| Objective: Comparison of the effect of anesthetic level after the two injection modes of local anesthetics,which one is injected by a micro-infusion pump and another one is administered manually.Meanwhile,comparison of the anesthetic level of spinal anesthesia after different rates of intrathecal injection of local anesthetics by the two injection modes.Method: one hundred and twenty patients,undergoing anus surgery were allocated randomly to two big groups according to the injection mode: group A(manual injection,n=60)and group B(micro-infusion pump injection,n=60).Then the each big group is divided into three subgroups according to the rate of injection: group 6s(group A1,group B1)and group 15s(group A2,group B2)and group100s(group A3,group B3).And each subgroup consists of 20 patients.Lumbar puncture was performed,with the patients in the right lateral decubitus position,at the L3-4 interspace with the bevel of spinal needle directed cephalad.After free flow of CSF was observed,2ml 0.5%isobaric bupivacaine(mixing 2ml 0.75% bupivacaine hydrochloride injection and 1ml 0.9% sodium chloride)was administered by two injection modes which were manual injection and micro-infusion pumpinjection,with different injection time(6s,15 s,100s).The patients were kept in the right lateral horizontal position for 2 min from the beginning of the injection.Then they were moved to the lithotomy position quickly.All patients were monitored with continuous electrocardiogram,a noninvasive automatic blood pressure device,and the pulse oxygen saturation.When the index of hemodynamics were changed,the vasoactive drugs were given if necessary,to maintain the circulation.It is necessary to record some sort of data separately such as the maximum sensory anesthetic level,the time to reach maximum sensory level,the sensory level and index of hemodynamic at the beginning of arriving the operating room,at 5min,10 min,15min,20 min,25min,30 min after injection,the highest motor block degree,the lasting time of motor block,time to regression of sensory block were recorded.Result: The maximum sensory level of group A3(T6.2±1.37)is higher than group A1(T7.8±1.28)and group A2(T7.7±1.45)(P<0.05).Group B3 produced a higher level of spinal anesthesia(T6.5±1.36)than B1 group(T8.3±1.22)and B2 group(T7.9±1.05)(P<0.05).The time to maximal sensory level is longer in group B3(361±70.76)min than group B1(284±75.41)min(P<0.05).The time to regress of motor block and sensory block is shoter in group B1(respectively 228±78.56,284±75.41)min than in group A1(respectively290±88.83,351±102.45)min(P<0.05).But no difference was observed between the hand-injection and micro-infusion pump injection in terms ofthe maximum level,the time to the maximum level of sensory block,heart rate and blood pressure(P > 0.05).Conclusion: The very slow injection of 0.5% isobaric bupivacaine results a higher maximum sensory anesthetic level than fast injection and produces a longer sensory blockage.There is no clinically relevant influence on the anesthetic characteristics when 0.5% isobaric bupivacaine is injected by micro-infusion pump or hands.However,the time to regress of motor block and sensory block is shorter when local anesthetic is injected by the micro-infusion pump in a very fast injection speed. |
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