A Case Report of Caudal Migration of a Lumbar Epidural Catheter Confirmed by Doppler Ultrasound: Ultrasound to the Rescue!

Combined spinal-epidural anaesthesia is an excellent technique for providing intraoperative and postoperative analgesia in patients undergoing total knee arthroplasty. Epidural catheters threaded through a Tuohy needle with a cephalad needle bevel orientation follow a winding pattern within the epidural space. Caudal or downward migration of an epidural catheter may lead to unsatisfactory anaesthesia and epidural failure. Colour flow Doppler sonography is emerging as an effective technique to determine the epidural catheter tip position. We report an interesting case of caudal migration of a lumbar epidural catheter confirmed by colour flow Doppler ultrasound.

Risk factors for epidural anesthesia blockade failure in cesarean section: a retrospective study.

BACKGROUND: Epidural anesthesia (EA) is the regional anesthesia technique preferred over spinal anesthesia for pregnant women requiring cesarean section and post-operative pain control. EA failure requires additional sedation or conversion to general anesthesia (GA). This may be hazardous during sedation or GA conversion because of potentially difficult airways. Therefore, this retrospective study aimed to determine the risk factors for epidural failure during cesarean section anesthesia. METHODS: We retrospectively analyzed parturients who underwent cesarean section under EA and catheterization at the Chang Gung Memorial Hospital in Taiwan between January 1 and December 31, 2018. Patient data were collected from the medical records. EA failure was defined as the administration of any intravenous anesthetic at any time during a cesarean section, converting it into GA. RESULTS: A total of 534 parturients who underwent cesarean section were recruited for this study. Of them, 94 (17.6%) experienced EA failure during cesarean section. Compared to the patients with successful EA, those with EA failure were younger (33.0 years vs. 34.7 years), had received EA previously (60.6% vs. 37%), were parous (72.3% vs. 55%), and had a shorter waiting time (14.9 min vs. 16.5 min) (p < 0.05). Younger age (OR 0.91, 95% CI 0.86-0.95), history of epidural analgesia (OR 2.61, 95% CI 1.38-4.94), and shorter waiting time (OR 0.91, 95% CI 0.87-0.97) were estimated to be significantly associated with a higher risk of epidural anesthesia failure. CONCLUSION: The retrospective study found that parturients of younger age, previous epidural catheterization history, and inadequate waiting time may have a higher risk of EA failure. Previous epidural catheterization increased the risk of EA failure by 2.6-fold compared to patient with no history of catheterization.

A simple technique to assess postoperative epidural functionality.

To describe an alternative method of measuring the Epidural Waveform Analysis (EWA), a technique through which anesthesiologists can confirm the position of a needle and/or catheter tip in the epidural space. EWA consists of epidural catheter transduction with a pressure system typically used for invasive arterial blood pressure monitoring which generates a characteristic oscillatory waveform (provided the catheter tip is within the epidural space) in synchrony with the pulsatile epidural circulation. The technique requires a double-male connector, a 3-way stopcock and an arterial pressure extension tubing along with the patient's existing arterial line setup while ensuring a meticulously sterile technique to mitigate the risks of neuraxial infection. The technique described herein has been successfully and routinely applied within our institution to measure EWA with the advantage of being potentially less wasteful. EWA allows anesthesiologists to confirm the correct position of an epidural needle/catheter. We describe a method of successfully measuring EWA while reducing wastefulness.

Sensitivity and specificity of waveform analysis for assessing postoperative epidural function.

STUDY OBJECTIVES: To characterize the accuracy of epidural waveform analysis (EWA) in assessing the functionality of thoracic epidural catheters in the immediate postoperative period (primary objective), and to determine the inter-rater reliability between EWA waveform observers (secondary outcome). DESIGN: Single center, prospective diagnostic accuracy cohort study. SETTING: Post-anesthetic care unit of a university teaching hospital. PATIENTS: 84 adult patients undergoing elective thoracic, gynecologic, vascular, urologic, or general surgery with preoperative placement of a thoracic epidural catheter for perioperative analgesia. INTERVENTIONS: EWA tracings were video recorded in the immediate postoperative period through the epidural catheter in the post-anesthetic care unit. MEASUREMENTS: Postoperative EWA tracings were compared with clinical assessments of the sensory block to ice produced by epidural local anesthetic in the immediate postoperative period. Additionally, intra-class correlation analysis of agreement between 3 independent (and blinded) EWA waveform observers was carried out. RESULTS: Among 80 patients with thoracic epidurals who completed the study protocol, 73 demonstrated postoperative functional epidurals with sensory block to ice and 7 demonstrated non-functional epidurals. EWA yielded 65 true positives, 6 true negatives, 8 false negatives, and 1 false positive. Postoperative EWA sensitivity, specificity, positive predictive value and negative predictive value, along with the 95% confidence intervals (CI) were 89% (79-95%), 86% (42-100%), 98% (92-100%), and 43% (18-71%) respectively. Intra-class correlation between waveform assessors was 0.870 (95% CI 0.818-0.910, p < 0.001). CONCLUSIONS: EWA is useful in assessing the position of thoracic epidural catheters in the immediate postoperative period, demonstrating high sensitivity and specificity as well as robust inter-rater reliability. For patients in whom sensory block to ice cannot be reliably assessed postoperatively, EWA may provide a useful adjunct for assessing epidural functionality.

Proficiency-based progression training: implementing a novel approach to training for epidural analgesia in labour.

BACKGROUND: Epidural insertion is a challenging anaesthetic procedural skill to learn and may require up to 75 attempts to achieve competency. Proficiency-based progression (PbP) training based on unambiguously defined metrics was associated with a 53% reduction in epidural failure rate. The aim of this observational study was to examine the feasibility of implementation of innovative PbP training for labour epidural insertion performed by novices in a busy tertiary hospital. METHODS: All trainees who were scheduled to commence their obstetric anaesthesia training were invited to participate. Novices undertook intensive PbP training with one-to-one supervision by an anaesthetist trained in PbP. Trainees proceeded to the clinical phase only after attaining the pre-defined proficiency benchmark. All subsequent attempts at labour epidural catheter placement were evaluated. RESULTS: All 12 novice trainees who were scheduled for their initial exposure to obstetric anaesthesia completed PbP training in epidural catheter insertion successfully. The average duration of the training courses was 70 (SD 11) min. Trainee characteristics were broadly similar. They performed a total of 180 labour epidural catheter placements with an overall epidural failure rate of 12.2% (22/180). The proportion of supervisor takeover was 6% (11/179). The incidence of complications was 4% (8/180) and difficulty in epidural catheter insertion due to patient factors was 16% (29/180). Patient satisfaction rates were 80% (satisfied or very satisfied), with 20% unsatisfied with their experience of epidural insertion. CONCLUSION: In our experience, PbP training in epidural placement is feasible within existing departmental resources in a busy tertiary teaching hospital setting.

Why epidurals do not always work.

The overwhelming majority of epidural catheters placed for labor provide satisfactory analgesia. There are, however, times when the catheter is not sited within the epidural space correctly, the patient's neuraxial anatomy is problematic, or a patient's labor progresses more quickly than expected by the anesthesiologist, and the epidural block does not set up on time. In this article, the basics of neuraxial labor analgesia, the causes of its failure, and the strategies anesthesiologists employ to rescue poorly functioning catheters are reviewed.