European Journal of Cardiovascular Medicine

Etomidate is a commonly used and preferred intravenous anesthetic agent owing to its rapid onset of action and clearance, cerebral protective effect, marginal histamine release, and is cardiostable with minimal respiratory side effects. However, pain during administration, myoclonus, and adrenocortical suppression are some of the associated side-effects. Myoclonus is a significant side-effect associated with intravenous administration and is defined as sudden, brief, involuntary muscle jerks (irregular or rhythmic), usually lasting for 10–50 ms.¹

EIM or Etomidate‑induced myoclonus can result in serious complications including increased myocardial oxygen (O2) consumption and increased intraocular pressure (IOP). Hence, prevention of Etomidate‑induced myoclonus is vital. A variety of drugs have been assessed for their ability to prevent the myoclonic movements. However, these agents can be associated with various side effects such as respiratory depression.²

It can be possible to eradicate the need for additive drug, its side-effects, and associated cost by altering the technique for administration of etomidate. However, existing literature data is scarce concerning the comparison of the efficacy of priming dose technique, combination of priming dose with slow IV administration technique, and slow IV administration of induction dose technique for prevention of EIM.^3,4 Hence, the present study was aimed to comparatively assess the efficacy of three techniques for administering etomidate in prevention of myoclonus induced by etomidate.

The present randomized, parallel group clinical study was aimed to comparatively assess the efficacy of three techniques for administering etomidate in prevention of myoclonus induced by etomidate. The present study assessed 592 study subjects where general anesthesia was induced using etomidate following the randomly allocated groups as control, priming, slow, and priming with slow injection. The grade, time of onset, and incidence of myoclonus was noted in all the subjects. The effect on various hemodynamic parameters and pain on injection grading was noted.

It was seen that overall incidence of myoclonus in study subjects was 53%. The incidence of myoclonus was highest in control group with 71% followed by priming group where incidence was 52%, slow technique with 48%, and priming with slow injection with 37% respectively. The incidence of myoclonus in four groups showed a statistically significant results with p=0.001. The incidence of myoclonus was lower in priming with slow injection with no statistical difference in priming with slow injection and priming group with p=0.07 or groups priming with slow injection and slow group with p=0.16 (Table 1).

The study results showed that myoclonus intensity had significant distribution with no symptoms in 47% and severe myoclonus in 26% subjects which was significant with p=0.0001. severe myoclonus was seen in control group. Inter-group comparison showed a significant difference in the intensity of myoclonus between control Group and priming with slow injection group with p=0.0001, slow and control group (p=0.001), control and priming with slow injection group (p=0.0001), priming with slow injection and slow group (p=0.04). Group priming with slow injection and slow injection had no significant difference in myoclonus intensity with p=0.911. However, priming with slow injection group had high incidence of grade 3 myoclonus with no significant difference in priming and priming with slow injection group with p=0.06 (Table 1).

It was also seen that slowest time for onset of myoclonus was seen in priming with slow injection group and fastest in control group with statistically significant difference and p=0.001. In majority of 97% subjects, no pain was felt on intravenous administration, pain score of 1 was seen in 2.3% subjects, and score of 2 was seen in 1% subjects. No subject reported a pain score of 3. The study results showed that mean heart rate in four study groups at 1 minute after induction and 2 minutes after intubation was statistically significant with p=0.007 and 0.01 respectively. SpO2, MAP, and heart rate were not significant statistically at any assessment time. The incidence of postoperative nausea and vomiting was non-significant in study groups with p=0.84.

The present randomized, parallel group clinical study was aimed to comparatively assess the efficacy of three techniques for administering etomidate in prevention of myoclonus induced by etomidate. The present study assessed 592 study subjects where general anesthesia was induced using etomidate following the randomly allocated groups as control, priming, slow, and priming with slow injection. The grade, time of onset, and incidence of myoclonus was noted in all the subjects. The effect on various hemodynamic parameters and pain on injection grading was noted.

It was seen that overall incidence of myoclonus in study subjects was 53%. The incidence of myoclonus was highest in control group with 71% followed by priming group where incidence was 52%, slow technique with 48%, and priming with slow injection with 37% respectively. The incidence of myoclonus in four groups showed a statistically significant results with p=0.001. The incidence of myoclonus was lower in priming with slow injection with no statistical difference in priming with slow injection and priming group with p=0.07 or groups priming with slow injection and slow group with p=0.16 (Table 1).

The study results showed that myoclonus intensity had significant distribution with no symptoms in 47% and severe myoclonus in 26% subjects which was significant with p=0.0001. severe myoclonus was seen in control group. Inter-group comparison showed a significant difference in the intensity of myoclonus between control Group and priming with slow injection group with p=0.0001, slow and control group (p=0.001), control and priming with slow injection group (p=0.0001), priming with slow injection and slow group (p=0.04). Group priming with slow injection and slow injection had no significant difference in myoclonus intensity with p=0.911. However, priming with slow injection group had high incidence of grade 3 myoclonus with no significant difference in priming and priming with slow injection group with p=0.06 (Table 1).

Table 1: Timing of onset, intensity, and incidence of etomidate‑induced myoclonus in four groups of study subjects

It was also seen that slowest time for onset of myoclonus was seen in priming with slow injection group and fastest in control group with statistically significant difference and p=0.001. In majority of 97% subjects, no pain was felt on intravenous administration, pain score of 1 was seen in 2.3% subjects, and score of 2 was seen in 1% subjects. No subject reported a pain score of 3. The study results showed that mean heart rate in four study groups at 1 minute after induction and 2 minutes after intubation was statistically significant with p=0.007 and 0.01 respectively. SpO2, MAP, and heart rate were not significant statistically at any assessment time. The incidence of postoperative nausea and vomiting was non-significant in study groups with p=0.84

The present study assessed 592 study subjects where general anesthesia was induced using etomidate following the randomly allocated groups as control, priming, slow, and priming with slow injection. The grade, time of onset, and incidence of myoclonus was noted in all the subjects. The effect on various hemodynamic parameters and pain on injection grading was noted. The study design was comparable to the design of the previous studies of Hosseinzadeh H et al7 in 2013 and Shah SB et al8 in 2015 where study design comparable to the present study was also adopted by the authors in their studies.

The study results showed that overall incidence of myoclonus in study subjects was 53%. The incidence of myoclonus was highest in control group with 71% followed by priming group where incidence was 52%, slow technique with 48%, and priming with slow injection with 37% respectively. The incidence of myoclonus in four groups showed a statistically significant results with p=0.001. The incidence of myoclonus was lower in priming with slow injection with no statistical difference in priming with slow injection and priming group with p=0.07 or groups priming with slow injection and slow group with p=0.16. These results were consistent with the findings of Aggarwal S et al9 in 2013 and Hosseinzadeh H et al10 in 2016 where results for overall incidence of myoclonus reported by the authors was similar to the results of the present study.

It was seen that myoclonus intensity had significant distribution with no symptoms in 47% and severe myoclonus in 26% subjects which was significant with p=0.0001. severe myoclonus was seen in control group. Inter-group comparison showed a significant difference in the intensity of myoclonus between control Group and priming with slow injection group with p=0.0001, slow and control group (p=0.001), control and priming with slow injection group (p=0.0001), priming with slow injection and slow group (p=0.04). Group priming with slow injection and slow injection had no significant difference in myoclonus intensity with p=0.911. However, priming with slow injection group had high incidence of grade 3 myoclonus with no significant difference in priming and priming with slow injection group with p=0.06. These findings were in agreement with the results of Luan HF et al11 in 2014 and Isitemiz I et al12 in 2015 where results for myoclonus intensity comparable to the present study was also reported by the authors in their studies.

The study results also showed that that slowest time for onset of myoclonus was seen in priming with slow injection group and fastest in control group with statistically significant difference and p=0.001. In majority of 97% subjects, no pain was felt on intravenous administration, pain score of 1 was seen in 2.3% subjects, and score of 2 was seen in 1% subjects. No subject reported a pain score of 3. The study results showed that mean heart rate in four study groups at 1 minute after induction and 2 minutes after intubation was statistically significant with p=0.007 and 0.01 respectively. SpO2, MAP, and heart rate were not significant statistically at any assessment time. The incidence of postoperative nausea and vomiting was non-significant in study groups with p=0.84. These results were in line with the findings of St Pierre M et al13 in 2000 and Sarkar M et al14 in 2005 where results similar to the present study was also reported by the authors in their studies.

Considering its limitations, the present study concludes that priming and slow injection techniques are similar concerning the incidence of etomidate‑induced myoclonus. However, using the combination of priming and slow technique is one of the most effective techniques in reducing the incidence of etomidate‑induced myoclonus

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