Electrically tunable space-time metasurfaces at optical frequencies.

Active metasurfaces enable dynamic manipulation of the scattered electromagnetic wavefront by spatially varying the phase and amplitude across arrays of subwavelength scatterers, imparting momentum to outgoing light. Similarly, periodic temporal modulation of active metasurfaces allows for manipulation of the output frequency of light. Here we combine spatial and temporal modulation in electrically modulated reflective metasurfaces operating at 1,530 nm to generate and diffract a spectrum of sidebands at megahertz frequencies. Temporal modulation with tailored waveforms enables the design of a spectrum of sidebands. By impressing a spatial phase gradient on the metasurface, we can diffract selected combinations of sideband frequencies. Combining active temporal and spatial variation can enable unique optical functions, such as frequency mixing, harmonic beam steering or shaping, and breaking of Lorentz reciprocity.

Perioperative Dexmedetomidine Infusion Improves Perioperative Care of Bariatric-Metabolic Surgery: A Single Center Experience with Meta-Analysis.

PURPOSE: This study aims to determine the effects of perioperative dexmedetomidine infusion (PDI) on Asian patients undergoing bariatric-metabolic surgery (BMS), focusing on the need for pain medications and management of postoperative nausea and vomiting (PONV), and to investigate the association with these variables, including patients' characteristics and BMS data. MATERIALS AND METHODS: A retrospective review of prospectively collected data was conducted in an Asian weight management center from August 2016 to October 2021. A total of 147 native patients with severe obesity were enrolled. All patients were informed of the full support of perioperative pain medications for BMS. The pain numeric rating scale scores, events of PONV, needs for pain medications, and the associated patients' characteristics were analyzed. A p-value of < 0.05 was considered statistically significant. Furthermore, to verify the effects of perioperative usage of dexmedetomidine for BMS, a systematic review with meta-analysis of currently available randomized control trials was performed. RESULTS: Among the 147 enrolled patients, 107 underwent laparoscopic sleeve gastrectomy and 40 underwent laparoscopic Roux-en-Y gastric bypass. PDI has been used as an adjunct multimodal analgesia for BMS in our institution since June 2017 (group D; n = 114). In comparison with those not administered with perioperative dexmedetomidine (group C; n = 33), lower pain numeric rating scale scores (2.52 ± 2.46 vs. 4.27 ± 2.95, p = 0.007) in the postanesthesia care unit, fewer PONV (32.46% vs. 51.52%; p = 0.046), and infrequent needs of additional pain medications (19.47% vs. 45.45%; p = 0.003) were observed in group D. Multivariable analysis demonstrated that type II diabetes mellitus was correlated with the decreased need of pain medications other than PDI (p = 0.035). Moreover, dexmedetomidine seemed to have a better analgesic effect for patients with longer surgical time based on our meta-analysis. CONCLUSION: Based on our limited experience, PDI could be a practical solution to alleviate pain and PONV in Asian patients undergoing BMS. Moreover, it might reduce the need for rescue painkillers with better postoperative pain management for patients with type II diabetes mellitus or longer surgical time.

Synchronized wearables for the detection of haemodynamic states via electrocardiography and multispectral photoplethysmography.

Cardiovascular health is typically monitored by measuring blood pressure. Here we describe a wireless on-skin system consisting of synchronized sensors for chest electrocardiography and peripheral multispectral photoplethysmography for the continuous monitoring of metrics related to vascular resistance, cardiac output and blood-pressure regulation. We used data from the sensors to train a support-vector-machine model for the classification of haemodynamic states (resulting from exposure to heat or cold, physical exercise, breath holding, performing the Valsalva manoeuvre or from vasopressor administration during post-operative hypotension) that independently affect blood pressure, cardiac output and vascular resistance. The model classified the haemodynamic states on the basis of an unseen subset of sensor data for 10 healthy individuals, 20 patients with hypertension undergoing haemodynamic stimuli and 15 patients recovering from cardiac surgery, with an average precision of 0.878 and an overall area under the receiver operating characteristic curve of 0.958. The multinodal sensor system may provide clinically actionable insights into haemodynamic states for use in the management of cardiovascular disease.

Self-powered, light-controlled, bioresorbable platforms for programmed drug delivery.

Degradable polymer matrices and porous scaffolds provide powerful mechanisms for passive, sustained release of drugs relevant to the treatment of a broad range of diseases and conditions. Growing interest is in active control of pharmacokinetics tailored to the needs of the patient via programmable engineering platforms that include power sources, delivery mechanisms, communication hardware, and associated electronics, most typically in forms that require surgical extraction after a period of use. Here we report a light-controlled, self-powered technology that bypasses key disadvantages of these systems, in an overall design that is bioresorbable. Programmability relies on the use of an external light source to illuminate an implanted, wavelength-sensitive phototransistor to trigger a short circuit in an electrochemical cell structure that includes a metal gate valve as its anode. Consequent electrochemical corrosion eliminates the gate, thereby opening an underlying reservoir to release a dose of drugs by passive diffusion into surrounding tissue. A wavelength-division multiplexing strategy allows release to be programmed from any one or any arbitrary combination of a collection of reservoirs built into an integrated device. Studies of various bioresorbable electrode materials define the key considerations and guide optimized choices in designs. In vivo demonstrations of programmed release of lidocaine adjacent the sciatic nerves in rat models illustrate the functionality in the context of pain management, an essential aspect of patient care that could benefit from the results presented here.

Closed-loop network of skin-interfaced wireless devices for quantifying vocal fatigue and providing user feedback.

Vocal fatigue is a measurable form of performance fatigue resulting from overuse of the voice and is characterized by negative vocal adaptation. Vocal dose refers to cumulative exposure of the vocal fold tissue to vibration. Professionals with high vocal demands, such as singers and teachers, are especially prone to vocal fatigue. Failure to adjust habits can lead to compensatory lapses in vocal technique and an increased risk of vocal fold injury. Quantifying and recording vocal dose to inform individuals about potential overuse is an important step toward mitigating vocal fatigue. Previous work establishes vocal dosimetry methods, that is, processes to quantify vocal fold vibration dose but with bulky, wired devices that are not amenable to continuous use during natural daily activities; these previously reported systems also provide limited mechanisms for real-time user feedback. This study introduces a soft, wireless, skin-conformal technology that gently mounts on the upper chest to capture vibratory responses associated with vocalization in a manner that is immune to ambient noises. Pairing with a separate, wirelessly linked device supports haptic feedback to the user based on quantitative thresholds in vocal usage. A machine learning-based approach enables precise vocal dosimetry from the recorded data, to support personalized, real-time quantitation and feedback. These systems have strong potential to guide healthy behaviors in vocal use.

Soft, bioresorbable coolers for reversible conduction block of peripheral nerves.

Implantable devices capable of targeted and reversible blocking of peripheral nerve activity may provide alternatives to opioids for treating pain. Local cooling represents an attractive means for on-demand elimination of pain signals, but traditional technologies are limited by rigid, bulky form factors; imprecise cooling; and requirements for extraction surgeries. Here, we introduce soft, bioresorbable, microfluidic devices that enable delivery of focused, minimally invasive cooling power at arbitrary depths in living tissues with real-time temperature feedback control. Construction with water-soluble, biocompatible materials leads to dissolution and bioresorption as a mechanism to eliminate unnecessary device load and risk to the patient without additional surgeries. Multiweek in vivo trials demonstrate the ability to rapidly and precisely cool peripheral nerves to provide local, on-demand analgesia in rat models for neuropathic pain.

Association of research timing with surgery resident perceptions of operative autonomy and satisfaction: A multi-institutional study.

BACKGROUND: General surgery residents commonly engage in research years after the second (Post-postgraduate year 2 [PostPGY2]) or third (PostPGY3) clinical training year. The impact of dedicated research training timing on training experience is unknown. Our aim was to examine the progression of residents' perceived meaningful operative autonomy and evaluate career satisfaction, in relation to research timing. METHODS: Categorical surgery residents with 2-year research requirements were surveyed regarding perceived autonomy for laparoscopic appendectomy, laparoscopic cholecystectomy, and right hemicolectomy and satisfaction with the impact of dedicated research training on professional development. Meaningful operative autonomy was defined as Zwisch scores ≥3 (passive help or supervision only). RESULTS: Residents from 17 programs participated (n = 233, 30.6%); 48% were PostPGY2. PostPGY3 residents were more likely to perceive meaningful operative autonomy when starting dedicated research training (laparoscopic appendectomy: 98% vs 74%, P < .001; laparoscopic cholecystectomy: 87% vs 48%, P < .001; right hemicolectomy: 27% vs 3%, P < .001). Meaningful operative autonomy declined during dedicated research training but was still higher for PostPGY3 residents for laparoscopic appendectomy (84% vs 42%, P < .001) and laparoscopic cholecystectomy (68% vs 30%, P < .001). By PGY4, PostPGY2 residents reported rates of meaningful operative autonomy comparable to PostPGY3 through training completion. A higher proportion of PostPGY3 residents reported dedicated research training satisfaction (90% vs 78%, P = .01). Training at PostPGY3 programs (odds ratio, 3.06, 95% confidence interval, 1.38-6.80) and postresearch training stage (compared with preresearch residents, odds ratio, 3.25, 95% confidence interval, 1.06-10.0) were independently associated with satisfaction. CONCLUSION: Significant differences existed in the progression of perceived operative autonomy and dedicated research training satisfaction between PostPGY2 and PostPGY3 residents. These results could help surgical educators make individualized decisions regarding research timing to promote surgical skill acquisition and resident well-being.

Effect of teleconferencing variables on faculty impression of mock residency applicants.

Purpose: The objective of this study was to assess how teleconferencing variables influence faculty impressions of mock residency applicants. Methods: In October 2020, we conducted an online experiment studying five teleconferencing variables: background, lighting, eye contact, internet connectivity, and audio quality. We created interview videos of three mock residency applicants and systematically modified variables in control and intervention conditions. Faculty viewed the videos and rated their immediate impression on a 1-10 scale. The effect of each variable was measured as the mean difference between the intervention and control impression ratings. One-way analysis of variance (ANOVA) was performed to assess whether ratings varied across applicants. Paired-samples Wilcoxon signed-rank tests were conducted to assess the significance of the effect of each variable. Results: Of 711 faculty members who were emailed a link to the experiment, 97 participated (13.6%). The mean ratings for control videos were 8.1, 7.2, and 7.6 (P < .01). Videos with backlighting, off-center eye contact, choppy internet connectivity, or muffled audio quality had lower ratings when compared with control videos (P < .01). There was no rating difference between home and conference room backgrounds (P = .77). Many faculty participants reported that their immediate impressions were very much or extremely influenced by audio quality (60%), eye contact (57%), and internet connectivity (49%). Conclusions: Teleconferencing variables may serve as a source of assessment bias during residency interviews. Mock residency applicants received significantly lower ratings when they had off-center eye contact, muffled audio, or choppy internet connectivity, compared to optimal teleconferencing conditions. Supplementary Information: The online version contains supplementary material available at 10.1007/s44186-022-00053-w.

Persistence of Gender Bias Over Four Decades of Surgical Training.

OBJECTIVE: Female surgeons face gender-specific obstacles during residency training, yet longitudinal data on gender bias experienced by female surgery residents are lacking. We aimed to investigate the evolution of gender bias, identify obstacles experienced by female general surgery residents, and discuss approaches to supporting female surgeons during residency training. METHODS: Between August 2019 and January 2021, we conducted a retrospective cohort study using structured telephone interviews of female graduates of the UCLA General Surgery Residency training program. Responses of early graduates (1981-2009) were compared with those of recent graduates (2010-2020). Quantitative data were compared with Fisher's exact tests and Chi-squared tests. Interview responses were reviewed to catalog gender bias, obstacles experienced by female surgeons, and advice offered to training programs to address women's concerns. RESULTS: Of 61 female surgery residency graduates, 37 (61%) participated. Compared to early graduates (N = 20), recent graduates (N = 17) were significantly more likely to pursue fellowship training (100% vs. 65%, p < 0.01) and have children before or during residency (65% vs. 25%, p = 0.02). A substantial proportion in each cohort experienced some form of gender bias (71% vs. 85%, p = 0.43). Compared to early graduates, recent graduates were significantly less likely to report experiencing explicit gender bias (12% vs. 50%, p = 0.02) but equally likely to report implicit gender bias (71% vs. 55%, p = 0.50). Female graduates across the decades advocated for specific measures to champion work-life balance in residency (51%), strengthen female mentorship (49%), increase childcare support (41%), and promote women into leadership positions (32%). CONCLUSIONS: While having children during residency has become more common and accepted over the decades, female surgery residents continue to experience implicit gender bias in the workplace. Female surgeons advocate for targeted interventions to establish systems for parental leave, address gender bias, and strengthen female mentorship.

Laparoscopic Revision for Gastric Clipping: a Single Center Experience and Taiwan Database Review.

PURPOSE: Laparoscopic gastric clipping (LGC) is a relatively novel restrictive bariatric surgery wherein a horizontal metallic clip is applied to the gastric fundus. Its intraoperative complications or the difficulties associated with the applied gastric clip (GC) during revisional procedures have seldom been mentioned. Herein, the experience of revisional procedures after initial gastric clipping is reported. MATERIALS AND METHODS: A retrospective cohort review of LGC based on the Taiwan Bariatric Registry of Taiwan Society Metabolic and Bariatric Surgery was performed. Six patients with severe obesity presented for revisional surgery after initial LGC by other surgeons. Patients' characteristics, indications, and details of revisional surgery were recorded. RESULTS: Between 2012 and 2019, 39 patients who underwent pure LGC and six patients with previous LGC history were referred for revisional surgery. Their mean age and the mean body mass index were 34.7 ± 9.5 years and 38.4 ± 10.5 kg/m2, respectively. Three, two, and one patient underwent revisional surgery for insufficient weight loss, weight recidivism, and intractable belching, respectively. The mean interval between initial LGC and revisional surgery was 40.5 ± 22.4 months. Laparoscopic removal of the GC with concomitant revisional surgeries were collected, including a revision to sleeve gastrectomy (n = 5) and revision to Roux-en-Y gastric bypass (n = 1). Moreover, the mean operative time was 286.8 ± 78.2 min. All patients had uneventful recovery postoperatively but experienced significant adhesion around the GC and the left liver. CONCLUSION: Laparoscopic revisional surgery with concomitant GC removal for patients with severe obesity after gastric clipping could be feasibly conducted by experienced bariatric surgeons.

Mechano-acoustic sensing of physiological processes and body motions via a soft wireless device placed at the suprasternal notch.

Skin-mounted soft electronics that incorporate high-bandwidth triaxial accelerometers can capture broad classes of physiologically relevant information, including mechano-acoustic signatures of underlying body processes (such as those measured by a stethoscope) and precision kinematics of core-body motions. Here, we describe a wireless device designed to be conformally placed on the suprasternal notch for the continuous measurement of mechano-acoustic signals, from subtle vibrations of the skin at accelerations of around 10-3 m s-2 to large motions of the entire body at about 10 m s-2, and at frequencies up to around 800 Hz. Because the measurements are a complex superposition of signals that arise from locomotion, body orientation, swallowing, respiration, cardiac activity, vocal-fold vibrations and other sources, we exploited frequency-domain analysis and machine learning to obtain-from human subjects during natural daily activities and exercise-real-time recordings of heart rate, respiration rate, energy intensity and other essential vital signs, as well as talking time and cadence, swallow counts and patterns, and other unconventional biomarkers. We also used the device in sleep laboratories and validated the measurements using polysomnography.

Revision using totally hand-sewn gastrojejunostomy and truncal vagotomy for refractory marginal ulcer after laparoscopic Roux-en-y gastric bypass: a case series.

BACKGROUND: Marginal ulcer (MU) is not infrequent after laparoscopic Roux-en-Y gastric bypass (LRYGB). Medication plus lifestyle modification remains the mainstay solution. Patients with refractory MU may be candidates for revisional surgery. OBJECTIVE: To summarize our experience of revisional surgery for treating refractory MU after LRYGB. SETTING: University hospital, Taiwan. METHODS: A retrospective analysis was performed for 11 patients with refractory MU undergoing totally hand-sewn gastrojejunostomy and truncal vagotomy at our institution between August 2005 and May 2015. The mean follow-up after surgery was 28.0±16.2 months (range, 10-48 mo); 9 patients (81.8%) were followed up more than 1 year after. RESULTS: The mean age of the cohort (7 males; 4 females) was 39.5±16.0 years (range, 19-66 yr), with a mean initial body mass index of 37.5±9.3 kg/m2 (range, 32.1-57 kg/m2). Intractability was the dominant manifestation (100%); 8 patients (72%) had stricture at the gastrojejunostomy. The mean interval from initial LRYGB to refractory MU and revisional surgery was 10.2±7.7 months (range, 4-28 mo) and 38.7±21.6 months (range, 10-67 mo), respectively. The average operation time was 150.4±59.8 minutes (range, 80-300 min), and the average length of hospital stay was 4.2±1.4 days (range, 2-7 d). The 9 patients with more than 1 year follow-up all achieved endoscopic resolution of the refractory MU. CONCLUSIONS: Although longer follow-up is warranted, revisional surgery with totally hand-sewn gastrojejunostomy and truncal vagotomy can be an effective solution for refractory MU.

Surgical standardization to prevent gastric stenosis after laparoscopic sleeve gastrectomy: a case series.

BACKGROUND: Laparoscopic sleeve gastrectomy (LSG) is accepted as a stand-alone bariatric procedure. A specific and potentially severe complication of LSG is gastric stenosis (GS). OBJECTIVE: Reviewing the treatment and prevention of GS after LSG. SETTING: University hospital, Taiwan. MATERIALS AND METHODS: A retrospective analysis was conducted involving all of the LSG cases (n = 927) at our institution between February 2007 and December 2015. RESULTS: Eight patients (0.8%) with GS were identified in our unit and 1 patient was transferred from another institution with symptomatic GS. The median intervals from initial LSG to the presence of symptoms, endoscopic dilation, and surgical revision were 14±30 days (range, 7-103 days), 21±35.6 days (range, 9-110 days), and 36±473.9 days (range, 11-1185 days), respectively. The majority of stenoses were located at the incisura angularis (8/9 [88.9%]). Among the 9 patients, only 1 responded satisfactorily to repetitive endoscopic dilation and the remaining 8 patients required revisional laparoscopic surgery, including conversion to Roux-en-Y gastric bypass (n = 6), stricturoplasty (n = 1), and Roux-en-Y gastric bypass after failed seromyotomy (n = 1). No patients experienced recurrent symptoms of GS after revisional surgery. In September 2013, we modified our surgical techniques for the subsequent 489 patients and GS did not occur after the change in surgical procedures. CONCLUSION: A combined treatment modality, endoscopic intervention with and without surgical revision is essential for managing GSs. Based on our own experience, we emphasize the clinical significance of surgical standardization to prevent the occurrence of GS.