Effect Of The Combination Of Lidocaine With Epinephrine Or Gamma Immunoglobulin On The Absorption Of Lidocaine Through Airaway

Objective Lidocaine has been the most frequently used medicine for local anesthesia in flexible bronchoscopy. However, its severe side effects have been reported in clinical application. This experiment is designed to explore whether the combination of lidocaine with epinephrine or gamma immunoglobulin will slow down or reduce the local absorption of lidocaine through airway. Method 20 adult male cats were Divided averagely and randomly into four groups: 1. Group L+I , admixture of 22mg/kg of lidocaine with 1/2 volume of gamma immunoglobulin was instilled into trachea; 2. Group L+N, admixture of 22mg/kg of lidocaine with 1/2 volume of physiological saline was instilled into trachea; 3. Group L+E, admixture of 22mg/kg of lidocaine with 1:10000 epinephrine was instilled into trachea; 4. Group C, saline in the volume as 1.5 times as that of 22mg/kg of 2% lidocaine was instilled into trachea. Each cat was instilled with each half of its dosage of the medicine at 0 and the 2nd minutes at the same speed. Blood samples were taken from femoral artery and invasive blood pressure and heart rate was recorded before administration, and at points of the 30th second, 60th second, 90th second, 3rd minute, 5th minute, 10th minute, 15th minute, 30th minute, 60th minute, 90th minute and 120th minute after administration. The concentrations of lidocaine in blood plasma were tested with High effective liquid chromatograph. Results The three groups, average Cmax are 1.39±0.23mg/L in Group L+I , 1.47±0.29 mg/L in Group L+N, 1.47±0.29 mg/L in Group L+E . The Cmax of Group L+I and Group L+N had no statistic difference(P =0.716)and all of them have statistic difference with Group L+E(P=0.016, 0.012).The descent arguments of average heart rate of four groups are 31.65% in Group L+I, 35.10% in Group L+N, 15.30% in Group L+E, 4.55% in Group C. The differences of descent argument of average heart rate among four groups are that no statistics significance between Group L+I and Group L+N (P=0.904), that Group L+I and Group L+E or Group L+I and Group C or Group L+N and Group L+E or Group L+N and Group C or Group L+E and Group C have statistic difference (P=0.000). The descent argument of average systolic blood pressure of four groups are 22.01% in Group L+I, 26.52% in Group L+N, 13.81% in Group L+E, 12.10% in Group C. The differences of descent argument of average systolic blood pressure of four groups are that no statistics significance between Group L+I and Group L+N (P=0.633), that Group L+I and Group L+E or Group L+I and Group C or Group L+N and Group L+E or Group L+N and Group C have statistic difference (P=0.000),that Group L+E and Group C have statistic difference (P=0.001). The descent argument of average diastolic blood pressure of four groups are 30.87% in Group L+I, 30.41% in Group L+N, 20.57% in Group L+E, 14.85% in Group C. The differences of descent argument of average diastolic blood pressure of four groups are that no statistics significance between Group L+I and Group L+N or Group L+E and Group C (P=0.934,0.888), that Group L+I and Group L+E or Group L+I and Group C or Group L+N and Group L+E have statistic difference (P=0.000),that Group L+N and Group C have statistic difference (P=0.001).Conclusion (1) Administration of lidocaine through trachea cause significant decreases in heart rate, systolic blood pressure and diastolic pressure in cats. (2)Combination with epinephrine reduces the peak concentration of lidocaine in blood plasma and prevents the significant decrease in cats'heart rate, systolic blood pressure and diastolic pressure caused by airway absorption of lidocaine. (3)Gamma immunoglobulin does not reduce the peak concentration of lidocaine in blood plasma and does not prevent the decrease of the cats'heart rate, systolic blood pressure and diastolic pressure caused by airway absorption of lidocaine.