ObjectiveTo investigate the optimal concentration of lidocaine in inhibiting the propofol injection pain, and evaluate its efficacy and safety.

MethodsThe optimal concentration of lidocaine in painless artifical abortion patients(ASA Ⅰ to Ⅱ)was detected using step by step increasing or decreasing mode.The patients injected with sufentanil were randomly divided into the blank group(group A injected with 1% propofol), control group(group B injected with 1% propofol after 40 mg of lidocain preinjection) and experimental group(group C injected with the mixture of 0.3% lidocaine and 0.83% propofol).The pain scores in three groups were evaluated during injection period.The blood pressure before and after injection, heart rate(HR) and SpO₂, waking time, respiratory or circulatory inhibition, nausea or vomiting and satisfaction degree in three groups were analyzed.

ResultsBefore medication, the differences of diastolic pressure among three groups were not statistically significant(P > 0.05), and the levels of systolic pressure in group B and group C were higher than that in group C(P < 0.01).After 1 min and 3 min of medication, the levels of diastolic pressure and systolic pressure in three groups significantly decreased compared with before medication(P < 0.01), and the differences of those among three groups were not statistically significant(P > 0.05).There was no difference in HR among three groups before medication, the HR in three groups after 1 min of medication significantly decreased(P < 0.05 to P < 0.01).After 3 min of medication, the HR in group A was lower than before medication(P < 0.05).After 3 min of medication, the HR in group B and group C were lower than before medication, and the difference of which was not statistically significant(P > 0.05).After medication, the HR in group C was significantly higher than that in group B(P < 0.05).After medication, the SpO₂ levels in three groups significantly decreased(P < 0.01), but the differences of which among three groups were not statistically significant(P > 0.05).After 3 min of medication, the SpO₂ levels in three groups significantly increased compared with after 1 min of medication(P < 0.01), and which in group B and group C were higher than that in group A(P < 0.01).The incidence rates of severe pain and satisfaction degree in group C, group B and group A gradually increased in turn, respectively(P < 0.05).The differences of the incidence rates of low SpO₂, blood pressure and heart rate, nausea, vomiting and movement among three groups were not statistically significant(P > 0.05).

ConclusionsThe mixture of 0.3% lidocaine and 0.83% propofol can safely and effectively eliminate the injection pain of propofol.