Electrical Stimulation Augmenting “Loss of Resistance” and “Saline Column” Techniques to Confirm a Scoliotic Epidural Placement
Andrew Wheeler MD, Ban C.H. Tsui MD
Department of Anesthesiology, Perioperative, and Pain Medicine
Stanford University School of Medicine, USA
Background
•Epidural catheter placement
•The "loss of resistance” (LOR) technique
•Further confirmation by attaching a saline-filled column to a needle within the epidural space, which serves as a manometer to monitor the descending liquid column within it [1]
•Both of these approaches rely on the same principle – the mechanism of free flow of fluid into the low or negative pressure epidural potential space, where negative and low pressures are present [2]
•May not work well in restricted space patient (e.g., severe scoliosis). Electrical stimulation can be used for verification of catheter placement into the epidural space [3]
Case Report – Intervention
•82-year-old female with acute fractures of her right-sided 8-11 ribs after a ground-level fall and completely uncontrolled pain
•History of high-dose opioids for chronic osteoarthritic shoulder pain
•Positioned sitting upright, standard monitors in place, with systolic blood pressure (BP) of 220 due to pain
•Ultrasonography to determine favorable needle entrance at T8-9 space
•Right-sided paramedian approach with “soft” LOR at 7 centimeters (cm) on the first attempt
•Saline column dropped 3 cm then ceased further droppage
•Epidural catheter threaded with mild resistance to depth of 15 cm
•Stimulation with 2 milliamps caused pronounced right lateral chest wall twitching in the T8-T10 distribution
•Catheter secured in place with no change in position
•Test dose of three milliliters (mL) 1.5% lidocaine with 1:200,000 epinephrine
•Systolic BP dropped to 140
•Pain score reduced from “twenty” out of ten to seven out of ten
Case Report – Post-Intervention
•Transferred to the floor with epidural pump:
•0.0625% bupivacaine at 6 mL per hour/Hydromorphone 0.1 milligrams per hour/ Fentanyl patient-controlled epidural analgesia (PCEA) regimen of 10 micrograms with a lockout interval of 15 minutes.
•On hospital day #3, worsening of pain with increased activity
•Bolus of ten mL of 1% lidocaine with brisk analgesic effect
•Increased hourly bupivacaine dose to 10 mL per hour
•Significant functional improvement, weaned off oxygen requirements, increased incentive spirometry figures, and worked with physical therapy
Discussion
•Merits of using an adjunct confirmation technique
•Utilizing different physical principle to increase confidence and certainty
•Scoliosis presents a distinct difficulty for epidural anesthesia
•Optimizing needle insertion and verifying the true epidural location
•Ultrasonography can optimize insertion position, but the accuracy of needle placement still relies primarily on achieving distinct LOR
•Saline column technique to identify the epidural space has become more commonplace, but alternate confirmatory techniques can play a role
•Scoliosis likely contributed to an increasingly restricted epidural space
•Affected the mechanical recognition of LOR
•Obstructed the flow into the epidural space
•Utility of confirmation via a different mechanism (i.e., electricity), rather than remaining tied solely to assessing and reassessing mechanical means
References
1. Robson MI, Fawcett WJ. Identifying a correctly positioned thoracic epidural catheter for major open surgery. BJA Educ. 2020 Oct;20(10):330-331. doi: 10.1016/j.bjae.2020.06.002. Epub 2020 Jul 15. PMID: 33456913; PMCID: PMC7808035.
2. Wilson, M.J.A. (2007), Epidural endeavour and the pressure principle. Anaesthesia, 62: 319-322. https://doi.org/10.1111/j.1365-2044.2007.05063.x
3. Tsui, B.C.H., Gupta, S. & Finucane, B. Confirmation of epidural catheter placement using nerve stimulation. Can J Anaesth 45, 640–644 (1998). https://doi.org/10.1007/BF03012093
