Comparison of Eastern and Western patients undergoing bariatric surgery at two US and Korean institutions: a retrospective analysis of differing bariatric patient populations.

BACKGROUND: Currently, there are differences in both demographics and indications for bariatric surgery between Eastern and Western countries. We compared postoperative outcomes between Korean and American bariatric programs in order to assess how bariatric surgery differently affects these populations. METHODS: We enrolled 540 patients who underwent bariatric surgery at University of California, Los Angeles (UCLA) and 85 patients who underwent surgery at Kosin University Gospel Hospital (KUGH) between January 2019 and December 2020. We compared demographics, complications, weight loss, and metabolic parameters between these groups. RESULTS: There was a difference in age between the UCLA and KUGH patient groups (44.3 years vs 37.6 years, P < 0.01). Frequencies of T2DM and OSA were also different (4.2% vs 50.6%, 34.1% vs 85.9% P < 0.01. Length of hospital stay varied (1.55 days vs 6.68 days, P < 0.01), but there was no difference in operating time and complications. There was no difference in percent of excess weight loss between the two groups at 6 months (29.7 vs 33.8, P = 0.13). Hepatic steatosis index (HSI) was higher in the UCLA group both before (54.2 vs 51.5, P < 0.01) and after (44.4 vs 40.0, P = 0.02) surgery. LSG was the most frequently performed operation, and robotic surgery and revisions were performed only in the UCLA program. CONCLUSION: There were differences in age, BMI, length of stay, and choice of operation between Korean and American bariatric patients. Also, there were differences in the degree of fatty liver disease using HSI and liver enzymes before and after surgery. There was no significant differences in operation time and complications. These findings suggest differences in bariatric practices and reactions to bariatric surgery in Eastern and Western settings.

Microbial changes from bariatric surgery alters glucose-dependent insulinotropic polypeptide and prevents fatty liver disease.

Bariatric surgery remains a potent therapy for nonalcoholic fatty liver disease (NAFLD), but its inherent risk and eligibility requirement limit its adoption. Therefore, understanding how bariatric surgery improves NAFLD is paramount to developing novel therapeutics. Here, we show that the microbiome changes induced by sleeve gastrectomy (SG) reduce glucose-dependent insulinotropic polypeptide (GIP) signaling and confer resistance against diet-induced obesity (DIO) and NAFLD. We examined a cohort of NALFD patients undergoing SG and evaluated their microbiome, serum metabolites, and GI hormones. We observed significant changes in Bacteroides, lipid-related metabolites, and reduction in GIP. To examine if the changes in the microbiome were causally related to NAFLD, we performed fecal microbial transplants in antibiotic-treated mice from patients before and after their surgery who had significant weight loss and improvement of their NAFLD. Mice transplanted with the microbiome of patients after bariatric surgery were more resistant to DIO and NAFLD development compared to mice transplanted with the microbiome of patients before surgery. This resistance to DIO and NAFLD was also associated with a reduction in GIP levels in mice with post-bariatric microbiome. We further show that the reduction in GIP was related to higher levels of Akkermansia and differing levels of indolepropionate, bacteria-derived tryptophan-related metabolite. Overall, this is one of the few studies showing that GIP signaling is altered by the gut microbiome, and it supports that the positive effect of bariatric surgery on NAFLD is in part due to microbiome changes.

A Novel Sensor for Tissue Mechanical Property Detection During Robotic Surgery.

Haptic feedback relays important tissue mechanical properties to surgeons during open surgery. However, this information is lost during Robot-assisted Minimally Invasive Surgery (RMIS). Here we present a proof-of-concept for a novel instrument-integrated sensor that uses fiber Bragg grating (FBG) arrays to identify tissues based on mechanical properties. Subjects were tasked with sorting tissue phantoms based on hardness. When using a conventional surgical robot, the average error for novices (N=5) and the expert user was 22.5% and 12.5% respectively. This reduced to 2.5% and 0% when sorting with direct palpation by hand. In contrast, the senorized instrument with automated analysis was able to perform the task without any error across all trials. Clinical Relevance - The proposed sensor has the potential of identifying different tissues based on mechanical properties and thus characterize tumors and other relevant structures. It is envisaged that this will improve decision making process during RMIS and also provide useful sensory information for autonomous surgery.

Incidence and risk factors for early gastrojejunostomy anastomotic stricture requiring endoscopic intervention following laparoscopic Roux-en-Y gastric bypass: a MBSAQIP analysis.

BACKGROUND: Gastrojejunostomy (GJ) stricture is one of the most commonly recognized complications following laparoscopic Roux-en-Y gastric bypass (LRYGB). The risks involving the formation of early GJ stomal stenosis are largely unknown. The aims of this study are to evaluate the rate and risk factors associated with GJ stricture in patients requiring esophagogastroduodenoscopy (EGD) within 30 days after LRYGB. METHODS: This is a retrospective study of patients who underwent EGD for GJ stricture following LRYGB. Data were retrieved from MBSAQIP database from 2015 to 2018. Descriptive, bivariate, and logistic regression analyses were performed. Those who had reoperation, readmission, and intervention for other indications rather than GJ stricture were excluded from the risk factor analysis. RESULTS: 760,076 patients underwent bariatric surgery. Of these, 184,660 (24.3%) underwent LRYGB and 875 had GJ stricture within 30 days postoperatively. The overall incidence of early GJ stricture after LRYGB was 4.7 per 1000 person-years. The incidence decreased from 6.2 to 3.4 per 1000 person-years during the 4-year period. 85% of patients with GJ stricture required therapeutic intervention. Median (IQR) day to the first endoscopic intervention was 25 (21-28) days. The overall 30-day readmission rate was 40%. 30-day reoperation rate due to GJ stricture was 5.6%. No 30-day mortality occurred. Factors independently associated with an increased risk for early GJ stricture include concurrent hiatal hernia repair (Adjusted Odds Ratio-AOR 1.8, 95% CI 1.5-2.2), revision case (AOR 1.4, 95% CI 1.1-1.6), African American (AOR 1.4, 95% CI 1.2-1.7), gastroesophageal reflux disease-GERD (AOR 1.4, 95% CI 1.2-1.5), drain placement (AOR 1.3, 95% CI1.1-1.4), and routine postoperative swallow study (AOR 1.3, 95% CI 1.1-1.50). CONCLUSION: The incidence of early GJ stricture following LRYGB decreased at MBSAQIP-accredited centers over the review period. Patients having additional manipulation at or around GJ were at risk of developing early GJ stricture after LRYGB.

Reducing retraction forces with tactile feedback during robotic total mesorectal excision in a porcine model.

Excessive tissue-instrument interaction forces during robotic surgery have the potential for causing iatrogenic tissue damages. The current in vivo study seeks to assess whether tactile feedback could reduce intraoperative tissue-instrument interaction forces during robotic-assisted total mesorectal excision. Five subjects, including three experts and two novices, used the da Vinci robot to perform total mesorectum excision in four pigs. The grip force in the left arm, used for retraction, and the pushing force in the right arm, used for blunt pelvic dissection around the rectum, were recorded. Tissue-instrument interaction forces were compared between trials done with and without tactile feedback. The mean force exerted on the tissue was consistently higher in the retracting arm than the dissecting arm (3.72 ± 1.19 vs 0.32 ± 0.36 N, p < 0.01). Tactile feedback brought about significant reductions in average retraction forces (3.69 ± 1.08 N vs 4.16 ± 1.12 N, p = 0.02), but dissection forces appeared unaffected (0.43 ± 0.42 vs 0.37 ± 0.28 N, p = 0.71). No significant differences were found between retraction and dissection forces exerted by novice and expert robotic surgeons. This in vivo animal study demonstrated the efficacy of tactile feedback in reducing retraction forces during total mesorectal excision. Further research is required to quantify the clinical impact of such force reduction.

Risk factors for readmission for early small bowel obstruction following laparoscopic Roux-en-Y gastric bypass: an MBSAQIP analysis.

BACKGROUND: Small bowel obstruction (SBO) following laparoscopic Roux-en-Y gastric bypass (LRYGB) is associated with significant morbidity. OBJECTIVES: To evaluate the rate of and risk factors for readmission for SBO within 30 days of LRYGB. SETTING: Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP)-accredited centers. METHODS: This is a retrospective study using the MBSAQIP database. A query was performed from 2015-2018 for patients who underwent LRYGB and required readmission for SBO. Those who had a reoperation, intervention, readmission, or expired from causes other than SBO were excluded. Descriptive, bivariate, and binary logistic regression analyses were performed. RESULTS: Among 184,660 patients undergoing LRYGB, 1189 (.64%) required readmission due to SBO. Among the readmission cases, 978 (82.5%) were identified as having intestinal obstruction (unspecified), 108 (9.1%) incisional hernia, and 100 (8.4%) internal hernia. Among these cases, 69% had a reoperation and 1.3% expired during the 30-day period. From a logistic regression model, parameters independently associated with an increased risk for readmission for early SBO include being female (adjusted odds ratio [AOR], 1.53) or black (AOR, 1.41) and having gastroesophageal reflux (AOR, 1.35), a history of myocardial infarction (AOR, 1.76), a history of deep vein thrombosis (AOR, 1.73), previous obesity surgery/foregut surgery (AOR, 1.79), a robotic-assisted procedure (AOR, 1.23), concurrent hiatal hernia repair (AOR, 1.66) and adhesiolysis (AOR, 1.42). CONCLUSION: The rate of readmission for early SBO following LRYGB was less than 1%. The majority of these cases required reoperation. The increased intraoperative complexity of LRYGB is associated with an increased risk of readmission due to early SBO.

Bio-Inspired Haptic Feedback for Artificial Palpation in Robotic Surgery.

Adding haptic feedback has been reported to improve the outcome of minimally invasive robotic surgery. In this study, we seek to determine whether an algorithm based on simulating responses of a cutaneous afferent population can be implemented to improve the performance of presenting haptic feedback for robot-assisted surgery. We propose a bio-inspired controlling model to present vibration and force feedback to help surgeons localize underlying structures in phantom tissue. A single pair of actuators was controlled by outputs of a model of a population of cutaneous afferents based on the pressure signal from a single sensor embedded in surgical forceps. We recruited 25 subjects including 10 expert surgeons to evaluate the performance of the bio-inspired controlling model in an artificial palpation task using the da Vinci surgical robot. Among the control methods tested, the bio-inspired system was unique in allowing both novices and experts to easily identify the locations of all classes of tumors and did so with reduced contact force and tumor contact time. This work demonstrates the utility of our bio-inspired multi-modal feedback system, which resulted in superior performance for both novice and professional users, in comparison to a traditional linear and the existing piecewise discrete algorithms of haptic feedback.

Smoothed particle hydrodynamics simulation of biphasic soft tissue and its medical applications.

Modeling the coupled fluid and elastic mechanics of blood perfused soft tissues is important for medical applications. In particular, the current study aims to capture the effect of tissue swelling and the transport of blood through damaged tissue under bleeding or hemorrhaging conditions. The soft tissue is considered a dynamic poro-hyperelastic material with blood-filled voids. A biphasic formulation-effectively, a generalization of Darcy's law-is utilized, treating the phases as occupying fractions of the same volume. A Stokes-like friction force and a pressure that penalizes deviations from volume fractions summing to unity serve as the interaction force between solid and liquid phases. The resulting equations for both phases are discretized with the method of smoothed particle hydrodynamics (SPH). The solver is validated separately on each phase and demonstrates good agreement with exact solutions in test problems. Simulations of oozing, hysteresis, swelling, drying and shrinkage, and tissue fracturing and hemorrhage are shown in the paper. Graphical Abstract In the paper, a new methodology for the numerical simulation of the full dynamic response of blood-perfused soft tissues was developed.

Improvement in Uncontrolled Eating Behavior after Laparoscopic Sleeve Gastrectomy Is Associated with Alterations in the Brain-Gut-Microbiome Axis in Obese Women.

BACKGROUND: Bariatric surgery is proven to change eating behavior and cause sustained weight loss, yet the exact mechanisms underlying these changes are not clearly understood. We explore this in a novel way by examining how bariatric surgery affects the brain-gut-microbiome (BGM) axis. METHODS: Patient demographics, serum, stool, eating behavior questionnaires, and brain magnetic resonance imaging (MRI) were collected before and 6 months after laparoscopic sleeve gastrectomy (LSG). Differences in eating behavior and brain morphology and resting-state functional connectivity in core reward regions were correlated with serum metabolite and 16S microbiome data. RESULTS: LSG resulted in significant weight loss and improvement in maladaptive eating behaviors as measured by the Yale Food Addiction Scale (YFAS). Brain imaging showed a significant increase in brain volume of the putamen (p.adj < 0.05) and amygdala (p.adj < 0.05) after surgery. Resting-state connectivity between the precuneus and the putamen was significantly reduced after LSG (p.adj = 0.046). This change was associated with YFAS symptom count. Bacteroides, Ruminococcus, and Holdemanella were associated with reduced connectivity between these areas. Metabolomic profiles showed a positive correlation between this brain connection and a phosphatidylcholine metabolite. CONCLUSION: Bariatric surgery modulates brain networks that affect eating behavior, potentially through effects on the gut microbiota and its metabolites.

Indications, Operative Techniques, and Outcomes for Revisional Operation Following Mini-Gastric Bypass-One Anastomosis Gastric Bypass: a Systematic Review.

In addition to being a relatively reversible and less complex operation, mini-gastric bypass-one anastomosis gastric bypass (MGB-OAGB) has demonstrated comparable weight loss and metabolic improvement rates with Roux-en-Y gastric bypass (RYGB). However, surgical strategies for managing its failures and late complications were poorly defined. This article aims to review the indications, operative techniques, and outcomes for revisional surgery following MGB-OAGB. A systematic review was performed using the PubMed database from 1997 to 2019. Of 179 included patients, 89 underwent revision to RYGB; 52 to sleeve gastrectomy (SG); 32 reversal to original anatomy; and 6 underwent partial revision with gastro-gastrostomy alone. Most common indications were severe malnutrition, chronic bile reflux, intractable marginal ulcerations, and insufficient weight loss. Postoperative complication rates ranged from 5 to 35%.

Short- and intermediate-term clinical outcome comparison between laparoscopic and robotic-assisted median arcuate ligament release.

While laparoscopic median arcuate ligament (MAL) release remains the most common approach, robotic-assisted MAL release has been increasingly performed by several institutions. This study aims to compare surgical outcomes between laparoscopic and robotic-assisted MAL release. This is a retrospective study of patients undergoing laparoscopic and robotic-assisted MAL release in a teaching hospital from January 1999 to December 2018. Intraoperative and postoperative outcomes as well as short- and intermediate-term clinical outcomes were compared between the two groups. A total of 16 laparoscopic and 18 robotic cases were included. Demographics and baseline characteristics were similar between the two comparison groups. Median operative time was shorter in the robotic group [179.5 (IQR 127.3-225) vs. 106 (IQR 80.8-122.8) minutes; p < 0.001]. The rates of conversion to open operation were similar in both groups (6.3% vs. 5.6%, p = 0.99). Conversions to laparotomy were performed due to bleeding and extensive adhesions in one laparoscopic case and due to technical difficulties in a patient with narrow body habitus in the robotic group. Postoperative complication rates were similar (12.5% vs. 16.7%, p = 0.99), all in grade I and II. Complete pain resolution rates (37.5% vs. 44.4%, p = 0.93), symptom recurrence rates (37.5% vs. 27.8%, p = 0.93), and overall clinical improvement at last follow-up (87.5% vs. 77.8%, p = 0.66) were not statistically different. Both laparoscopic and robotic-assisted MAL release offer similar short- and intermediate-term clinical outcomes. A shortened operative time may be achieved by incorporating the robot platform.

Factors Associated with Symptomology of Celiac Artery Compression and Outcomes following Median Arcuate Ligament Release.

BACKGROUND: This study aims to identify potential risk factors for becoming symptomatic in patients with radiographic celiac artery compression (CAC) as well as prognostic factors for patients with median arcuate ligament syndrome (MALS) who underwent surgical ligament release. METHODS: This is a retrospective cohort study of patients with findings of CAC on computed tomography or magnetic resonance angiography (CT/MRA) who were asymptomatic and who were diagnosed with MALS at a single university hospital between January 2001 and 2018. RESULTS: Following a review of 1,330 CT/MRA reports, a total of 109 patients were identified as having radiographically apparent CAC. Among these, 48 (44.0%) patients were symptomatic. Univariate comparison between those with and without symptoms showed that symptomatic patients were more commonly younger than 30 years old [17/48 (35.4%) vs. 8/61 (13.1%), P = 0.006], had a history of prior abdominal surgery [25/48 (52.1%) vs. 18/61 (29.5%), P = 0.017], and had high-grade stenosis [32/43 (74.4%) vs. 25/61 (41.0%), P = 0.001]. Among 41 included patients who underwent surgical release of the median arcuate ligament including open, laparoscopic, and robotic approaches, 82.9% reported overall clinical improvement, 5/41 (12.2%) reported persistent pain, and 13/36 (36.0%) experienced pain recurrence. The only identified risk factor associated with symptom recurrence was American Society of Anesthesiologists class III [7/13 (53.8%) vs. 4/23 (17.4%), P = 0.029]. CONCLUSIONS: The severity of stenosis and prior abdominal surgery both contributed to symptom development in patients with radiographically apparent CAC from the median arcuate ligament.

A robotic system for telementoring and training in laparoscopic surgery.

A laparoscopic surgical training system, the LapaRobot, is introduced. The system is composed of an expert station and a trainee station connected through the Internet. Embedded actuators allow the trainee station to be driven by an expert surgeon so that a trainee learns proper technique through physical feedback. The surgical-tool trajectory and video feed can be recorded and later "played back" to a trainee to hone operative skills through guided repetition without the need for expert supervision. The system is designed to create a high-fidelity approximation of the intracorporeal workspace, incorporate commercially available surgical instruments, and provide a wealth of high-resolution data for quantitative analysis and feedback. Experimental evaluation demonstrated a 55% improvement in surgical performance with use of our system. In this paper, we introduce the details of the design and fabrication of the LapaRobot, illustrate the mechatronics and software-control schemes, and evaluate the system in a study.

Multi-Modal Haptic Feedback for Grip Force Reduction in Robotic Surgery.

Minimally invasive robotic surgery allows for many advantages over traditional surgical procedures, but the loss of force feedback combined with a potential for strong grasping forces can result in excessive tissue damage. Single modality haptic feedback systems have been designed and tested in an attempt to diminish grasping forces, but the results still fall short of natural performance. A multi-modal pneumatic feedback system was designed to allow for tactile, kinesthetic, and vibrotactile feedback, with the aims of more closely imitating natural touch and further improving the effectiveness of HFS in robotic surgical applications and tasks such as tissue grasping and manipulation. Testing of the multi-modal system yielded very promising results with an average force reduction of nearly 50% between the no feedback and hybrid (tactile and kinesthetic) trials (p < 1.0E-16). The multi-modal system demonstrated an increased reduction over single modality feedback solutions and indicated that the system can help users achieve average grip forces closer to those normally possible with the human hand.

Methods for registering and calibrating in vivo terahertz images of cutaneous burn wounds.

A method to register THz and visible images of cutaneous burn wounds and to calibrate THz image data is presented. Images of partial and full thickness burn wounds in 9 rats were collected over 435 mins. = 7.25 hours following burn induction. A two-step process was developed to reference the unknown structure of THz imaging contrast to the known structure and the features present in visible images of the injury. This process enabled the demarcation of a wound center for each THz image, independent of THz contrast. Threshold based segmentation enabled the automated identification of air (0% reflectivity), brass (100% reflectivity), and abdomen regions within the registered THz images. Pixel populations, defined by the segmentations, informed unsupervised image calibration and contrast warping for display. The registered images revealed that the largest variation in THz tissue reflectivity occurred superior to the contact region at ~0.13%/min. Conversely the contact region showed demonstrated an ~6.5-fold decrease at ~0.02%/min. Exploration of occlusion effects suggests that window contact may affect the measured edematous response.

Intestinal failure after bariatric surgery: Treatment and outcome at a single-intestinal rehabilitation and transplant center.

BACKGROUND: Though intestinal failure (IF) after bariatric surgery (BS) is uncommon, its prevalence is increasing. However, data on the outcomes for these patients are limited. OBJECTIVES: To analyze the outcomes of treatment for patients with IF after BS. SETTING: University hospital. METHODS: A single-center analysis (1991-2016) of outcomes according to treatment arms established by a multidisciplinary team. RESULTS: Twenty-five IF patients were identified (median age 45 yr). BS was 92% Roux-en-Y gastric bypass. The major cause of IF was volvulus/internal hernia (72%). Median time from BS to IF was 48 months. Treatment arms were intestinal rehabilitation (IR, n = 15), transplantation (TXP, n = 5), and parenteral nutrition (PN, n = 5). For IR, median bowel length was 60 cm. Forty-six percent ultimately discontinued PN. Twenty-seven percent were partially weaned PN and 27% failed IR. Common surgical rehabilitation was Roux-en-Y gastric bypass reversal and restoration of gastrointestinal continuity. The 5-year overall survival was 74%. For TXP, 7 patients were listed for TXP (5 initially and 2 after failed IR). Three underwent TXP, 2 isolated intestine and 1 isolated liver. Three were delisted (1 improvement and 2 death). For PN, 6 patients required long-term PN (5 initially and 1 after failed IR). Four patients are alive currently. CONCLUSIONS: IF after BS is an increasing problem facing IR centers. Internal hernia is the major cause. Surgical IR is the first-line therapy and affords the best outcome. TXP is reserved for rescuing patients who failed IR or develop PN complications. Long-term PN is suitable for patients in whom IR or TXP is impractical.

Care fragmentation is associated with increased short-term mortality during postoperative readmissions: A systematic review and meta-analysis.

BACKGROUND: Recent trends toward regionalization of complex surgical procedures may increase the risk for care fragmentation during readmissions. Conflicting conclusions have been reported regarding risk factors and consequences of nonindex readmissions (ie, readmission to a separate hospital than the one where surgery was originally performed). We seek to perform a comprehensive review of existing literature. METHODS: Four electronic databases were searched to identify all eligible studies examining the risk factors and outcomes of postoperative nonindex readmission. The pooled odds ratio and 95% confidence interval were calculated using a random-effects model. RESULTS: A total of 444 studies were retrieved from database searches and 23 were included after applying eligibility criteria. Nonindex readmissions constituted 10%-47% of 30-day readmissions. Risk factors for nonindex readmission predominantly represented proxy variables for patient care access that may not be modifiable, such as residing in a location further away from the original hospital, being older in age, living in rural areas, and having lower income. Nonindex readmissions occurred more commonly under urgent conditions. Ten of the 14 studies that employed short-term mortality as the primary outcome concluded that nonindex readmissions were significantly associated with higher mortality after adjusting for available confounders. CONCLUSION: The findings of the current study suggest that nonindex readmission is a common phenomenon after surgery and is associated with increased mortality. Further studies are required to evaluate whether enhancing health information continuity between hospitals would be helpful for mitigating the adverse consequences of care fragmentation.

Complete Impact of Care Fragmentation on Readmissions Following Urgent Abdominal Operations.

BACKGROUND: Urgent abdominal operations commonly occurred in low-volume hospitals with high failure-to-rescue rates. Recent studies have demonstrated a survival benefit associated with readmission to the original hospital after operation, presumably due to improved continuity of care. It is unclear if this survival benefit persists in low-volume hospitals. We seek to evaluate differences in mortality between readmission to the original hospital and a higher-volume hospital after urgent abdominal operations. METHODS: A retrospective cohort study using the National Readmissions Database from 2010 to 2014 was performed. Propensity score-weighted multilevel regression analysis was used to examine the association between readmission destination and mortality after accounting for hospital volume. RESULTS: A total of 71,551 adult patients who experienced 30-day readmission following urgent abdominal operations were identified, among whom 10,368 (14.5%) were readmitted to a different hospital. Patients with higher baseline comorbidity scores, lower income, less comprehensive insurance coverage, systemic complications, prolonged length of stay, or non-home disposition were more likely to experience readmission to a different hospital. Following stratification by readmission hospital volume and propensity score weighting to adjust for baseline mortality risk differences, readmission to a different hospital is still associated with higher mortality rates than the original hospital. CONCLUSIONS: The adverse outcomes associated with case fragmentation are present even after adjusting for readmission hospital volume. Patients who received urgent abdominal operations at low-volume hospitals should return to the original hospital for concern of care fragmentation.