British Journal of Anaesthesia

BackgroundThere is disparity between the incidence of malignant hyperthermia (MH) reactions and the prevalence of variants in the RYR1 gene associated with susceptibility to MH (where susceptibility is determined by in vitro contracture tests). Our aims were to use clinical and genetic data from the UK to explain this disparity and to examine if these data are consistent with the clinical risk of MH being inherited as an autosomal dominant trait. MethodsClinical MH and genotyping data were extracted from the UK MH registry. The numbers of general anaesthetics delivered in the UK were estimated from national surveys and reports, with population data obtained from government statistics. The prevalence of RYR1 variants in the UK population was estimated using UK Biobank data. The incidence of MH reactions 1988-93 was used to estimate the prevalence of the clinical risk of MH in the UK. Bayesian modelling, calibrated against actual data, was used to evaluate the likely mode of inheritance of the clinical risk of MH and the relative risk of clinical MH associated with different RYR1 variants. ResultsThe probability of index cases developing MH with each general anaesthetic can be expressed as a constant hazard of 0.46 (95% CI 0.42 - 0.50, n=375). We used peak incidence data (1988-93) to estimate the prevalence of the risk of MH as 1 in 44,000 (95% credibility interval, 1 in 40,000 to 1 in 48,000). The incidence of MH has declined over the past 22 years but the rate of decline is inconsistent with autosomal dominant inheritance (P < 10-10). The risk of MH varied by up to 150-fold between carriers of 28 recurrent RYR1 variants. ConclusionThese findings support a threshold inheritance model for clinical MH and have implications for diagnostics, both genotyping and in vitro contracture test phenotyping.

BackgroundPropofol dosing guidelines recommend age-based reductions because hypnotic sensitivity increases in older adults. Most real-world evaluations of induction practice, however, have relied on total weight-normalized dose (mg/kg) rather than estimating cerebral exposure using pharmacokinetic models. Because age-related pharmacokinetic changes alter the relationship between administered dose and peak effect-site concentration (Ce,max), mg/kg surrogates may misrepresent true age-dependent exposure during induction. MethodsA retrospective reconstruction of 250,640 adult anesthetic inductions was performed using high-fidelity EHR medication timestamps. Propofol effect-site concentration trajectories were simulated at 1-second resolution using the Eleveld model. Ce,maxwas benchmarked against age-adjusted hypnotic requirements (Ce50) derived from the Eleveld model (standardized to a target Bispectral Index{approx} 47). Age-exposure relationships were estimated using covariate-adjusted natural cubic splines, controlling for BMI, sex, and ASA physical status. ResultsFrom young adulthood (18-24 years) to the oldest cohort (85-89 years), weight-normalized induction doses were reduced by 32% (3.16 to 2.16 mg/kg). However, modeled Ce,max declined by only 17% (3.70 to 3.06 {micro}g/mL), while the estimated physiological requirement declined by 34% (3.37 to 2.21 {micro}g/mL), creating a widening titration offset with age. At age 75, the adjusted probability of exceeding the individual hypnotic requirement was 89.6% (95% CI: 89.3-89.8%). Notably, 54.7% (95% CI: 54.2-55.2%) of 75-year-old patients achieved peak exposures exceeding the aver-age requirement of a healthy 20-year-old, indicating persistent anchoring of exposure to youthful levels. Findings were robust across model specifications and inclusion criteria. ConclusionsIn over a quarter-million inductions, real-world age-based dose re-ductions did not produce proportional reductions in peak propofol brain exposure. Achieved concentrations declined far more slowly than modeled geriatric sensitivity increases, consistent with systematic over-exposure in older adults. These findings suggest that weight-based dosing heuristics inadequately capture age-dependent exposure and support a transition toward exposure-informed and neurophysiologically guided induction titration in geriatric anesthesia.

BackgroundDelirium is a frequent complication in hospitalized older adults post-surgery associated with adverse outcomes. Although anaesthesia is traditionally linked to increased delirium risk, the causal relationship remains uncertain. MethodsWe conducted Mendelian randomization (MR) analyses using genome-wide association studies (GWAS) summary statistics to explore the causal effects of different anaesthesia types (general, regional, and local) on delirium risk. We employed the weighted median, MR-Egger, and MR-PRESSO methods for estimation and conducted sensitivity analyses to address pleiotropy and heterogeneity. ResultsGenetically determined anaesthesia types showed no significant causal effect on delirium risk. Sensitivity analyses confirmed the robustness of these findings, with no evidence of horizontal pleiotropy or significant heterogeneity. ConclusionsMendelian randomization provides strong evidence against a causal link between genetically determined anaesthesia and increased delirium risk.

BackgroundChronic postsurgical pain after caesarean delivery impairs postpartum recovery and maternal quality of life. Existing risk models focus on demographic or procedural factors, limiting opportunities for early intervention. This study developed and prospectively evaluated a biopsychosocial predictive model, SPACE-Postpartum (Sleep, Pain, Affect, Cognition, Energy), which assesses early postpartum symptoms across five domains. MethodsIn this prospective cohort study, adults undergoing caesarean delivery at a tertiary centre completed validated patient-reported outcome measures at baseline, 2 weeks, and 3 months postpartum. Chronic pain was defined as pain at any site persisting >3 months. A five-item model with one early postpartum indicator from each SPACE domain was derived using logistic regression with ridge regularisation, supported by latent class and causal mediation analyses. ResultsOf 143 participants, 100 (70%) completed 3-month follow-up; 40% reported chronic pain. The SPACE ridge model demonstrated good discrimination (AUC 0.76, 95% CI 0.67-0.85) with internal validation and acceptable calibration. Higher acute pain intensity, pain interference, and sleep disturbance, with a trend for reduced perceived control, predicted chronic pain. Latent class analysis identified an early high-burden SPACE profile (52%) associated with greater pain interference at 3 months. Mediation analysis indicated acute pain exerted a direct effect, while sleep disturbance acted as an independent prognostic marker. Exploratory sensitivity analyses suggested potential incremental value of quadratic models (AUC 0.83-0.87), although these risked overfitting in this small dataset. ConclusionsChronic pain after caesarean delivery is common and linked to potentially modifiable early symptoms, particularly sleep disturbance and pain-related interference. Across predictive, phenotypic, and causal analyses, pain and sleep symptoms consistently demonstrated prognostic value. This single-centre proof-of-concept study provides early internal validation of the SPACE-Postpartum model. Multicentre external validation is warranted to confirm generalisability and support development of symptom-informed decision tools.

BackgroundEEG is a common tool for monitoring anaesthetic depth but is rarely reused at large for biomedical research. This study sets out to explore repurposing of EEG during anaesthesia to learn biomarkers of brain ageing in the absence of consciousness. MethodsWe focused on brain age estimation as an example. Using machine learning, we reanalysed 4-electrodes EEG of 323 patients under propofol and sevoflurane. We included spatio-spectral features from stable anaesthesia for EEG-based age prediction applying recently published reference methods. Anaesthesia was considered stable when 95% of the total power was below a frequency between 8Hz and 13Hz. ResultsWe considered moderate-risk patients (ASA <= 2) with propofol anaesthesia to explore predictive EEG signatures. Average alpha-band power (8-13Hz) was informative about age. Yet, state-of-the-art prediction performance was achieved by analysing the entire power spectrum from all electrodes (MAE = 8.2y, R2 = 0.65). Clinical exploration revealed that brain age was systematically linked with intra-operative burst suppression - commonly associated with age-related postoperative cognitive issues. Surprisingly, the brain age was negatively correlated with burst suppression in high-risk patients (ASA = 3), pointing at unknown confounding effects. Secondary analyses revealed that brain-age EEG signatures were specific to propofol anaesthesia, reflected by limited prediction performance under sevoflurane and poor cross-drug generalisation. ConclusionsEEG from general anaesthesia may enable state-of-the-art brain age prediction. Yet, differences between anaesthetic drugs can impact the effectiveness of repurposing EEG from anaesthesia. To unleash the dormant potential of repurposing EEG-monitoring for clinical and health research, in the absence of consciousness, collecting larger datasets with precisely documented drug dosage will be key enabling factors.

BackgroundAnaesthesia delivery in Pakistan remains limited to conventional intraoperative procedures, with research showing ongoing challenges in quality and resourcing. We aimed to identify systemic challenges in the delivery of quality anaesthesia services for surgical support in Pakistans Punjab province. MethodsThis qualitative study included 22 semi-structured interviews with purposively selected anaesthesia system experts in Punjab province, including heads of teaching hospital anaesthesia departments, healthcare commission representatives, and health department officials. We analysed data thematically, using deductive and inductive coding. ResultsWe identified three themes of anaesthetist recruitment and retention, quality-of-care and in-service training, and discrepancies between specialities, describing major challenges experienced within the speciality. Findings indicated that workforce shortages and maldistribution, insufficient in-service training and standards, inadequate equipment maintenance, and lack of anaesthesia representation in decision-making compromised anaesthesia provision quality and safety. ConclusionsImproving anaesthesia provision in Punjab would require increasing physician and non-physician anaesthetist numbers and rotation to peripheral postings, strengthening training quality, and ensuring availability of minimum essential equipment and supplies. To achieve essential anaesthesia provision standards, policy interventions are needed to, for example, balance anaesthesiologist and surgeon numbers, require that anaesthesiology graduates work a few years in-country (e.g. scholarship bonds), ensure in-service training attendance for skills updates, and implement quality assurance standards for equipment and supplies. HIGHLIGHTSO_ST_ABSWhat is already known on this topic?C_ST_ABSExisting research on anaesthesia in lower-income economies focuses on provision discrepancies and capacity measurement of HIC-partnered interventions. However, managerial and frontline challenges that weaken quality anaesthesia provision in countries such as Pakistan, and thus affect global surgery indicators, are largely unexamined. What this study addsThis study is the first to highlight ongoing challenges within the anaesthesia delivery system in Punjab province as experienced by senior practitioners and health officials, thus contributing to the knowledge base on anaesthesia provision challenges in lower-income economies. How this study might affect research, practice, or policyFindings show the urgent need to increase recruitment, retention, and peripheral distribution of physician and non-physician anaesthetists along with developing clear national legislation and practice guidelines for standardised quality of anaesthesia care and raising the public profile of anaesthesia in Pakistan.

Postoperative delirium is a severe complication associated with poor overall and especially neurocognitive prognosis after anesthesia and surgery. As a systemic phenomenon, peripheral immune response to surgical trauma may play a central role. Although analysis of differential gene expression in peripheral immune cells could provide insights into immune dysregulation in postoperative delirium (POD), no such analysis has been conducted yet in a sufficiently sized prospective cohort. We performed gene expression analysis in N=599 cognitively healthy male and female patients [&ge;]65 years who provided blood samples for microarray-based transcriptomics before major elective surgery and on the first postoperative day. Patients were followed up for delirium until the seventh postoperative day. We identified differentially expressed genes in POD using a multivariable linear regression framework adjusted for sex, age, body mass index, preoperative physical status, duration of anesthesia and operative procedure. Preoperative gene expression was not significantly different in patients who were later diagnosed with POD. However, we identified a total of 1063 unique significantly associated genes which differed in baseline-corrected mRNA abundance among POD patients after surgery (n=394 positively, n=681 inversely). This set was significantly enriched for genes related to cellular and humoral immune response, RNA metabolism and platelet function. Post-, but not preoperative gene expression in peripheral immune cells has been found to be altered in patients with POD. Whereas most enriched pathways were related to immune response and acute phase reaction, few molecular alterations were found, which may reflect nervous system alterations and need further clarification. HIGHLIGHTSO_LIPostoperative delirium (POD) is a common severe complication in older surgical patients C_LIO_LISystemic inflammation has been considered a major hallmark of POD C_LIO_LIWe describe immune cell gene expression in a large prospective cohort of surgical patients C_LIO_LIPOD is associated with postoperative, but no preoperative alteration in gene expression C_LIO_LIDifferentially expressed genes are involved in immune, platelet, but also neuronal function C_LI

BACKGROUNDConventional vital signs lack the specificity for intraoperative nociception. The Surgical Pleth Index (SPI), calculated from photoplethysmographic waveforms, provides a quantitative measure of nociceptive status ranging from 0 to 100. Elevated SPI values correspond to increased nociceptive intensity. While some evidence suggests that SPI may help predict pain, its accuracy in forecasting postoperative pain requires further validation. AIMThis study aimed to assess the capacity of the Surgical Pleth Index (SPI) to predict moderate to severe pain following surgery. METHODSWe conducted a systematic literature search across three databases to identify studies investigating SPIs predictive value for postoperative pain. A random-effects model was applied to pool summary estimates of sensitivity, specificity, and the area under the summary receiver operating characteristic curve (SROC-AUC). RESULTSAnalysis included ten studies encompassing 1,042 patients. Pooled sensitivity and specificity were 0.74 (95% CI: 0.67-0.80) and 0.65 (95% CI: 0.55-0.74), respectively. The SROC-AUC reached 0.76, suggesting a moderate level of predictive accuracy. Significant heterogeneity was observed and not explained by differences in SPI cutoff values. CONCLUSIONThe SPI demonstrates moderate accuracy in forecasting moderate-to-severe postoperative pain and may serve as a useful adjunct to conventional clinical assessment. What is known?The Surgical Pleth Index has been suggested as a reliable monitor for nociceptive states. What new information does this article contribute?The Surgical Pleth Index (SPI) demonstrated moderate accuracy in predicting moderate-to-severe postoperative pain. Current evidence supports its role as a validated supplementary instrument to guide analgesic administration during surgery. Core Tip:This meta-analysis confirms that the Surgical Pleth Index (SPI) provides moderate predictive accuracy for moderate-to-severe postoperative pain and, as such, has a complementary role in guiding intraoperative analgesia, provided its outputs are interpreted within the context of a comprehensive clinical assessment.

BackgroundHypertension therapy in older adults is often suboptimal, in part due to inadequate suppression of the renin-angiotensin-aldosterone system (RAAS). We hypothesised that distinct endotypes of RAAS activation before noncardiac surgery are associated with increased risk of myocardial injury. MethodsThis was a pre-specified analysis of a multicentre randomised controlled trial (ISRCTN17251494) which randomised patients [&ge;]60 years undergoing elective non-cardiac surgery to either continue, or stop, RAAS inhibitors (determined by pharmacokinetic profiles). Unsupervised hierarchical cluster analysis identified distinct groups of patients with similar RAAS activation from samples obtained before induction of anesthesia, quantified by enzyme-linked immunoassays for plasma renin, aldosterone, angiotensin-converting enzyme 2 (ACE2) and dipeptidyl peptidase-3 (DPP3). The primary outcome, masked to investigators and participants, was myocardial injury (plasma high-sensitivity troponin-T). ResultsWe identified three clusters, with similar proportions of RAAS inhibitors randomised to stop/continue. Cluster 1 (n=52; mean age (SD), 75{+/-}8 years; 54% female) and cluster 3 (n=25; 75{+/-}6 years; 44% female) had higher rates of myocardial injury (23/52 (44%) and 13/25 (52%), respectively), compared with 51/164 (31.1%) in cluster 2 (n=153; 70{+/-}6 years; 46% female; odds ratio:1.95, 95% CI:1.12-3.39, p=0.018). Cluster 2 was characterized by lower NT-proBNP (mean difference, 698pg.ml-1, 95% CI, 576-820) and higher renin (mean difference:350pg.ml-1, 95% CI:123-577), compared with clusters 1 and 3 with the higher rate of myocardial injury. ConclusionEffective preoperative RAAS inhibition is associated with lower risk of myocardial injury before non-cardiac surgery, independent of stopping/continuing RAAS inhibitors before surgery.

Purpose To quantify and compare the peak force applied on the glottis during endotracheal intubation across five laryngoscopy techniques, two intubation conditions (standard and simulated laryngospasm), and two operator experience levels, and to assess the effects of stylet use and operator anthropometric characteristics on applied force. Methods This prospective, manikin-based experimental study enrolled 50 operators (30 experienced, 20 less experienced). Each performed endotracheal intubation using five techniques: direct laryngoscopy and videolaryngoscopy with a Macintosh blade, each with and without stylet, and videolaryngoscopy with a hyperangulated blade with stylet. A calibrated force sensor positioned at the glottis measured peak forces during standard and simulated laryngospasm conditions. Non-parametric statistical methods were used (Mann-Whitney U, Wilcoxon signed-rank, Friedman tests); effect sizes are reported as rank-biserial correlations. Results Across all techniques, median glottic forces ranged from 4.8 N (IQR: 3.3-6.5) for videolaryngoscopy without stylet to 11.1 N (IQR: 7.5-14.5) for direct laryngoscopy with stylet under standard conditions. No significant differences in applied force were observed between experienced and less experienced operators for any technique-condition combination (all adjusted p = 1.0; |r| < 0.27). Stylet use significantly increased glottic force across all conditions and groups (median increases 3.4-7.3 N; all p < 0.001; rank-biserial r > 0.75). Videolaryngoscopy with a Macintosh blade produced significantly lower forces than hyperangulated videolaryngoscopy under standard conditions (adjusted p = 0.049). Neither grip strength nor hand size correlated with applied force. Conclusion Glottic force during endotracheal intubation is determined primarily by technique and stylet use, not operator experience or anthropometrics. Stylet use is the single largest modifiable contributor to glottic force. These findings have implications for device selection, clinical training, and strategies to minimize airway trauma during intubation.

BackgroundAccurate intraoperative detection of nociceptive events is essential for optimizing analgesic administration and improving postoperative outcomes. While deep learning models promise to capture complex temporal dynamics of physiological signals, their added complexity may not always yield clinically meaningful gains compared to well-engineered classical approaches. MethodsWe evaluated two classical supervised models--L1-regularized logistic regression and Random Forests (with and without drug dosing features)--against a Temporal Convolutional Network (TCN) transfer-learning framework. We used a dataset of 101 adult surgical cases (~50,000 annotated nociceptive events over ~18,500 minutes) sourced from PhysioNet that tracked 30 physiologic and 18 drug-related features in 5-second windows. All models were assessed under a leave-one-surgery-out cross-validation, with AUROC and AUPRC as primary metrics. We further examined probability calibration (Platt scaling, isotonic regression) and four ensemble strategies--including a meta-learner, MLP, and a feature-conditioned gated network--to quantify the benefit of deep personalization. ResultsDrug-aware Random Forests achieved the highest discrimination (AUROC 0.716; AUPRC 0.399), significantly outperforming the TCN transfer-learning model (AUROC 0.649; AUPRC 0.311). Isotonic calibration reduced expected calibration error by over 80% but did not alter discrimination. None of the ensemble methods surpassed the standalone Random Forest, and the gated network consistently assigned > 84% weight to the classical model. Permutation importances revealed critical mechanistic features related to sympathetic physiologic response. ConclusionsIn this head-to-head benchmark, interpretable classical models on expertly curated features matched or exceeded the performance of a complex deep learning approach, while offering superior computational efficiency and transparency. These findings underscore the importance of rigorous comparative evaluation before adopting high-complexity AI solutions in clinical practice. Data Availability StatementAll data was sourced from Subramanian et al. on PhysioNet under data usage agreement and proper citations in the manuscript. All code and analysis can be provided upon reasonable request. The authors plan to upload their code on GitHub. Competing Interests StatementThe authors declare no conflict of interests or financial stakes in this work. Funding DisclosuresThere is no funding to declare for this work.

BackgroundA growing body of literature suggests that intraoperative opioid administration can lead to both increased post-operative pain and opioid requirements. However, there has been minimal data regarding the effects of the intraoperative administration of intermediate duration opioids such as hydromorphone on post-operative outcomes. Causal inference using observational studies is often hampered by unmeasured confounding, where classical adjustment techniques, such as multivariable regression, are insufficient. Instrumental variable analysis is able to generate unbiased causal effect estimates in the presence of unmeasured confounding, assuming a valid instrumental variable can be found. We previously demonstrated, using a natural experiment, how hydromorphone presentation dose, i.e. the unit dose provided to the clinician, affects intraoperative administration dose, with the switch from a 2-mg to a 1-mg vial associated with decreased administration. As the change in hydromorphone presentation dose was unrelated to any external factors, presentation dose could serve as an instrumental variable to estimate the effect of intraoperative hydromorphone administration dose on post-operative outcomes. MethodsIn this observational study with 6,751 patients, an instrumental variable analysis was employed to estimate the causal effect of an increased intraoperative administration dose of hydromorphone on post-operative pain and opioid administration. The study population included patients who received intraoperative hydromorphone as part of an anesthetic at the University of California, Los Angeles, from October 2016 to November 2018. Before July 2017, hydromorphone was available as a 2-mg unit dose. From July 1, 2017 to November 20, 2017, hydromorphone was only available in a 1-mg unit dose. A two-stage least squares regression analysis was performed to estimate the effect of intraoperative hydromorphone administration dose on post-operative pain scores and opioid administration. ResultsAn increase in hydromorphone administration caused a statistically significant decrease in Post-Anesthesia Care Unit pain scores as well as maximum and mean pain scores on post-operative days one and two, without a statistically significant effect on post-operative opioid administration. Various sensitivity analyses support the validity of the instrumental variable assumptions and suggest that the results are robust against violations of these assumptions. ConclusionsThe results of this study suggests that the intraoperative administration of intermediate duration opioids do not cause the same effects as short acting opioids with respect to post-operative pain. Instrumental variables, when identified, can be invaluable in estimating causal effects using observation data whereby unmeasured confounding is likely present.

BackgroundPostoperative delirium (POD) is a common neurocognitive complication following major surgery, particularly in older adults and those undergoing liver resections. Neuroinflammatory mechanisms are considered central to its pathophysiology, yet molecular mediators remain poorly defined. Autoantibodies (aABs) targeting G protein-coupled receptors (GPCRs)--especially those relevant to neurotransmission--may contribute to POD by disrupting neuroimmune homeostasis. This study explored the perioperative dynamics of GPCR-specific aABs and their association with POD incidence. MethodsIn this secondary analysis of the PHYDELIO randomized controlled trial (ISRCTN18978802), we evaluated serum aAB levels targeting five GPCRs (M3R, M4R, {beta}2AR, D2R, and 5-HT2AR) in 142 patients undergoing liver surgery. Samples were collected preoperatively and on postoperative days 1, 2, and 7. POD was diagnosed using a comprehensive clinical assessment integrating validated screening tools and chart reviews. Repeated-measures ANOVAs examined time x group interactions, with additional post hoc and nonparametric tests applied as appropriate. ResultsSerum levels of four GPCR aABs (M3R, M4R, D2R, and 5-HT2AR) declined significantly following surgery and returned near baseline by day 7. {beta}2AR aAB levels remained stable. Patients who developed POD (45.8%) exhibited consistently lower aAB levels, reaching statistical significance for M3R (p = .029). No significant time x delirium interaction was found for any antibody. DiscussionMajor abdominal surgery transiently alters GPCR aAB levels, suggesting perioperative immune modulation or adsorption to tissue following disrupted barriers. Lower M3R aAB concentrations were associated with POD, aligning with proposed cholinergic involvement in its pathogenesis. While only M3R-specific effects reached significance, the consistent trend across aABs supports further investigation into their role as biomarkers or mediators of POD. Future studies should assess their functional activity and potential utility in risk stratification and therapeutic targeting.

BackgroundChronic subdural haematoma (cSDH) is a common neurosurgical condition, many patients have significant comorbidity or are living with frailty. Surgery is effective and can be performed under local anaesthesia (with or without sedation) or general anaesthesia. Optimal technique for both GA and LA is poorly defined but similar questions have been explored in other surgical settings. We sought to clarify the breadth of evidence for anaesthetic technique in cSDH surgery, while drawing on relevant literature from other disciplines to understand how a definitive trial of this question could be performed. Materials and MethodsWe used a combination of systematic and narrative literature search, review of trial registries, the Cochrane database, and a survey of anaesthetic and neurosurgical practitioners. An updated systematic review and meta-analysis of trial and observational studies in this area was performed following PROSPERO registration. ResultsWe identified a paucity of high-quality studies, especially randomised trials, exploring this question. The literature, and a survey of anaesthetists and surgeons, suggest that local anaesthesia may bring benefits in shorter hospital stay and reduced complications. Registered studies in this field are single centre in nature while a synthesis of Cochrane reviews in other fields echoes issues of equipoise, study design, and outcome choice as key challenges in designing a definitive trial. ConclusionsThere is significant interest in this topic as evidenced by published and emerging literature and views of anaesthetists and surgeons. No registered trial is multi-centre or draws on challenges identified in similar trials from other disciplines. Our paper helps create a roadmap to a definitive trial of this crucial question.

BackgroundMaintaining an open airway in a spontaneously-breathing patient under deep sedation, or deep monitored anaesthesia care, can be challenging. Specifically, current oral airways are not long enough to displace obstruction caused by redundant pharyngeal tissue, prompting external maneuvers by anesthetists that can impact patient outcomes and facility operational efficiency. As procedures increase at outpatient surgical centers, there is a need for an anesthesia provider-validated airway device that can sufficiently open an obstructed airway and maintain airway patency. MethodsThis prospective, multi-center user-experience survey evaluated anesthesia provider experience of a new airway device for adult patients with airway obstruction during deep sedation. The novel external airway has a longer flexible tubing allowing for displacement of pharyngeal tissue, smaller diameter to allow placement alongside an endoscopy bite block, and is manufactured with softer material to allow ease of insertion and patient comfort. ResultsFifty-four anaesthetists at 15 hospital systems reported their experience of airway use in 86 cases. The novel airway device was 95% successful in establishing and maintaining a patent airway (n=68). Survey responses indicated that the airway was easy to place (93%), allowed for a "hands-off approach" (98%), and would improve airway management practice and patient outcomes (86%). ConclusionsThis pilot study demonstrated that the novel external airway is an effective and satisfactory method for anaesthesia providers to alleviate airway obstruction during deep sedation. Additional studies will be initiated to confirm efficacy and cost-effectiveness in patient populations and clinical environments that will most benefit from the new airway device.

PurposeWe investigated if the use of peripheral nerve blockade (PNB) was associated with a lower incidence of prescription opioid fill within 30 days post-surgery and persistent postoperative opioid use (PPOU) in patients undergoing foot and ankle surgery. MethodsWe identified adults who had undergone foot or ankle surgery between 2012 and 2018 and did or did not receive PNB in an Optums de-identified Integrated Claims-Clinical dataset (n=12,643). Pharmacy data was used to track opioid prescription fill date and supply. PPOU was defined as >90 days of continuous opioid use. Entropy balancing was used to control differences in the distribution of covariates. Log-binomial models in unweighted and weighted data estimated crude and adjusted relative risk (RR) with 95% confidence intervals (CI) for the outcomes. ResultsOne-third of the sample filled an opioid within 30 days of surgery, and among these patients, 57.3% continued use for > 90 days. Performance of PNB was associated with an increased risk for filling opioid prescriptions within 30 days post-surgery before (RR=1.40; 95%CI:1.32-1.49) and after (RR=1.31; 95%CI:1.22-1.41; p<0.0001) controlling for confounding. However, the group that received a PNB showed significantly lower risk of PPOU before (0.91; 95%CI:0.85-0.98; p=0.016) and after controlling for confounding (RR=0.92; 95%CI:0.85-0.99; p=0.029). ConclusionPerformance of PNB for patients undergoing foot and ankle surgery was associated with a 31% increased risk of any opioid prescription fill within 30 days after surgery. However, among the patients that initially filled their prescriptions, patients that received PNB had a significantly (8%) lower risk for PPOU.

BackgroundChronic postsurgical pain after caesarean delivery affects 10-20% of women at 3-6 months postpartum, yet its broader impact on recovery is underexplored. This study examined lived experiences of chronic postsurgical pain and identified key domains of impact. MethodsTwenty-four women with self-reported pain at 3-6 months after intrapartum or planned caesarean delivery were recruited from two prospective studies. Semi-structured interviews, conducted in English or Spanish via secure video call, were transcribed and analysed using inductive reflexive thematic analysis. ResultsParticipants described a multidimensional, interconnected symptom burden. Pain persisted or worsened unpredictably, interfering with mobility, infant care, and daily life. Poor sleep and fatigue compounded distress. Cognitive and affective disruptions, including anxiety and fear, were common. Many avoided strong analgesics due to concerns about alertness or breastfeeding. Participants sometimes reported feeling dismissed or unsupported by healthcare professionals. Ten themes were identified: pain and sensory disruption; functional limitations and fatigue; interference with infant care and identity; psychological distress and cognitive load; sleep disruption; control and coping; intimacy and embodied recovery; healthcare gaps; peer and online normalisation; and reflections on future health. ConclusionsChronic pain after caesarean rarely occurs in isolation. Inter-related symptoms across sleep, pain, affect, cognition, and energy domains contribute to the lived experience of chronic caesarean delivery pain. These findings align with the multidomain SPACE-Postpartum framework, and support its further evaluation as a model for understanding and predicting postpartum pain outcomes. HighlightsO_LIChronic postsurgical pain (CPSP) after caesarean delivery is a multidimensional burden beyond pain intensity. C_LIO_LITen CPSP themes spanned physical, emotional, social, and care impacts. C_LIO_LISymptoms reinforced each other, compounding recovery challenges. C_LIO_LINarratives align with the SPACE (Sleep, Pain, Affect, Cognition, Energy) - Postpartum framework of domains. C_LI

BackgroundDelayed emergence from anaesthesia presents clinical challenges, including prolonged stays in the post-anaesthesia care unit (PACU). The neurobiological mechanisms underlying delayed emergence, particularly in remimazolam-induced anaesthesia, remain poorly understood. This study aimed to elucidate these mechanisms by comparing remimazolam and propofol anaesthesia, focusing on prefrontal electroencephalogram (EEG). MethodsPatients (age > 18, n = 48) underwent laparoscopic cholecystectomy randomly received remimazolam or propofol general anaesthesia. Power spectrogram analysis and functional connectivity measures, phase lag entropy (PLE) and phase lag index (PLI), were employed to the prefrontal EEG data collected at baseline, unconsciousness, and emergence. Correlation between EEG measures and Patient State Index (PSI) at PACU, as well as time to Aldrete 9, were compared. ResultsPSI values (P < 0.0001, P = 0.006) and time to Aldrete 9 at PACU (P < 0.001) revealed slower recovery in remimazolam-induced anaesthesia. Remimazolam group exhibited residual effects in power at theta (P = 0.018) and alpha (Ps < 0.001) bands and lower PLE during emergence in the alpha (P < 0.0001, P = 0.015) and beta (P = 0.016, P < 0.001) bands. Delayed consciousness recovery (time to Aldrete 9) under remimazolam was significantly correlated with PLE (Pearsons r = -.78, P < 0.0001), and PLI (Pearsons r = .69, P = 0.028) in the alpha band during deep anaesthesia. ConclusionDynamic changes in prefrontal EEG and the correlation analyses show the potential of EEG in predicting emergence speed, providing insights into the neurobiological mechanisms of short-term delayed emergence in remimazolam anaesthesia.

BackgroundEnhanced recovery in spinal surgery (ERSS) has shown promising improvements in clinical and economical outcomes. We have proposed an ERSS pathway based on societal recommendations and qualitative reviews. We aimed to delineate the clinical efficacy of individual pathway components in ERSS through a systematic narrative review. MethodsWe included systematic reviews and meta-analysis, randomized controlled trials, non-randomized controlled studies, and observational studies in adults and pediatric patients evaluating any one of the 22 pre-defined care components. Our primary outcomes included all-cause mortality, morbidity outcomes (e.g., pulmonary, cardiac, renal, surgical complications), patient-reported outcomes and experiences (e.g., pain, quality of care experience), and health services outcomes (e.g., length of stay and costs). We searched the following databases (1990 onwards) MEDLINE, EMBASE, and Cochrane Library (Cochrane Database of Systematic Reviews and CENTRAL). Two reviewers independently screened all citations, full-text articles, and abstracted data. A narrative synthesis was provided. Where applicable, we constructed Evidence Profile (EP) tables for each individual element. Due to clinical and methodological heterogeneity, we did not conduct a meta-analyses. Confidence in cumulative evidence for each component of the pathway was classified according to the GRADE system. ResultsWe identified 5423 relevant studies excluding duplicates as relating to the 22 pre-defined components of enhanced recovery in spinal surgery. We included 664 studies in the systematic review. We found specific evidence within the context of spinal surgery for 14/22 proposed components. Evidence was summarized in EP tables for 12/22 components. We performed thematic synthesis without EP for 6/22 elements. We identified appropriate societal guidelines for the remainder of the components. DiscussionWe identified the following components with high quality of evidence as per GRADE system: pre-emptive analgesia, peri-operative blood conservation (antifibrinolytic use), surgical site preparation and antibiotic prophylaxis. There was moderate level of evidence for implementation of prehabilitation, minimally invasive surgery, multimodal perioperative analgesia, intravenous lignocaine and ketamine use as well as early mobilization. This review allows for the first formalized evidence-based unified protocol in the field of ERSS. Further studies validating the multimodal ERSS framework are essential to guide the future evolution of care in patients undergoing spinal surgery.

BackgroundBoth basic and clinical consciousness research aims to find objective measures that reliably distinguish conscious from unconscious brain states. Electroencephalogram (EEG) measures are widely used, although they may be contaminated by electrical signals from muscles. MethodsTo assess this source of error, we investigated the impact of neuromuscular blockade (NMB) on proposed measures of consciousness (spectral slope, Lempel-Ziv complexity (LZc), connectivity, alpha peak frequency, power in canonical EEG frequency bands) computed from spontaneous high-density EEG recorded from six healthy volunteers in three different conditions: (1) awake-unparalysed, (2) awake-paralysed caused by neuromuscular blocking agent (NMBA), and (3) sedated-paralysed (sedated with propofol, paralysed by NMBA, (un)consciousness non-confirmable). ResultsThe markers we investigated distinguished awake-unparalysed states from sedated-paralysed with close to perfect accuracy. Our analysis revealed a serious failure of all measures, except alpha power, to recognise awake-paralysed, without sedation, as an aware state. Errors ranged from 19% of awake-paralysed time segments predicted as unaware (using spectral slope) to 100% (using LZc). Using alpha power, only 1% of all awake-paralysed segments were misclassified. Critically, the awake-paralysed is the state that is important to detect in sedated-paralysed patients, to prevent the experience of accidental awareness during general anaesthesia (AAGA). ConclusionsThis study clearly demonstrates that many EEG-based measures fail to recognise awareness in awake-paralysed subjects, by using a unique high-density EEG data set. Alpha power was determined to be the most robust measure to detect AAGA, but this may not generalise to all types of general anaesthetic agents.