Eyes on the needle: Identification and confirmation of the epidural space

Value of CT in targeted CT-guided epidural blood patching: Predictors for successful epidural punctures

BACKGROUND AND PURPOSE

Differentiating epidural from intrathecal punctures before computed tomography (CT)-guided epidural blood patching (EBP) is subjective, relying on operator experience. This study aimed to investigate CT findings for epidural and intrathecal punctures and identify reliable predictors for successful epidural punctures before targeted CT-guided EBP.

MATERIALS AND METHODS

We included 65 patients with low-cerebrospinal fluid (CSF)-pressure headache receiving targeted CT-guided EBP between January 2021 and October 2022 in this retrospective study. We analyzed clinical data, technical information, and CT features before EBP. Fisher's exact test was used for discrete variables, while Mann-Whitney U test was used for continuous variables. Positive (PLR) and negative likelihood ratios (NLR) were calculated to identify predictors for confirming epidural punctures.

RESULTS

We confirmed 43 patients as epidural punctures and 22 patients as intrathecal punctures. Before contrast injection, epidural fat at the needle tip in the epidural group was higher than the intrathecal group (37.2 % [16/43] vs. 4.5 % [1/22], p = 0.006). After contrast injection, the "contrast-needle tip connection" sign was mostly observed in the epidural group than the intrathecal group (95.3 % [41/43] vs. 9.1 % [2/22], p < 0.001). Additionally, the epidural group had significantly higher boomerang-shaped contrast morphology than the intrathecal group (65.1 % [28/43] vs. 9.1 % [2/22], p < 0.001). The "contrast-needle tip connection" sign had the highest PLR (10.49) and lowest NLR (0.05).

CONCLUSION

Identifying epidural fat at the needle tip, "contrast-needle tip connection" sign, and boomerang-shaped contrast morphology on CT scans are useful for confirming proper placement of the needle tip within the epidural space.

AutoInFocus, a new paradigm for ultrasound-guided spine intervention: a multi-platform validation study

PURPOSE

Ultrasound-guided spine interventions often suffer from the insufficient visualization of key anatomical structures due to the complex shapes of the self-shadowing vertebrae. Therefore, we propose an ultrasound imaging paradigm, AutoInFocus (automatic insonification optimization with controlled ultrasound), to improve the key structure visibility.

METHODS

A phased-array probe is used in conjunction with a motion platform to image a controlled workspace, and the resulting images from multiple insonification angles are combined to reveal the target anatomy. This idea is first evaluated in simulation and then realized as a robotic platform and a miniaturized patch device. A spine phantom (CIRS) and its CT scan were used in the evaluation experiments to quantitatively and qualitatively analyze the advantages of the proposed method over the traditional approach.

RESULTS

We showed in simulation that the proposed system setup increased the visibility of interspinous space boundary, a key feature for lumbar puncture guidance, from 44.13 to 67.73% on average, and the 3D spine surface coverage from 14.31 to 35.87%, compared to traditional imaging setup. We also demonstrated the feasibility of both robotic and patch-based realizations in a spine phantom study.

CONCLUSION

This work lays the foundation for a new imaging paradigm that leverages redundant and controlled insonification to allow for imaging optimization of the complex vertebrae anatomy, making it possible for high-quality visualization of key anatomies during ultrasound-guided spine interventions.

Alternative Technique for Difficult Epidural Needle Placement: A Case Report

A central neuraxial block may be difficult to perform in elderly patients with lumbar spine deformities, calcified ligaments, and narrowing of the epidural space. We report a case of difficult epidural needle placement in an elderly patient scheduled for bilateral total knee replacement (TKR). We attempted epidural needle placement many times without success. However, when a modified technique was used, the epidural space was identified easily and confirmed, the epidural catheter was inserted and fixed, and the postoperative epidural analgesia was effective.

The Development of a Novel Device Based on Loss of Guidewire Resistance to Identify Epidural Space in a Porcine Model

Background

The application of additive manufacturing (3D printing) has been recently expanded to various medical fields. The new technique named loss of guide wire resistance (LOGR) was developed via 3D printing for the detection of epidural space using a guide wire instead of air or saline used in the loss of resistance (LOR) technique.

Methods

The prototype model of epidural space finder consists of a polyactic acid (PLA) or a resin. It was manufactured with 3D printing. Biocompatibility test (eluate and sterility tests) was performed in both products. The advantage of the newly developed device was compared with conventional loss of resistance (LOR) technique in a porcine model.

Results

Eluate and sterility tests revealed that the PLA was more biocompatible than the resin. The LOGR technique facilitated rapid access to epidural space compared with the LOR technique (41.64 ± 32.18 vs. 92.28 ± 61.46 seconds, N = 14, p=0.0102, paired sample t-test), without any differences in success rate (87.5%).

Conclusion

We conclude that LOGR technique is comparable to LOR technique to access the epidural space, although the advantage of either technique in terms of complications such as dural puncture or epidural hematoma is unknown. We demonstrated the potential benefit of 3D printer for the development of a new medical device for anesthesia.

The impact of fluoroscopic confirmation of thoracic imaging on accuracy of thoracic epidural catheter placement on postoperative pain control

Background

Thoracic epidural analgesia (TEA) provides superior postoperative pain control compared to parenteral opioids after major thoracic and abdominal surgeries. However, some studies with respect to benefits of continuous TEA have shown mixed results. The purpose of this study was to determine the rate of successful TEA catheter insertion into the epidural space using contrast fluoroscopy and the impact of placement location on postoperative analgesia and opioid use.

Patients and methods

After Advocate health care institutional review board approval, we conducted a prospective, open-label, single intervention study on patients undergoing thoracic or upper abdominal surgery. A thoracic paramedian epidural approach and a loss of resistance to saline technique were used to place an epidural catheter above the T11 level and fluoroscopic images with injected contrast were taken to locate the catheter tip in the epidural space.

Results

Twenty-five subjects were included in the study, of which 3 catheters (12%) were not identified as being in the epidural space. We found an average difference of 1.5 vertebral levels between clinical and radiological assessments of catheter tips. Thirteen catheters (52%) were more than 1 vertebral level away from the clinically assessed level. No significant difference was found in the pain scores at 1, 24, and 48 hours after surgery between patients with correct versus incorrect catheter placement. Less opioids were used in the correct catheter placement group at 24 hours (256 morphine milligram equivalent [MME] vs 201 MME) and at 48 hours after surgery (250 MME vs 173 MME), but it was not statistically significant (p=0.149 and p=0.068, respectively).

Conclusion

Improvement in assuring success in the technique for TEA catheter placement following major thoracic or upper abdominal surgery exists, for which contrast-enhanced fluoroscopy might be a promising solution.

Smart Optical Catheters for Epidurals

Placing the needle inside the epidural space for locoregional anesthesia is a challenging procedure, which even today is left to the expertise of the operator. Recently, we have demonstrated that the use of optically sensorized needles significantly improves the effectiveness of this procedure. Here, we propose an optimized configuration, where the optical fiber strain sensor is directly integrated inside the epidural catheter. The new design allows the solving of the biocompatibility issues and increases the versatility of the former configuration. Through an in vivo study carried out on a porcine model, we confirm the reliability of our approach, which also opens the way to catheter monitoring during insertion inside biological spaces.