BackgroundThe addition of intravenous dexamethasone can significantly prolong analgesia and reduce opioid-related side effects after brachial plexus blockade, but the most effective administration time is yet unknown. The objective of this study is to determine if the timing of administration of dexamethasone affects the duration of analgesia after supraclavicular brachial plexus block.MethodsThis is a double-blind, placebo-controlled, randomized trial performed at a single-center, tertiary academic health sciences center. Patients were randomly assigned to one of four treatment groups to receive dexamethasone 8 mg intravenously (or normal saline infusions) at 1-hour preblock, at the time of the block, and 1 or 2 hours postblock.Results197 patients were randomized and received the intervention (in one of four treatment groups) between January 2018 and November 2023. 39 patients were excluded due to loss to follow-up and unavailability of primary outcome data. The remaining 158 patients have complete data sets and were analyzed. The time to first reported pain was not significantly different between groups (p=0.904). Secondary outcomes including pain scores and opioid consumption, recovery scores and block recovery time did not vary significantly among groups up to 48 hours. Adverse effects such as postoperative neurological symptoms and nausea were similar across groups up to 3 months postoperatively.Conclusions and relevanceOur results suggest that perioperative administration of 8 mg of intravenous dexamethasone (from 1 hour prior and up to 2 hours postblock) provides similar duration of analgesia to administration at the time of brachial plexus block.Trial registration numberNCT03394820.

BACKGROUND:Hip fractures are a major global health issue with high mortality and morbidity, especially in older adults. One-year mortality post-surgery ranges from 22% to 36%, with many patients never regaining baseline mobility. While several predictors of mortality have been identified, their relative contribution to mortality risk within a unified survival prediction framework remains unclear. This study used machine learning to rank key perioperative predictors of mortality following hip fracture surgery. METHODS:Over 11,000 patients from the Australian and New Zealand Hip Fracture Registry were analyzed. Twenty demographic, clinical, and perioperative variables were assessed using a Random Survival Forest (RSF) model. Model performance was evaluated using the concordance index and Brier scores. Permutation-based feature importance ranked predictors according to their contribution to predictive performance for mortality risk. RESULTS:During the follow-up period (median 630 days), 31% of patients died. The RSF model performed well (test C index: 0.7305). The four most important predictors of mortality were American Society of Anesthesiologists (ASA) grade (importance score: 0.051), pre-existing dementia (0.036), age (0.019), and preadmission walking ability (0.016). Other factors like male sex (0.009) and acute hospital stay (0.006) had weaker associations with mortality prediction in this model. CONCLUSIONS:Machine learning identified ASA grade, dementia, age, and mobility as the top predictors of mortality after hip fracture surgery. RSF modeling offered strong performance and better interpretability than traditional methods. These findings support individualized stratification to inform perioperative discussions and goals-of-care planning in this high-risk population.

Background: Spinal anesthesia in older patients can be technically challenging due to degenerative spinal disease. The L5-S1 interspace often remains accessible and is a useful fallback; however, it has been associated with higher rates of therapeutic failure due to inadequate block height. Injection of hypobaric local anesthetic may promote cranial intrathecal spread and address this limitation. We investigated this by evaluating the efficacy and block characteristics of low-dose hypobaric bupivacaine injected at the L5-S1 level in a prospective observational study.Methods: Fifty-four patients undergoing elective total hip or knee arthroplasty received ultrasound-assisted spinal anesthesia at L5–S1 with 10 mg of 0.33% hypobaric bupivacaine. The primary outcome was surgical completion without conversion to general anesthesia, supplemental opioids, or local anesthetic infiltration. Secondary outcomes included adequate anesthesia for surgical incision, block pharmacodynamics, hemodynamic stability, adverse effects, patient satisfaction, and surgeon-perceived quality of anesthesia.Results: Surgical completion without anesthetic supplementation was successful in 50 patients (92.6%, 95% CI [82.1–97.8]). Adequate anesthesia for surgical incision was achieved in 53 patients (98.2%, 95% CI [90.1–100]). Four patients required supplemental opioids: one for surgical incision, and three for surgical completion following prolonged injection-to-incision intervals (47–59 minutes) due to unanticipated delays in operating room readiness. No patients required conversion to general anesthesia. Full motor recovery occurred within 198 ± 53 minutes. Patient and surgeon satisfaction with quality of anesthesia was high.Conclusions: Hypobaric 0.33% bupivacaine injected at L5–S1 may be a useful fallback option in lower-extremity arthroplasty if challenging spinal anatomy renders other interspaces inaccessible.

Digital twins are virtual representations of real-world objects or systems that can be used to model and predict their behavior in response to various scenarios. Digital twins are becoming increasingly relevant in planning medical care, e.g. , in neurology, cardiology, and oncology. They also hold significant promise for advancing anesthesia and critical care medicine by tailoring interventions to a patient’s physiological data, imaging, monitoring streams, and clinical history rather than relying on population averages, ultimately helping to enhance clinical decision‑making and improve health outcomes. However, their adoption raises concerns over data privacy, dependency on technology, and cost. This article explores the concept of digital twins and their potential applications, benefits, and challenges within the fields of anesthesia and critical care medicine.

INTRODUCTION:Certain specialized hand surgery procedures benefit from intraoperative motor testing and patient-demonstrated active range of motion. This requires motor-sparing regional anesthesia of the hand using targeted ultrasound-guided nerve blocks in the forearm. OBJECTIVE:We present a joint surgical and anesthetic perspective covering the utility and indications for motor-sparing forearm blocks. We describe the anatomical principles and technical details of their performance and discuss other considerations for surgical and anesthetic success. FINDINGS:Patient selection and expectation setting are critical for success. Four terminal nerves must be blocked: median nerve, ulnar nerve, superficial radial nerve, and lateral antebrachial cutaneous nerve. These must be targeted distal to origin of motor branches to extrinsic muscles of the hand, with precise deposition of limited volumes of local anesthetic. The nerves can be readily identified with ultrasound imaging by their predictable anatomical relationship to specific muscles and blood vessels. CONCLUSION:Intraoperative motor testing in complex surgical repair of the hand is associated with improved surgical outcomes, as well as greater patient satisfaction. Ultrasound-guided motor-sparing forearm blocks are a safe and effective method for achieving surgical anesthesia and optimal operating conditions in this context.

The sacral erector spinae plane (S-ESP) block is a recently described regional anesthesia technique that targets sacral dermatomes. First reported in 2019, it has been increasingly explored as a potential option for perioperative analgesia in surgeries involving the sacral, perineal, and pelvic regions. This review aims to summarize and critically appraise the current anatomical, technical, and clinical evidence on the S-ESP block, outlining its mechanisms of action, approaches, efficacy, and safety while identifying research gaps and future directions. We performed a narrative review integrating anatomical descriptions, sonographic techniques, and available randomized controlled trials (RCTs) evaluating the clinical efficacy of the S-ESP block. A comprehensive literature search was conducted in PubMed, Embase, Scopus, Web of Science, and Ovid (Medline) from inception to July 21, 2025, without language or date restrictions. Full-text RCTs investigating ultrasound-guided S-ESP blocks for perioperative analgesia were reviewed and summarized. Fourteen RCTs (published 2023–2025) were included, conducted predominantly in Turkey, India, and Egypt, spanning pediatric (6 months to 12 years) and adult populations undergoing circumcision, hypospadias repair, hemorrhoidectomy, pilonidal sinus surgery, transurethral resection of prostate, lumbar discectomy, and total hip arthroplasty. Most pediatric trials compared midline S-ESP with caudal or penile blocks, generally demonstrating a longer time to first rescue analgesia and reduced postoperative analgesic consumption, although one study reported a superior duration with caudal block. In adults, the S-ESP block consistently reduced pain scores and opioid requirements. Current evidence suggests that both midline and paramedian S-ESP techniques are technically feasible, appear safe in the short term, and provide clinically relevant postoperative analgesia in selected pediatric urogenital, adult anorectal, and orthopedic surgeries. However, heterogeneity in techniques, small single-center samples, and a narrow range of indications limit its generalizability. Large, multicenter RCTs with standardized protocols are needed to clarify the optimal approaches, dosing strategies, and comparative role of S-ESP block versus established neuraxial and peripheral techniques.

The pericapsular nerve group (PENG) block is a novel regional technique for hip analgesia. Traditionally, intrathecal morphine has been administered for analgesia in hip fracture surgery. Compared with intrathecal morphine, the PENG block may provide superior or equivalent pain score reduction with a more favourable side effect profile and superior patient satisfaction. This is a multicentre blinded randomised controlled trial (RCT) that is being conducted at present at two large teaching institutions in Australia. The pericapsular nerve group block (PENG block) shall be compared to low-dose intrathecal morphine for analgesic effect in elective total Hip arthroplasty via the direct anterior approach. Primary outcome shall be dynamic pain score evaluation at 3 and 24 h postoperatively. This is the protocol of our RCT which is currently in the early stages of active recruitment. Ethics approval was obtained from the Southern Area Local Health Network prior to recruitment of the first patient. This trial was prospectively registered prior to initiation on the Australian and New Zealand Clinical Trials Registry. Australian New Zealand Clinical Trial Registry, ACTRN12623001309673P, 15/12/23, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=386688 showOriginal=true isReview=true .

Since its description in 2016, the erector spinae plane block (ESPB) has become a widely employed regional anesthetic technique and kindled interest in a range of related techniques, collectively termed intertransverse process blocks. There has been ongoing controversy over mechanism of action of the ESPB, mainly due to incongruities between results of cutaneous sensory testing, clinical efficacy studies, and investigations into the neural structures that are reached by injected local anesthetic (LA). This paper reviews the spread of LA to the paravertebral and epidural space and the cutaneous anesthesia in ESPB, with specific emphasis on the dorsal root ganglion (DRG). We hypothesize that the DRG, due to its unique and complex microarchitecture, represents a key therapeutic target for modulation of nociceptive signaling in regional anesthesia. This paper discusses how the anatomical and physiological characteristics of the DRG may be one of the factors underpinning the clinical analgesia observed in ESPB and other intertransverse process blocks.

Ni Eochagain and colleagues report that programmed intermittent bolus and continuous infusion regimens in continuous erector spinae plane (ESP) block catheters produced similar quality of recovery (QoR-15) scores, pain scores, and use of rescue opioids after video-assisted thoracic surgery. This is a reassuring finding for practitioners without access to pumps with programmed intermittent bolus functionality. Nevertheless, it remains plausible that the benefit of one regimen over another might vary depending on the specific infusion parameters. There continues to be scope for research into optimising programmed intermittent bolus delivery and dosing regimens and identifying the most appropriate clinical applications for this mode of infusion.

Background Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks. Methods We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as >= 75% agreement and weak consensus as 50%-74% agreement. Results A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research. Conclusions We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.

Same-day mobilization and early hospital discharge is increasingly emphasized following hip and knee arthroplasty. One challenge of spinal anesthesia in this setting is achieving adequate block height while avoiding excessively large local anesthetic doses and prolonged motor and sensory blockade. Using a hypobaric local anesthetic solution is one potential strategy, as its intrathecal distribution can be reliably manipulated by patient positioning to achieve adequate block height independent of dose. We conducted a prospective observational study to determine the clinical characteristics of spinal anesthesia with low-dose hypobaric mepivacaine and bupivacaine in patients undergoing hip and knee arthroplasty. Thirty patients scheduled for same-day discharge received 51 mg of hypobaric 1.5

PurposeConcerns around delayed emergence and opioid-induced ventilatory impairment in bariatric surgery can lead to intraoperative reliance on short-acting opioids and avoidance of long-acting analgesics with potential sedative effects. Nevertheless, an overly-conservative intraoperative analgesic strategy may result in significant pain at emergence and higher opioid requirements in later phases of care. We sought to establish the pattern of intraoperative analgesic use in bariatric surgical patients as well as their postoperative pain trajectory and opioid requirements.MethodsWe undertook a single-centre historical cohort study. We explored associations between intraoperative analgesic interventions and pain scores and opioid requirements in postanesthesia care units (PACUs), and associations between the quality of analgesia at emergence and subsequent pain and patient-centred recovery outcomes.ResultsWe extracted perioperative data for 939 patients who underwent bariatric metabolic surgery between January 2018 and October 2019. Only 39% of patients received long-acting opioids intraoperatively and there was minimal use of nonopioid analgesic adjuncts. Nearly 80% of patients reported moderate-to-severe pain on PACU arrival; 97% of patients received intravenous opioids for rescue analgesia (mean dose, 31 mg oral morphine equivalents). Lower pain scores at PACU admission and discharge were associated with subsequent lower inpatient pain scores, lower opioid requirements, shorter time to ambulation, and shorter length of hospital stay.ConclusionIn bariatric surgical patients, effective intraoperative analgesic strategies that improve early pain control may have an impact on recovery and pain experience. Judicious use of intraoperative opioids coupled with opioid-sparing multimodal analgesic techniques should be considered and balanced against concerns regarding opioid-related adverse effects in this patient population. ObjectifLes pré occupations concernant l'é mergence retardé e et l'insuffisance ventilatoire induite par les opioï des en chirurgie bariatrique peuvent conduire à une dé pendance peropé ratoire aux opioï des à courte duré e d'action et à l'é vitement des analgé siques à action prolongé e ayant des effets sé datifs potentiels. Né anmoins, une straté gie analgé sique peropé ratoire trop conservatrice peut entraî ner une douleur importante à l'é mergence et des besoins en opioï des plus é levé s dans les phases ulté rieures des soins. Nous avons cherché à é tablir le profil d'utilisation des analgé siques peropé ratoires chez les patientes en chirurgie bariatrique ainsi que leur trajectoire de douleur postopé ratoire et leurs besoins en opioï des.Mé thodeNous avons mené une é tude de cohorte historique monocentrique. Nous avons exploré les associations entre les interventions analgé siques peropé ratoires et les scores de douleur et les besoins en opioï des dans les salles de ré veil, ainsi que les associations entre la qualité de l'analgé sie à l'é mergence et la douleur ulté rieure et les ré sultats de ré cupé ration centré s sur les patientes.Ré sultatsNous avons extrait les donné es pé riopé ratoires de 939 patientes ayant bé né ficié d'une chirurgie mé tabolique bariatrique entre janvier 2018 et octobre 2019. Seulement 39 % des patientes ont reç u des opioï des à action prolongé e en peropé ratoire et l'utilisation d'analgé siques auxiliaires non opioï des a é té minimale. Prè s de 80 % des patientes ont signalé une douleur modé ré e à sé vè re à leur arrivé e en salle de ré veil; 97 % des patientes ont reç u des opioï des par voie intraveineuse pour une analgé sie de secours (dose moyenne, é quivalents de morphine orale de 31 mg). Des scores de douleur plus faibles à l'admission et à la sortie de la salle de ré veil ont é té associé s à des scores de douleur plus faibles en milieu hospitalier, à des besoins en opioï des plus faibles, à un dé lai avant l'ambulation plus court et à une duré e d'hospitalisation plus courte.ConclusionChez la patientè le de chirurgie bariatrique, des straté gies analgé siques peropé ratoires efficaces qui amé liorent le contrô le pré coce de la douleur peuvent avoir un impact sur la ré cupé ration et l'expé rience de la douleur. L'utilisation judicieuse d'opioï des peropé ratoires associé e à des techniques analgé siques multimodales d'é pargne opioï de doit ê tre envisagé e et mise en balance avec les pré occupations concernant les effets indé sirables lié s aux opioï des dans cette population de patientes.

Online video sharing platforms like YouTube (Google LLC, San Bruno, CA, USA) have become a substantial source of health information. We sought to conduct a systematic review of studies assessing the overall quality of perioperative anesthesia videos on YouTube. We searched Embase, MEDLINE, and Ovid for articles published from database inception to 1 May 2023. We included primary studies evaluating YouTube videos as a source of information regarding perioperative anesthesia. We excluded studies not published in English and studies assessing acute or chronic pain. Studies were screened and data were extracted in duplicate by two reviewers. We appraised the quality of studies according to the social media framework published in the literature. We used descriptive statistics to report the results using mean, standard deviation, range, and n/total N ( https://osf.io/ajse9 ); first posted, 1 May 2023.

Background The effects of spinal versus general anesthesia on long-term outcomes have not been well studied. This study tested the hypothesis that spinal anesthesia is associated with better long-term survival and functional recovery than general anesthesia. Methods A prespecified analysis was conducted of long-term outcomes of a completed randomized superiority trial that compared spinal anesthesia versus general anesthesia for hip fracture repair. Participants included previously ambulatory patients 50 yr of age or older at 46 U.S. and Canadian hospitals. Patients were randomized 1:1 to spinal or general anesthesia, stratified by sex, fracture type, and study site. Outcome assessors and investigators involved in the data analysis were masked to the treatment arm. Outcomes included survival at up to 365 days after randomization (primary); recovery of ambulation among 365-day survivors; and composite endpoints for death or new inability to ambulate and death or new nursing home residence at 365 days. Patients were included in the analysis as randomized. Results A total of 1,600 patients were enrolled between February 12, 2016, and February 18, 2021; 795 were assigned to spinal anesthesia, and 805 were assigned to general anesthesia. Among 1,599 patients who underwent surgery, vital status information at or beyond the final study interview (conducted at approximately 365 days after randomization) was available for 1,427 (89.2%). Survival did not differ by treatment arm; at 365 days after randomization, there were 98 deaths in patients assigned to spinal anesthesia versus 92 deaths in patients assigned to general anesthesia (hazard ratio, 1.08; 95% CI, 0.81 to 1.44, P = 0.59). Recovery of ambulation among patients who survived a year did not differ by type of anesthesia (adjusted odds ratio for spinal vs. general, 0.87; 95% CI, 0.67 to 1.14; P = 0.31). Other outcomes did not differ by treatment arm. Conclusions Long-term outcomes were similar with spinal versus general anesthesia. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

BACKGROUND:Structured training in regional anaesthesia includes pretraining on simulation-based educational platforms to establish a safe and controlled learning environment before learners are provided clinical exposure in an apprenticeship model. This scoping review was designed to appraise the educational outcomes of current simulation-based educational modalities in regional anaesthesia. METHODS:This review conformed to PRISMA-ScR guidelines. Relevant articles were searched in PubMed, Scopus, Google Scholar, Web of Science, and EMBASE with no date restrictions, until November 2023. Studies included randomised controlled trials, pre-post intervention, time series, case control, case series, and longitudinal studies, with no restrictions to settings, language or ethnic groups. The Kirkpatrick framework was applied for extraction of educational outcomes. RESULTS:We included 28 studies, ranging from 2009 to 2023, of which 46.4% were randomised controlled trials. The majority of the target population was identified as trainees or residents (46.4%). Higher order educational outcomes that appraised translation to real clinical contexts (Kirkpatrick 3 and above) were reported in 12 studies (42.9%). Two studies demonstrated translational patient outcomes (Level 4) with reduced incidence of paraesthesia and clinical complications. The majority of studies appraised Level 3 outcomes of performance improvements in either laboratory simulation contexts (42.9%) or demonstration of clinical performance improvements in regional anaesthesia (39.3%). CONCLUSIONS:There was significant heterogeneity in the types of simulation modalities used, teaching interventions applied, study methodologies, assessment tools, and outcome measures studied. When improvisations were made to regional anaesthesia simulation platforms (hybrid simulation), there were sustained educational improvements beyond 6 months. Newer technology-enhanced innovations such as virtual, augmented, and mixed reality simulations are evolving, with early reports of educational effectiveness.

BackgroundRegional anaesthesia use is growing worldwide, and there is an increasing emphasis on research in regional anaesthesia to improve patient outcomes. However, priorities for future study remain unclear. We therefore conducted an international research prioritisation exercise, setting the agenda for future investigators and funding bodies.MethodsWe invited members of specialist regional anaesthesia societies from six continents to propose research questions that they felt were unanswered. These were consolidated into representative indicative questions, and a literature review was undertaken to determine if any indicative questions were already answered by published work. Unanswered indicative questions entered a three-round modified Delphi process, whereby 29 experts in regional anaesthesia (representing all participating specialist societies) rated each indicative question for inclusion on a final high priority shortlist. If ≥75% of participants rated an indicative question as ‘definitely’ include in any round, it was accepted. Indicative questions rated as ‘definitely’ or ‘probably’ by <50% of participants in any round were excluded. Retained indicative questions were further ranked based on the rating score in the final Delphi round. The final research priorities were ratified by the Delphi expert group.ResultsThere were 1318 responses from 516 people in the initial survey, from which 71 indicative questions were formed, of which 68 entered the modified Delphi process. Eleven ‘highest priority’ research questions were short listed, covering themes of pain management; training and assessment; clinical practice and efficacy; technology and equipment.ConclusionsWe prioritised unanswered research questions in regional anaesthesia. These will inform a coordinated global research strategy for regional anaesthesia and direct investigators to address high-priority areas.

PurposeSARS-CoV-2 poses a significant occupational health threat to health care workers performing aerosol-generating medical procedures, with a threefold increased risk of a positive test and predicted infection compared with the general population. Nevertheless, the personal protective equipment (PPE) configuration that provides better protection with lower contamination rates is still unknown.MethodsWe enrolled 40 practitioners with airway management training (anesthesiologists, anesthesia assistants/nurses) in an exploratory, simulation-based randomized study. We evaluated the performance of a novel, locally designed hood (n = 20) in terms of protection from surrogate contamination using an ultraviolet (UV) marker during a standardized urgent intubation procedure and a simulated episode of coughing in a high-fidelity simulation setting compared with standard PPE (n = 20). The primary outcome was the presence of residual UV fluorescent contamination on any base clothing or exposed skin of the upper body after doffing PPE assessed by a blinded evaluator.ResultsThe proportion of participants with residual contamination on any base clothing or exposed skin of the upper body after doffing was less than half in the hood PPE group compared with the standard PPE group (8/20 [40%] vs 18/20 [90%], respectively; P = 0.002).ConclusionsCompared with standard PPE, enhanced PPE with a locally designed prototype hood was associated with reduced contamination of the upper torso and fewer body areas being exposed to droplets after a simulated aerosol-generating scenario without designed airflow.Study registrationClinicalTrials.gov (NCT04373096); registered 4 May 2020.

Learning objectivesBy reading this article you should be able to:•Describe the technical performance and patient-centred benefits of the paraspinous approach to lumbar neuraxial anaesthesia.•Discuss the application of spinal ultrasound imaging to the paraspinous approach and real-time ultrasound-guided techniques.•Develop strategies to increase success in performing spinal anaesthesia in challenging scenarios, such as patients with degenerative spinal disease, suboptimal positioning, obesity and scoliosis.Key points•Poorly palpable spinous processes or narrowed interspinous spaces can make a midline approach to lumbar neuraxial blockade challenging.•A paraspinous approach to spinal analgesia and anaesthesia can increase the success rate and reduce complications.•Ultrasound imaging before the procedure facilitates both midline and paraspinous approaches.•Real-time ultrasound-guided neuraxial anaesthesia is feasible but requires advanced imaging and needling skills.•The L5–S1 interlaminar space is widest and often remains patent in spinal disease. By reading this article you should be able to:•Describe the technical performance and patient-centred benefits of the paraspinous approach to lumbar neuraxial anaesthesia.•Discuss the application of spinal ultrasound imaging to the paraspinous approach and real-time ultrasound-guided techniques.•Develop strategies to increase success in performing spinal anaesthesia in challenging scenarios, such as patients with degenerative spinal disease, suboptimal positioning, obesity and scoliosis. •Poorly palpable spinous processes or narrowed interspinous spaces can make a midline approach to lumbar neuraxial blockade challenging.•A paraspinous approach to spinal analgesia and anaesthesia can increase the success rate and reduce complications.•Ultrasound imaging before the procedure facilitates both midline and paraspinous approaches.•Real-time ultrasound-guided neuraxial anaesthesia is feasible but requires advanced imaging and needling skills.•The L5–S1 interlaminar space is widest and often remains patent in spinal disease. Lumbar neuraxial anaesthesia is a core skill for all anaesthetists. It is associated with improved outcomes compared with general anaesthesia in surgeries such as hip and knee arthroplasty.1Memtsoudis S.G. Cozowicz C. Bekeris J. et al.Anaesthetic care of patients undergoing primary hip and knee arthroplasty: consensus recommendations from the International Consensus on Anaesthesia-Related Outcomes after Surgery group (ICAROS) based on a systematic review and meta-analysis.Br J Anaesth. 2019; 123: 269-287Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar These outcomes include lower risks of pulmonary and renal complications, venous thrombosis, blood transfusion and possibly mortality.1Memtsoudis S.G. Cozowicz C. Bekeris J. et al.Anaesthetic care of patients undergoing primary hip and knee arthroplasty: consensus recommendations from the International Consensus on Anaesthesia-Related Outcomes after Surgery group (ICAROS) based on a systematic review and meta-analysis.Br J Anaesth. 2019; 123: 269-287Abstract Full Text Full Text PDF PubMed Scopus (163) Google Scholar However, multiple factors can contribute to technical difficulty, including spinal degenerative disease, scoliosis, obesity, previous spinal surgery, and hindrances to optimal positioning of the patient. A large multicentre randomised controlled trial (RCT) in hip fracture surgery, a group that embodies many of these factors, reported a failure rate of 8.6% with spinal anaesthesia.2Neuman M.D. Feng R. Carson J.L. et al.Spinal anesthesia or general anesthesia for hip surgery in older adults.N Engl J Med. 2021; 385: 2025-2035Crossref PubMed Scopus (186) Google Scholar This article presents high yield strategies for successful neuraxial anaesthesia in the patient with challenging anatomy, specifically the paraspinous or paramedian approach and the application of spinal ultrasound imaging. Whereas the focus is on spinal anaesthesia, the principles for successful needle insertion into the interlaminar space can be extrapolated to lumbar epidural anaesthesia. Fluoroscopic guidance has also been described to assist with difficult spinal anaesthesia, but this is limited to one case report.3Eidelman A. Shulman M.S. Novak G.M. Fluoroscopic imaging for technically difficult spinal anesthesia.J Clin Anesth. 2005; 17: 69-71Crossref PubMed Scopus (14) Google Scholar It is not feasible in labour epidural analgesia because of the radiation exposure, and its main role in anaesthesia to date has been to assist thoracic epidural catheter insertion. One RCT demonstrated that fluoroscopy increased correct catheter placement within the thoracic epidural space from 74% to 98% compared with the conventional loss-of-resistance technique alone.4Parra M.C. Washburn K. Brown J.R. et al.Fluoroscopic guidance increases the incidence of thoracic epidural catheter placement within the epidural space: a randomized trial.Reg Anesth Pain Med. 2017; 42: 17-24Crossref PubMed Scopus (32) Google Scholar Fluoroscopic guidance in lumbar neuraxial anaesthesia is likely to remain a niche application as it requires a degree of expertise not possessed by most anaesthetists unless trained in chronic pain interventions, and we therefore consider it outside the scope of this article. The fundamental reason for using the paraspinous approach is to avoid having to locate and traverse the midline interspinous space accurately. This space can be difficult to identify in patients with poor-quality surface landmarks, or it may be narrowed by degenerative disease and inadequate lumbar flexion resulting from suboptimal positioning. It is thus a useful technique where these considerations apply, and a valuable fallback option if there is persistent bony contact when attempting a midline needle approach. We favour the term paraspinous instead of paramedian in describing the needle approach as it emphasises a critical principle that simplifies the technique and increases success: insert the needle close to the midline (spinous process) at a small lateral-to-medial angle.5Veering B.T. Cousins M.J. Epidural neural blockade.in: Cousins M.J. Bridenbaugh P.O. Carr D.B. Horlocker T.T. Cousins and Bridenbaugh's neural blockade in clinical anesthesia and pain medicine. 4th Edn. Lippincott Wilkins & Williams, Philadelphia2008: 241-295Google Scholar,6Chin K.J. Perlas A. Chan V. The ultrasound-assisted paraspinous approach to lumbar neuraxial blockade: a simplified technique in patients with difficult anatomy.Acta Anaesthesiol Scand. 2015; 59: 668-673Crossref PubMed Scopus (13) Google Scholar This is a subtle but important variation on the traditional paramedian approach, which is often taught as needle insertion in a lateral-to-medial direction starting at a skin insertion site up to 2 cm or a fingerbreadth away from the midline.7Puigdellívol-Sánchez A. Reina M.A. Sala-Blanch X. et al.Pythagoras and cosines: the skin-dural sac distance and optimal angles in paramedian spinal anesthesia.Clin Anat. 2016; 29: 1046-1052Crossref PubMed Scopus (5) Google Scholar However it then becomes challenging to triangulate the needle trajectory accurately in order to enter the interlaminar space, as the appropriate angle varies both with this distance and the depth to the space. Without knowledge of the depth to the space, the anaesthetist is faced with a wide range of potential lateral-to-medial angles to choose from during initial insertion and subsequent redirections. Redirection is further complicated by the choice of appropriate cranial angulation. An inappropriate lateral-to-medial angle will potentially contact the bony surface of not just the lamina, but also the spinous process (too medial) or the articular processes (too lateral) (Fig. 1). Distinguishing between these bony structures based on tactile feedback can be challenging for novice anaesthetists. They may not appreciate the difference in needle insertion depth when contacting the side of the spinous process (shallower) vs the lamina (deeper), or the significance of back pain localised to one side that often accompanies needle contact with the articular processes and facet joint. An inability to make a reasoned deduction as to what bony structure is being contacted by the needle will hamper decision-making around corrections to needle trajectory on subsequent passes. As the entire premise of the paraspinous approach is merely to avoid the midline interspinous space, the needle only needs to be inserted immediately lateral to the spinous process. By starting much closer to the midline, the lateral-to-medial angle can be kept small, allowing the needle to slide alongside the spinous process. We recommend a skin insertion site no more than 0.5–1 cm lateral to the midline and a lateral-to-medial angle of 5–15°, typically about 10°. In this trajectory, depending on the transverse plane of the skin insertion site relative to the interlaminar space, the needle tip will either (i) pass directly from paraspinous muscle into the ligamentum flavum, a transition that is clearly signalled by a distinct and characteristic change in tactile feedback from the soft buttery feel of muscle to the firm rubbery resistance of ligamentum flavum; or (ii) contact a bony surface, which will almost inevitably be the vertebral lamina (Fig. 1). In the latter instance, incremental cranial angulation will walk the needle tip off the superior edge of the lamina and into the ligamentum flavum, which will again be clearly signalled by its feel and ability to advance the needle deeper. The advantage of the paraspinous approach compared with the traditional paramedian technique was demonstrated in a magnetic resonance imaging study, which found that a skin insertion site 1 cm lateral to the midline, instead of 2 cm, resulted in less variation in the optimal lateral-to-medial angle of insertion with increasing depth to the subarachnoid space.7Puigdellívol-Sánchez A. Reina M.A. Sala-Blanch X. et al.Pythagoras and cosines: the skin-dural sac distance and optimal angles in paramedian spinal anesthesia.Clin Anat. 2016; 29: 1046-1052Crossref PubMed Scopus (5) Google Scholar Successful needle entry at the usual depths from skin to the vertebral canal (4–8 cm in adults) could be achieved with a narrower range of lateral-to-medial angles (5–15o), thus reducing the guesswork involved in selecting an appropriate trajectory (Fig. 2). This principle was confirmed by a large RCT that found significantly higher first-attempt success rates of lumbar spinal (59% vs 20%), epidural (65% vs 14%) and combined spinal-epidural (CSE) blockade (47% vs 15%) among trainees who utilised a needle insertion point 0.5 cm lateral to the midline vs 1 cm lateral.8Chen S.H. Chen S.S. Lai C.L. et al.Modified paramedian versus conventional paramedian technique in the residency training: an observational study.BMC Med Educ. 2020; 20: 211Crossref PubMed Scopus (6) Google Scholar In the the epidural and CSE groups that used the closer insertion point of 0.5 cm there was also a lower complication rate (composite of post-dural puncture headache, infection, haematoma) and lower rates of epidural catheter-related mishaps (difficulty threading, dural puncture, intravascular placement).8Chen S.H. Chen S.S. Lai C.L. et al.Modified paramedian versus conventional paramedian technique in the residency training: an observational study.BMC Med Educ. 2020; 20: 211Crossref PubMed Scopus (6) Google Scholar In summary, inserting the needle closer to the midline demands less precision when considering an appropriate lateral-to-medial angle, thus simplifying the technique and increasing the odds of success. In addition to the benefits described above, technical advantages of the paraspinous approach over the midline approach have been demonstrated, particularly in older patients who are more likely to have narrowed interspinous spaces. In particular, lumbar epidural catheters were easier to insert with less frequent paraesthesia.9Leeda M. Stienstra R. Arbous M.S. et al.Lumbar epidural catheter insertion: the midline vs. the paramedian approach.Eur J Anaesthesiol. 2005; 22: 839-842Crossref PubMed Scopus (28) Google Scholar A study using epiduroscopy in cadavers found that epidural catheters inserted in a midline approach caused more dural tenting and tended to deviate laterally or turn caudally, whereas paraspinous catheters threaded more consistently in a cranial direction.10Blomberg R. Technical advantages of the paramedian approach for lumbar epidural puncture and catheter introduction. A study using epiduroscopy in autopsy subjects.Anaesthesia. 1988; 43: 837-843Crossref PubMed Scopus (56) Google Scholar Possible reasons for these observations include the steeper cranial angle of insertion usually used with the paraspinous approach vs the more perpendicular angle of a midline approach, and the presence of posterior epidural ligaments that may impede midline catheter advancement. The paraspinous approach may confer additional patient-centred benefits. Randomised controlled trials have shown that back pain after the procedure is less common with the paraspinous vs midline approach.11Lee J.H. Yoon D.H. Heo B.H. Incidence of newly developed postoperative low back pain with median versus paramedian approach for spinal anesthesia.Korean J Anesthesiol. 2020; 73: 518-524Crossref PubMed Scopus (7) Google Scholar,12Singh B. Sohal A.S. Singh I. et al.Incidence of postspinal headache and low backache following the median and paramedian approaches in spinal anesthesia.Anesth Essays Res. 2018; 12: 186-189Crossref PubMed Google Scholar In one study, the overall incidence of back pain after a single pass with a 25 G spinal needle was 16% in the paraspinous group compared with 36% in the midline group.11Lee J.H. Yoon D.H. Heo B.H. Incidence of newly developed postoperative low back pain with median versus paramedian approach for spinal anesthesia.Korean J Anesthesiol. 2020; 73: 518-524Crossref PubMed Scopus (7) Google Scholar This suggests that needle trauma to supraspinous and interspinous ligaments, rather than paraspinal muscles, may be a more important factor in back pain after neuraxial blockade. A lower incidence of post-dural puncture headache has also been observed with the paraspinous vs midline approach.12Singh B. Sohal A.S. Singh I. et al.Incidence of postspinal headache and low backache following the median and paramedian approaches in spinal anesthesia.Anesth Essays Res. 2018; 12: 186-189Crossref PubMed Google Scholar In an RCT of 100 patients undergoing spinal anaesthesia with a 25 G needle for lower abdominal surgery, the incidence of mild-moderate headache over the following 7 days was 4% when a paraspinous approach was used vs 20% with a midline approach.12Singh B. Sohal A.S. Singh I. et al.Incidence of postspinal headache and low backache following the median and paramedian approaches in spinal anesthesia.Anesth Essays Res. 2018; 12: 186-189Crossref PubMed Google Scholar It is postulated that the cranial angulation of the needle in a paraspinous approach results in perforations of the ligamentum flavum, the densely multilayered dura mater and the arachnoid mater, that are slightly offset relative to each other. As a result, the edges of each layer overlap one another, creating a flap-valve effect that minimises cerebrospinal fluid (CSF) leakage. There are four fundamental steps to the anatomical surface landmark-guided paraspinous approach. The ultrasound-assisted method is described in a later section.(i)Determine the needle insertion site.(a)Establish the position of the tips of the lumbar spinous processes and the interspinous spaces by palpation. Choose a desired interspinous space and palpate the superior border of the lower spinous process.(b)We recommend using two fingers of the non-dominant hand for palpation, rolling the fingertips over the protrusions of the spinous processes and down into the depressions of the intervening interspinous spaces. The fingers are then separated slightly to straddle the width of the spinous process tips and chosen interspinous space, and to stabilise the overlying skin relative to the bony landmarks.(c)The appropriate needle insertion site is in the same transverse plane as the superior border of the lower spinous process, and ∼0.5–1 cm lateral to the neuraxial midline—the midpoint of your fingertip is a useful marker for judging this distance (Fig. 3).(ii)Scout the planned trajectory of the spinal needle with the local anaesthetic skin infiltration needle.(a)Infiltrate the skin and deeper underlying paraspinal muscles with local anaesthetic along the planned trajectory of the spinal needle. There should be no resistance to injection or advancement. Readjust the needle insertion site and angle as needed if the tip engages the bony spinous process or midline ligaments rather than passing smoothly through muscle.(iii)Insert the introducer or spinal needle with an initial trajectory comprising a lateral-to-medial angle of ∼10° with little to no cranial angulation (Fig. 4).(a)There should be a characteristic soft feel as the needle tip advances through paraspinal muscle. This will be followed by either a change in tactile feedback to the typical rubbery resistance of ligamentum flavum, or bony contact. If there is bony contact at a shallow depth <3 cm, this is likely to be the lateral aspect of the spinous process and signifies that the lateral-to-medial angle is too large (Fig. 1). Deeper bony contact is almost always the lamina. Gentle contact should not elicit any pain. If the patient reports back pain localised to the side of insertion, this usually represents contact with the ipsilateral facet joint and signifies that the lateral-to-medial angle is too small or that there is a rotational scoliotic deformity.Fig 4The introducer/spinal needle is inserted 0.5–1 cm from the midline in the same transverse plane as the superior edge of the lower spinous process bordering the chosen interspace. The initial needle trajectory should be at a lateral-to-medial angle of approximately 10o, with little-to-no cranial angulation. If the needle tip contacts bone this will almost inevitably be with the lamina of the lower vertebra. The needle should then be re-inserted with small incremental changes in cranial angulation to walk the needle tip off the lamina and into the interlaminar space. This is signalled by a perception of the needle tip advancing deeper and engaging the ligamentum flavum with its characteristic rubbery feel.View Large Image Figure ViewerDownload Hi-res image Download (PPT)(iv)Perform systematic incremental redirections as needed.(a)If the lamina is contacted, the needle should be redirected cranially without altering the lateral-to-medial angle, to walk the tip of the needle off into the interlaminar space. This is signalled by an increase in needle insertion depth and the tactile feedback from penetrating the ligamentum flavum (Fig. 4). It is critical that the redirections are small and incremental to avoid overshooting the interlaminar space. Smaller-gauge needles should be handled carefully to avoid flexion of the needle shaft and inadvertent deviation during advancement. If the patient is in the lateral decubitus rather than the sitting position, the anaesthetist's mental construct is now rotated 90⁰ when computing angles and redirecting the needle. The principles governing site and angle of needle insertion relative to the spine itself remain the same. The needle should be inserted from the dependent side of the body to allow gravity-assisted CSF backflow. Depending on patient position and handedness of the operator, the fingers of the non-needling hand will straddle either the upper or lower spinous process bordering the chosen interspace, as illustrated in Figure 3. Ultrasound imaging before the procedure is very useful in delineating spinal anatomy and thus is invaluable in patients with poorly palpable surface landmarks or anatomical distortion. The standard technique of ultrasound imaging and skin marking for a midline approach is well established and described in detail elsewhere.13Kalagara H. Nair H. Kolli S. et al.Ultrasound imaging of the spine for central neuraxial blockade: a technical description and evidence update.Current Anes Reports. 2021; 11: 326-339Crossref Scopus (9) Google Scholar In this section, familiarity with the basic principles of neuraxial ultrasound is assumed and the focus will be on aspects pertinent to the paraspinous approach. The pre-procedural ultrasound-assisted (PPUSA) paraspinous technique involves using ultrasound imaging to first obtain a parasagittal oblique (PSO) view and perform a qualitative assessment of the patency and size of paraspinous interlaminar spaces on either side, based on the length of the gap between bony lamina shadows and visible anterior complexes (Fig. 5A). Visualisation of an anterior complex confirms that this trajectory will successfully enter the vertebral canal. In patients with narrowed interlaminar spaces, the anterior complex may not be visible. In this same PSO view, the transverse plane of a suitable intervertebral space is marked on the skin. The transverse midline view is then used to identify and mark the location of the spinous processes (Fig. 5B). An appropriate skin insertion point is 0.5–1 cm lateral to the marked midline and 0.5–1 cm caudad to the selected interspace, so that the needle trajectory adheres to the principles outlined in the surface landmark-guided paraspinous approach (Fig. 6).6Chin K.J. Perlas A. Chan V. The ultrasound-assisted paraspinous approach to lumbar neuraxial blockade: a simplified technique in patients with difficult anatomy.Acta Anaesthesiol Scand. 2015; 59: 668-673Crossref PubMed Scopus (13) Google Scholar Needle advancement is guided by tactile feedback as described above.Fig 6Paraspinous approach using pre-procedural ultrasound imaging to identify landmarks. This is especially useful in obese patients as illustrated here. The location of the spinous processes can always be identified by their characteristic hyperechoic tip with acoustic dropout shadow, and then marked on the patient's skin (blue arrows) together with the midline. The interlaminar space should lie somewhere between adjacent spinous processes (red arrow). The appropriate skin insertion point (yellow circle) can be estimated from these marks using the principles described earlier. Incremental cranial angulation, while maintaining a constant lateral-to-medial angle, will walk the needle tip off the lower vertebral lamina and into the interlaminar space.View Large Image Figure ViewerDownload Hi-res image Download (PPT) It is important to note that this method differs significantly from the PPUSA paramedian technique described elsewhere in the literature.14Srinivasan K.K. Iohom G. Loughnane F. et al.Conventional landmark-guided midline versus preprocedure ultrasound-guided paramedian techniques in spinal anesthesia.Anesth Analg. 2015; 121: 1089-1096Crossref PubMed Scopus (56) Google Scholar, 15Srinivasan K.K. Leo A.M. Iohom G. et al.Pre-procedure ultrasound-guided paramedian spinal anaesthesia at L5-S1: is this better than landmark-guided midline approach? A randomised controlled trial.Indian J Anaesth. 2018; 62: 53-60Crossref PubMed Scopus (23) Google Scholar, 16Rizk M.S. Zeeni C.A. Bouez J.N. et al.Preprocedural ultrasound versus landmark techniques for spinal anesthesia performed by novice residents in elderly: a randomized controlled trial.BMC Anesthesiol. 2019; 19: 208Crossref PubMed Scopus (14) Google Scholar, 17Park S.K. Bae J. Yoo S. et al.Ultrasound-assisted versus landmark-guided spinal anesthesia in patients with abnormal spinal anatomy: a randomized controlled trial.Anesth Analg. 2020; 130: 787-795Crossref PubMed Scopus (30) Google Scholar In these studies, a PSO view of the interlaminar space is obtained and the needle insertion site is marked by the intersection point of two lines joining the midpoints of long and short borders of the probe. The lateral-to-medial angulation of the probe is noted for later replication when inserting the needle. The main drawback of this technique is that the large footprint of a curved probe invariably results in a more lateral needle insertion site and a larger lateral-to-medial angle. This re-introduces the challenges of triangulation and correct replication of the angulation of the curvilinear probe that produced the required image, thus increasing the chance of error.18Wardhan R. Smith C.R. A Miss is as good as a mile: ultrasound estimation of needle angulation cannot be overlooked in paramedian spinal approach.Anesth Analg. 2020; 131: e24Crossref PubMed Scopus (2) Google Scholar These challenges may explain conflicting results in the literature. One study reported the PPUSA paramedian technique to be more effective in patients with abnormal spinal anatomy compared with a surface landmark-guided technique using either a midline or paramedian approach (at the operator's discretion) when performed by experienced anaesthetists.17Park S.K. Bae J. Yoo S. et al.Ultrasound-assisted versus landmark-guided spinal anesthesia in patients with abnormal spinal anatomy: a randomized controlled trial.Anesth Analg. 2020; 130: 787-795Crossref PubMed Scopus (30) Google Scholar However, other studies involving consultant anaesthetists have failed to demonstrate any advantages over a surface landmark-guided midline technique.14Srinivasan K.K. Iohom G. Loughnane F. et al.Conventional landmark-guided midline versus preprocedure ultrasound-guided paramedian techniques in spinal anesthesia.Anesth Analg. 2015; 121: 1089-1096Crossref PubMed Scopus (56) Google Scholar,15Srinivasan K.K. Leo A.M. Iohom G. et al.Pre-procedure ultrasound-guided paramedian spinal anaesthesia at L5-S1: is this better than landmark-guided midline approach? A randomised controlled trial.Indian J Anaesth. 2018; 62: 53-60Crossref PubMed Scopus (23) Google Scholar On the contrary, in the hands of novice practitioners, the PPUSA paramedian technique resulted in more needle passes compared with either a surface landmark-guided or PPUSA midline technique (median of 4 vs 2 vs 2), and a longer block performance time (mean of 155 vs 87 vs 116 min).16Rizk M.S. Zeeni C.A. Bouez J.N. et al.Preprocedural ultrasound versus landmark techniques for spinal anesthesia performed by novice residents in elderly: a randomized controlled trial.BMC Anesthesiol. 2019; 19: 208Crossref PubMed Scopus (14) Google Scholar Block performance time, compared with a landmark-guided or PPUSA midline approach, was also a median of 67 s and 38 s longer, respectively, in the hands of novice practitioners.16Rizk M.S. Zeeni C.A. Bouez J.N. et al.Preprocedural ultrasound versus landmark techniques for spinal anesthesia performed by novice residents in elderly: a randomized controlled trial.BMC Anesthesiol. 2019; 19: 208Crossref PubMed Scopus (14) Google Scholar We therefore recommend that ultrasound imaging be used only to identify the location of spinous processes and to confirm the presence of a patent interlaminar space. The position and angle of the probe should not determine the needle insertion site or lateral-to-medial needle insertion angle. These should instead follow the principles outlined for the surface landmark-guided paraspinous approach. Real-time ultrasound-guided (RTUSG) neuraxial blockade is an advanced technique that requires expertise with both conventional spinal ultrasound imaging and neuraxial blockade. It invariably utilises a paraspinous needle approach to the interlaminar space, although multiple variations using different imaging views have been described.19Chen L. Huang J. Zhang Y. et al.Real-time ultrasound-guided versus ultrasound-assisted spinal anesthesia in elderly patients with hip fractures: a randomized controlled trial.Anesth Analg. 2022; 134: 400-409Crossref PubMed Scopus (8) Google Scholar A recent RCT involving three experienced anaesthetists compared RTUSG paraspinous and PPUSA paraspinous techniques of neuraxial blockade in elderly patients with hip fractures.19Chen L. Huang J. Zhang Y. et al.Real-time ultrasound-guided versus ultrasound-assisted spinal anesthesia in elderly patients with hip fractures: a randomized controlled trial.Anesth Analg. 2022; 134: 400-409Crossref PubMed Scopus (8) Google Scholar They observed that the RTUSG technique was significantly more difficult, as demonstrated by lower first-pass success rates (32% vs 63%), more needle passes overall (median of 3 vs 1) and longer block performance times (median of 488 vs 200 s). Furthermore, CSF backflow was absent in 14% of the RTUSG group; in these patients, successful spinal anaesthesia was obtained with crossover to the PPUSA technique. The authors postulated several reasons for this including needle blockage, and misplacement of the needle tip because the insertion point was too lateral or deviated from the intended trajectory. The RTUSG technique cannot therefore be recommended for routine use at this time. Nevertheless, we have occasionally found it helpful in certain circumstances, notably where the target interlaminar space was adequately seen but so small as to require a degree of precision that could only be obtained with real-time guidance. It should also be noted that concerns have been raised regarding potential toxicity of ultrasound gel introduced into the neuraxial space.20Carter H.K. Wong E.M. Safety of ultrasound gel in real-time scanning of the lumbar spine in obstetric anaesthesia.Int J Obstet Anesth. 2022; 52103594Abstract Full Text Full Text PDF PubMed Scopus (1) Google Scholar This can be avoided by applying gel sparingly and meticulously cleaning the site of needle puncture, or by using saline as an alternative medium for probe-skin contact. If the patient is in a lateral decubitus position, adopting a modified Sims position, in which the patient's back slants away from the operator, can be helpful as it provides a more stable position and creates more space between the needle hub and bed surface during insertion, particularly if using a long needle >90 mm in length. However, this slant of the surface of the patient's back must be factored in when estimating the lateral-to-medial angle of needle trajectory relative to the horizontal plane of the patient's bed (Fig. 7). Flexion of the hips and lumbar spine is not critical to successful paraspinous neuraxial blockade, as the width of the paraspinous interlaminar space is minimally affected.21Podder S. Kumar N. Yaddanapudi L.N. Chari P. Paramedian lumbar epidural catheter insertion with patients in the sitting position is equally successful in the flexed and unflexed spine.Anesth Analg. 2004; 99: 1829-1832Crossref PubMed Scopus (21) Google Scholar This is a distinct advantage when optimal positioning is not feasible, such as in hip fracture. However, a recent RCT found that elevating the chest and shoulders by 30° significantly improved metrics of technical performance in elderly patients with hip fracture (Fig. 8).22Zhang W. Wang T. Wang G. et al.Elevated lateral position improves the success of paramedian approach in subarachnoid puncture in spinal anesthesia before hip fracture surgery in elderly patients: a randomized controlled study.Med Sci Monit. 2020; 26 (-1–e923813-8)e923813Crossref Scopus (3) Google Scholar This was attributed to widening of the dependent paraspinous interlaminar space created by lateral flexion in the thoracolumbar spine and is a concept worthy of further investigation. In some older patients, the skin insertion site may have to be >1 cm lateral to the neuraxial midline. This is because age-related calcification of the supraspinous ligaments can distort and widen the tip of the spinous process, creating a 'mushroom top' shape (Fig. 9). This is often evident during palpation but will also be signalled by gritty or bony needle contact during local anaesthetic skin infiltration. The skin insertion site should be adjusted as needed until it is lateral to the enlarged tip of the spinous process and the needle can pass unimpeded through the paraspinal muscles. The lateral-to-medial angle should be increased slightly up to 15–20° to geometrically compensate for this lateral shift in insertion site (Fig. 9). Accurate localisation of the spinous processes by palpation may be difficult in patients with obesity. Their approximate position can sometimes be determined by deep palpation and then confirmed by using the skin infiltration needle to probe for bony contact or injection resistance, signifying engagement of supraspinous or interspinous ligaments. Ultrasound imaging is also extremely helpful as the location of the midline and spinous processes can always be ascertained, even if the anterior and posterior complexes signifying interlaminar windows cannot be clearly seen (Fig. 6). Other major challenges in obesity are the increased needle insertion depth and mobility of overlying soft tissues. This can lead to inadvertent deviations in needle trajectory during insertion. The precision of needle handling demanded by a midline approach thus makes it more susceptible to failure, particularly if the patient also has narrowed interlaminar spaces. As discussed earlier, the paraspinous approach is more forgiving of imprecision during needle insertion. Systematic redirection is also simplified by the fact that deep bony contact almost certainly signifies the ipsilateral lamina and incremental cranial angulation is therefore the logical next step to eventual success (Fig. 1). For these reasons, we often adopt the paraspinous approach as the first-line technique in patients who are very obese. Finally, when using needles >90 mm in length, regardless of approach, we recommend using 22 G (vs 25 G) Quincke-tip needles to reduce tissue resistance to insertion and the risk of needle shaft flexion and deviation. Related to this, some anaesthetists suggest a CSE technique to achieve spinal anaesthesia in patients with challenging anatomy, citing the greater rigidity and better tactile feedback of the epidural needle. One RCT demonstrated non-inferiority, but not superiority, of the CSE technique compared with single-injection spinal anaesthesia in morbidly obese patients undergoing Caesarean section.23Ross V.H. Dean L.S. Thomas J.A. Harris L.C. Pan P.H. A randomized controlled comparison between combined spinal-epidural and single-shot spinal techniques in morbidly obese parturients undergoing cesarean delivery: time for initiation of anesthesia.Anesth Analg. 2014; 118: 168-172Crossref PubMed Scopus (24) Google Scholar It should be further noted that reported incidences of spinal haematoma and other instances of permanent injury are several orders of magnitude greater with CSE and epidural anaesthesia compared with spinal anaesthesia.24Cook T.M. Counsell D. Wildsmith J.A.W. Major complications of central neuraxial block: report on the third national audit project of the royal college of anaesthetists.Br J Anaesth. 2009; 102: 179-190Abstract Full Text Full Text PDF PubMed Scopus (629) Google Scholar,25Moen V. Dahlgren N. Irestedt L. Severe neurological complications after central neuraxial blockades in Sweden 1990-1999.Anesthesiology. 2004; 101: 950-959Crossref PubMed Scopus (765) Google Scholar We therefore do not advocate this strategy of using an epidural needle purely for its handling characteristics in non-obstetric and particularly in older patients. The CSE technique remains a valuable clinical option where the flexibility of extending the duration or height of neuraxial anaesthesia is desired. Challenges with a midline approach in scoliotic patients include narrowed interspinous spaces and rotational deformity. It is critical to identify the direction of the lateral scoliotic curve in the lumbar spine; this will be opposite to that of the thoracic curve, which is often more clinically obvious. The paraspinous interlaminar spaces are widened on the convex side of the curve and narrowed on the concave side, and the needle should thus always be inserted on the convex side (Fig. 10). A lateral curve of the spine is always accompanied by an axial rotational deformity of the vertebrae, with the body of the vertebrae rotating towards the convex side of the lateral curve. This means that little to no lateral-to-medial angulation may be needed for entry into the vertebral canal with a paraspinous approach. Conversely, medial-to-lateral angulation is now required if inserting the needle along a midline approach (Fig. 11). Ultrasound imaging is very helpful in identifying the direction and degree of curvature and rotation in these patients, in locating suitably wide paraspinous interlaminar spaces and in planning the appropriate needle trajectory.Fig 11A scoliotic curve in the spine is always accompanied by a rotational deformity (inset image A). This is evident on ultrasound imaging as a midline acoustic shadow (yellow dashed line) that is tilted away from the vertical when the probe is placed in a transverse orientation with the beam perpendicular to the surface of the back (image 1A and 1B). The direction and angle of rotation is determined by rocking the probe in the transverse plane to bring the midline acoustic shadow back to the vertical (image 2A and 2B). This medial-to-lateral probe-beam angle must be replicated for successful needle insertion using a midline approach (image 3).View Large Image Figure ViewerDownload Hi-res image Download (PPT) The L5–S1 interlaminar space tends to remain patent in degenerative spinal disease and is thus a useful option in challenging neuraxial blockade. The original description, Taylor's approach, was for spinal anaesthesia in the prone position in elderly patients and advocated a paramedian approach utilising a needle insertion point 1 cm medial and 1 cm caudal to the posterior superior iliac spine, with subsequent craniomedial redirections to walk the needle off the sacrum into the interspace. This bony surface landmark is difficult to reliably ascertain, especially in the obese. However, the L5–S1 space can be easily located with ultrasound imaging and its patency simultaneously confirmed.13Kalagara H. Nair H. Kolli S. et al.Ultrasound imaging of the spine for central neuraxial blockade: a technical description and evidence update.Current Anes Reports. 2021; 11: 326-339Crossref Scopus (9) Google Scholar A PPUSA midline or paraspinous approach can then be performed. Note that the S1 foramen can sometimes mimic the sonographic appearance of the L5–S1 space. The latter is characterised by the sawtooth appearance of the L5 lamina and its constant visibility with small lateral-medial sliding motions of the probe. One important consideration when targeting the L5–S1 space for spinal anaesthesia is adequate cranial distribution. Insufficient block height is a common cause of secondary spinal anaesthesia failure even when injection is performed at higher levels.26Fettes P.D. Jansson J.R. Wildsmith J.A.W. Failed spinal anaesthesia: mechanisms, management, and prevention.Br J Anaesth. 2009; 102: 739-748Abstract Full Text Full Text PDF PubMed Scopus (152) Google Scholar A recent dose-finding study reported that sensory loss above the T10 dermatome with Taylor's approach was only consistently obtained with a relatively large dose of at least 25 mg of plain bupivacaine 0.5%.27Liu Y. Yang S. Yao W. et al.Minimum effective dose of plain bupivacaine 0.5% for ultrasound-guided spinal anaesthesia using Taylor's approach.Br J Anaesth. 2020; 124 (–e231): e230Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar A detailed discussion of baricity and the most appropriate local anaesthetic solution for spinal anaesthesia performed at the L5–S1 space is beyond the scope of this journal. Although the densities of plain local anaesthetic solutions are numerically lower than CSF, their distribution within the CSF is not affected by postural changes in as predictable a manner as hyperbaric solutions.28Richardson M.G. Wissler R.N. Densities of dextrose-free intrathecal local anesthetics, opioids, and combinations measured at 37 degrees C.Anesth Analg. 1997; 84: 95-99Crossref PubMed Google Scholar,29Hocking G. Wildsmith J.A.W. Intrathecal drug spread.Br J Anaesth. 2004; 93: 568-578Abstract Full Text Full Text PDF PubMed Scopus (232) Google Scholar Using hyperbaric or hypobaric local anaesthetic solutions should be considered, in conjunction with appropriate positioning of the patient after the block to achieve the desired cranial distribution.30Srinivasan K.K. Leo A.M. Iohom G. Loughnane F. Lee P.J. Pre-procedure ultrasound-guided paramedian spinal anaesthesia at L5-S1: is this better than landmark-guided midline approach? A randomised controlled trial.Indian J Anaesth. 2018; 62: 53-60Crossref PubMed Scopus (23) Google Scholar, 31Faust A. Fournier R. Van Gessel E. Weber A. Hoffmeyer P. Gamulin Z. Isobaric versus hypobaric spinal bupivacaine for total hip arthroplasty in the lateral position.Anesth Analg. 2003; 97: 589-594Crossref PubMed Scopus (24) Google Scholar, 32Vergari A. Frassanito L. Nestorini R. et al.Hypobaric versus isobaric spinal levobupivacaine for total hip arthroplasty.Minerva Anestesiol. 2017; 83: 361-368Crossref PubMed Scopus (7) Google Scholar Lumbar neuraxial analgesia and anaesthesia is a core skill for all anaesthetists but can be technically challenging to perform in patients with abnormal spinal anatomy. Using some combination of the strategies presented in this article should help to maximise success when difficulty is anticipated or encountered.