From the Departments of *Anesthesia and Perioperative Care, and †Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California.
Anesth Analg. 2014 Apr;118(4):766-71. doi: 10.1213/ANE.0000000000000144.
Blood hemoglobin can be monitored continuously and noninvasively with a noninvasive spectrophotometric sensor (Masimo SpHb). The perfusion index (PI) of the finger is directly related to the clinical accuracy of SpHb. We evaluated those variables that influence PI without the influences of surgery and anesthesia.
Based on our past studies, 12 awake adult volunteers were studied. A SpHb sensor was attached to the same finger of each hand. The temperature of each finger was measured via a skin surface probe. A digital nerve block (DNB) was performed with 1% lidocaine on one finger and 0.25% bupivacaine on the other finger of the opposite hand. SpHb, PI, and finger temperature were monitored continuously 30 minutes before and 3 to 4 hours after placement of the DNB. A random effects spline regression was used to flexibly model the outcomes before and after the DNB and to compare the effects of lidocaine and bupivacaine.
The DNBs increased the PI for both lidocaine and bupivacaine (P < 0.0001) and finger temperature from both lidocaine (P < 0.0001) and bupivacaine (P = 0.02). The duration of action of bupivacaine was markedly longer than that of lidocaine (P < 0.0001). Between 45 and 75 minutes after insertion of the DNB, the PI with bupivacaine was substantially higher than that of lidocaine. The PI was directly related to changes in finger temperature and SpHb. During this time interval, 11 of the 12 volunteers receiving bupivacaine descriptively had increases in finger temperature ranging from no change to 6.1°C. In contrast, only 6 of the 12 lidocaine volunteers had increases in finger temperature ranging from no change to 4°C. Changes in PI were directly correlated with SpHb values (correlation coefficient = 0.7).
A DNB increases PI and finger temperature. These increases lasted 2 to 3 hours longer with bupivacaine than lidocaine. The increases in PI were associated with slightly higher SpHb values. We conclude that the DNB induces increases in PI and temperature of the finger. Because of the close relationship between finger temperature, PI, and SpHb, consistently increasing finger temperature and PI could increase the accuracy of SpHb.
非侵入式分光光度传感器（Masimo SpHb）可连续、非侵入式监测血液血红蛋白。手指的灌注指数（PI）与 SpHb 的临床准确性直接相关。我们评估了那些不考虑手术和麻醉影响的影响 PI 的变量。
基于我们过去的研究，对 12 名清醒的成年志愿者进行了研究。每个手的同一手指上都附有一个 SpHb 传感器。通过皮肤表面探头测量每个手指的温度。在一只手上的手指上进行数字神经阻滞（DNB），用 1%利多卡因进行阻滞，在对侧手上的另一只手指上用 0.25%布比卡因进行阻滞。在放置 DNB 前 30 分钟和放置 DNB 后 3 至 4 小时连续监测 SpHb、PI 和手指温度。使用随机效应样条回归灵活地对 DNB 前后的结果进行建模，并比较利多卡因和布比卡因的效果。
DNB 增加了利多卡因和布比卡因的 PI（P<0.0001）和手指温度（利多卡因 P<0.0001，布比卡因 P=0.02）。布比卡因的作用持续时间明显长于利多卡因（P<0.0001）。DNB 插入后 45 至 75 分钟，布比卡因的 PI 明显高于利多卡因。PI 与手指温度和 SpHb 的变化直接相关。在此时间间隔内，接受布比卡因的 12 名志愿者中有 11 名手指温度升高，范围从无变化到 6.1°C。相比之下，接受利多卡因的 12 名志愿者中只有 6 名手指温度升高，范围从无变化到 4°C。PI 的变化与 SpHb 值直接相关（相关系数=0.7）。
DNB 增加 PI 和手指温度。布比卡因引起的 PI 和手指温度升高持续时间比利多卡因长 2 至 3 小时。PI 的升高与 SpHb 值略有升高有关。我们得出结论，DNB 会引起 PI 和手指温度升高。由于手指温度、PI 和 SpHb 之间的密切关系，持续升高的手指温度和 PI 可以提高 SpHb 的准确性。
