Preoperative Dexmedetomidine & EC50 of Propofol

Phase 4

Completed

• Conditions: Urologic Surgery

• Registration Number: NCT02097407
• Lead Sponsor: Seoul National University Hospital

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

Study Timeline

• Study Start: 2012-05
• Primary Completion: 2012-08
• Study Completion: 2012-08
• Status Verified: 2014-03
• Study First Submitted: 2014-03-24
• Study First Submitted QC: 2014-03-24
• Last Update Submitted: 2014-03-24
• Study First Posted: 2014-03-27
• Last Update Posted: 2014-03-27

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 37

Inclusion Criteria

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

Read More

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

Read More

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Primary Outcome Measures

Name	Time	Method
EC50 of propofol required for successful i-gel insertion	During i-gel insertion anticipated up to 1 min	The EC50 of propofol for successful i-gel insertion was determined by a modification of Dixon's up-and-down method. The response of each patient determined the effect-site propofol concentration for the next patient. If the response was deemed 'successful', the next target concentration of propofol was decreased by 0.5 µg mL-1. If the response was deemed a 'failure', the target concentration was increased by the same dose. The process was repeated until the sixth crossover point (success/failure) was obtained.

Secondary Outcome Measures

Name	Time	Method
the total dose of propofol infused before i-gel insertion	During i-gel insertion time anticipated upto 1min	The total amount of propofol infused before i-gel insertion was noted. The insertion time, defined as the time from picking up the i-gel until the initiation of mechanical ventilation.
the presence/severity of airway trauma after i-gel insertion	At the time point of removing the i-gel from patient's mouth	After removing the i-gel, airway trauma (defined as any blood staining on the device) was recorded.

Trial Locations

Locations (1)

Seoul National University of Hospital; 🇰🇷 Seoul, Korea, Republic of