Preoperative Dexmedetomidine & EC50 of Propofol

Urologic Surgery Clinical Trial

— PreopDXM  

Official title:

Preoperative Dexmedetomidine Reduces the EC50 of Propofol for Successful i-gelTM Insertion Without Muscle Relaxants

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02097407
• Other study ID #: PreopDXM_PPF
• Status: Completed
• Phase: Phase 4
• First received: March 24, 2014
• Last updated: March 24, 2014
• Start date: May 2012
• Est. completion date: August 2012

Study information

• Verified date: March 2014
• Source: Seoul National University Hospital
• Contact: n/a
• Is FDA regulated: No
• Health authority: Korea: Food and Drug Administration
• Study type: Interventional

Clinical Trial 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.

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

Recruitment information / eligibility

• Status: Completed
• Enrollment: 37
• Est. completion date: August 2012
• Est. primary completion date: August 2012
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 20 Years to 65 Years

Eligibility

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

Study Design

Allocation: Randomized, Endpoint Classification: Pharmacokinetics Study, Intervention Model: Single Group Assignment, Masking: Double Blind (Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Supportive Care

Related Conditions & MeSH terms

• Urologic Surgery

Intervention

Drug:
• Group C : Saline + propofol group
All patients were pre-oxygenated with 100% oxygen with spontaneous breathing for 3 min before the end of loading of normal saline. Anaesthesia was induced with predetermined effect-site propofol concentrations using a target-controlled infusion device (Orchestra; Fresenius-Vial, Brezins, France). The first patient in Group C received an effect-site propofol concentration of 3 and 5 µg mL-1, respectively, over 5 min. After equilibration of the plasma and effect-site propofol concentrations, i-gel (size 4 for patients weighing 50-90 kg, size 3 for patients weighing 30-50 kg) was inserted using the standard technique by a single anaesthesiologist staff member with expertise in i-gel insertion and who entered the operating room immediately before i-gel insertion to blind him to the group assignment
• Group D : Dexmedetomidine + propofol group
All patients were pre-oxygenated with 100% oxygen with spontaneous breathing for 3 min before the end of loading of dexmedetomidine. Anaesthesia was induced with predetermined effect-site propofol concentrations using a target-controlled infusion device (Orchestra; Fresenius-Vial, Brezins, France). The first patient in Group D received an effect-site propofol concentration of 3 and 5 µg mL-1, respectively, over 5 min. After equilibration of the plasma and effect-site propofol concentrations, i-gel (size 4 for patients weighing 50-90 kg, size 3 for patients weighing 30-50 kg) was inserted using the standard technique by a single anaesthesiologist staff member with expertise in i-gel insertion and who entered the operating room immediately before i-gel insertion to blind him to the group assignment.

Locations

Country	Name	City	State
Korea, Republic of	Seoul National University of Hospital	Seoul

Sponsors (1)

Lead Sponsor	Collaborator
Seoul National University Hospital

Country where clinical trial is conducted

Korea, Republic of, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	EC50 of propofol required for successful i-gel insertion	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.	During i-gel insertion anticipated up to 1 min	No
Secondary	the total dose of propofol infused before i-gel insertion	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.	During i-gel insertion time anticipated upto 1min	No
Secondary	the presence/severity of airway trauma after i-gel insertion	After removing the i-gel, airway trauma (defined as any blood staining on the device) was recorded.	At the time point of removing the i-gel from patient's mouth	No