Department of Anesthesiology, Washington University School of Medicine, St Louis, MO, USA.
Washington University School of Medicine, St Louis, MO, USA.
Int J Obstet Anesth. 2021 May;46:102981. doi: 10.1016/j.ijoa.2021.102981. Epub 2021 Mar 26.
Effective epidural anesthesia is confirmed in humans by sensory assessments but these tests are not feasible in mice. We hypothesized that, in mice, infrared thermography would demonstrate selective segmental warming of lower extremities following epidural anesthesia.
We anesthetized 10 C57BL/6 mice with isoflurane and then inserted a PU-10 epidural catheter under direct surgical microscopy at T11-12. A thermal camera (thermal sensitivity ±0.05°C, pixel resolution 320x240 pixels, and spatial resolution 200 μm) recorded baseline temperature of front and rear paws, tail and ears. Thermography was assessed at baseline and 2, 5, 10, and 15 min after an epidural bolus dose of 50 μL bupivacaine 0.25% or 50 μL saline (control) using a cross-over design with dose order randomized and investigators blinded to study drug. Thermal images were recorded from video and analyzed using FLIR software. Effect over time and maximal effect (E) were assessed by repeated measures ANOVA and paired t-tests. Comparisons were between bupivacaine and control, and between lower vs upper extremities.
Epidural bupivacaine caused progressive warming of lower compared with upper extremities (P <0.001), typically returning to baseline by 15 min after administration. Mean (±SD) E was +3.73 (±1.56) °C for lower extremities compared with 0.56 (±0.68) °C (P=0.03) for upper extremities. Following epidural saline, there was no effect over time (E for lower extremities -0.88 (±0.28) °C compared with the upper extremities -0.88 (±0.19) °C (P >0.99).
Thermography is a useful tool to confirm epidural catheter placement in animals for which subjective, non-noxious, sensory measures are impossible.
在人体中，有效的硬膜外麻醉通过感觉评估得到证实，但这些测试在小鼠中不可行。我们假设，在小鼠中，红外热像仪将显示在硬膜外麻醉后下肢选择性的节段性升温。
我们用异氟烷麻醉 10 只 C57BL/6 小鼠，然后在 T11-12 直接手术显微镜下插入 PU-10 硬膜外导管。热像仪（热灵敏度±0.05°C，像素分辨率 320x240 像素，空间分辨率 200 μm）记录前爪、后爪、尾巴和耳朵的基础温度。使用交叉设计，以剂量顺序随机化，研究人员对研究药物不知情，在硬膜外推注 50 μL 0.25%布比卡因或 50 μL 生理盐水（对照）后 2、5、10 和 15 分钟评估热成像。使用 FLIR 软件从视频中记录热图像并进行分析。通过重复测量方差分析和配对 t 检验评估随时间的变化和最大效应（E）。比较布比卡因和对照，以及上下肢之间的比较。
硬膜外布比卡因引起下肢比上肢的渐进性升温（P <0.001），通常在给药后 15 分钟左右恢复到基线。下肢的平均（±SD）E 为+3.73（±1.56）°C，而上肢为 0.56（±0.68）°C（P=0.03）。硬膜外生理盐水后，随时间没有变化（下肢 E -0.88（±0.28）°C，与上肢 E -0.88（±0.19）°C 相比（P >0.99）。
热成像技术是一种有用的工具，可以在无法进行主观、非疼痛、感觉测量的动物中确认硬膜外导管的放置。
