A comparative study of intubating conditions of rocuronium bromide and suxamethonium in adult patients.

AIM: Intubating conditions after Suxamethonium, a time tested popular short acting depolarizing neuromuscular blocking agent, and Rocuronium, a recently introduced intermediate acting non depolarizing neuromuscular blocking agent, with Thiopentone as the sole induction agent, were compared in this study.
MATERIALS AND METHODS: The patients were divided into two groups, each consisting of 30 patients: group a patient's received Rocuronium bromide, 0.6 mg/kg and group B patients received Suxamethonium chloride 1.5 mg/kg. In both the groups, jaw relaxation and vocal cord relaxation were considered for atraumatic laryngoscopy at 60 seconds or, if needed, at 75 seconds and then at 90 seconds.
RESULTS: Intubation conditions were rated as excellent in 90% and good in 10% of the patients who received Rocuronium, and excellent in 100% of the patients who received Suxamethonium.
CONCLUSION: It is concluded from this study that intubation can be performed under good to excellent conditions at 60-90 seconds after a bolus dose of Rocuronium of 0.6 mg/kg. The result of this study indicates that this new nondepolarizing neuromuscular blocking agent may be considered as a valuable alternative to Suxamethonium for rapid tracheal intubation, i.e., within 60 seconds, even after induction with Thiopentone as the sole anesthetic agent.

INTRODUCTION

Two important uses of muscle relaxation are to facilitate endotracheal intubation and to provide surgical relaxation. Suxamethonium, with its rapid onset time and good Intubating conditions, is still the drug of choice for rapid endotracheal intubation. However, it falls short of the ideal muscle relaxant due to its potentially hazardous side effects, such as hyperkalemia, cardiac arrest and malignant hyperthermia, which are more frequently reported in children when Suxamethonium is administered to facilitate rapid sequence endotracheal intubation.[1-4] Rocuronium bromide, a newer amino-steroidal compound, is a derivative of vecuronium; Rocuronium has a rapid onset time, an intermediate duration of action and rapid recovery with cardiovascular stability.[5] It has no significant histamine release. Onset time of a 0.6 mg/kg-1 dose of Rocuronium ranges from 1 to 1.5 minutes under nitrous oxide opioid anesthesia.[67] Nevertheless, with this dose Rocuronium, the intubating conditions at 60 seconds are similar to those observed with Suxamethonium.[89] This might persuade many clinicians to use Rocuronium to facilitate endotracheal intubation not only in elective cases under adequate anesthesia but also in emergency situations requiring rapid sequence intubation. The aim of this study was to assess the efficacy of Rocuronium in comparison Suxamethonium for endotracheal intubating conditions, following induction with Sodium Thiopentone as a sole anesthetic agent in elective, otherwise healthy, adult population.

MATERIALS AND METHODS

After informed consents were taken, 60 adult patients aged between 11 and 60 years, ASA physical status I or II for operative procedure from routine operation lists, were selected randomly for this study to observe comparison of intubating conditions after Rocuronium versus Suxamethonium. The patients were divided into two groups, group A and group B, each consisting of 30 patients group A and group according to the neuromuscular blocking agent received. The groupings were as follows:

Group A received Rocuronium bromide 0.6 mg/kg-1 (n=30)

Group B received Suxamethonium chloride 1.5mg/kg-1 (n=30).

Patients were excluded if they were known to have neuromuscular disease or were receiving medications known to influence neuromuscular function. All the patients underwent thorough preoperative evaluation and investigations. All the patients were premedicated with inj. Glycopyrrolate 4 μg/kg i.v., inj. Ranitidine 1 mg/kg i.v., inj. Ondansetron 80 μg/kg i.v. and inj. Tramadol 1 mg/kg i.v. Then pulse, blood pressure, SpO2 and ECG were noted as preinduction data. All the patients were pre-oxygenated with 100% O2 with face mask for 3 minutes. In group a, anesthesia was induced with inj. Sodium Thiopentone 5 mg/kg, slowly followed by inj. Rocuronium bromide 0.6mg/kg i.v. In group B, anesthesia was induced with inj. Sodium Thiopentone 5 mg/kg i.v., slowly followed by inj. Suxamethonium 1.5 mg/kg.

In both the groups, jaw relaxation and vocal cord relaxation were considered for atraumatic laryngoscopy at 60 seconds or, if needed, at 75 seconds and then at 90 seconds. During laryngoscopy, the patients’ cardiovascular response was assessed. From the time of intubation (time=0 minute) and at 2, 5, 10 minutes and then every 10 minutes, pulse, blood pressure and SpO2 were recorded. Intubating conditions were assessed using the criteria of Cooper et al.[10] the three items of this score are as follows:

Ease of laryngoscopy (evaluated together with jaw relaxation),

Aspects of vocal cords, and

Response of the diaphragm to tracheal intubations.

These offer a four-point scale. The appropriate values were selected and added up to a total numeric score of a maximum of 9.

A total score of

8-9 is rated as excellent;

6-7 rated as good;

3-5 rated as fair and

0- is rated as poor intubating conditions.

Good and excellent intubating conditions were taken to be “clinically acceptable” by Cooper et al. Anesthesia was maintained using of a closed circuit with circle absorber having 50% N2O 50% O2 with controlled ventilation. After clinical recovery from intubating dose of muscle relaxant, the period for study was over, and anesthesia was continued using O2, N2O, isoflurane and further dose of muscle relaxant.

After completion of the surgery, reversal of neuromuscular blockade was achieved with inj. Neostigmine 0.05 mg/kg and inj. Glycopyrrolate 0.008 mg/kg i.v. After satisfactory recovery, the patients were extubated.

RESULTS

A total of 60 patients were in this study with 30 patients in each group. The two groups were comparable with regard to the demographic data [Table 1]. The duration of surgeries undertaken for study in group A ranged from 30 to 150 minutes with a mean of 74.83 minutes, whereas in group B it ranged from 35to 150 minutes with a mean of 71.16 minutes.

Table 1

Demographic data

Ease of laryngoscopy was different in both the groups. Jaw relaxation was good in 23 patients of Rocuronium group but in 25 patients in Suxamethonium group, while the other patients of both the groups had moderate jaw relaxation. Vocal cords were open and immobile at 60 seconds in 26 patients after administration of Rocuronium, while they were open and immobile at 60 seconds in 29 patients after administration of Suxamethonium. But vocal cords were found to be moving in four patients given Rocuronium and in one patient given Suxamethonium. “No diaphragmatic movements” and “slight diaphragmatic movements” were observed in 25 and 5 patients, respectively, given Rocuronium (group A) and “no diaphragmatic movements” was observed in any patient given Suxamethonium group B). Reaction of diaphragm to intubation was more pronounced at 60 seconds after the administration of Rocuronium. Intubation conditions were rated as excellent in 90% and good in 10% of the patients who received Rocuronium, and excellent in 100% of the patients who received Suxmethonium [Tables 2 and 3].

Table 2

Intubating condition

Table 3

Intubating scoring system

In Group A, heart rate (on cardioscopic monitoring) increased maximum up to 16.47% after intubation and reached at 105.36 (±16.90) from the pre-induction value of 90.46 (±8.21), while that in Group B increased maximum up to 18.27% after intubation and reached at 102.26 (±14.26) from the pre-induction value of 86.46 (±11.59). The heart rate changes returned to near baseline levels at 10 minutes after intubation in both the groups and these were statistically non-significant (P>0.05), Table 4, Figure 1.

Table 4

Pulse rate changes

Figure 1

Changes in mean pulse rate

Systolic blood pressure increased in both the groups after intubation and returned to baseline (at pre-induction value) within 10 minutes. In group A, there was an increase in systolic blood pressure after intubation up to a mean value of 139.9 (±8.2) mm Hg from the baseline (pre-induction pre-intubation) value of a mean 126.7 (±8.5) mm Hg, which returned to baseline within 10 minutes, whereas in group B the increase in the systolic blood pressure after intubation reached a mean of 138.1(±6.17) mm Hg from the pre-induction pre-intubation value of 122.06 (±9.8) mm Hg, which returned to baseline within 10 minutes. The changes were not significant (P>0.05) Table 5–6, Figures 2–3.

Table 5

Systolic blood pressure changes

Table 6

Diastolic blood pressure changes

Figure 2

Changes in systolic blood pressure

Figure 3

Changes in diastolic blood pressure

In group A, diastolic blood pressure reached after intubation a maximum mean value of 90.86 (±8.6) and returned to baseline 79 (±7) within 10 minutes, while in group B diastolic blood pressure reached after intubation a maximum mean value of 89±5.6 from a baseline value of 76.13±6.9 and reached baseline value within 10 minutes.

In group A, time required for cessation of respiration was 60-70 seconds in 22 (73.33%), 71-80 seconds in 6 (20%) and 81-90 seconds in 2 (6.66%) patients, while in group B, it was 60-70 seconds in all the patients

In group A, the time required for cessation of respiration was 60-70 seconds in 22 (73.33%),71-80 seconds in 6 (20%) and 81-90 seconds in 2 (6.66%) patients, while in group B, it was 60-70 seconds in all the patients [Table 7] Figure 4.

Table 7

Time required for cessation of respiration

Figure 4

Cessation of respiration

DISCUSSION

Rocuronium bromide is a newer, low potency non-depolarizing neuromuscular blocking agent waiting to get established in India. This clinical study was undertaken to evaluate, whether Rocuronium onset time was sufficiently short to permit its use for rapid sequence induction of anesthesia and whether intubating conditions achieved by Rocuronium were similar to those achieved by Suxamethonium.

The endotracheal intubation was commenced at 60 seconds and intubating conditions noted every 15 seconds. Similar clinically acceptable (excellent or good) intubating conditions were found in both Rocuronium 0.6 mg/kg-1 and Suxamethonium 1.5 mg/kg-1 groups. After Rocuronium administration, the response of diaphragm to intubation was more pronounced than that after administration of Suxamethonium. But the overall intubating conditions were similar to those after Suxamethonium administration.

Similar results about onset time and intubating conditions were found in other studies of Dubois et al.[11] and Huizinga et al.[12] in these studies, no difference was observed in the frequency distribution of clinically acceptable intubating conditions at 60 and 90 seconds after the administration of Suxamethonium or Rocuronium.

It is concluded from this study that intubation can be performed under good to excellent conditions at 60-90 seconds after a bolus dose of Rocuronium of 0.6 mg/kg. The result of this study indicates that this new non depolarizing neuromuscular blocking agent may be considered as a valuable alternative to Suxamethonium for rapid tracheal intubation, i.e., within 60 seconds even after induction with Thiopentone as the sole anesthetic agent.