Ex vivo animal-model assessment of a non-invasive system for loss of resistance detection during epidural blockade

FBG-Based Soft System for Assisted Epidural Anesthesia: Design Optimization and Clinical Assessment

Fiber Bragg grating sensors (FBGs) are considered a valid sensing solution for a variety of medical applications. The last decade witnessed the exploitation of these sensors in applications ranging from minimally invasive surgery to biomechanics and monitoring physiological parameters. Recently, preliminary studies investigated the potential impact of FBGs in the management of epidural procedures by detecting when the needle reaches the epidural space with the loss of resistance (LOR) technique. In this article, we propose a soft and flexible FBG-based system capable of detecting the LOR, we optimized the solution by considering different designs and materials, and we assessed the feasibility of the optimized soft sensor (SS) in clinical settings. The proposed SS addresses some of the open challenges in the use of a sensing solution during epidural punctures: it has high sensitivity, it is non-invasive, the sensing element does not need to be inserted within the needle, and the clinician can follow the standard clinical practice. Our analysis highlights how the material and the design impact the system response, and thus its performance in this scenario. We also demonstrated the system’s feasibility of detecting the LOR during epidural procedures.

Pressure monitoring devices may undetect epidural space: a report on the use of Compuflo® system for epidural injection

Lumbar epidural infiltration (EI) is a feasible procedure performed in pain therapy. Even though epidural analgesia is widely applied, it remains a blind technique, based on the operator's hand sensations, and it is associated with significant failure rate and several potential complications. Compuflo® (Compuflo, Milestone Scientific, Livingston, NJ) is a computerized injection pump which precisely detects the real time pressure at the tip of a Tuohy needle when placed in human tissues, thanks to a continuous fluid path. In our institution, we usually perform EI for chronic back pain guided by the Compuflo device, especially for expected difficult procedures. However, we report 6 false negative cases on a total number of 60 procedures in which the Compuflo system didn't meet the criteria of epidural space entry, even though the epidural space was actually reached. A mild pressure decrease (less than 50%) which lasted for more than 5 s was reported on the monitor, and the acoustic signal changed in a little bit lower sound, without a clear indication on stopping or not the needle advancement. This unspecific drop in monitored pressure gives false negatives using the Compuflo® system and may lead to excessive advancing of the needle. In conclusion, we consider the epidural pressure monitoring device Compuflo as a tool which may be able to ease the correct positioning of an epidural needle. The percentage of 10% false negative identifications of the epidural space in our case series however suggests more investigations on adequate or specific settings for this epidural system. In the meantime, in chronic pain patients, this anesthetic technique should only be used by experienced hands.

An Operator's Experience of the Loss-of-Resistance Technique in Epidural Injections: An Observational Study

Objective

A successful interlaminar epidural injection relies on correct epidural space needle placement. Most interlaminar epidural steroid injection (ESI) procedures are performed with a blind technique known as loss-of-resistance (LOR) without an imaging guide. This study aims to evaluate the success rate of the LOR technique in interlaminar epidural steroid injection under fluoroscopic control.

Materials and Methods

Patients who underwent interlaminar ESI owing to a history of at least 3 months of chronic low back and leg pain not responding to medications and physical therapies were included in an observational trial. Participants' age was between 27 and 88 years, and they had an American Society of Anesthesiologists physical status of I-III. The patients were placed in a prone position, and a Tuohy needle was introduced at the level of the L5-S1 interlaminar foramen using fluoroscopic image with an anteroposterior view. A lateral view was obtained when the LOR was felt. The procedures that achieved epidural spread by contrast agent in the first attempt were deemed successful. Those that did not and those that had false positive LOR were regarded as unsuccessful.

Results

Interlaminar ESİ was administered to 150 patients. The procedure's success and failure rates were 76% (114 patients) and 24% (36 patients), respectively. A total of 58.3% (21 patients) of patients who underwent an unsuccessful procedure had a false LOR, whereas 41.6% (15 patients) of the same group exhibited other causes. Sex, age, and body mass index (BMI) showed no statistical significance in terms of procedural success. There were statistically significant differences in the distance between the skin and the epidural space according to the body mass index groups.

Conclusion

The LOR technique identified the epidural space in most epidural procedures. However, in some cases, LOR was shown to be inadequate. Therefore, we suggest that the LOR technique must be supported by imaging such as fluoroscopy during epidural injections.