Brainomaly: Unsupervised Neurologic Disease Detection Utilizing Unannotated T1-weighted Brain MR Images.

Harnessing the power of deep neural networks in the medical imaging domain is challenging due to the difficulties in acquiring large annotated datasets, especially for rare diseases, which involve high costs, time, and effort for annotation. Unsupervised disease detection methods, such as anomaly detection, can significantly reduce human effort in these scenarios. While anomaly detection typically focuses on learning from images of healthy subjects only, real-world situations often present unannotated datasets with a mixture of healthy and diseased subjects. Recent studies have demonstrated that utilizing such unannotated images can improve unsupervised disease and anomaly detection. However, these methods do not utilize knowledge specific to registered neuroimages, resulting in a subpar performance in neurologic disease detection. To address this limitation, we propose Brainomaly, a GAN-based image-to-image translation method specifically designed for neurologic disease detection. Brainomaly not only offers tailored image-to-image translation suitable for neuroimages but also leverages unannotated mixed images to achieve superior neurologic disease detection. Additionally, we address the issue of model selection for inference without annotated samples by proposing a pseudo-AUC metric, further enhancing Brainomaly's detection performance. Extensive experiments and ablation studies demonstrate that Brainomaly outperforms existing state-of-the-art unsupervised disease and anomaly detection methods by significant margins in Alzheimer's disease detection using a publicly available dataset and headache detection using an institutional dataset. The code is available from https://github.com/mahfuzmohammad/Brainomaly.

The Polyanalgesic Consensus Conference (PACC)®: Intrathecal Drug Delivery Guidance on Safety and Therapy Optimization When Treating Chronic Noncancer Pain.

INTRODUCTION: The International Neuromodulation Society convened a multispecialty group of physicians and scientists based on expertise with international representation to establish evidence-based guidance on intrathecal drug delivery in treating chronic pain. This Polyanalgesic Consensus Conference (PACC)® project, created more than two decades ago, intends to provide evidence-based guidance for important safety and efficacy issues surrounding intrathecal drug delivery and its impact on the practice of neuromodulation. MATERIALS AND METHODS: Authors were chosen on the basis of their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from 2017 (when PACC® last published guidelines) to the present. Identified studies were graded using the United States Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence is scant. RESULTS: The PACC® examined the published literature and established evidence- and consensus-based recommendations to guide best practices. Additional guidance will occur as new evidence is developed in future iterations of this process. CONCLUSIONS: The PACC® recommends best practices regarding intrathecal drug delivery to improve safety and efficacy. The evidence- and consensus-based recommendations should be used as a guide to assist decision-making when clinically appropriate.

Body-Mounted MR-Conditional Robot for Minimally Invasive Liver Intervention.

MR-guided microwave ablation (MWA) has proven effective in treating hepatocellular carcinoma (HCC) with small-sized tumors, but the state-of-the-art technique suffers from sub-optimal workflow due to the limited accuracy provided by the manual needle insertions. This paper presents a compact body-mounted MR-conditional robot that can operate in closed-bore MR scanners for accurate needle guidance. The robotic platform consists of two stacked Cartesian XY stages, each with two degrees of freedom, that facilitate needle insertion pose control. The robot is actuated using 3D-printed pneumatic turbines with MR-conditional bevel gear transmission systems. Pneumatic valves and control mechatronics are located inside the MRI control room and are connected to the robot with pneumatic transmission lines and optical fibers. Free-space experiments indicated robot-assisted needle insertion error of 2.6 ± 1.3 mm at an insertion depth of 80 mm. The MR-guided phantom studies were conducted to verify the MR-conditionality and targeting performance of the robot. Future work will focus on the system optimization and validations in animal trials.

Ordinal Classification with Distance Regularization for Robust Brain Age Prediction.

Age is one of the major known risk factors for Alzheimer's Disease (AD). Detecting AD early is crucial for effective treatment and preventing irreversible brain damage. Brain age, a measure derived from brain imaging reflecting structural changes due to aging, may have the potential to identify AD onset, assess disease risk, and plan targeted interventions. Deep learning-based regression techniques to predict brain age from magnetic resonance imaging (MRI) scans have shown great accuracy recently. However, these methods are subject to an inherent regression to the mean effect, which causes a systematic bias resulting in an overestimation of brain age in young subjects and underestimation in old subjects. This weakens the reliability of predicted brain age as a valid biomarker for downstream clinical applications. Here, we reformulate the brain age prediction task from regression to classification to address the issue of systematic bias. Recognizing the importance of preserving ordinal information from ages to understand aging trajectory and monitor aging longitudinally, we propose a novel ORdinal Distance Encoded Regularization (ORDER) loss that incorporates the order of age labels, enhancing the model's ability to capture age-related patterns. Extensive experiments and ablation studies demonstrate that this framework reduces systematic bias, outperforms state-of-art methods by statistically significant margins, and can better capture subtle differences between clinical groups in an independent AD dataset. Our implementation is publicly available at https://github.com/jaygshah/Robust-Brain-Age-Prediction.

Post-mastectomy Pain Syndrome: A Review Article and Emerging Treatment Modalities.

Post-mastectomy pain syndrome (PMPS) is a syndrome broadly applied to the development of chronic pain after surgical breast intervention (i.e., lumpectomy and mastectomy). The incidence of PMPS is likely underreported, and this has contributed to a paucity of high-level evidence related to the treatment of the aforementioned condition. A drive to reduce the burden of opioid use has led to pain management physicians trialing a variety of strategies to help patients manage PMPS. This review discusses the latest evidence behind treatment options for PMPS, exploring medications as well as interventional techniques (e.g., nerve blocks, radiofrequency ablation, neuromodulation, and intrathecal drug delivery systems). Recent advances in neuromodulation technology are of particular interest here due to the well-localized nature of PMPS-related pain and the specificity with which modern neuromodulation techniques can generate an effect. Finally, the review proposes a framework with which to approach the care of patients with PMPS, with a specific emphasis on the early consideration of neuromodulation techniques along with functional and physical therapy to reduce patient medication burden and improve overall quality of life.

Misinformation Persists in Complementary Health: Evaluating the Reliability and Quality of YouTube-Based Information on the Use of Acupuncture for Chronic Pain.

Introduction: Acupuncture is commonly used to treat chronic pain. Patients often access public social media platforms for healthcare information when querying acupuncture. Our study aims to appraise the utility, accuracy, and quality of information available on YouTube, a popular social media platform, on acupuncture for chronic pain treatment. Methods: Using search terms such as "acupuncture for chronic pain" and "acupuncture pain relief", the top 54 videos by view count were selected. Included videos were >1 minute duration, contained audio in English, had >7000 views, and was related to acupuncture. One primary outcome of interest was categorizing each video's usefulness as useful, misleading, or neither. Another primary outcome of interest was the quality and reliability of each video using validated instruments, including the modified DISCERN (mDISCERN) tool and the Global Quality Scale (GQS). The means were calculated for the video production characteristics, production sources, and mDISCERN and GQS scores. Continuous and categorical outcomes were compared using Student's t-test and chi-square test, respectively. Results: Of the 54 videos, 57.4% were categorized as useful, 14.8% were misleading, and 27.8% were neither. Useful videos had a mean GQS and mDISCERN score of 3.77±0.67 and 3.48±0.63, respectively, while misleading videos had mean GQS and mDISCERN score of 2.50±0.53 and 2.38±0.52, respectively. 41.8% of the useful videos were produced by a healthcare institution while none of the misleading videos were produced by a healthcare institution. However, 87.5% of the misleading videos were produced by health media compared to only 25.8% of useful videos from health media. Discussion: As patients increasingly depend on platforms like YouTube for trustworthy information on complementary health practices such as acupuncture, our study emphasizes the critical need for more higher-quality videos from unbiased healthcare institutions and physicians to ensure patients are receiving reliable information regarding this topic.

Incidence of Sudden Cardiac Death in Low- and Middle-Income Countries: A Systematic Review of Cohort Studies.

Sudden cardiac death (SCD) is a leading cause of mortality worldwide and, in recent years, has become an urgent public health concern in low- and middle-income countries (LMICs). Data from LMICs, however, remains limited. As such, the aim of this article is to systematically review the current literature on the incidence of SCD in LMICs to inform policymakers and identify potential research gaps. A search of PubMed and Embase was utilized to capture the targeted condition, outcome, and setting. Only peer-reviewed cohort studies in LMICs reporting SCD incidence estimates in the general population of individuals aged ≥1 year were eligible for selection. Papers providing incidence data for specific types of SCD, including sudden coronary death or death from sudden cardiac arrest, were also included. After deduplication, 1941 citations were identified and screened. Seven studies representing four countries-Cameroon, China, India, and Iran-met the criteria for inclusion and were considered in our analysis. The crude incidence rate for SCD ranged from 19.9 to 190 cases per 100,000 person-years, while age-adjusted rates ranged from 33.6 to 230 cases per 100,000 person-years. There was notable variability in methods utilized to ascertain SCD cases. These findings suggest that the incidence of all-cause SCD in LMICs and may exceed that of high-income countries; however, observed disparities may be partly attributable to differences in case ascertainment methods. Additional research is needed to better understand the true incidence of SCD in developing countries. It is crucial that future studies across regions utilize standard diagnostic criteria and methodology for identifying SCD, which would provide a framework by which to compare outcomes between settings.

Early Detection of Myeloid-Derived Suppressor Cells in the Lung Pre-Metastatic Niche by Shortwave Infrared Nanoprobes.

Metastatic breast cancer remains a significant source of mortality amongst breast cancer patients and is generally considered incurable in part due to the difficulty in detection of early micro-metastases. The pre-metastatic niche (PMN) is a tissue microenvironment that has undergone changes to support the colonization and growth of circulating tumor cells, a key component of which is the myeloid-derived suppressor cell (MDSC). Therefore, the MDSC has been identified as a potential biomarker for PMN formation, the detection of which would enable clinicians to proactively treat metastases. However, there is currently no technology capable of the in situ detection of MDSCs available in the clinic. Here, we propose the use of shortwave infrared-emitting nanoprobes for the tracking of MDSCs and identification of the PMN. Our rare-earth albumin nanocomposites (ReANCs) are engineered to bind the Gr-1 surface marker of murine MDSCs. When delivered intravenously in murine models of breast cancer with high rates of metastasis, the targeted ReANCs demonstrated an increase in localization to the lungs in comparison to control ReANCs. However, no difference was seen in the model with slower rates of metastasis. This highlights the potential utility of MDSC-targeted nanoprobes to assess PMN development and prognosticate disease progression.

A Validated Risk Stratification That Incorporates MAGIC Biomarkers Predicts Long-Term Outcomes in Pediatric Patients with Acute GVHD.

Acute graft versus host disease (GVHD) is a common and serious complication of allogeneic hematopoietic cell transplantation (HCT) in children but overall clinical grade at onset only modestly predicts response to treatment and survival outcomes. Two tools to assess risk at initiation of treatment were recently developed. The Minnesota risk system stratifies children for risk of nonrelapse mortality (NRM) according to the pattern of GVHD target organ severity. The Mount Sinai Acute GVHD International Consortium (MAGIC) algorithm of 2 serum biomarkers (ST2 and REG3α) predicts NRM in adult patients but has not been validated in a pediatric population. We aimed to develop and validate a system that stratifies children at the onset of GVHD for risk of 6-month NRM. We determined the MAGIC algorithm probabilities (MAPs) and Minnesota risk for a multicenter cohort of 315 pediatric patients who developed GVHD requiring treatment with systemic corticosteroids. MAPs created 3 risk groups with distinct outcomes at the start of treatment and were more accurate than Minnesota risk stratification for prediction of NRM (area under the receiver operating curve (AUC), .79 versus .62, P = .001). A novel model that combined Minnesota risk and biomarker scores created from a training cohort was more accurate than either biomarkers or clinical systems in a validation cohort (AUC .87) and stratified patients into 2 groups with highly different 6-month NRM (5% versus 38%, P < .001). In summary, we validated the MAP as a prognostic biomarker in pediatric patients with GVHD, and a novel risk stratification that combines Minnesota risk and biomarker risk performed best. Biomarker-based risk stratification can be used in clinical trials to develop more tailored approaches for children who require treatment for GVHD.

World Endometriosis Research Foundation Endometriosis Phenome and Biobanking Harmonization Project: V. Physical examination standards in endometriosis research.

OBJECTIVE: The World Endometriosis Research Foundation established the Endometriosis Phenome and Biobanking Harmonisation Project (EPHect) to create standardized documentation tools (with common data elements) to facilitate the comparison and combination of data across different research sites and studies. In 2014, 4 data research standards were published: clinician-reported surgical data, patient-reported clinical data, and fluid and tissue biospecimen collection. Our current objective is to create an EPHect standard for the clinician-reported physical examination (EPHect-PE) for research studies. DESIGN: An international consortium involving 26 clinical and academic experts and patient partners from 11 countries representing 25 institutions and organizations. Two virtual workshops, followed by the development of the physical examination standards underwent multiple rounds of iterations and revisions. SUBJECTS: N/A MAIN OUTCOME MEASURE(S): N/A RESULT(S): The EPHect-PE tool provides standardized assessment of physical examination characteristics and pain phenotyping. Data elements involve examination of back and pelvic girdle; abdomen including allodynia and trigger points; vulva including provoked vestibulodynia; pelvic floor muscle tone and tenderness; tenderness on unidigital pelvic examination; presence of pelvic nodularity; uterine size and mobility; presence of adnexal masses; presence of incisional masses; speculum examination; tenderness and allodynia at an extra-pelvic site (e.g., forearm); and recording of anthropometrics. CONCLUSION(S): The EPHect-PE standards will facilitate the standardized documentation of the physical examination, including the assessment and documentation of examination phenotyping of endometriosis-associated pelvic pain.

Comparative outcomes after treatment of peri-implant, periprosthetic, and interprosthetic femur fractures: which factors increase mortality risk?

Objectives: To compare mortality rates between patients treated surgically for periprosthetic fractures (PPF) after total hip arthroplasty (THA), total knee arthroplasty (TKA), peri-implant (PI), and interprosthetic (IP) fractures while identifying risk factors associated with mortality following PPF. Design: Retrospective. Setting: Single, Level II Trauma Center. Patients/Participants: A retrospective review was conducted of 129 consecutive patients treated surgically for fractures around a pre-existing prosthesis or implant from 2013 to 2020. Patients were separated into 4 comparison groups: THA, TKA, PI, and IP fractures. Intervention: Revision implant or arthroplasty, open reduction and internal fixation (ORIF), intramedullary nailing (IMN), percutaneous screws, or a combination of techniques. Main Outcome Measurements: Primary outcome measures include mortality rates of different types of PPF, PI, and IP fractures at 1-month, 3-month, 6-month, 1-year, and 2-year postoperative. We analyzed risk factors associated with mortality aimed to determine whether treatment type affects mortality. Results: One hundred twenty-nine patients were included for final analysis. Average follow-up was similar between all groups. The overall 1-year mortality rate was 1 month (5%), 3 months (12%), 6 months (13%), 1 year (15%), and 2 years (22%). There were no differences in mortality rates between each group at 30 days, 90 days, 6 months, 1 year, and 2 years (P-value = 0.86). A Kaplan-Meier survival curve demonstrated no difference in survivorship up to 2 years. Older than 65 years, history of hypothyroidism and dementia, and discharge to a skilled nursing facility (SNF) led to increased mortality. There was no survival benefit in treating patients with PPFs with either revision, ORIF, IMN, or a combination of techniques. Conclusion: The overall mortality rates observed were 1 month (5%), 3 months (12%), 6 months (13%), 1 year (15%), and 2 years (22%), and no differences were found between each group at all follow-up time points. Patients aged 65 and older with a history of hypothyroidism and/or dementia discharged to an SNF are at increased risk for mortality. From a mortality perspective, surgeons should not hesitate to choose the surgical treatment they feel most comfortable performing. Level of Evidence: Level III.

A case of image-guided hematometrocolpos drainage requiring tissue plasminogen activator in a pediatric patient.

Hematometrocolpos (HMC) is a rare disorder that occurs when an anatomical anomaly like imperforate hymen causes menstrual blood to be retained in the uterus and vagina. There is no standard of care established for HMC beyond urgent vaginoplasty which requires a demanding post-operative course that may not be suited for all pediatric patients. This is a case report of successful use of image-guided percutaneous drainage of HMC with tissue plasminogen activator (TPA) followed by vaginoplasty in a 13-year-old female with lower vaginal atresia. Additionally, this case explores the role of menstrual suppression and the need for individualized guidelines. It emphasizes the potential of image-guided percutaneous drainage with TPA as a promising, less-invasive treatment option for pediatric HMC as well as the impact on follow-up surgery.

Hybrid Molecular Beam Epitaxy for Single-Crystalline Oxide Membranes with Binary Oxide Sacrificial Layers.

The advancement in thin-film exfoliation for synthesizing oxide membranes has led to possibilities for creating artificially assembled heterostructures with structurally and chemically incompatible materials. The sacrificial layer method is a promising approach to exfoliate as-grown films from a compatible material system, allowing for their integration with dissimilar materials. Nonetheless, the conventional sacrificial layers often possess an intricate stoichiometry, thereby constraining their practicality and adaptability, particularly when considering techniques such as molecular beam epitaxy (MBE). This is where easy-to-grow binary alkaline-earth-metal oxides with a rock salt crystal structure are useful. These oxides, which include (Mg, Ca, Sr, Ba)O, can be used as a sacrificial layer covering a much broader range of lattice parameters compared to conventional sacrificial layers and are easily dissolvable in deionized water. In this study, we show the epitaxial growth of the single-crystalline perovskite SrTiO3 (STO) on sacrificial layers consisting of crystalline SrO, BaO, and Ba1-xCaxO films, employing a hybrid MBE method. Our results highlight the rapid (≤5 min) dissolution of the sacrificial layer when immersed in deionized water, facilitating the fabrication of millimeter-sized STO membranes. Using high-resolution X-ray diffraction, atomic-force microscopy, scanning transmission electron microscopy, impedance spectroscopy, and scattering-type near-field optical microscopy (SNOM), we demonstrate single-crystalline STO membranes with bulk-like intrinsic dielectric properties. The employment of alkaline earth metal oxides as sacrificial layers is likely to simplify membrane synthesis, particularly with MBE, thus expanding the research and application possibilities.

Practice Changes in Checkpoint Inhibitor-Induced Immune-Related Adverse Event Management at a Tertiary Care Center.

Understanding of immune-related adverse events (irAEs) has evolved rapidly, and management guidelines are continually updated. We explored temporal changes in checkpoint inhibitor-induced irAE management at a tertiary cancer care center to identify areas for improvement. We conducted a single-center retrospective study of patients who developed a gastrointestinal, pulmonary, renal, or cardiac irAE between July and 1 October in 2019 or 2021. We collected patient demographic and clinical information up to 1 year after toxicity. Endoscopic evaluation and specialty follow-up after discharge for patients with gastrointestinal irAEs declined between the 2019 and 2021 periods. Symptom duration and steroid taper attempts also declined. For pulmonary irAEs, rates of specialty consultation, hospital admission and readmission, and mortality improved in 2021 compared with 2019. Follow-up rates after hospital discharge were consistently low (<50%) in both periods. For cardiac irAEs, consultation with a cardiologist was frequent and prompt in both periods. Outpatient treatment and earlier specialty consultation improved outcomes with gastrointestinal irAEs. Our study exploring irAE practice changes over time identified areas to improve management; specifically, timely specialty consultation was associated with better outcomes for gastrointestinal irAEs. These findings can help improve the quality of management algorithms at our institution and may inform policies in other institutions.

Upper partial sternal split for pediatric cardiac surgery.

OBJECTIVES: We introduced the use of an upper partial sternal split for pediatric cardiac surgical procedures in our unit in 2016. We report the outcomes of our experience in 51 patients using this approach. METHODS: From February 2016 to September 2022, 51 patients underwent congenital cardiac surgical procedures using an upper partial sternal split including vascular ring repair (n = 20), subaortic membrane (n = 12), ventricular septal defect closure with aortic valve resuspension (n = 9), aortic arch repair (n = 4), pulmonary artery band (n = 2), pulmonary artery sling (n = 1), supravalvular aortic stenosis (n = 1), aortic valve replacement (n = 1), and pulmonary artery plasty (n = 1). The surgical approach involved a midline skin incision, based on the manubrium, followed by an upper manubriotomy. No special surgical instrumentation was required. Median patient age was 2.9 years (IQR 1.3, 6.0); median body weight was 15 kg (IQR 9.8, 20). RESULTS: There was no mortality and no patient required intraoperative conversion to full sternotomy. One patient required re-exploration for bleeding when the incision was converted to a full sternotomy. There were no wound complications in any patient. Twenty-one patients (41%) were extubated on the table and of the remaining 30 patients, 23 patients (76%) were extubated within 24 h of surgery. Eleven patients did not require intensive care unit (ICU) admission. Median ICU and hospital stay was 1 day (IQR 1, 1.25) and 5 days (IQR 4, 8) ,respectively. CONCLUSION: An upper partial sternal split approach is straightforward and can be performed safely with a preferable cosmetic result in selected pediatric cardiac operations.

Clinical Characteristics of Primary Snoring vs Mild Obstructive Sleep Apnea in Children: Analysis of the Pediatric Adenotonsillectomy for Snoring (PATS) Randomized Clinical Trial.

Importance: It is unknown whether children with primary snoring and children with mild obstructive sleep apnea (OSA) represent populations with substantially different clinical characteristics. Nonetheless, an obstructive apnea-hypopnea index (AHI) of 1 or greater is often used to define OSA and plan for adenotonsillectomy (AT). Objective: To assess whether a combination of clinical characteristics differentiates children with primary snoring from children with mild OSA. Design, Setting, and Participants: Baseline data from the Pediatric Adenotonsillectomy Trial for Snoring (PATS) study, a multicenter, single-blind, randomized clinical trial conducted at 6 academic sleep centers from June 2016 to January 2021, were analyzed. Children aged 3.0 to 12.9 years with polysomnography-diagnosed (AHI <3) mild obstructive sleep-disordered breathing who were considered candidates for AT were included. Data analysis was performed from July 2022 to October 2023. Main Outcomes and Measures: Logistic regression models were fitted to identify which demographic, clinical, and caregiver reports distinguished children with primary snoring (AHI <1; 311 patients [67.8%]) from children with mild OSA (AHI 1-3; 148 patients [32.2%]). Results: A total of 459 children were included. The median (IQR) age was 6.0 (4.0-7.5) years, 230 (50.1%) were female, and 88 (19.2%) had obesity. A total of 121 (26.4%) were Black, 75 (16.4%) were Hispanic, 236 (51.5%) were White, and 26 (5.7%) were other race and ethnicity. Black race (odds ratio [OR], 2.08; 95% CI, 1.32-3.30), obesity (OR, 1.80; 95% CI, 1.12-2.91), and high urinary cotinine levels (>5 µg/L) (OR, 1.88; 95% CI, 1.15-3.06) were associated with greater odds of mild OSA rather than primary snoring. Other demographic characteristics, clinical examination findings, and questionnaire reports did not distinguish between primary snoring and mild OSA. A weighted combination of the statistically significant clinical predictors had limited ability to differentiate children with mild OSA from children with primary snoring. Conclusions and Relevance: In this analysis of baseline data from the PATS randomized clinical trial, primary snoring and mild OSA were difficult to distinguish without polysomnography. Mild OSA vs snoring alone did not identify a clinical group of children who may stand to benefit from AT for obstructive sleep-disordered breathing. Trial Registration: ClinicalTrials.gov Identifier: NCT02562040.

Evaluation of the Catheter Clamp over Hydrophilic Guide Wire Central Venous Catheter Exchange Technique for Air Embolism Prophylaxis in an In Vitro Model.

PURPOSE: To develop a reproducible in vitro model simulating central venous catheter (CVC) exchange with high potential for air embolization and test the hypothesis that a closed catheter clamp over hydrophilic guide wire exchange technique will significantly reduce the volume of air introduced during CVC exchange. MATERIALS AND METHODS: The model consisted of a 16-F valved sheath, 240-mL container, and pressure transducer submerged in water in a 1,200-mL suction canister system. Continuous wall suction was applied to the canister to maintain negative pressure at -7 mm Hg or -11 mm Hg. Each trial consisted of 0.035-inch hydrophilic guide wire introduction, over-the-wire catheter exchange, and wire removal following clinical protocol. A total of 256 trials were performed, 128 trials at each pressure with the catheter clamp open (n = 64) or closed (n = 64) around the hydrophilic guide wire. RESULTS: There was a statistically significant lower volume of air introduced with closed clamp over-the-wire exchanges than with open clamp exchanges at both pressures (2-tailed t-test, P < .001). At -7 mm Hg, a mean of 48.0 mL (SD ± 9.3) of air was introduced with open clamp and 20.6 mL (SD ± 4.7) of air was introduced with closed clamp. At -11 mm Hg, 97.8 mL (SD ± 11.9) of air was introduced with open clamp and 37.8 mL (SD ± 6.3) of air was introduced with closed clamp. CONCLUSIONS: This study demonstrated the use of a reproducible in vitro model mimicking conditions causing air embolism during CVC exchange. Results showed that CVC exchange using closed catheter clamp over hydrophilic guide wire exchange technique significantly reduced the volume of air introduced per exchange.