[Coin tossing: Development of a computerized test to assess cognitive flexibility in older adults]. / Lanzando la moneda. Desarrollo de una prueba informática para evaluar la flexibilidad cognitiva en las personas mayores.

BACKGROUND: The aging population is increasing. Aging has been associated with some degree of cognitive decline, especially in functions such as cognitive flexibility. The voluntary task-switching paradigm is a novel model for studying this function. The aim of this work was to design and test a computerized instrument to assess cognitive flexibility with this paradigm. METHODS: A non-probabilistic and intentional sample of individuals aged 60 and above (N=57; M=70; SD=7.5), 72% of whom were women, was utilized. A general cognitive screening test (ACE III) and the "Coin Tossing" task, a computerized program consisting of four levels of complexity, were administered. RESULTS: A Wilcoxon test was used to contrast parity versus size responses (z(56)=-1.16, P=.24). To assess repetition bias, a Wilcoxon test was conducted between new and repeated responses (TR: z(56)=-1.81, P=.07 // Accuracy: z(56)=-6.33, P=.00). A repeated measures ANOVA was performed between reaction times before, during, and after a response change, F(1.02)=59.6, P<.01, η2=.937, B-1=1. And a repeated measures ANOVA between mean RTs per level, F(3)=7.92, P<.001, η2=.128, B-1=.98. CONCLUSIONS: The test was designed with a progressive structure across levels. The theoretical assumptions of the paradigm were partially demonstrated, showing its utility for the assessment and training of cognitive flexibility.

Global challenges in aging: insights from comparative biology and one health.

The well-being of wildlife populations, ecosystem health, and human health are interlinked, and preserving wildlife is crucial for sustaining healthy ecosystems. Wildlife numbers, and in particular avian populations, have steeply declined over the past century, associated with anthropogenic factors originating from industry, urbanization, changing land use, habitat loss, pollution, emerging diseases, and climate change. All these factors combine to exert increasing stress and impair health for both humans and wildlife, with diminished metabolic, immune, and reproductive function, deteriorating overall health, and reduced longevity. The "toxic aging coin" suggests that these stressors may have dual impacts on aging-they can accelerate the aging process, and older individuals may struggle to cope with pollutants compared to younger ones. These responses are reflected in the health and productivity of individuals, and at a larger scale, the health and ability of populations to withstand disturbances. To understand the potential risk to health over the lifespan, it is important to articulate some of these global challenges and consider both their impacts on aging populations and on the aging process. In this review, we use the toxic aging coin and One Health conceptual frameworks to examine the interconnected health of humans, wildlife, and ecosystems. This exploration aims to develop proactive approaches for optimizing wildlife and human health.

Determining the Maximum Tolerable Concentration of Ropivacaine to Maintain Sensation of the Nerve Root in Percutaneous Endoscopic Transforaminal Lumbar Discectomy: Can Epidural Anaesthesia Achieve Pain-Tactile Separation Block to Avoid Nerve Injury?

Introduction: Nerve injury is a serious complication of percutaneous endoscopic transforaminal lumbar discectomy due to nerve root contact. The maximum tolerable concentration (MTC) of ropivacaine concentration for epidural anaesthesia, is defined as the concentration that minimises pain while preserving the sensation of the nerve roots. This distinct advantage allows the patient to provide feedback to the surgeon when the nerve roots are contacted. Methods: We used a biased-coin design to determine the MTC, which was estimated by the 10% effective concentration (EC10), ie, the concentration at which 10% of patients lost sensation in the nerve roots. The determinant for positive response was lack of sensory feedback upon contact with the nerve root, and the feedback from occurrence of sensations in the innervation area upon contact with the nerve root was defined as a negative response. Primary outcome was the response from contact nerve root. Secondary outcomes were the type and number of statements of negative response and each patient's pain score during surgery. Results: Fifty-four patients were included in this study. The EC10 was 0.434% (95% CI: 0.410%, 0.440%) using isotonic regression in comparison with 0.431% (95% CI: 0.399%, 0.444%) using probit regression. Three type statements of negative response were reported including "tactile sensation", radiculalgia, and numbness. Conclusion: The MTC of ropivacaine used for epidural anaesthesia was 0.434% to avoid nerve injury in percutaneous endoscopic transforaminal lumbar discectomy.

Employing a Toxic Aging Coin approach to assess hexavalent chromium (Cr[VI])-induced neurotoxic effects on behavior: Heads for age differences.

We are facing a rapidly growing geriatric population (65+) that will live for multiple decades and are challenged with environmental pollution far exceeding that of previous generations. Consequently, we currently have a poor understanding of how environmental pollution will impact geriatric health distinctly from younger populations. Few toxicology studies have considered age differences with geriatric individuals. Critically, all top ten most prevalent age-related diseases are linked to metal exposures. Hexavalent chromium [Cr(VI)] is a metal of major environmental health concern that can induce aging phenotypes and neurotoxicity. However, there are many knowledge gaps for Cr(VI) neurotoxicity, including how Cr(VI) impacts behavior. To address this, we exposed male rats across three ages (3-, 7-, and 18-months old) to Cr(VI) in drinking water (0, 0.05, 0.1 mg/L) for 90 days. These levels reflect the maximum contaminant levels determined by the World Health Organization (WHO) and the U.S. Environmental Protection Agency (US EPA). Here, we report how these Cr(VI) drinking water levels impacted rat behaviors using a battery of behavior tests, including grip strength, open field assay, elevated plus maze, Y-maze, and 3-chamber assay. We observed adult rats were the most affected age group and memory assays (spatial and social) exhibited the most significant effects. Critically, the significant effects were surprising as rats should be particularly resistant to these Cr(VI) drinking water levels due to the adjustments applied in risk assessment from rodent studies to human safety, and because rats endogenously synthesize vitamin C in their livers (vitamin C is a primary reducer of Cr[VI] to Cr[III]). Our results emphasize the need to broaden the scope of toxicology research to consider multiple life stages and suggest the current regulations for Cr(VI) in drinking water need to be revisited.

Coin-cidence? Have cashless payments reduced the incidence of upper aerodigestive foreign body insertion? A study of UK Hospital Episode Statistics.

OBJECTIVES: Insertions of nasal and oral foreign bodies (FB) are common presentations in the emergency department, with coins frequently implicated among paediatric populations. Contactless payments were first introduced in the UK in 2007, and cash payments significantly declined from 2012. This study aims to explore the potential implications of increasing contactless payments on FB ingestion. METHODS: UK Hospital Episode Statistics (HES) were reviewed between 2000 and 2022. All FB retrieval procedures involving the alimentary tract, respiratory tract and nasal cavity were included. Regression analysis was performed to assess trends in the incidence of FB ingestion before and following the transition to cashless payments in 2012. RESULTS: Following the decline in cash payments in 2012, the frequency of alimentary tract FB removal procedures decreased significantly by 27.78 procedures per year (p < 0.001). Similarly, respiratory FB removal procedure decreased by 4.83 per year (p = 0.009) and nasal cavity FB removal procedures decreased by 52.82 per year (p < 0.001). CONCLUSIONS: This study suggests a statistically significant decline in the number of procedures for removal of FB performed in the UK from 2012. Although this relationship is multifactorial, our data suggest an association between the introduction of contactless payments and a reduction in the number of FB retrieval procedures from the of upper aerodigestive tract.

Pulmonary presentation and coil marcation of dirofilaria lung coin nodes - case report.

Clinicians face significant diagnostic challenges when dealing with nodal lesions of the lung. The majority of lung nodules are benign; however, a significant number can be cancerous. Dirofilaria infestation should also be considered in the differential diagnosis of nodal lung lesions. Most patients with Dirofilaria infestation are asymptomatic. To determine the etiology of nodal lung infiltrations, procedures like radiological imaging, bronchoscopy, endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA), transthoracic biopsy (TTB), tumor markers, nonspecific serological tests, or surgical removal of the lung coin lesions can be performed. Coil marking of the smaller lung lesions under computed tomography (CT) guidance is a helpful tool in determining the position and localization of the nodal lung lesions. Video-assisted thoracoscopic surgery (VATS) or robot-assisted thoracoscopic surgery (RATS) wedge resection is a diagnostic and therapeutic method of choice. No additional treatment of Dirofilaria other than wedge resection of the lung is necessary.

Emerging human pulmonary dirofilariasis in Hungary: a single center experience.

BACKGROUND: Human pulmonary dirofilariasis (HPD) is rare in Hungary, and it stems from Dirofilaria immitis, mainly transmitted through mosquito bites, with dogs as primary hosts. Despite its prevalence in veterinary settings, human cases are infrequent. Historically, Mediterranean countries report most HPD cases, but sporadic cases occur in temperate European regions. Radiologically, HPD often manifests in a non-specific manner, resembling pulmonary neoplasms, leading to unnecessary surgery and patient distress. METHODS: This study presents a notable case series from Hungary, encompassing a 12-year period, documenting 5 instances of HPD with the aim to provide baseline estimate of occurrence for future comparison. RESULTS: Among the patients studied, all were of middle age (median: 52 years, range: 37-69) and exhibited tumor-like lesions, primarily localized to the right lung, necessitating lobectomy or wedge resection. Histological examination consistently revealed a necrotizing granulomatous response characterized by remnants of helminths, without the presence of ovules. Furthermore, rigorous diagnostic procedures excluded other potential infectious agents through specialized staining techniques. Polymerase chain reaction analysis definitively confirmed the diagnosis of HPD in each case. CONCLUSIONS: This case series highlights HPD as a seldom zoonosis, with a probable escalation in its occurrence within temperate regions. Therefore, clinicians should maintain a heightened awareness of HPD in the differential diagnosis of pulmonary coin lesions. Early recognition and diagnosis are paramount for appropriate management and prevention of potential complications associated with this increasingly recognized infectious entity.

Colour-dependent dishonesty in a game of chance.

We report an odd result of a coin-flip experiment which incentivises dishonest behaviour. Participants of two treatments were asked to flip a coin in private, of which one side was WHITE and the other side BLACK, and report the colour shown by the coin. Payoff depended on the reported colour: in one treatment WHITE was the more profitable outcome whereas in the other treatment BLACK was more profitable. Surprisingly, the magnitude of cheating, as reflected by the difference between the frequency of reporting the more profitable colour and its statistical expectation (50%) was not, more or less, the same in both treatments. Rather, significantly more participants cheated when BLACK was the profitable outcome. This result reappeared in two variants of the coin-flip task. We suggest that a sense of entitlement triggered by a WHITE outcome may explain this behaviour.

Robustness of response-adaptive randomization.

Doubly adaptive biased coin design (DBCD), a response-adaptive randomization scheme, aims to skew subject assignment probabilities based on accrued responses for ethical considerations. Recent years have seen substantial advances in understanding DBCD's theoretical properties, assuming correct model specification for the responses. However, concerns have been raised about the impact of model misspecification on its design and analysis. In this paper, we assess the robustness to both design model misspecification and analysis model misspecification under DBCD. On one hand, we confirm that the consistency and asymptotic normality of the allocation proportions can be preserved, even when the responses follow a distribution other than the one imposed by the design model during the implementation of DBCD. On the other hand, we extensively investigate three commonly used linear regression models for estimating and inferring the treatment effect, namely difference-in-means, analysis of covariance (ANCOVA) I, and ANCOVA II. By allowing these regression models to be arbitrarily misspecified, thereby not reflecting the true data generating process, we derive the consistency and asymptotic normality of the treatment effect estimators evaluated from the three models. The asymptotic properties show that the ANCOVA II model, which takes covariate-by-treatment interaction terms into account, yields the most efficient estimator. These results can provide theoretical support for using DBCD in scenarios involving model misspecification, thereby promoting the widespread application of this randomization procedure.

Preventing aspiration incidents: redesigning inhalers for enhanced safety: A case study of coin aspiration.

The conventional metered dose inhaler (MDI) has long served as a cornerstone in the management of asthma and chronic obstructive pulmonary disease (COPD), affecting millions annually. Despite its advantages, a persistent challenge is seen in the form of patient education and the unchanged design of these inhalers since their inception in 1956. This lack of progress in MDI design has inadvertently contributed to incidences of foreign body inhalation. In this case presentation we report a 50-year-old male with a past medical history of asthma, who faced an incident of foreign body inhalation with use of his inhaler. The patient aspirated a dime when he administered his inhaler, as it had become lodged in the device's mouthpiece, which was uncapped. This case, like many others, demonstrates the need for innovative changes in MDI inhaler design. While numerous articles or cases concentrate on foreign body removal, the primary objective of this case report is to investigate preventative measures and solutions aimed at averting incidents of inhalation.

Mycotic aortic aneurysms: characteristic macroscopic findings in a case series.

Infected or mycotic aortic aneurysms (MAAs) are a rare type of aneurysms. Due to the high risk of rupture, MAAs are life-threatening conditions. Early diagnosis and treatment are necessary, yet MAAs are usually found coincidentally. We report 10 patients with MAAs in whom macroscopically, similar coined-sized lesions of the inner aortic wall were seen in all cases. When a coin-sized lesion in the inner aortic wall is seen during open surgical repair of an aortic aneurysm, the surgeon should consider an infectious cause. Microbiological tissue samples should be collected, and additional targeted antibiotic therapy should be started.

An inexpensive "do-it-yourself" device for rapid generation of uniform tumor spheroids.

Three-dimensional (3D) cancer cell culture models such as tumor spheroids better recapitulate in vivo tumors than conventional two-dimensional (2D) models. However, two major challenges limit the routine use of 3D tumor spheroids. Firstly, most existing methods of generating tumor spheroids are not high-throughput. Secondly, tumor spheroids generated using current methods are highly variable in dimension. Here, we describe a simple 'Do-It-Yourself (DIY)' device that can be assembled for less than $7 of parts and generate uniform tumor spheroids in a high-throughput manner. We used a simple phone coin vibrating motor to superimpose the vibration for breaking a laminar jet of cell-loaded alginate solution into equally sized spherical beads. We generated 3,970 tumor spheroids/min, which exhibited a hypoxic core recapitulating in vivo tumors and could be used to test the diffusion efficacy of anticancer drugs. Such low-cost, easy-to-fabricate, simple-to-operate systems with high-throughput outcomes are essential to democratize and standardize cancer research.

The image dataset of Indian coins: A machine learning approach for Indian currency.

In an increasingly digital world, the significance of creating a Comprehensive Image Dataset of Contemporary Indian Coins (CIDCIC) cannot be overstated. This research presents a dataset comprising 6,672 images of 53 different classes of Indian coins, including denominations of 25 Paisa, 50 Paisa, 1 Rupee, 2 Rupee, 5 Rupee, 10 Rupee, and 20 Rupee. The images of coins with various shapes and sizes are taken from obverse and reverse sides in various environments and different backgrounds. The core significance of this dataset unfolds in its potential to offer invaluable assistance to visually impaired individuals as they navigate their daily financial transactions. The dataset is a significant contribution to the domains of computer vision, artificial intelligence, and machine learning, specifically addressing the challenges related to coin detection, recognition, and monetary system integrity. These technologies can empower visually impaired individuals to independently and accurately recognize and distinguish between various coin denominations, thereby enhancing their participation in the financial realm. The dataset addresses limitations in existing dataset of having limited size, and scope. It addresses the limitations associated to the limited number of coins and the lack of diversity in images, encompassing various angles, environments, backgrounds, and directions of coins. The dataset provides a broader and more up-to-date representation of contemporary Indian coins.

A Retrospective Analysis of Foreign Body Ingestions Among the Pediatric Age Group in a Tertiary Care Hospital in Jeddah, Saudi Arabia.

BACKGROUND: Foreign body ingestion (FBI) among the pediatric age group is considered a major clinical problem that can cause life-threatening complications, as it can obstruct the airway due to poor/immature airway protection reflexes. OBJECTIVE: In this study, we aimed to retrospectively describe the epidemiology, clinical characteristics, and outcomes of FBI among the pediatric age group in Dr. Soliman Fakeeh Hospital, Jeddah, Saudi Arabia. METHODS: We conducted a retrospective study of pediatric patients (0-14 years) presenting to a tertiary care hospital in Jeddah, Saudi Arabia, from January 2019 to October 2022. The study reviewed records of patients with FBI in the emergency department. Data collection included age, gender, comorbidities, foreign body (FB) type, anatomical location, presenting symptoms, time to emergency room (ER) presentation, need for endoscopy, and complications. We performed a statistical analysis using the Statistical Package for Social Sciences (SPSS) 25 (IBM SPSS Statistics, Armonk, NY), where p<0.05 was considered statistically significant. RESULTS: We identified 244 FBI cases, with most cases being male (62.7%). The most common site of FB impaction was the stomach (38.9%), followed by the upper esophagus (29.1%). Clinical presentation was variable, with 20.5% of cases experiencing vomiting, 13.5% experiencing drooling, and 9.4% experiencing dysphagia. Out of 244 cases, 132 (54.1%) were referred to gastroenterology for urgent FB removal by endoscopy. A total of 186 cases (76.2%) did not have complications, whereas 3.6% had serious sequela. The association between age and FBI was statistically significant (p=0.00), whereas there was no association between gender and FBI. CONCLUSION: Our results showed that FB ingestion was prevalent among children at our tertiary care hospital, with urgent endoscopy being the most common removal procedure. Early detection and immediate presentation to the emergency room are crucial for preventing complications. Common FBI included coins and batteries, with most incidents in 1-3-year-old males. Parents should be aware of the dangers of FBI and implement preventive measures to reduce its incidence.

Minimal invasive transnasal endoscopic removal of intracranial foreign body after airbag deployment.

Airbag induced injuries such as skull and cervical spine fractures, epidural and subdural hematomas, atlantooccipital dislocations or brainstem lacerations are already documented in published literature, however, no previous case have been published about a penetrating foreign body of the skull base following airbag deployment. Removal of an intracranial foreign body is very dangerous and difficult, or even if it possible and necessary, requires open surgery in most of the cases. In this article we present the minimal invasive, transnasal removal of a coin from the intracranial, frontobasal region using high-resolution endoscopy combined with image-guided navigation.
We report the case of a 59-year-old male who was brought to the emergency department after a car accident. He suffered a penetrating injury by a coin that was placed on the car’s airbag at the moment of the accident. Upon the airbag being deployed the foreign body entered the skin through the right lower eyelid, crossing the orbital cavity, ethmoid cells, sphenoid sinus and the anterior part of the planum sphenoidale at an equal distance of 2mm from the two internal carotid arteries, extending into the intracranial space, without injuring the pituitary stalk and the chiasm. We proceeded to remove the coin endoscopically using a transnasal transseptal transsphenoidal approach under general anesthesia. The dura was closed with a multilayer skull base reconstruction technique using two layers of abdominal free fat and nasal septal mucoperiosteal flap. There were no postoperative complications, nor CSF rhinorrhea. The patient was discharged 10 days after the operation.
To our knowledge, this is the first publi­shed case of a penetrating foreign body of the skull base, extending into the intracranial cavity following airbag deployment. In some dedicated cases, a minimal invasive endoscopic approach should be considered as an alternative to anterior craniotomy if access is possible when foreign bodies from the skull base area need to be removed. This procedure is efficient, safe and minimally invasive. 

Directly Sputtered Molybdenum Disulfide Nanoworms Decorated with Binder-less VN and W2N Nanoarrays for Bendable Large-Scale Asymmetric Supercapacitor.

Considering the superior capacitive performance and rich redox kinetics, the two-dimensional (2D) layered molybdenum disulfide (MoS2) and transition metal nitrides (TMNs) have emerged as the latest set of nanomaterials. Direct incorporation of key materials vanadium nitride (VN) and tungsten nitride (W2N) into a MoS2 array has been achieved on cost-effective, bendable stainless steel (SS) foil via a reactive cosputtering route. Herein, we have utilized the synergistic effect of intermixed nanohybrids to develop a flexible asymmetric supercapacitor (FASC) device from MoS2-VN@SS (negative) and MoS2-W2N@SS (positive) electrodes. As-constructed FASC cell possesses a maximum operational potential of 1.80 V and an exceptional gravimetric capacitance of 200 F g-1 at a sweep rate of 5 mV s-1. The sustained capacitive performance mainly accounts for the synergism induced through unique interfacial surface architecture provided by MoS2 nanoworms and TMN conductive hosts. The sulfur and nitrogen edges ensure the transport channels to Li+/SO4-2 ions for intercalation/deintercalation into the composite nanostructured thin film, further promoting the pseudocapacitive behavior. Consequently, the supercapacitor cell exhibits a distinctive specific energy of 87.91 Wh kg-1 at 0.87 kW kg-1 specific power and a reduced open circuit potential (OCP) decay rate (∼42% self-discharge after 60 min). Moreover, the assembled flexible device exhibits nearly unperturbed electrochemical response even at bending at 165° angle and illustrates a commendable cyclic life-span of 82% after 20,000 charge-discharge cycles, elucidating advanced mechanical robustness and capacitance retentivity. The powering of a multicolor light-emitting diode (LED) and electronic digital watch facilitates the practical evidence to open up possibilities in next-generation state-of-the-art wearable and miniaturized energy storage systems.

Foley catheter technique for the extraction of coins lodged in the upper esophagus of children.

INTRODUCTION: Coins are the most commonly ingested foreign bodies in children. They usually become lodged in the upper oesophagus and should be managed immediately. The aim of the present study was to evaluate the characteristics and outcomes of patients with coins lodged in the upper oesophagus, who underwent coin removal using a silicone Foley balloon catheter without fluoroscopy or anaesthesia and evaluate the safety of the procedure. MATERIALS AND METHODS: Patients who were admitted from January 2007 to December 2022 for coins lodged in the oesophagus and extracted with silicone Foley balloon catheter without anestehesia were evaluated retrospectively. We focused on the patient characteristics and clinical presentations, and the treatment safety, efficacy, and outcomes. RESULTS: 773 patients (416 male, 357 female), with a mean age of 3.5 years (range 6 months to 16 years), who ingested coin and extracted with Foley catether is included. The majority of patients (n = 728, 94.17%) were successfully managed by silicone Foley balloon catheter extraction. Our overall success was 94.17%, with 88.30% of coins retrieved and 5.9% pushed into the stomach. Patients who were successfully treated with Foley catheter were discharged on the same day except for 7 (0.90%) who had minimal bleeding. Only 45 (5.82%) patients required oesophagoscopy in the operating room and these patients were kept overnight for clinical follow-up, without any further interventions. CONCLUSION: A Foley balloon catheter can be used to safely and effectively remove coins that are lodged in the upper oesophagus avoiding the risk of general anesthesia.

A Monte Carlo simulation study comparing the up and down, biased-coin up and down and continual reassessment methods used to estimate an effective dose (ED95 or ED90) in anaesthesiology research.

Background: Dose-finding studies in anaesthesiology aim to target the effective dose (ED) of an anaesthetic agent in a specific population. The common dose-finding designs used are the up and down method (UDM), the biased-coin up and down (BCD), and the continual reassessment method (CRM). Although the advantages of CRM over the UDM and BCD methods have been described in the statistical literature in terms of precision and direct estimation of ED, CRM may also offer attractive properties from an ethical point of view. Methods: Based on Monte Carlo simulations, this article aims to compare the three methods with regard to 1) their ability to find as close an estimate as possible for the ED95 or ED90 and 2) the total number of patients needed to treat and the number of failures. Results: In contrast to BCD and UDM, CRM does find an estimate for ED95 and ED90. UDM underestimates both ED95 and ED90. BCD is close to the targeted EDs when the starting dose does not exceed the ED of interest, otherwise it overestimates it. CRM with cohorts of two patients is closest to the ED of interest independently of the starting doses. CRM requires between 20 and 50 observations, UDM should include 90 patients, and BCD 100 or 60 observations. Lastly, CRM is associated with fewer failures, compared with BCD and UDM. Conclusions: Based on Monte Carlo simulations, our work suggests that the UDM is not an adequate dose-finding method because it underestimates the ED of interest. Compared with BCD, CRM offers the advantages of being more efficient, requires fewer patients to be included, and is associated with fewer failures.

The 90% minimum effective volume of 0.5 ropivacaine for ultrasound-guided supraclavicular brachial plexus block : A biased coin up-and-down design.

BACKGROUND: Ultrasound-guided supraclavicular brachial plexus block is widely used in upper limb surgery; however, it requires a higher dose (20-30 mL) of local anesthetic. In this study, we aimed to determine the 90% minimum effective volume for ultrasound-guided supraclavicular brachial plexus block. METHODS: All patients received an ultrasound-guided two-point injection of 0.5% ropivacaine at a starting volume of 0.18 mL/mm2 cross-sectional nerve area. In cases of a successful block, the next patient had the same volume with a probability of 0.89, and the volume was reduced by 0.04 mL/mm2 cross-sectional nerve area with a probability of 0.11. When the block failed, the dose was increased by 0.04 mL/mm2 cross-sectional nerve area. After 45 cases of successful blocks, the 90% minimum effective volume of local anesthetic was calculated using the centered isotonic regression function. RESULTS: Centered isotonic regression analysis resulted in a 90% minimum effective volume and a 95% confidence interval of 0.189 mL/mm2 and 0.176-0.225 mL/mm2 for the supraclavicular brachial plexus block. CONCLUSION: A good blocking effect can be achieved with 0.189 mL/mm2 of 0.5% ropivacaine with more precise dosing, thereby reducing the risk of local anesthetic poisoning.