Clinical trial NCT02097407: Preoperative Dexmedetomidine & EC50 of Propofol
Official title: Preoperative Dexmedetomidine Reduces the EC50 of Propofol for Successful i-gelTM Insertion Without Muscle Relaxants
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Urologic Surgery
Lead sponsor: Seoul National University Hospital
Sponsor class: OTHER
First posted: 2014-03-27
Enrollment: 37
Sex: ALL
Minimum age (years): 20
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: SINGLE_GROUP
Primary purpose: SUPPORTIVE_CARE

Brief summary: Dexmedetomidine is a useful anaesthetic adjuvant for general anaesthesia. In this prospective randomised study, we determined whether preoperative dexmedetomidine administration could reduce the half maximal effective concentration (EC50) of propofol for successful i-gelTM insertion without muscle relaxants.

Detailed description: Propofol is a useful induction agent for LMA insertion without muscle relaxants because it profoundly inhibits pharyngeal and laryngeal reactivity. A previous report showed that the effect-site concentration of propofol for successful classic LMA insertion in 50% of adults (EC50) without muscle relaxants in healthy male patients was 8.72 (0.55) µg ml-1. The EC50 of propofol may be dependent on the type of LMA used. A previous study comparing the EC50 of the propofol concentration between classic and proseal LMA insertions demonstrated that the EC50 of propofol needed for proseal LMA insertion was 35% greater than that needed for classic LMA insertion. Unfortunately, no investigation has been performed to determine the EC50 of the propofol concentration required for i-gel insertion without muscle relaxants.

Dexmedetomidine (DEX), a selective alpha-2 agonist, has sympatholytic, sedative, and analgesic properties. Such beneficial characteristics make DEX a useful anaesthetic adjuvant for general anaesthesia. Many reports have revealed the beneficial effects of DEX in terms of reducing intraoperative anaesthetic requirements, postoperative analgesic demand, and increased haemodynamic responses to noxious stimuli such as endotracheal intubation. A previous investigation showed that preoperative clonidine, an alpha-2 agonist, decreased the EC50 required for LMA insertion.

We hypothesised that preoperative DEX administration can reduce the propofol concentration required for i-gel insertion. In this study, we compared the EC50 of propofol needed for successful i-gel insertion without muscle relaxants between DEX and placebo groups

Eligibility criteria: Inclusion Criteria:

* ASA physical status I-II patients who were 20-65 years old and scheduled for general anaesthesia for urologic surgery

Exclusion Criteria:

* Patients with an allergy to alpha-2 adrenergic agonists or propofol
* Patients who anticipated difficult airway (cervical spinal disease, Mallampati score of III or IV, a mouth opening of \<2.5 cm, and/or body mass index of \>30 kg m-2), unstable teeth
* Patients with bradycardia of \<50 beats/min, heart block greater than first degree, severe cardiorespiratory dysfunction
* Patients with symptoms of upper respiratory infection

Primary outcomes:
measure: EC50 of propofol required for successful i-gel insertion
timeFrame: During i-gel insertion anticipated up to 1 min
Secondary outcomes:
measure: the total dose of propofol infused before i-gel insertion
timeFrame: During i-gel insertion time anticipated upto 1min
measure: the presence/severity of airway trauma after i-gel insertion
timeFrame: At the time point of removing the i-gel from patient's mouth
Other outcomes:
Locations:
city: Seoul
country: Korea, Republic of
facility: Seoul National University of Hospital
Study officials:
affiliation: Professor
name: Hee Pyung Park, MD PhD
role: STUDY_DIRECTOR
affiliation: Professor
name: Young Cheol Kim, Md PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Jang YE, Kim YC, Yoon HK, Jeon YT, Hwang JW, Kim E, Park HP. A randomized controlled trial of the effect of preoperative dexmedetomidine on the half maximal effective concentration of propofol for successful i-gel insertion without muscle relaxants. J Anesth. 2015 Jun;29(3):338-345. doi: 10.1007/s00540-014-1949-9. Epub 2014 Nov 14.