Ultrasound-guided peripheral nerve blockade

Peripheral nerve blocks for through-knee amputation in a patient on extracorporeal membrane oxygenation

A woman in her 40s with an ischaemic right lower limb, who was on extracorporeal membrane oxygenation (ECMO) following cardiopulmonary failure secondary to bilateral alveolar haemorrhage, was scheduled for through-knee amputation. She was under mechanical ventilation and continuous intravenous medications. Considering her significant comorbidities, peripheral nerve blocks were chosen for anaesthesia. Ultrasound-guided traditional nerve blockade techniques of the femoral and sciatic nerves were not possible because of the presence of an ECMO cannula, altered anatomy following previous surgery on the same side and inability to turn the patient to a lateral position. An ultrasound-guided trans fascia iliaca for femoral and anterior approach for sciatic were rather used to accomplish the nerve blockades. Surgery completed without any complications and with reduced postoperative outcomes such as opioid consumption, other morbidities and mortality. This report is unique as the literature on peripheral nerve block approaches for lower limb amputations in ECMO patients is sparse.

Efficacy and Safety of Ultrasound-Guided Radiofrequency Treatment for Chronic Pain in Patients with Knee Osteoarthritis: A Systematic Review and Meta-Analysis

Background

Knee osteoarthritis (KOA) is a common degenerative disease associated with joint dysfunction and pain. Ultrasound-guided radiofrequency (RF) may be a promising therapy in the treatment of chronic pain for KOA patients.

Objective

To evaluate the efficacy and safety of ultrasound-guided RF treatment for chronic pain in patients with KOA.

Design

A systematic review was conducted, and a meta-analysis was carried out when possible. Setting. We examined the studies evaluating the clinical efficiency of ultrasound-guided RF on chronic pain in KOA population.

Method

A systematic review for the efficacy and safety of ultrasound-guided RF treatment for pain management of KOA patients was carried out in PubMed, EMBASE, Cochrane Library, Web of Science, Wanfang Data, and China National Knowledge Infrastructure (CNKI) from the date of inception to February 2020, and a meta-analysis was conducted. The primary outcomes of pain intensity (visual analogue scale or numerical rating scale) and knee function [the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)] were evaluated from baseline to various follow-up times by random-effects model. Heterogeneity was assessed by I ² statistic and the potential sources of heterogeneity by subgroup and metaregression analyses, respectively.

Results

Eight publications with 256 patients were included in the meta-analysis. RF could relieve pain with -4.196 of pooled mean difference and improve knee function by decreasing 23.155 points in WOMAC. Three patients had ecchymosis, two with hypoesthesia and one with numbness after the procedure, and improved within 6 months. Furthermore, study design and treatment target were the sources of heterogeneity by subgroup and metaregression analyses, accounting for 37% and 74% of variances, respectively. Target of genicular nerve achieved better pain relief than intra-articular or sciatic nerve. Sensitivity analysis showed that removal of any single study was unlikely to overturn the findings. Limitations. There were some limitations in the study. Firstly, the small number of relevant studies limited the confidence level of the meta-analysis. Also, the significant heterogeneity may not be explained due to the limited data. Secondly, the direct comparison of two different guidance methods (ultrasound vs. fluoroscopy) for RF therapy is lacking. In addition, the outcomes were blindly assessed in the meta-analysis from all studies according to evaluation of bias, which could affect the reality of the data. Finally, most of the studies only provided short follow-up times, so we could not analyze the long-term effectiveness of ultrasound-guided RF in the treatment of patients with KOA.

Conclusions

Ultrasonography is an effective, safe, nonradiative, and easily applicable guidance method for RF in pain relief and functional improvement in KOA patients.

[Regional anesthesia in daily clinical practice: an economic analysis based on case vignettes]

BACKGROUND

The economic effect is a crucial aspect of every medical procedure. This article analyzes the economic implications of various methods in anesthesia based on three case vignettes.

METHODS

The management of anesthesia of a forearm fracture with sufficient brachial plexus blockade, general anesthesia and insufficient brachial plexus blockade with subsequent general anesthesia was analyzed with respect to the relevant cost factors (personnel costs, durables, consumables, fixed assets costs, anesthesia-related overhead costs).

RESULTS

Sufficient regional anesthesia was the least expensive method for a forearm fracture with 324.26 €, followed by general anesthesia with 399.18 € (+23% compared with regional anesthesia). Insufficient regional anesthesia was most the expensive method, which necessitated an additional general anesthesia (482.55 €, +49% compared with sufficient regional anesthesia).

CONCLUSION

Even considering that this cost analysis was calculated based on data from only one medical institution (General Hospital of Vienna, Medical University of Vienna), regional anesthesia appeared to be cost efficient compared with other anesthesia procedures. Main cost drivers in this example were personnel costs.

Resiniferatoxin for Pain Treatment: An Interventional Approach to Personalized Pain Medicine

This review examines existing preclinical and clinical studies related to resiniferatoxin (RTX) and its potential uses in pain treatment. Like capsaicin, RTX is a vanilloid receptor (TRPV1) agonist, only more potent. This increased potency confers both quantitative and qualitative advantages in terms of drug action on the TRPV1 containing nerve terminal, which result in an increased efficacy and a long duration of action. RTX can be delivered by a central route of administration through injection into the subarachnoid space around the lumbosacral spinal cord. It can also be administered peripherally into a region of skin or deep tissue where primary afferents nerves terminate, or directly into a nerve trunk or a dorsal root ganglion. The central route is currently being evaluated as a treatment for intractable pain in patients with advanced cancer. Peripheral administration offers the possibility to treat a wide diversity of pain problems because of the ability to bring the treatment to the site of the pain (the peripheral generator). While not all pain disorders are appropriate for RTX, tailoring treatment to an individual patient's needs via a selective and local intervention that chemically targets a specific population of nerve terminals provides a new capability for pain therapy and a simplified and effective approach to personalized pain medicine.

High or low current threshold for nerve stimulation for regional anaesthesia

BACKGROUND

The purpose of this study was to determine whether the application of high stimulation current thresholds (SCT) leads to a distant needle to nerve proximity (NNP) compared with low SCT during nerve localization for regional anaesthesia in pigs.

METHODS

A minimal motor response to the stimulation of femoral or brachial plexus nerves in 16 anaesthetized pigs was triggered either by a minimal SCT of a low (0.01-0.3 mA) or a high (0.8-1.0 mA) current in a random order. After eliciting a motor response with a predetermined SCT, synthetic resin was injected via the needle. After postmortem dissection of the injection site, the localization of the resin deposition was determined verifying the final position of the needle tip. Depending on the proximity of resin deposition to the nerve epineurium, the needle tip placement was considered either as a close or a distant NNP.

RESULTS

A total of 235 punctures were performed. Ninety-one punctures were carried out with low SCT and 92 with a high SCT. Fifty-two punctures served as a control (1.8-2.0 mA). All injectates following both high or low SCT were considered 'close needle tip to nerve placement', whereas 27 of 52 injectates of the control group appeared distant to nerve epineurium.

CONCLUSION

Regardless of the applied SCT, i.e. high or low, all resin deposition was found adjacent to nerve epineurium. These findings suggest that high and low SCT result in equivalent needle tip localization in pigs.

Accuracy of ultrasound guided injections in the foot and ankle

BACKGROUND

Ultrasonography is an emerging imaging modality which affords dynamic, real-time, cost-effective and surgeon controlled visualization of the foot and ankle. The purpose of this study was to evaluate the accuracy of ultrasound guided injections for common injection sites in the foot and ankle.

MATERIALS AND METHODS

In 10 fresh cadaver feet, ultrasound guidance was utilized to inject a methylene blue-saline mixture into (1) the first MTP joint, (2) the second MTP joint, (3) the tibiotalar joint, (4) the Achilles peritendinous space, (5) the flexor hallucis longus sheath, (6) the posterior tibial tendon sheath, and (7) the subtalar joint. Dissection was then undertaken to assess injection accuracy.

RESULTS

Ultrasound guidance allowed the avoidance of intervening neurovascular and tendinous structures. Ultrasound guided MTP, ankle, Achilles, PTT and FHL peritendinous injections were 100% accurate. Ultrasound guided subtalar injection was 90% accurate.

CONCLUSION

Ultrasound appears to be a highly accurate method of localizing injections into a variety of locations in the foot and ankle.

CLINICAL RELEVANCE

Ultrasound's ability to display soft-tissue structures may be an advantage over blind injection and fluoroscopic injection techniques.