Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Department of Anaesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Department of Anaesthesiology, Shenzhen Second People's Hospital, Shenzhen, China.
Br J Anaesth. 2018 Oct;121(4):859-866. doi: 10.1016/j.bja.2018.05.065. Epub 2018 Jul 4.
Laser speckle contrast imaging allows real-time, non-invasive, quantitative measurements of regional blood flow. The objectives of this prospective observational study were to use laser speckle contrast imaging to evaluate blood flow changes after sciatic nerve block, and to determine whether this novel optical technique can evaluate block success.
This observational study included 63 adult patients undergoing elective lower limb surgery with sciatic nerve block. Blood flow images and blood flow index (BFI) values of toes were recorded using laser speckle contrast imaging 5 min before nerve block and at 5 min intervals until 30 min after sciatic block. The sensitivity, specificity, and cut-off value of laser speckle contrast imaging for predicting successful sciatic block were determined by receiver operator characteristic (ROC) curve analysis.
The BFI values of toes were significantly increased at each time point after successful sciatic block, compared with the baseline value obtained 5 min before nerve block; in failed sciatic block, there were no significant differences. For successful sciatic block, the highest increase of BFI value was at the big toe. BFI increase of the big toe at 10 min after sciatic block has great potential as an indicator of block success. The area under the ROC curve was 0.954 at a cut-off value of 8.48 perfusion units (PU) with a sensitivity of 89% and a specificity of 100%.
Laser speckle contrast imaging might be an early, objective, quantitative, and reliable indicator of successful sciatic block. BFI increase of the big toe not reaching 8.48 PU within 10 min after sciatic block indicates block failure.
NCT03169517.
激光散斑对比成像可实时、无创、定量测量局部血流。本前瞻性观察研究的目的是使用激光散斑对比成像评估坐骨神经阻滞后的血流变化，并确定这种新型光学技术是否可以评估阻滞的成功。
本观察性研究纳入了 63 例接受择期下肢手术并接受坐骨神经阻滞的成年患者。使用激光散斑对比成像术在神经阻滞前 5 分钟及之后每隔 5 分钟记录足部血流图像和血流指数（BFI）值，直至坐骨神经阻滞后 30 分钟。通过受试者工作特征（ROC）曲线分析确定激光散斑对比成像预测坐骨神经阻滞成功的灵敏度、特异性和截断值。
与神经阻滞前 5 分钟获得的基线值相比，成功坐骨神经阻滞后每个时间点的足趾 BFI 值均显著增加；而在坐骨神经阻滞失败的情况下，两者之间没有显著差异。对于成功的坐骨神经阻滞，BFI 值增加最大的是大脚趾。坐骨神经阻滞后 10 分钟大脚趾 BFI 值的增加具有作为阻滞成功指标的巨大潜力。ROC 曲线下面积在截断值为 8.48 灌注单位（PU）时为 0.954，灵敏度为 89%，特异性为 100%。
激光散斑对比成像可能是一种早期、客观、定量、可靠的坐骨神经阻滞成功指标。坐骨神经阻滞后 10 分钟内大脚趾的 BFI 值增加未达到 8.48 PU 表明阻滞失败。
NCT03169517。
