Does lidocaine more effectively prevent pain upon induction with propofol or etomidate when given preemptively than when mixed with the drug?

Study ObjectiveTo compare the efficacy of 2% lidocaine “timing” on alleviation of pain upon induction using propofol or etomidate.DesignProspective, randomized, double-blinded study.SettingAcademic teaching hospital.Patients80 adult, ASA physical status I, II, and III patients scheduled for elective outpatient or inpatient surgery with an intravenous induction agent.InterventionsPatients were randomly assigned to two groups. Group A received preemptive saline 4 mL and lidocaine 4 mL mixed with either propofol 20 mL (n = 20) or etomidate 20 mL (n = 20). Group B received preemptive lidocaine 4 mL and saline 4 mL mixed with either propofol 20 mL (n = 20) or etomidate 20 mL (n = 20). The 4 mL dose of preemptive drug dwelled for three minutes.MeasurementsThe induction drug mixture was injected over 60 seconds while the patient was assessed for pain using a 4-point scale (0 = no pain,1 = mild, 2 = moderate, and 3 = severe).Main ResultsMean induction pain scores were 1.0 (SD = 0.89) for propofol and 0.9 (SD = 0.90) for etomidate, representing mild induction pain. Mean induction pain scores were 0.93 (SD = 0.92) for the simultaneous treatment groups and 0.98 (SD = 0.87) for the preemptive treatment groups. The observed differences in pain scores between the techniques were not statistically (P > 0.62) or clinically meaningful.ConclusionsAlleviation and intensity of post-injection pain were not significantly influenced by the “timing” of administration of lidocaine 80 mg or by the specific induction drug. Pre-lidocaine and “simultaneous” lidocaine with either propofol or etomidate prevented severe pain in 95% of patients.