Optimal Lidocaine Propofol Mixture for Painless Induction of Anesthesia

Study Overview
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Brief Summary
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This research will be carried out in order to determine the optimal lidocaine dose in propofol lidocaine mixture to prevent pain on propofol injection during induction of general anesthesia using a modified Dixon's up-and-down method. Patients & methods: Include assessment of severity of pain on propofol injection using seven doses of lidocaine in lidocaine propofol mixture in ASA I&II patients aged 18-60 years with exclusion of patients with history of drug allergy, hepatic or renal impairment, cardiac problems, neurologic deficits or psychiatric disorders. The primary outcome will be pain scale during injection and volume of propofol-lidocaine mixture used. Secondary outcome will be increase in heart rate and/or hand or forearm withdrawal during injection, patient satisfaction, demographic data, type and duration of surgery, Time for unconsciousness. Aim of the work: To determine the Minimal effective dose of lidocaine in propofol lidocaine mixture to achieve painless induction of anesthesia using propofol.

Detailed Description
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Rapid onset of action, smooth induction, favorable recovery and low rate of adverse effects have made propofol the most commonly used intravenous anesthetic for induction and maintenance of anesthesia. However, pain associated with propofol injection is still considered by many patients as the worst prioperative unpleasant experience.1 Therefore, a diversity of techniques have been suggested in the literature to solve this problem including pretreatment with local anesthetics, opiates, ketamine and alfentanil. 2-5 New propofol formulation was another way to alleviate this pain.6 Among these techniques lidocaine was investigated extensively whether as a pretreatment with the use of tourniquet, which is a time consuming technique, or mixed with propofol. Evaluation of optimal dose of lidocaine in propofol lidocaine mixture was widely assessed. However, evaluation of optimal lidocaine dose in propofol lidocaine mixture to prevent pain with newer formulations of propofol should be further evaluated. We hypothesize that optimal dose of lidocaine to alleviate pain with propofol injection might need further evaluation. Patients and methods This prospective randomized and double blinded study will be conducted in Sohag University Hospital after obtaining approval from Institutional Review Board and written informed consent from all patients before enrolment in this study. Patients scheduled for elective surgery under general anesthesia, aged 18 to 60 years and American Society of Anesthesiologists (ASA)physical status I & II will be selected for this study. Patients with history of drug allergy, hepatic or renal impairment, cardiac problems, neurologic deficits, psychiatric disorders or anxious patients who need sedation preoperatively will be excluded from the study. Before entering the operating room premedication will not be allowed. In the operating room 20 gauge cannula will be inserted into a vein on the dorsum of the non-dominant hand & basic monitoring (pulse oximetry, electrocardiography, noninvasive blood pressure & end tidal carbon dioxide) will be applied to the patient before induction and throughout the procedure. Mixtures of propofol, lidocaine and saline will be prepared by an anesthetist who is not involved in the study team according to the lidocaine dose sequence as shown in table (1) resulting into eight mixtures. The mixture will be injected at a rate of 20ml/minute using syringe pump until patient loose consciousness. The anesthetist who inject the propofol and the patient will be blinded to the lidocaine dose in the mixture. Table 1 propofol lidocaine mixtures Mixture Propofol Lidocaine 2% (ml)(20mg/ml) Lidocaine concentration (%) 20ml 0.5 20ml 1 0.095 20ml 1.5 0.139 20ml 2 0.181 20ml 2.5 0.222 20ml 3 0.26 20ml 3.5 0.297 20ml 4 0.333 Pain scale will be explained to all patients preoperatively and they will be asked to report for pain sensation (no pain or mild, moderate or severe pain) The dose of lidocaine, in propofol lidocaine mixture, administered to each patient will be determined by the response of the previous patient using a modified Dixon's up-and-down method (using 10mg as a step size). The first patient will receive a mixture with 10mg lidocaine. If the patient report pain with propofol injection, then the next patient will receive a mixture with 10mg higher dose of lidocaine, if the patient report no pain with injection, then the next patient will receive a mixture with 10mg lower dose of lidocaine. The study will continue until we obtain seven crossover midpoints (No limited number). The minimal effective dose of lidocaine that results in painless injection of propofol for 50% (ED50) of patients will be determined by calculating the midpoint dose of all independent pairs of patients after at least seven crossover points. The following data will be recorded; Primary outcome: pain scale during injection and volume of propofol-lidocaine mixture used. Secondary outcome: increase in heart rate and/or hand or forearm withdrawal during injection, patient satisfaction(will be assessed in the post anesthesia care unit (PACU) after regaining consciousness), demographic data, type and duration of surgery, Time for unconsciousness. Aim of the work To determine the Minimal effective dose of lidocaine in propofol lidocaine mixture to achieve painless induction of anesthesia using propofol.

Official Title
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Optimal Lidocaine Propofol Mixture for Painless Induction of Anesthesia

Conditions
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Pain, During Injection of Propofol for Induction of Anesthesia

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients scheduled for elective surgery under general anesthesia. Aged 18 to 60 years American Society of Anesthesiologists physical status I & II Exclusion Criteria History of drug allergy Hepatic or renal impairment .Cardiac disease Neurologic deficits ,psychiatric disorders Anxious patients who need sedation preoperatively

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pain scale | Pain scale (mild, moderate or severe) during injection of propofol | 9 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart rate | Heart rate | Before injection of propofol-lidocaine mixture and every minute for three minutes after start of injection | 
| time for unconsciousness | time in seconds starting from injection of Propofol-lidocaine mixture until patient loose consciousness | 2 minutes after start of injection of propofol | 
| patient satisfaction | describes satisfaction level of the patient regarding relief of propofol injection (not satisfied, less satisfied, satisfied, highly satisfied) | 30 minutes after recovery | 
| hand or forearm withdrawal | withdrawal due to pain during injection of propofol | 2 minutes duration during injection of propofol | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Propofol - Lidocaine - Painless Induction