Peripheral nerve stimulation through a 'dry' peripheral nerve catheter for shoulder analgesia: a case report.

Revision shoulder surgery can pose significant analgesic challenges as locoregional blocks are often avoided to enable early recognition of iatrogenic nerve injuries. Our case describes the utilisation of pre-operative and intra-operative low-frequency percutaneous peripheral nerve stimulation via a 'dry' interscalene catheter, inserted pre-operatively for a patient presenting for revision total shoulder arthroplasty who was experiencing significant shoulder joint pain despite a prior total shoulder arthroplasty. The clinical considerations and safety aspects are discussed further.

Pain management using a novel hybrid technique of perineural stimulation combined with regional anaesthesia through a stimulating perineural catheter for below knee amputation.

Pain after amputation can be difficult to manage due to its complex aetiology. A multimodal approach to analgesia, including regional anaesthetic techniques, is advised. However, optimal pain management cannot always be achieved, and high doses of opioid analgesics may contribute to adverse effects. We describe the management of an elderly patient with significant co-morbidities undergoing below knee amputation. Pre-operatively, a popliteal sciatic stimulating perineural catheter and a femoral non-stimulating perineural catheter were placed. When pain control was suboptimal on the first postoperative day, a combination of local anaesthetic and a brief period of peripheral nerve stimulation through the sciatic stimulating perineural catheter was used to augment pain control, thereby avoiding additional opioid use. Although nerve stimulation utilising specialised equipment, such as percutaneous stimulator electrodes, has been previously described in acute pain medicine, we demonstrate the use of a novel hybrid technique which combines nerve stimulation through a perineural catheter and local anaesthetic. Further research is warranted to explore the utility of this neuromodulation technique in clinical practice.

Neuraxial anaesthesia and peripheral nerve blocks during the COVID-19 pandemic: a literature review and practice recommendations.

Coronavirus disease 2019 (COVID-19) has had a significant impact on global healthcare services. In an attempt to limit the spread of infection and to preserve healthcare resources, one commonly used strategy has been to postpone elective surgery, whilst maintaining the provision of anaesthetic care for urgent and emergency surgery. General anaesthesia with airway intervention leads to aerosol generation, which increases the risk of COVID-19 contamination in operating rooms and significantly exposes the healthcare teams to COVID-19 infection during both tracheal intubation and extubation. Therefore, the provision of regional anaesthesia may be key during this pandemic, as it may reduce the need for general anaesthesia and the associated risk from aerosol-generating procedures. However, guidelines on the safe performance of regional anaesthesia in light of the COVID-19 pandemic are limited. The goal of this review is to provide up-to-date, evidence-based recommendations or expert opinion when evidence is limited, for performing regional anaesthesia procedures in patients with suspected or confirmed COVID-19 infection. These recommendations focus on seven specific domains including: planning of resources and staffing; modifying the clinical environment; preparing equipment, supplies and drugs; selecting appropriate personal protective equipment; providing adequate oxygen therapy; assessing for and safely performing regional anaesthesia procedures; and monitoring during the conduct of anaesthesia and post-anaesthetic care. Implicit in these recommendations is preserving patient safety whilst protecting healthcare providers from possible exposure.

Association of obesity with failure of ultrasound-guided axillary brachial plexus block: a two-centre, prospective, observational, cohort study.

The objective of this study was to evaluate whether the failure rate of ultrasound-guided axillary brachial plexus block is similar in obese patients compared with non-obese patients when performed as the primary anaesthetic technique. We recruited 105 obese (body mass index ≥ 30 kg.m-2 ) and 144 non-obese patients to this prospective, observational, cohort study conducted at two Canadian centres. A perineural technique of axillary brachial plexus block was performed using 30 ml ropivacaine 0.5% under real-time ultrasound guidance. Sensory and motor block assessment was carried out every 5 min until 30 min after block completion in all four terminal nerve distributions (radial, median, ulnar and musculocutaneous nerve). A composite score consisting of three sensory points and three motor points was used for assessment in each nerve distribution. A failed block was defined as a score of less than 14 points out of a possible 16 points, or a sensory block score less than 7 out of 8 points 30 min after block completion. Thirty minutes after block completion, obese patients had a higher failure rate of 33.7% (34/101) compared with 17.8% (24/135) for non-obese patients, with a failure rate difference (95%CI) of 15.9% (6.4-27.1%) between the groups. The median (IQR [range]) time to achieve a successful block in obese patients was 25 (20-30 [5-30]) min, compared with non-obese patients at 20 (15-30 [5-30]) min (p = 0.003). Despite a higher sensory-motor failure rate as per the composite score, the axillary brachial plexus block provided adequate surgical anaesthesia as indicated by a low need for conversion to general anaesthetic in obese (8.6%) and non-obese patients (7.0%; p = 0.656). This study showed that despite ultrasound guidance, obese patients had a slower onset time and higher axillary brachial plexus block failure rate at 30 min compared with non-obese patients.

Comparative evaluation of the visibility and block characteristics of a stimulating needle and catheter vs an echogenic needle and catheter for sciatic nerve block with a low-frequency ultrasound probe.

BACKGROUND: Clear visibility of the needle and catheter tip is desirable to perform safe and successful ultrasound-guided peripheral nerve blocks. This can be challenging with deeper blocks in obese patients. This study compared the visibility of echogenic and non-echogenic block needles and catheters in proximal sciatic blocks when performed with a low-frequency curved probe. METHODS: Seventy-eight patients undergoing total knee joint arthroplasty were randomized to receive an ultrasound-guided continuous sciatic nerve block using either a non-echogenic needle and stimulating catheter or an echogenic needle and echogenic non-stimulating catheter. Block needles in both groups were placed using both neurostimulation and ultrasound guidance, after which the catheter was positioned using either neurostimulation alone (Stimulating group) or imaging alone (Echogenic group). Three anaesthetists blinded to group allocation graded video clips recorded during the blocks for nerve, needle and catheter visibility. Performance characteristics and block parameters were also compared. RESULTS: No significant differences between the two groups were observed with regard to needle or catheter visibility (P=0.516). The Stimulating group required more needle redirections (P=0.009), had a longer procedure time [Echogenic median 274 s vs Stimulating 344 s (P=0.016)], and resulted in greater patient discomfort (P=0.012). There were no significant differences between the two groups in terms of block onset or completion time. CONCLUSIONS: Use of echogenic needles and catheters reduced procedure time and patient discomfort compared with a stimulating catheter system. There were no differences in the visibility scores of the two systems. CLINICAL TRIAL REGISTRATION: CTR Protocol ID: R-11-495, Clinical Trials.Gov ID: NCT 01492660.

Injectate spread following ultrasound-guided lateral to medial approach for dual transversus abdominis plane blocks.

BACKGROUND: Bilateral dual transversus abdominis plane (BD-TAP) injections were devised to cover the T7-8 and L1 dermatomes, which are usually spared with classical and mid-axillary TAP injections. The purpose of this study was to delineate the vertical and lateral extent of injectate spread following a lateral to medial approach for TAP injections in embalmed cadavers. METHODS: Ultrasound-guided subcostal and lateral TAP injections were performed on nine embalmed cadavers using 30 ml of 0.5% methylcellulose (20 ml for subcostal and 10 ml for lateral injections) with a 12-cm Tuohy needle in the first six cadavers (nine hemi-abdomens). Vertical extent and the medial to lateral extent of the dye spread were recorded after dissections of the abdominal wall. In a pilot of three cadavers not receiving TAP injections, anatomical impediments to proximal injectate spread were explored separately. RESULTS: The vertical spread of injectate was T7-L1 (n = 2/9), T8-L1 (n = 5/9) and T9-L1 (n = 2/9). None of the TAP injections extended beyond the mid-axillary line. No anatomical impediments for the flow of injectate to the T7 or T8 intercostal nerves were found at the level of the interdigitations of the transversus abdominis muscle and diaphragm. CONCLUSION: A lateral to medial approach for TAP injection resulted in spread of the injectate ranging from T7/8-L1 dermatomes in the majority of the hemi-abdomens. Subcostal and lateral TAP injections do not cover the lateral cutaneous branches of the segmental nerves.