative to rocuronium bromide 0.6 mg/kg for endotracheal intubation with shorter time of onset and better intubating conditions.

INTRODUCTION

One of the uses of muscle relaxants is to provide conditions necessary for easy and atraumatic intubation. Succinylcholine, a depolarizing muscle relaxant has been the muscle relaxant of choice owing to its short duration of action, but this comes with its side effects and thus limitation of use in various pathological conditions. Provision of muscle relaxation for this purpose needs a drug, safer than succinylcholine and onset time comparable to it and minimum side effects.

Rocuronium bromide is a steroidal nondepolarizing neuromuscular blocking agent, related structurally to vecuronium. It has been shown to have a rapid onset of action, believed primarily due to its low potency and has an intermediate duration of action.[1,2]

Randomized clinical trials[3] conducted have shown that rocuronium used with propofol creates intubation conditions equivalent to those with succinylcholine for rapid sequence inductions.

However, rocuronium bromide in lower doses may not provide adequate muscle relaxation which is of utmost importance for easy and safe intubation. This study is conducted to evaluate the optimal dose of rocuronium bromide for intubation and to compare the onset time, duration of action, intubating conditions, and hemodynamic effects of two doses of rocuronium bromide, i.e., 0.6 mg/kg and 0.9 mg/kg for hassle-free intubation.

MATERIALS AND METHODS

This study was a prospective, randomized, double blind study carried out in 40 adults of American Society of Anesthesiologists Grade I and II after obtaining the requisite Hospital Ethics Committee approval. Patients were in the age group of 20–60 years, scheduled for various surgical procedures under general anesthesia.

Patients with renal disease, hepatic disease, cardiorespiratory compromise and patients with anticipated airway difficulty, and pregnant patients were excluded.

Written informed consent for surgery and general anesthesia was obtained from the patients. All the patients underwent a thorough preanesthetic checkup including baseline investigations.

The patients were divided into two groups in randomized, double-blind fashion. The intubating person was not aware of the type of muscle relaxant used and waiting period from the administration of muscle relaxant to intubation attempt. Group I patients (n = 20) received injection rocuronium bromide 0.6 mg/kg and intubated at 60 s. Group II (n = 20) patients received injection rocuronium bromide 0.9 mg/kg and intubated at 60 s.

All patients received tablet clonazepam 0.5 mg, the night before surgery. On arrival to the operating theater, an intravenous (IV) access was established. Pulse and blood pressure were recorded and monitors for heart rate, electrocardiogram, noninvasive blood pressure, SpO₂, neuromuscular monitoring were attached. Patients were premedicated with injection fentanyl 2 µg/kg IV, injection ondansetrone 4 mg and injection ranitidine 50 mg IV 15 min before induction. After preoxygenation for 3 min anesthesia was induced with injection propofol 2 mg/kg IV.

Neuromuscular monitoring was commenced immediately after induction of anesthesia using single twitch stimulation of 0.1 Hz. After the stabilization of the recordings, the control response was assessed and calculated dose of either of the two relaxants was administered. Group I patients received injection rocuronium bromide 0.6 mg/kg and Group II patients received injection rocuronium bromide 0.9 mg/kg.

Endotracheal intubation was performed by the person who was unaware of twitch response and the muscle relaxant used. Intubating conditions were assessed according to the four-point scale of Cooper et al. [Table 1]. Intubating conditions were graded as excellent if score was 8–9, good if score was 6–7, fair if score was 3–5, and poor if score was 0–2 [Table 2].

Table 1.

Criteria and score of intubating condition

Table 2.

Grading of intubation

Time taken from end of injection of muscle relaxant to maximum depression of twitch height was recorded (onset time).

The time from the end of injection of muscle relaxant to 25% recovery of twitch height was recorded (duration). The neuromuscular block was maintained by applying train of four response after every 5 min and injection rocuronium bromide 0.1 mg/kg IV was supplemented at 25% recovery of control.

All patients were maintained with oxygen and nitrous oxide mixture and inhalational agent halothane/isoflurane.

At the end of surgery, residual neuromuscular blockade was reversed with injection neostigmine 0.05 mg/kg and glycopyrrolate 10 µg/kg after ensuring adequacy of reversal and thorough suctioning. Patients were extubated when fully awake and when T₁ had returned to 90% of the control.

RESULTS

The results were compiled and analyzed statistically using Chi-square test for qualitative data and Student's t-test for quantitative data.

Patients in both the groups were comparable to each other in terms of demographic profile, i.e., age, weight, and sex [Table 3].

Table 3.

Demographic characteristics

The mean onset time for Group II was 46.05 (±4.7) s and for Group I was 80.1 (±5.42) s. The difference was statistically significant (P < 0.01) [Table 4].

Table 4.

Time course of action

Duration of action of Group II (30.8 ± 3.17 min) was significantly longer (P < 0.0001) than Group I (10.9 ± 0.95 min).

The intubating conditions were graded as excellent in 19 (95%) patients of Group II and 10 (50%) patients of Group I. The difference was statistically significant [Table 5].

Table 5.

Overall intubating condition

Good intubating conditions were seen in 1 (5%) patient of Group II and 6 (15%) patients of Group I and the difference was statistically significant between the groups (P < 0.02).

Fair intubating conditions were seen in Group I patients only and the difference was statistically significant (P < 0.05).

No significant change in pulse rate and mean arterial pressure from the baseline value (before induction value) were observed in both the groups after the administration of the relaxant.

DISCUSSION

Neuromuscular blocking agents are firmly entrenched as an integral part of everyday anesthesia practice. Anesthesia providers practiced for nearly 100 years without these drugs, but it would be difficult to imagine the practice of modern day anesthesia without these agents.

Rocuronium bromide, 2–morpholino16allylpyrrolidine3desa cetyl derivative of vecuronium, is a monoquaternary amino steroidal neuromuscular blocking agent. It is structurally similar to vecuronium in its time course of neuromuscular blocking action. Rocuronium has a rapid onset time, an intermediate duration of action, and rapid recovery characteristics coupled with cardiovascular stability and virtually no histamine release[4] or any other side effects.

Wierda et al.[5] observed that Org 9426 appeared to be 6–8 times less potent than vecuronium and showed a faster rate of development of neuromuscular block, with good to excellent intubation conditions within 60 s after administration of a dose of 500 µg/kg. Barve et al.[6] found rocuronium (0.9 mg/kg) as a suitable alternative to succinylcholine for tracheal intubation in pediatric age group for rapid sequence induction as there is dose-dependent decrease in onset time of rocuronium.

Vishwas et al.[7] while comparing the two nondepolarizing neuromuscular blocking agent rocuronium bromide (0.6 mg/kg body weight) and vecuronium bromide (0.1 mg/kg body weight) in elective surgery under general anesthesia concluded that rocuronium had a more rapid onset of action and provided conditions suitable for more rapid tracheal intubation than vecuronium.

Chatrath et al.[8] compared the intubating conditions of rocuronium bromide and vecuronium bromide with succinylcholine using “timing principle.” They concluded that rocuronium 0.6 mg/kg provides good to excellent intubating conditions at 60 s comparable to succinylcholine after the induction of anesthesia. Kwon et al.[9] in their study observed that the modified rapid sequence intubation (RSI) with rocuronium showed shorter intubation sequence, acceptable intubation conditions, and a similar level of complications compared to those of conventional RSI with succinylcholine.

Oh et al.[10] in their study opined that the intubation dose of rocuronium for obtaining ideal intubating condition should be 0.8 mg/kg.

Belekar and Shubhangi[11] while comparing rocuronium with succinylcholine concluded that rocuronium 0.6 mg/kg provided acceptable intubation conditions in most of the patients at 60 s but, unable to provide excellent intubating conditions in all of them. In the present study also, rocuronium 0.9 mg/kg provided better intubation condition as compared to rocuronium 0.6 mg/kg.

Magorian et al.[12] recommended to wait for 90 s after 0.6 mg/kg rocuronium to achieve optimum intubating conditions in RSI while the onset times for the two larger doses of rocuronium, i.e., 0.9 mg/kg and 1.2 mg/kg were similar to suxamethonium in adult patients.

The previous update of Cochrane analysis (2008) identified 53 potential studies and included 37 combined for meta-analysis. In the latest update, published in 2015[13] they identified a further 13 studies and included 11, summarizing the results of fifty trials including 4151 participants.

They found that overall, succinylcholine was superior to rocuronium for achieving excellent intubating conditions. They also found no statistically significant difference in intubation conditions, when succinylcholine was compared to 1.2 mg/kg rocuronium.

Zhou et al.[14] observed that rapacuronium 1.5 mg/kg had a more rapid onset, similar intubating conditions, and shorter recovery times than rocuronium 0.6 mg/kg.

In this study, we found that clinically acceptable intubating conditions with Rocuronium 0.9 mg/kg at 60 s (Group II) were excellent in 19 (95%) patients. In Group I only 16 (80%) of the patients showed clinically acceptable intubating conditions with rocuronium 0.6 mg/kg at 60 s with excellent conditions seen only in 10 (50%) patients.

CONCLUSIONS

Based on the observation of this study, it is concluded that rocuronium bromide 0.9 mg/kg is a safer alternative to rocuronium bromide 0.6 mg/kg for endotracheal intubation with shorter time of onset and better intubating conditions.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.