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AbstractObjectiveTo evaluate tumor control and facial nerve outcomes after gross‐total (GTR), near‐total (NTR), and subtotal resection (STR) of sporadic vestibular schwannomas (VS).Data SourcesPubMed, Cochrane Central Register of Controlled Trials, Web of Science, and Scopus databases were searched in August 2021 through inception following PRISMA guidelines.Review MethodsEnglish language articles reporting tumor control and facial nerve outcomes of adults (≥18 years) with NTR and STR of VS were evaluated. Study characteristics, demographics data, tumor characteristics, type of surgical intervention, and outcome measures on tumor control and facial nerve function were collected. Pooled relative risk (RR) estimates for tumor recurrence and facial nerve outcomes were calculated and stratified by extent of resection.ResultsFrom an initial search of 2504 articles, 48 studies were included in the analysis. When comparing 1108 patients who underwent NTR to 3349 patients with GTR, the pooled RR of recurrence in the NTR cohort was 2.94 (95% confidence interval [CI] 1.65‐5.24, P = .0002). When comparing 1016 patients who underwent STR to 6171 patients with GTR, the pooled RR of recurrence in the STR cohort was 11.50 (95% CI 6.64‐19.92, P < .0001). Estimates for risk of tumor regrowth for less‐than‐complete resection are presented. There was no elevated risk of adverse facial nerve outcome (defined as House‐Brackmann grade III and above) in each category of extent of resection compared to GTR.ConclusionExtent of resection predicts risk of tumor recurrence/regrowth following microsurgical resection. Favorable facial nerve outcome should be weighed against the increased risk of regrowth and the potential need for further treatment.

Extracorporeal membrane oxygenation (ECMO) is often used in acute respiratory distress syndrome (ARDS) with refractory hypoxemia. There is limited literature highlighting the development of right ventricular (RV) failure while on ECMO. We conducted a retrospective multicenter observational study including 70 patients who were placed on veno-venous (VV)-ECMO for respiratory failure at Mayo Clinic, Jacksonville, and Mayo Clinic, Rochester, between January 2018 and June 2022 and had at least two post-ECMO transthoracic echoes. The primary outcomes were the incidence and progression of RV dysfunction and dilatation. The secondary outcome was in-patient mortality. Among 70 patients in our cohort, 60.6% had a normal RV function at the time of ECMO placement, whereas only 42% had a normal RV function at the second post-ECMO echo. On multinomial regression, a moderate decrease in RV function was associated with ECMO flow (odds ratio [OR] = 2.32, p = 0.001) and ECMO duration (OR = 1.01, p = 0.01). A moderately dilated RV size was also associated with ECMO flow (OR = 2.62, p < 0.001) and ECMO duration (OR = 1.02, p = 0.02). An increasing degree of RV dysfunction was associated with worse outcomes. Our study showed that the increasing duration and flow of VV-ECMO correlated with progressive RV dilatation and dysfunction, which were associated with poor survival.

Background: Despite growing interest in delivering high-value orthopaedic care, the costs associated with hip arthroscopy remain poorly understood. By employing time-driven activity-based costing (TDABC), we aimed to characterize the cost composition of hip arthroscopy for labral pathological conditions and to identify factors that drive variation in cost. Methods: Using TDABC, we measured the costs of 890 outpatient hip arthroscopy procedures for labral pathological conditions across 5 surgeons at 4 surgery centers from 2015 to 2022. All patients were ≥18 years old and were treated by surgeons who each performed ≥20 surgeries during the study period. Costs were normalized to protect the confidentiality of internal hospital cost data. Descriptive analyses and multivariable linear regression were performed to identify factors underlying cost variation. Results: The study sample consisted of 515 women (57.9%) and 375 men (42.1%), with a mean age (and standard deviation) of 37.1 ± 12.7 years. Most of the procedures were performed in patients who were White (90.6%) or not Hispanic (93.4%). The normalized total cost of hip arthroscopy per procedure ranged from 43.4 to 203.7 (mean, 100 ± 24.2). Of the 3 phases of the care cycle, the intraoperative phase was identified as the largest generator of cost (>90%). On average, supply costs accounted for 48.8% of total costs, whereas labor costs accounted for 51.2%. A 2.5-fold variation between the 10th and 90th percentiles for total cost was attributed to supplies, which was greater than the 1.8-fold variation attributed to labor. Variation in total costs was most effectively explained by the labral management method (partial R 2 = 0.332), operating surgeon (partial R 2 = 0.326), osteoplasty type (partial R 2 = 0.087), and surgery center (partial R 2 = 0.086). Male gender (p < 0.001) and younger age (p = 0.032) were also associated with significantly increased costs. Finally, data trends revealed a shift toward labral preservation techniques over debridement during the study period (with the rate of such techniques increasing from 77.8% to 93.2%; P trend = 0.0039) and a strong correlation between later operative year and increased supply costs, labor costs, and operative time (p < 0.001 for each). Conclusions: By applying TDABC to outpatient hip arthroscopy, we identified wide patient-to-patient cost variation that was most effectively explained by the method of labral management, the operating surgeon, the osteoplasty type, and the surgery center. Given current procedural coding trends, declining reimbursements, and rising health-care costs, these insights may enable stakeholders to design bundled payment structures that better align reimbursements with costs. Level of Evidence: Economic and Decision Analysis Level IV . See Instructions for Authors for a complete description of levels of evidence.

Background. Anesthesia providers categorize patients utilizing the American Society of Anesthesiologists Physical Status (ASA-PS) classification originally created by the ASA in 1941. There is published variability and discordance among providers when assigning patient ASA scores in part due to the subjectivity of scoring utilizing patient medical conditions, but variability is also found using objective findings like BMI. To date, there are few studies evaluating the accuracy of anesthesia providers’ ASA assignment based on objective body mass index (BMI) alone. The aim of this retrospective chart review is to determine improvement in accuracy of anesthesia providers to correctly assign patient ASA scores, based on BMI criteria added to the ASA-PS in October of 2014, utilizing a multifaceted strategy including creation of an active finance committee in the fall of 2015, multiple e-mail communications about the updated definitions and recommendations for ASA-PS scoring in the fall of 2015 and spring of 2016, a department grand rounds presentation in February 2016, placement of laminated copies of the ASA definitions and recommendations in the anesthesia chartrooms, and the development of a tool embedded into our EMR providing a recommendation of ASA-PS based on patient comorbidity findings. Methods. After attaining IRB approval, all eligible patients over the age of 18 who had surgical procedures under general anesthesia at Mayo Clinic in Rochester, MN, between January 1, 2010, and December 31, 2020, were retrospectively analyzed. A segmented logistic regression model was used to estimate the trends (per-year change in odds) of ASA under classification according to severity of obesity during 3 epochs: preimplementation (2010–2014), implementation (2015), and postimplementation (2016–2020). Results. A total of 16,467 patients of the 200,423 (8.2%) patients with obesity (class 1, 2, and 3) were underscored based on BMI alone. Accuracy of ASA-PS classification, as it pertains to BMI alone, was found to show meaningful improvement year-to-year following the updated ASA-PS guidelines with examples released in October of 2014 (P<0.001). Most of the improvement occurred in 2015–2017 with relatively little between-year variability in the rate of underscoring from 2017–2020. Conclusion. Despite updated ASA-PS published guidelines, providers may still be unaware of the updated guidelines and inclusion of examples used within the ASA-PS classification system. Accuracy of scoring did improve annually following the release of the updated guidelines with examples as well as department-wide educational activities on the topic. Additional education and awareness should be offered to those responsible for preanesthesia evaluation and assignment of ASA-PS in patients to improve accuracy as it pertains to BMI.

This study aimed to investigate the impact of central α2-adrenergic mechanisms on arterial baroreflex control of sympathetic and cardiovagal outflow in healthy humans. R-R interval (ECG), blood pressure (brachial arterial catheter), and muscle sympathetic nerve activity (MSNA; peroneal microneurography) were measured in eight healthy participants (5 females; 28±7 years). Sympathetic action potentials (AP) were extracted from the filtered MSNA neurogram (continuous wavelet transform) during a 5-minute baseline (BSL) and an intravenous dexmedetomidine infusion consisting of a loading dose (LD; 10 minutes at 0.225 μg/kg/hr) and a maintenance dose (MD; ~0.15 μg/kg/hr). Sympathetic AP baroreflex threshold gain was measured as the slope of the linear relationship between AP discharge probability and diastolic blood pressure. The linear relationship between R-R interval and systolic blood pressure (sequence technique) quantified cardiovagal baroreflex gain. Mixed-effects analyses and post-hoc t-tests were performed. Data are reported as mean ± SD. Dexmedetomidine reset the baroreflex threshold operating points for all sympathetic AP clusters downwards to lower firing probabilities (cluster 4; BSL: 20±6, LD: 13±8, MD: 6±5%, both p<0.01 vs. BSL) and leftwards to lower diastolic pressures (BSL: 72±9, LD: 69±8, MD: 65±10 mmHg, both p<0.01 vs. BSL). Dexmedetomidine reduced baroreflex threshold gain for the subpopulation of medium-sized sympathetic APs (cluster 4; BSL: -6.5±2.0, LD: -2.6±1.6, MD: -2.0±0.7 %/mmHg, both p<0.01 vs. BSL). Dexmedetomidine did not affect baroreflex threshold gain of small (cluster 1; BSL: -1.9±1.1, LD: -1.3±1.6, MD: -1.1±0.8 %/mmHg, both P>0.88 vs. BSL) or large AP clusters (cluster 9; BSL: -0.8±0.4, LD: -0.8±1.0, MD: -0.2±0.7 %/mmHg, both P>0.98 vs. BSL). Dexmedetomidine reset the cardiovagal baroreflex to lower systolic pressures but did not affect R-R interval (BSL: 1035±261, LD: 1025±308, MD: 1005±292ms, Main effect P=0.45) or gain (BSL: 24±11, LD: 30±20, MD: 26±25 ms/mmHg, Main effect P=0.63). These findings suggest that central α2-adrenergic mechanisms differentially affect arterial baroreflex control of sympathetic and cardiovagal outflow in humans by minimally affecting cardiovagal baroreflex gain but strongly affecting the baroreflex gain for the subpopulation of medium-sized sympathetic APs. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the National Institutes of Health (NIH). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

This study investigated the impact of integrated muscle sympathetic nerve activity (MSNA) discharge patterns on human neurocirculatory regulation. In 13 healthy females (42 ± 15 years), the transduction of integrated MSNA (peroneal microneurography) into mean arterial pressure (MAP; arterial catheter) was studied during an intravenous infusion of a nicotinic ganglionic antagonist (trimethaphan camsylate, 1-7 mg/min). Neurovascular transduction (signal averaging) was studied based on the overall response, burst sequence (singlet, doublet, and triplet+), and burst amplitude (binned into tertials: small, medium, and large bursts). Data (mean ± SD) are reported for a 10-minute baseline (BSL), the one-minute period at the midpoint of the trimethaphan infusion with integrated MSNA bursts (TM-Mid), and the last minute of trimethaphan infusion with integrated MSNA bursts (TM-Last). During BSL, the MAP transduction responses were greatest for triplets+ (singlets: 0.9 ± 0.2 mmHg, doublets: 2.0 ± 0.6 mmHg, triplet+: 2.6 ± 0.9 mmHg; P < 0.01) and large bursts (small: 1.0 ± 0.3 mmHg, medium: 1.7 ± 0.5 mmHg, large: 2.2 ± 0.7 mmHg; P < 0.01). Trimethaphan infusion reduced integrated MSNA burst frequency resulting in a greater proportion of singlets (BSL: 45 ± 18 %, TM-Mid: 75 ± 23 %, TM-Last: 94 ± 20 %; P < 0.01), a lower proportion of doublets, and a lower proportion of triplets+ (BSL: 23 ± 19 %, TM-Mid: 9 ± 18 %, TM-Last: 0 ± 0 %; P < 0.01). Trimethaphan infusion reduced integrated MSNA burst amplitude resulting in a greater proportion of small bursts (BSL: 33 ± 0.2 %, TM-Mid: 60 ± 26 %, TM-Last: 78 ± 37 %; P < 0.01), a lower proportion of medium bursts, and a lower proportion of large bursts (BSL: 34 ± 1 %, TM-Mid: 17 ± 26 %, TM-Last: 1 ± 5 %; P < 0.01). Trimethaphan-mediated changes in MSNA burst frequency and amplitude were associated with reduced overall MAP transduction responses (BSL: 1.6 ± 0.5 mmHg, TM-Mid: 0.5 ± 0.2 mmHg, TM-Last: 0.3 ± 0.3 mmHg; P < 0.01). Linear regression analyses demonstrated that the trimethaphan-mediated reduction in the proportion of large bursts ( β = 0.02 ± 0.008 mmHg/%, R2 = 0.13, P = 0.03) more strongly affected sympathetic neurovascular transduction responses than reductions in the proportion of triplet+ burst sequences (P = 0.91). These findings suggest that time varying MSNA discharge patterns, particularly variations in burst amplitude, support human neurocirculatory regulation. This work was supported by the National Institutes of Health and the Natural Sciences and Engineering Research Council of Canada. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Background. Minority race, ethnicity, and financial barriers are associated with lower rates of living donor (LD) kidney transplantation (LDKT). Financial reimbursement for LD costs may impact social determinants of health and, therefore, impact disparities in access to LDKT. Methods. Among US LDKTs, we studied associations between racial and ethnic minority status and utilization of the National Living Donor Assistance Center (NLDAC), a means-tested reimbursement program for nonmedical LD costs. We analyzed demographic, clinical, income, and survey data from NLDAC and the Scientific Registry of Transplant Recipients (January 1, 2011, to December 31, 2022) to identify predictors of NLDAC utilization. Results. Among 70 069 US LDKTs, 6093 NLDAC applicants were identified (9% of US LDKTs). Racial and ethnic minorities were over-represented in NLDAC-supported LDKTs compared with non-NLDAC US LDKTs (Black donors 12% versus 9%; Black recipients 15% versus 12%; Hispanic donors 21% versus 14%; Hispanic recipients 23% versus 15%; all P < 0.001). Among preemptive transplants, use of NLDAC by donors to Hispanic recipients (11%) was nearly twice as high as that of non-Hispanic recipients (6%) (P < 0.001). At time of NLDAC application, 72% stated NLDAC “will make it possible” to donate; higher proportions of minority applicants agreed (Black 80%, White 70%, P < 0.001; Hispanic 79%, non-Hispanic 70%, P < 0.001). Racial and ethnic minority-concordant transplants were significantly more likely to use NLDAC (donor/recipient: Black/Black risk-adjusted odds ratio [OR], 1.85, other/other OR 2.59, Hispanic/Hispanic OR 1.53; all P < 0.05). Conclusions. Reduction of LD financial barriers may increase access to LDKT, particularly in racial and ethnic minority communities.

Purpose To (1) analyze trends in the publishing of statistical fragility index (FI)–based systematic reviews in the orthopaedic literature, including the prevalence of misleading or inaccurate statements related to the statistical fragility of randomized controlled trials (RCTs) and patients lost to follow‐up (LTF), and (2) determine whether RCTs with relatively “low” FIs are truly as sensitive to patients LTF as previously portrayed in the literature. Methods All FI‐based studies published in the orthopaedic literature were identified using the Cochrane Database of Systematic Reviews, Web of Science Core Collection, PubMed, and MEDLINE databases. All articles involving application of the FI or reverse FI to study the statistical fragility of studies in orthopaedics were eligible for inclusion in the study. Study characteristics, median FIs and sample sizes, and misleading or inaccurate statements related to the FI and patients LTF were recorded. Misleading or inaccurate statements—defined as those basing conclusions of trial fragility on the false assumption that adding patients LTF back to a trial has the same statistical effect as existing patients in a trial experiencing the opposite outcome—were determined by 2 authors. A theoretical RCT with a sample size of 100, P = .006, and FI of 4 was used to evaluate the difference in effect on statistical significance between flipping outcome events of patients already included in the trial (FI) and adding patients LTF back to the trial to show the true sensitivity of RCTs to patients LTF. Results Of the 39 FI‐based studies, 37 (95%) directly compared the FI with the number of patients LTF. Of these 37 studies, 22 (59%) included a statement regarding the FI and patients LTF that was determined to be inaccurate or misleading. In the theoretical RCT, a reversal of significance was not observed until 7 patients LTF (nearly twice the FI) were added to the trial in the distribution of maximal significance reversal. Conclusions The claim that any RCT in which the number of patients LTF exceeds the FI could potentially have its significance reversed simply by maintaining study follow‐ups is commonly inaccurate and prevalent in orthopaedic studies applying the FI. Patients LTF and the FI are not equivalent. The minimum number of patients LTF required to flip the significance of a typical RCT was shown to be greater than the FI, suggesting that RCTs with relatively low FIs may not be as sensitive to patients LTF as previously portrayed in the literature; however, only a holistic approach that considers the context in which the trial was conducted, potential biases, and study results can determine the merits of any particular RCT. Clinical Relevance Surgeons may benefit from re‐examining their interpretation of prior FI reviews that have made claims of substantial RCT fragility based on comparisons between the FI and patients LTF; it is possible the results are more robust than previously believed.