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Hyunjoo J Lee, Manishi A Desai, Natalie Sadlak, Marissa G Fiorello, Wanjiku G Githere, Manju L SubramanianOn behalf of The Oral versus Intravenous Sedation Study GroupDepartment of Ophthalmology, Boston Medical Center, Boston, MA, USACorrespondence: Hyunjoo J Lee, Department of Ophthalmology, Boston Medical Center, 85 East Concord Street, 8th Floor, Boston, MA, 02118, USA, Tel +1 617 414 2020, Fax +1 617 414 2929, Email leehj@bu.eduPurpose: To determine whether oral sedation is as safe and effective as IV sedation for ophthalmic surgeries other than cataract surgery, we tested whether patient satisfaction with oral triazolam was non-inferior to IV midazolam for cornea and glaucoma surgeries.Patients and Methods: Seventy-five cornea and 49 glaucoma surgery patients 18 years and older at Boston Medical Center (Boston, MA) were randomized within each study group (cornea or glaucoma) to receive oral triazolam + IV placebo, or oral placebo + IV midazolam before surgery in a double-masked fashion. Supplemental IV anesthesia was administered as needed during surgery. The primary outcome measure was patient satisfaction with anesthesia, compared between oral and IV sedation groups via t-test for non-inferiority, based on 70 cornea and 43 glaucoma subjects completing the study. Secondary outcome measures included surgeon and anesthesia provider satisfaction with anesthesia, rate of supplemental IV anesthesia, and incidence of adverse events and surgical complications.Results: Using an a priori non-inferiority margin of 0.5, initial oral sedation was non-inferior to initial IV sedation in cornea (n=70, p< 0.001) and glaucoma (n=43, p=0.017) groups, even after excluding subjects administered supplemental IV anesthesia. There were no significant differences in anesthesia provider or surgeon satisfaction, intra-operative complications, adverse events, or supplemental anesthesia between groups, except for higher anesthesia provider satisfaction with oral sedation in an Ahm

Natalie Sadlak,1 Marissa G Fiorello,1 Howard J Cabral,2 Manju L Subramanian,1 Manishi A Desai,1 Hyunjoo J Lee1 1Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USA; 2Department of Biostatistics, Boston University School of Public Health, Boston, MA, USACorrespondence: Hyunjoo J Lee, Boston University School of Medicine, 85 East Concord Street, 8th Floor, Boston, MA, 02118, USA, Tel +1 617 414-2230, Fax +1 617 638-8301, Email leehj@bu.eduPurpose: This secondary analysis of a clinical trial that measured surgeon, anesthesiologist, and patient satisfaction following ophthalmic surgery under monitored anesthesia care (MAC) with a benzodiazepine investigates the degree of association between patient satisfaction with anesthesia compared to surgeon and anesthesiologist satisfaction with anesthesia.Patients and Methods: Data from analogous 6-point surgeon satisfaction surveys and anesthesiologist satisfaction surveys were compared to data from a 6-point validated patient satisfaction survey collected from a clinical trial investigating satisfaction with different forms of benzodiazepine for patients undergoing cataract, retina, cornea, or glaucoma surgery. Relationships between measures were analyzed using Pearson’s correlation coefficient, with further subgroup analysis based on language groups and single-question measures of satisfaction.Results: A total of 283 ophthalmic surgical cases were analyzed. Mean surgeon satisfaction was 5.27 (range, 1.33– 6.00), mean anesthesiologist satisfaction was 5.12 (range, 1.17– 6.00), and mean patient satisfaction was 5.28 (range, 2.58– 6.00). The correlation between surgeon and patient satisfaction was 0.333 (p = 9.06e-9), while the correlation between anesthesiologist and patient satisfaction was 0.319 (p = 4.28e-8). There was no difference between English and non-English speaking patients in correlation between surgeon and patient satisfaction (p = 0.08) and anesthesiologist and patient satisfa

Objective. Low-intensity transcranial ultrasound stimulation (TUS) is a promising non-invasive brain stimulation (NIBS) technique. TUS can reach deeper areas and target smaller regions in the brain than other NIBS techniques, but its application in humans is hampered by the lack of a straightforward and reliable procedure to predict the induced ultrasound exposure. Here, we examined how skull modeling affects computer simulations of TUS. Approach. We characterized the ultrasonic beam after transmission through a sheep skull with a hydrophone and performed computed tomography (CT) image-based simulations of the experimental setup. To study the skull model s impact, we varied: CT acquisition parameters (tube voltage, dose, filter sharpness), image interpolation, segmentation parameters, acoustic property maps (speed-of-sound, density, attenuation), and transducer-position mismatches. We compared the impact of modeling parameter changes on model predictions and on measurement agreement. Spatial-peak intensity and location, total power, and the Gamma metric (a measure for distribution differences) were used as quantitative criteria. Modeling-based sensitivity analysis was also performed for two human head models. Main results. Sheep skull attenuation assignment and transducer positioning had the most important impact on spatial peak intensity (overestimation up to 300%, respectively 30%), followed by filter sharpness and tube voltage (up to 20%), requiring calibration of the mapping functions. Positioning and skull-heterogeneity-structure strongly affected the intensity distribution (gamma tolerances exceeded in >80%, respectively >150%, of the focus-volume in water), necessitating image-based personalized modeling. Simulation results in human models consistently demonstrate a high sensitivity to the skull-heterogeneity model, attenuation tuning, and transducer shifts, the magnitude of which depends on the underlying skull structure complexity. Significance. Ou

Objective. Low-intensity transcranial ultrasound stimulation (TUS) is emerging as a non-invasive brain stimulation technique with superior spatial resolution and the ability to reach deep brain areas. Medical image-based computational modeling could be an important tool for individualized TUS dose control and targeting optimization, but requires further validation. This study aims to assess the impact of the transducer model on the accuracy of the simulations. Approach. Using hydrophone measurements, the acoustic beam of a single-element focused transducer (SEFT) with a flat piezoelectric disc and an acoustic lens was characterized. The acoustic beam was assessed in a homogeneous water bath and after transmission through obstacles (3D-printed shapes and skull samples). The acoustic simulations employed the finite-difference time-domain method and were informed by computed tomography (CT) images of the obstacles. Transducer models of varying complexity were tested representing the SEFT either as a surface boundary condition with variable curvature or also accounting for its internal geometry. In addition, a back-propagated pressure distribution from the first measurement plane was used as source model. The simulations and measurements were quantitatively compared using key metrics for peak location, focus size, intensity and spatial distribution. Main results. While a surface boundary with an adapted, 'effective' curvature radius based on the specifications given by the manufacturer could reproduce the measured focus location and size in a homogeneous water bath, it regularly failed to accurately predict the beam after obstacle transmission. In contrast, models that were based on a one-time calibration to the homogeneous water bath measurements performed substantially better in all cases with obstacles. For one of the 3D-printed obstacles, the simulated intensities deviated substantially from the measured ones, irrespective of the transducer model. We attribute th

Background: Low-intensity transcranial focused ultrasound stimulation (TFUS) holds great promise as a highly focal technique for transcranial stimulation even for deep brain areas. Yet, knowledge about the safety of this novel technique is still limited. Objective: To systematically review safety related aspects of TFUS. The review covers the mechanisms-of-action by which TFUS may cause adverse effects and the available data on the possible occurrence of such effects in animal and human studies. Methods: Initial screening used key term searches in PubMed and bioRxiv, and a review of the literature lists of relevant papers. We included only studies where safety assessment was performed, and this results in 33 studies, both in humans and animals. Results: Adverse effects of TFUS were very rare. At high stimulation intensity and/or rate, TFUS may cause haemorrhage, cell death or damage, and unintentional blood-brain barrier (BBB) opening. TFUS may also unintentionally affect long-term neural activity and behaviour. A variety of methods was used mainly in rodents to evaluate these adverse effects, including tissue staining, magnetic resonance imaging, temperature measurements and monitoring of neural activity and behaviour. In 30 studies, adverse effects were absent, even though at least one Food and Drug Administration (FDA) safety index was frequently exceeded. Two studies reported microhaemorrhages after long or relatively intense stimulation above safety limits. Another study reported BBB opening and neuronal damage in a control condition, which intentionally and substantially exceeded the safety limits. Conclusion: Most studies point towards a favourable safety profile of TFUS. Further investigations are warranted to establish a solid safety framework for the therapeutic window of TFUS to reliably avoid adverse effects while ensuring neural effectiveness. The comparability across studies should be improved by a more standardized reporting of TFUS parameters.

Low-intensity transcranial focused ultrasound stimulation (TFUS) holds great promise as a highly focal technique for transcranial stimulation even for deep brain areas. Yet, knowledge about the safety of this novel technique is still limited. To systematically review safety related aspects of TFUS. The review covers the mechanisms-of-action by which TFUS may cause adverse effects and the available data on the possible occurrence of such effects in animal and human studies. Initial screening used key term searches in PubMed and bioRxiv, and a review of the literature lists of relevant papers. We included only studies where safety assessment was performed, and this results in 33 studies, both in humans and animals. Adverse effects of TFUS were very rare. At high stimulation intensity and/or rate, TFUS may cause haemorrhage, cell death or damage, and unintentional blood-brain barrier (BBB) opening. TFUS may also unintentionally affect long-term neural activity and behaviour. A variety of methods was used mainly in rodents to evaluate these adverse effects, including tissue staining, magnetic resonance imaging, temperature measurements and monitoring of neural activity and behaviour. In 30 studies, adverse effects were absent, even though at least one Food and Drug Administration (FDA) safety index was frequently exceeded. Two studies reported microhaemorrhages after long or relatively intense stimulation above safety limits. Another study reported BBB opening and neuronal damage in a control condition, which intentionally and substantially exceeded the safety limits. Most studies point towards a favourable safety profile of TFUS. Further investigations are warranted to establish a solid safety framework for the therapeutic window of TFUS to reliably avoid adverse effects while ensuring neural effectiveness. The comparability across studies should be improved by a more standardized reporting of TFUS parameters.