Clinical Study On Intravenous Lidocaine Eliminates Fentanyl-induced Cough

Objective:To evaluate the effects of different doses of lidocaine on fentanyl-induced cough and determine a safe suppressing dose.Methods:Two hundred patients,ASAâ… -â…¡,aged 18-60 yr,scheduled for elective surgery under general anesthesia,were randomized to four groups evenly.The following medications were given within ten seconds:normal saline 10ml(groupâ… ,control group),lidocaine 1mg.kg^-1(groupâ…¡),lidocaine 1.5mg.kg^-1(groupâ…¢),lidocaine 2mg.kg^-1(groupâ…£),all lidocaine was mixed with saline to 10ml.Toxic symptoms of lidocaine were recorded after medicaine for 1 min,then fentanyl 3 ug.kg-1 was given intravenously within 5 sec.Cough incidence and cough grade were recorded within 2 min after the administration of fentanyl. Severity of coughing was graded based on the number of episodes of cough(mild,1-2; moderate,3-4;and severe,5 or more).Systolic blood pressure(SBP),diastolic blood pressure (DBP),heart rates(HR),and saturation of pulse oximeter(SpO₂)were recorded before anesthesia(T₀),1 min after lidocaine administration(T₁),2 min after fentanyl administration(T₂), 1 min after general anesthesia(T₃),immediately after intubation(T₄),5 min after intubation(T₅), and 10 min after intubation(T₆).All recorded data were analysed by the statistical software,P value＜0.05 was considered statistically significant.Results:cough occurred in about one third of patients in Groupâ… (32%),while the frequencies of cough were significantly decreased in Groupâ…¡(8%),Groupâ…¢(6%)and Groupâ…£(8%);there were no significant differences in the incidence and severity of cough among Groupâ…¡,Groupâ…¢and Groupâ…£.The number of toxicated patients and severity of symptoms increased along with the increasing doses of lidocaine.In Groupâ…£,the number and numbness of the tongue,lips and tinnitus were significantly less compared with that of groupâ…¡.Tinnitus of groupâ…¢was significantly less compared with that of Groupâ…¡.SBP,DBP and SpO2 showed no significant differences among 4 groups at the same time points.Groupâ…¢,â…£have a higher HR,compared with that of groupâ… at T₁,T₂;compared with T₄.HR of groupâ…¢andâ…£decreased at T₅,T₆,while there were no alter in HR of groupâ… andâ…¡..The SBP and DBP showed no Significant differences among 4 groups in the same time point(P＞0.05)。The SBP and DBP in the T₃ point compared with that of the other point were significantly decreased (P＜0.05);the SBP and DBP in the T₅ and T₆ points were significantly decreased compared with that of the T₄(P＜0.05)Conclusion:Intravenous lidocaine 1-2mg·kg^-1,administered one min before fentanyl,are effective in suppressing fentanyl-induced cough.â…£lidocaine 1mg·kg^-1is a more safe and feasible dosage in clinical practice.