The Effects of Spinal Anesthesia on ED50 and BIS50 of Etomidate for the Loss of Consciousness
Description:
The combination of spinal with general anesthesia has been demonstrated to provide many
clinically relevant advantages, however, this technique often experiences hypotension and
bradycardia in the induction period of combined anesthesia. Etomidate is a carboxylated
imidazole-derived hypnotic, and it is the most cardiovascularly stable intravenous induction
drug, with the possible exception of ketamine. Meanwhile, the previous and our studies have
been reported that spinal anesthesia has a direct sedative effect on animals and humans, and
it markedly reduces the dose of hypnotic agents. To date, there is no dose-ranging study on
the effect of spinal anesthesia on dosage of etomidate for the loss of consciousness (LOC).
In the present study, investigators aim to investigate the effect of spinal anesthesia on the
median effective dose (ED50) and the BIS value (BIS50) of etomidate at which 50% of patients
lose consciousness compared to etomidate alone by using up-and-down method.
Patients were randomly allocated to one of two groups: only etomidate in group E (n=27) and
spinal anesthesia combined with etomidate in group SE (n=21) using a randomization table.
Patients in the SE group received spinal anesthesia first, and bilateral sensory anesthesia
level was confirmed to remain at the T4-T6 level. After confirmation of the level of sensory
anesthesia, the administration of etomidate was conducted. The etomidate (Nhwa
Pharmaceutical, Jiangsu, China) starting dose of E group and SE group is 0.105 mg/kg and
0.089mg/kg, respectively. The dose of etomidate used for next patient was determined
according to the response of the previously tested patient using the up-and-down method. If
the patient lose consciousness, the dose of etomidate was reduced by one dose gradient for
the next patient, and if didn’t lose consciousness, the dose of etomidate was increased by
one dose gradient (one dose gradient is r=1:0.85, that is, the ratio of high dose/low dose
which are adjacent two doses). The testing of different dose levels of etomidate continued on
consecutive randomised patients until a sample size of seven crossover points from
"conscious" to "LOC" was reached
Condition:
Dose-Response Relationship, Drug
Treatment:
spinal anesthesia
Start Date:
June 1, 2017
Sponsor:
General Hospital of Ningxia Medical University
For More Information:
https://clinicaltrials.gov/show/NCT03240055