Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
INTRODUCTION: Propofol often causes pain during injection, which can be reduced by prior injection of lidocaine or fentanyl. The purpose of this study is to compare lidocaine and fentanyl in their inhibitory effects on injection pain and tracheal intubation-induced hemodynamic instability when injected simultaneously with propofol.
METHODS: After institutional approval and informed consent, 30 adults patients (ASA physical status I or II) were randomly assigned to one of three groups; 3 ml saline (S), 1.5 mg/kg lidocaine (L), and 2 [micro sign]g/kg fentanyl (F) groups. Anesthesia was induced with one of these agents mixed with 2mg/kg propofol. Vecuronium (0.12mg/kg) was used for a muscle relaxant. Propofol was infused at 8mg/kg/hr after a bolus injection. Pain was scored into 4 grades by asking each patient at the half dose injection; 0=none, 1= mild, 2=moderate, 3= severe. Blood pressure (BP) and heart rate were measured with a tonometer. Pain sore and hemodynamic data were statistically analyzed by Chi-square analysis and nonparametrical ANOVA (Kruskal-Wallis tests) with the Mann Whitney tests, respectively. A p<0.05 was considered to be significant.
RESULTS: The pain score in the L group (0 [0-1], median [range]) was significantly lower than the S (1 [0-3]) and F (0 [0-3]) groups. In each group, mean BP decreased significantly after bolus injection of propofol. Within one minute after intubation, BP increased over the control value and reached peak pressure. The increase in BP was significantly lower in the F group than in the S or L groups. Heart rate was not significantly changed by propofol injection, whereas it increased at intubation and reached the peak within 1 minute after intubation. The heart rate changes were less in the F group than in the S or L group. (Figure 1)
DISCUSSION: Our results demonstrate that simultaneous infusion of lidocaine (1.5 mg/kg) can effectively reduce pain occurring during a bolus administration of propofol, however fentanyl (2 [micro sign]g/kg) is not effective. On the other hand, fentanyl can effectively reduce hemodynamic alterations responding to tracheal intubation, however lidocaine is less effective than fentanyl. Lidocaine may act locally at an injection site to reduce pain due to its local neural block and/or titration of pH change associated with propofol, whereas the effect of fentanyl may be due to central opiate mechanisms.