Preoperative Dexmedetomidine & EC50 of Propofol (PreopDXM)

Seoul National University

Status and phase: Completed; Phase 4

Conditions: Urologic Surgery

Treatments: Drug: Group C : Saline + propofol group; Drug: Group D : Dexmedetomidine + propofol group

Study type: Interventional

Funder types: Other

Identifiers

NCT02097407

PreopDXM_PPF

Details and patient eligibility

About

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.

Full 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

Enrollment: 37 patients

Sex: All

Ages: 20 to 65 years old

Volunteers: No Healthy Volunteers

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

Trial design

Primary purpose: Supportive Care

Allocation: Randomized

Interventional model: Single Group Assignment

Masking: Triple Blind

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37 participants in 2 patient groups, including a placebo group

Group D : Dexmedetomidine + propofol group

Experimental group

Description:

In Group D, DEX (1 µg kg-1) was intravenously loaded for 10 min before induction of anaesthesia.

Treatment:

Drug: Group D : Dexmedetomidine + propofol group

Group C : Saline + propofol group

Placebo Comparator group

Description:

In Group C, 0.9% of normal saline (1 µg kg-1) was loaded 10 min before induction of anaeshtesia.

Treatment:

Drug: Group C : Saline + propofol group