From the Department of Anesthesiology and Critical Care Medicine, Lapeyronie University Hospital, Montpellier Cedex 5, France.
Department of Medical Statistics and Epidemiology, Montpellier University Hospital, Montpellier Cedex 5, France.
Anesth Analg. 2021 Feb 1;132(2):556-565. doi: 10.1213/ANE.0000000000005308.
Nerve damage can occur after peripheral nerve block (PNB). Ultrasound guidance does not eliminate the risk of intraneural injection or nerve injury. Combining nerve stimulation and injection pressure (IP) monitoring with ultrasound guidance has been suggested to optimize needle tip location in PNB. In this prospective observational study, we hypothesized that measured pairs of IP and minimum intensity of stimulation (MIS) might differentiate successive needle tip locations established by high-resolution ultrasound during PNB.
For this exploratory study, 240 observations for 40 ultrasound-guided PNBs were studied in 28 patients scheduled for orthopedic surgery. During the progression of the needle to the nerve observed by ultrasonography, the IP was measured continuously using a computerized pressure-sensing device with a low flow rate of solution. Stimulation thresholds and electrical impedance were obtained by an impedance analyzer coupled to the nerve stimulator at 6 successive needle positions. The median (quartile) or mean (95% confidence interval [CI]) was reported. A mixed model analysis was used, and the sample was also explored using a classification and regression tree (CART) algorithm.
Specific combinations of IP and MIS were measured for subcutaneous, epimysium contact, intramuscular, nerve contact (231 mm Hg [203-259 mm Hg] and 1.70 mA [1.38-2.02 mA]), intraneural location (188 mm Hg [152-224 mm Hg] and 0.58 mA [0.46-0.70 mA]), and subparaneural location (47 mm Hg [41-53 mm Hg] and 1.35 mA [1.09-1.61 mA]). The CART algorithm shows that the optimal subparaneural needle tip position might be defined by the lowest pressure (<81.3 mm Hg) and MIS (<1.5 mA) cutoffs.
Our exploratory study evaluated concepts to generate hypotheses. The combinations of IP and MIS might help the physician during a PNB procedure. A low IP and low MIS might confirm a subparaneural location, and a high IP and a low MIS might be an alert for the intraneural location of the needle tip.
外周神经阻滞（PNB）后可能会发生神经损伤。超声引导并不能消除神经内注射或神经损伤的风险。结合神经刺激和注射压力（IP）监测与超声引导已被建议用于优化 PNB 中针尖的位置。在这项前瞻性观察研究中，我们假设在 PNB 过程中，通过高分辨率超声确定的连续针尖位置，可以通过测量 IP 和最小刺激强度（MIS）来区分。
这项探索性研究共纳入 28 例拟行骨科手术的患者，对 40 例超声引导 PNB 中的 240 次观察进行了研究。在超声监测下，针尖向神经推进的过程中，使用计算机化压力感应装置以低流速溶液连续测量 IP。通过与神经刺激器相连的阻抗分析仪，在 6 个连续的针尖位置获得刺激阈值和电阻抗。报告中位数（四分位数）或平均值（95%置信区间[CI]）。使用混合模型分析，同时还使用分类回归树（CART）算法对样本进行了探索。
皮下、筋膜接触、肌肉内、神经接触时，分别测量到特定的 IP 和 MIS 组合（231mmHg[203-259mmHg]和 1.70mA[1.38-2.02mA]）、神经内位置（188mmHg[152-224mmHg]和 0.58mA[0.46-0.70mA]）和神经旁位置（47mmHg[41-53mmHg]和 1.35mA[1.09-1.61mA]）。CART 算法显示，最佳的神经旁针尖位置可能通过最低压力（<81.3mmHg）和 MIS（<1.5mA）的截止值来定义。
这项探索性研究评估了产生假设的概念。IP 和 MIS 的组合可能有助于医生在 PNB 过程中进行操作。低 IP 和低 MIS 可能证实针尖位于神经旁，而高 IP 和低 MIS 可能提示针尖位于神经内。
