Larson M D, Kurz A, Sessler D I, Dechert M, Tayefeh F, Bjorksten A R
Department of Anesthesia, University of California, San Francisco 94143-0648, USA.
Reg Anesth. 1997 Sep-Oct;22(5):461-5. doi: 10.1016/s1098-7339(97)80034-x.
Pupillary dilation in response to dermatomal electrical stimulation is one method of determining sensory block level during combined epidural and general anesthesia. Use of this technique may, however, be confounded by systemic absorption of epidurally administered local anesthetics. Accordingly, the effects of intravenous lidocaine on the magnitude and duration of reflex pupillary dilation were evaluated.
Six volunteers were each anesthetized twice with desflurane 3.5-6.0%. During one anesthetic, intravenous lidocaine was administered to a plasma concentration of 5.3 +/- 1.5 micrograms/mL. When the plasma concentrations were stable, a 5-second tetanic electrical stimulus was applied. Pupil size was then recorded for 8 minutes.
Lidocaine, at plasma concentrations near 5 micrograms/mL, did not significantly alter the pupillary response to electrical stimulation. In contrast, stimulus-induced increase in heart rate was obliterated. Painful stimulation did not increase systolic blood pressure in either case.
Typical plasma lidocaine concentrations observed during epidural anesthesia are unlikely to prevent the use of pupillary responses to evaluate sensory block level.
对皮节进行电刺激时的瞳孔散大是在硬膜外麻醉与全身麻醉联合应用期间确定感觉阻滞平面的一种方法。然而，硬膜外给予局部麻醉药的全身吸收可能会干扰该技术的应用。因此，评估了静脉注射利多卡因对反射性瞳孔散大的幅度和持续时间的影响。
6名志愿者每人接受两次3.5% - 6.0%地氟醚麻醉。在一次麻醉期间，静脉注射利多卡因使血浆浓度达到5.3±1.5微克/毫升。当血浆浓度稳定后，施加5秒的强直电刺激。然后记录瞳孔大小8分钟。
血浆浓度接近5微克/毫升时，利多卡因并未显著改变瞳孔对电刺激的反应。相比之下，刺激引起的心率增加被消除。在两种情况下，疼痛刺激均未使收缩压升高。
硬膜外麻醉期间观察到的典型血浆利多卡因浓度不太可能妨碍使用瞳孔反应来评估感觉阻滞平面。
