European Journal of Cardiovascular Medicine

Succinylcholine remains unsurpassed in providing ideal intubating conditions. However, an increase in Intraocular Pressure (IOP) after Succinylcholine is one of its undesirable effects, especially in patients with an open eye injury. Rocuronium is a non-depolarizing neuromuscular blocking drug which provides a rapid onset of action with an intermediate duration of action.  At a dose of 0.9–1.2 mg /kg, onset time of Rocuronium has been shown to be similar to that of Succinylcholine.  As with other non-depolarizing neuromuscular blocking agents, Rocuronium has been shown to cause a decrease in IOP during steady state anaesthesia.

Aim

The primary aim of this study was designed to compare the effect on Intraocular Pressure of Rocuronium with that of Succinylcholine during Rapid Sequence Induction of anaesthesia using Propofol and Fentanyl. The secondary aim was to compare hemodynamic changes and ease of intubation.

After obtaining Hospital Ethics Committee approval and informed written consent  40 ASA I patients  Aged 18–40 yr. Requiring tracheal intubation as part of the anaesthetic technique for elective non-ophthalmic surgery were studied. Patients with Mallampati class2, 3 or 4 were excluded.

Sample size

Among the parameters measured, the most important one in our study is the Intra Ocular Pressure.  Thus expecting a 15% difference in the IOP between the two groups a 95% confidence interval  and a power of 85%  the sample size calculated for each group was 20.

Methods

This was a sequential controlled study.  Patients were allocated sequentially to one of two groups (n20 in each group) to receive  Succinylcholine (group S) and  Rocuronium (group R).

All patients were medicated with Tab Alprazolam 0.5 mg orally night before surgery.  Preoxygenation was done for 3 min,  Anaesthesia was induced with Inj Fentanyl 2 mcg/kg and a sleep dose of Propofol given at a rate of 100 mg /min until loss of verbal response.  Followed immediately by either Succinylcholine 2 mg/ kg or Rocuronium 1 mg/ kg, diluted to 10 ml with normal saline as per the group of the patient.

The lungs were not ventilated before tracheal intubation.  Laryngoscopy and tracheal intubation were performed 60 s after administration of Succinylcholine or Rocuronium  In all patients intubation was completed within 30 s.  Patients’ lungs were ventilated with 66% nitrous oxide in oxygen after tracheal intubation to maintain normocapnia.  Throughout Induction, all patients were monitored using a Pulse Oximeter, Non Invasive blood pressure monitor, Capnograph and Electrocardiograph.

Measurements of Intraocular Pressure (IOP ), Mean arterial pressure (MAP) , Heart rate (HR) were made at the following times:  Before Induction (baseline);  1 min after administration of Succinylcholine or Rocuronium (just before intubation);  Every minute after intubation for 5 min.

An i care hand held Perkins tonometer was used for the IOP measurements. Intraocular pressure readings were obtained in the right eye . The measurements were made by a  Ophthalmologist who was always present in the theatre during the study, was not aware of the grouping of the patients and with a good experience in Hand held applanation Tonometers

INTUBATIONINTUBATION SCORING SYSTEM • A simple scoring system (1–4) was used to grade intubation:  1.Excellent- jaw relaxed, vocal cords abducted and immobile, no diaphragmatic movement  2. Good- jaw relaxed, vocal cords abducted and immobile, some diaphragmatic movement  3. Poor- jaw relaxed, vocal cords moving, coughing •4.Inadequate- jaw not relaxed and vocal cords closed.

There was no significant difference between groups in Age, Sex, Weight, Propofol dose, Baseline IOP, Baseline MAP or Baseline HR.

Table 1. Baseline Data of Succinylcholine and Rocuronium

Changes in IOP

In the Succinylcholine group, IOP increased significantly (from 14.8 to 19.9 mm Hg; (P=0.009) after induction.  Tracheal intubation caused a further increase in IOP compared with baseline (14.8 to 22.8 mm Hg; (P=0.001).  In the Rocuronium group, there was initially a decrease in IOP (from 13.3 to 9.2 mm Hg; (P=0.001) after induction.  Although tracheal intubation caused an increase in IOP compared with values after induction (from 9.2 to 13.0 mm Hg; (P=0.009), it remained below baseline throughout induction.  The difference in the changes in IOP between the Succinylcholine and Rocuronium groups was highly significant (P=0.001).

Table 2. Changes in IOP Between the Succinylcholine and Rocuronium

Changes in MAP

There was no significant difference in changes in MAP during induction between the two groups.  At 1 min after intubation, there was a slight increase in MAP compared with baseline in both the Succinylcholine (85.3 to 90.2 mm Hg) and Rocuronium (82.2 to 88.2 mm Hg) groups  This increase was not statistically significant.

Table 3. Changes in MAP

Changes in HR during induction

Although Rocuronium was associated with a greater increase in HR than Succinylcholine, this was not statistically significant.

Table 4. Changes in HR induction

Intubating conditions

Eighteen of 20 patients who received Rocuronium 1 mg /kg achieved excellent intubating conditions at 1 min  Two of 20 achieved good intubating conditions  Nineteen of 20 patients in the Succinylcholine group achieved excellent intubating conditions  One of 20 achieved good intubating conditions.

Larygoscopy and tracheal intubation can cause a raise in intraocular pressure even in anaesthetized patients.  This is probably due to a raise in arterial pressure as result of sympathetic stimulation.  This increase disappears in a few minutes and may not be of any great significance in the majority of the patients who undergo elective ophthalmic surgery, but may be harmful to many patients with penetrating eye injuries or patients already having elevated IOP like in glaucoma.  In our study, pressure response to intubation was statistically comparable in between the two groups.

C.L Chiu et al compared the effect of rocuronium and succinylcholine on intraocular pressure (IOP) during rapid sequence induction of anaesthesia using propofol and fentanyl • Found that IOP in the Succinylcholine group was significantly greater than that in the Rocuronium group mean 21.6 mm Hg vs 13.3 mm Hg. P(0.001)  Intubating conditions were equally good in both groups using rapid sequence induction of anaesthesia using propofol and fentanyl  Concluded that Rocuronium did not cause as great an increase in IOP as Succinylcholine and may be an alternative in open eye injury cases D.

Mitra S et al compared the effect of rocuronium on intraocular pressure (IOP) with that of succinylcholine  Found that upon induction, the fall in IOP in both the groups was significant (p0.5).  Thus, in comparison to succinylcholine, rapid sequence induction with rocuronium 1 mg/ kg when performed within 60 seconds after induction did not produce any rise in intraocular pressure.

A study of changes in intraocular pressure during intubation was studied in 40 patients of ASA physical status I undergoing elective surgical procedures.  Intraocular pressure was elevated after giving Succinylcholine high above the baseline values while in Rocuronium group the Intraocular Pressure reduced below the baseline values.  Though in both the groups IOP rose after intubation and decreased after three and five minutes after intubation, it remained below the baseline value.

To conclude Rocuronium bromide in a dose of 1 mg/kg  Provides Good to Excellent intubating conditions comparable to that of Succinylcholine.  It is a suitable agent for tracheal intubation in patients undergoing elective and emergency ophthalmic surgery where raise in intraocular pressure is undesirable.

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