Comparative assessment of side effects of etomidate and propofol: A double blinded study from urban Karnataka

Abstract               Background: Propofol and Etomidate is commonly used in anaesthesia practice. However pain on injection and myoclonus are the most common side effects of this drug. Objectives: To compare the side effects between Etomidate and Propofol. Methodology: In this prospective randomized double blinded study, we studied 60 patients randomly allocated into either group P (propofol group) or to group E (Etomidate group) of 30 each. All patients premedicated with inj. midazolam 0.02mg/kg IV, inj. Fentanyl 2 microgm/kg IV. Group P received propofol infusion at 0.5 mg/kg/hr and group E at 0.05mg/kg/hr until BIS value dropped to 50. Then patients were intubated with vecuronium 0.1mg/kg and anaesthesia maintained according to institutional protocol followed by extubation after adequate recovery. Hemodynamic parameters and side effects during induction were recorded between both groups until the infusion of study drug. Results: So prevalence of myoclonus was found to be 40% in Etomidate group. Prevalence of Thrombophlebitis in etomidate was found to be 13.3%. Proportion of patients experienced pain was more in Propofol group i.e. 36.7% as compared to Etomidate i.e. 20%. (>0.05). 10 patients in Etomidate group experienced nausea i.e. 33.3% as compared to 2 in Propofol group i.e. 6.7%. (<0.05). 3 patients in Etomidate group experienced vomiting i.e. 10% as compared to 1 in Propofol group i.e. 3.3% (>0.05) Conclusion: Myoclonus and Thrombophlebitis was observed in Etomidate group only (<0.05). Propofol causes more pain as compared to Etomidate (>0.05). Propofol causes less nausea (<0.05) and vomiting (<0.05) as compared to Etomidate.

Key Word: Side effects, Etomidate; Propofol

INTRODUCTION

Over years there has been a continuous search for better and safer intravenous agent. Presently etomidate and propofol are popular, rapid acting and safe induction agent, however these two drugs have different induction characteristics. ¹ The discovery of IV anaesthetics has long been an important milestone in the development of anaesthesia. Prior to this, induction of general anaesthesia necessarily required inhalation of gases or vapour which was an unpleasant experience to most of the patients. Presently Etomidate and Propofol are popular rapid acting inducing agents.² In 1970 a new inducing agent 2, 6- di-isopropofol was discovered and introduced in clinical practice in 1977. Propofol was introduced clinically by kay and rolly in 1977. As a new anaesthetic agent, it provides faster onset of action, anti emesis, potent attenuation of pharyngeal, laryngeal, tracheal reflex and adequate depth of anaesthesia during intubation and a clear and smooth recovery. It is a commonly used IV induction agent in recent years.^{3, 4, 5} However high doses can cause side effects like hypotension due to direct myocardial depression and decreased peripheral vasodilatation along with venodilatation, respiratory depression/ apnea. It also causes pain on injection when injected into smaller veins. Pain is due to concentration of free propofol in the aqueous phase of emulsion.⁶ Etomidate is a carboxylated imidazole drug used for induction of general anaesthesia and sedation introduced into clinical practice in 1972. Preclinical experiments demonstrated that etomidate injection was associated with minimal hemodynamic changes or respiratory depression, features that were presumed to result in its unusually safety profile.⁷ However pain on injection and myoclonus are the most common side effects of this drug.⁸ Propofol and Etomidate is commonly used in anaesthesia practice. So we planned the study in Navodaya Medical College and Hospital, Raichur in order to assess the side effects of propofol and etomidate in patients undergoing surgeries under general anaesthesia and to find which causes less side effects.

OBJECTIVES

1. To compare the side effects like pain on injection and postoperative nausea and vomiting
2. To compare the incidence of adverse effects like myoclonus and thrombophlebitis

 MATERIALS AND METHODS

This double blind prospective randomized study was done from November 2016 to May 2018 on patients who were admitted to Navodaya Medical College and Hospital, Raichur and posted for elective surgeries requiring general anesthesia. These patients were undergoing gynecological surgery, general surgery, or orthopedic surgery. The study has been conducted after obtaining clearance from ethical committee of the institution. Informed consent was taken from all the patients who participated within the study.

Inclusion criteria

1. Patients between the age group of 20 and 60 years belonging to American society of anesthesiology grade I to III undergoing surgery under general anesthesia.
2. Those who are willing to participate after informed consent

Exclusion criteria

1. Patients allergic to any drugs
2. History of seizure disorder.
3. Presence of primary and secondary steroid deficiency or on steroid medication
4. Presence of hypotension.

Data analysis: Data entered in MS excel sheet and analysed by using SPSS 21.0 version IBM USA. Comparison of mean and SD between two groups was done by using unpaired t test to assess whether the mean difference between groups is significant or not.

RESULTS

Figure 1: Bar diagram showing Distribution according to age group

In our study, we included 30 subjects in each group. In-group receiving Etomidate as intervention, majority were from 21-30 years age i.e. 17(56.7%) followed by 6 from 31-40 years age group (20%). In group receiving Propofol as intervention, majority were from 21-30 years age i.e. 9(30%) followed by 8 from 41-50 years age group (26.7%).

Table 1: Distribution according to occurrence of myoclonus

Chi square test-11.88, p-0.0005(<0.05), Significant

Myoclonus was seen in 12 out of 30 subjects from Etomidate group. So prevalence of myoclonus was found to be 40% in Etomidate group. On the contarary this side effect was not observed with Propofol (<0.05). So Etomidate causes more myoclonus compared to Propofol.

Table 2: Distribution according to occurrence of Thrombophlebitis

Fischer’s exact test-1.96, p-0.16(>0.05), Not Significant

Thrombophlebitis was seen in 4 out of 30 subjects from Etomidate group. So prevalence of Thrombophlebitis in etomidate was found to be 13.3%. On the contarary this side effect was not seen with Propofol (<0.05)

Table 3: Distribution according to occurrence of Pain

Chi square test-2.05, p-0.14(>0.05), Not Significant

Pain perceived by the patients in both groups. But proportion was more in Propofol group i.e. 36.7% as compared to Etomidate i.e. 20%. It means Propofol causes more pain as compared to Etomidate(>0.05)

Table 4: Distribution according to occurrence of Nausea

Chi square test-6.66, p-0.0009(<0.05), Significant

10 patients in Etomidate group experienced nausea i.e. 33.3% as compared to 2 in Propofol group i.e. 6.7%. So nausea is more seen in etomidate group (<0.05).

Table 5: Distribution according to occurrence of Vomiting

Fischer’s exact test-1.04, p-0.34(>0.05), Not significant

3 patients in Etomidate group experienced vomiting i.e. 10% as compared to 1 in Propofol group i.e. 3.3% (>0.05)