Identifying regions of importance in wall-bounded turbulence through explainable deep learning.

Despite its great scientific and technological importance, wall-bounded turbulence is an unresolved problem in classical physics that requires new perspectives to be tackled. One of the key strategies has been to study interactions among the energy-containing coherent structures in the flow. Such interactions are explored in this study using an explainable deep-learning method. The instantaneous velocity field obtained from a turbulent channel flow simulation is used to predict the velocity field in time through a U-net architecture. Based on the predicted flow, we assess the importance of each structure for this prediction using the game-theoretic algorithm of SHapley Additive exPlanations (SHAP). This work provides results in agreement with previous observations in the literature and extends them by revealing that the most important structures in the flow are not necessarily the ones with the highest contribution to the Reynolds shear stress. We also apply the method to an experimental database, where we can identify structures based on their importance score. This framework has the potential to shed light on numerous fundamental phenomena of wall-bounded turbulence, including novel strategies for flow control.

Rescue from complications after pancreaticoduodenectomies at a low-volume Caribbean center: Value of tailored peri-pancreatectomy protocols.

BACKGROUND: Pancreaticoduodenectomy (PD) is a technically complex operation, with a relatively high risk for complications. The ability to rescue patients from post-PD complications is as a recognized quality measure. Tailored protocols were instituted at our low volume facility in the year 2013. AIM: To document the rate of rescue from post-PD complications with tailored protocols in place as a measure of quality. METHODS: A retrospective audit was performed to collect data from patients who experienced major post-PD complications at a low volume pancreatic surgery unit in Trinidad and Tobago between January 1, 2013 and June 30, 2023. Standardized definitions from the International Study Group of Pancreatic Surgery were used to define post-PD complications, and the modified Clavien-Dindo classification was used to classify post-PD complications. RESULTS: Over the study period, 113 patients at a mean age of 57.5 years (standard deviation [SD] ± 9.23; range: 30-90; median: 56) underwent PDs at this facility. Major complications were recorded in 33 (29.2%) patients at a mean age of 53.8 years (SD: ± 7.9). Twenty-nine (87.9%) patients who experienced major morbidity were salvaged after aggressive treatment of their complication. Four (3.5%) died from bleeding pseudoaneurysm (1), septic shock secondary to a bile leak (1), anastomotic leak (1), and myocardial infarction (1). There was a significantly greater salvage rate in patients with American Society of Anesthesiologists scores ≤ 2 (93.3% vs 25%; P = 0.0024). CONCLUSION: This paper adds to the growing body of evidence that volume alone should not be used as a marker of quality for patients requiring PD. Despite low volumes at our facility, we demonstrated that 87.9% of patients were rescued from major complications. We attributed this to several factors including development of rescue protocols, the competence of the pancreatic surgery teams and continuous, and adaptive learning by the entire institution, culminating in the development of tailored peri-pancreatectomy protocols.

A comparative clinical study of postoperative care by teleophthalmology and in-person consultation at hospital outpatient department after an uncomplicated cataract surgery.

BACKGROUND: Teleophthalmology provides an opportunity to conduct consultations in far-flung and remote areas that have no access to specialized eye care. However, there is a paucity of studies to assess the effect of missing in-person follow-up on initial postoperative visits. The study thus aims to compare postoperative satisfaction and uncorrected distance visual activity after an uneventful phacoemulsification cataract surgery in patients with teleconsultation approach to those with hospital visit. MATERIALS AND METHODS: The prospective observation study (n = 240) was conducted in patients who underwent surgery for cataract. Pre- and post-operative data were collected and divided into two groups based on the type of postoperative follow-up. All patients were scheduled for ophthalmic reviews in the hospital on day 1, day 7, and day 30-40 (hospital visit group) or through teleconsultation on days 1 and 7 followed by a hospital visit on days 30-40 (teleconsultation group). Outcomes evaluated in both groups were complications, patient satisfaction, and uncorrected distance visual acuity. RESULTS: Most patients in both groups were in the age group of 51-70 years. Overall satisfaction was comparable in teleconsultation and hospital visit groups (3.74 ± 0.23 vs. 3.72 ± 0.27; P = 0.22). The majority of patients had visual acuity 6/18-6/6 on postoperative day 1, day 7, and day 30-40 in both groups. Lid edema, pain, redness, watering, and congestion complications were more in the hospital visit group on postoperative day 1. CONCLUSION: The study concludes that patients with no preexisting ocular and systemic comorbidity undergoing an uneventful phacoemulsification cataract surgery teleconsultation approach can be used for follow-up without any impact on the postoperative visual outcome and patient satisfaction, thereby increasing the efficiency and productivity of health-care system.

Simultaneous Quantitation and Discovery (SQUAD) Analysis: Combining the Best of Targeted and Untargeted Mass Spectrometry-Based Metabolomics.

Untargeted and targeted approaches are the traditional metabolomics workflows acquired for a wider understanding of the metabolome under focus. Both approaches have their strengths and weaknesses. The untargeted, for example, is maximizing the detection and accurate identification of thousands of metabolites, while the targeted is maximizing the linear dynamic range and quantification sensitivity. These workflows, however, are acquired separately, so researchers compromise either a low-accuracy overview of total molecular changes (i.e., untargeted analysis) or a detailed yet blinkered snapshot of a selected group of metabolites (i.e., targeted analysis) by selecting one of the workflows over the other. In this review, we present a novel single injection simultaneous quantitation and discovery (SQUAD) metabolomics that combines targeted and untargeted workflows. It is used to identify and accurately quantify a targeted set of metabolites. It also allows data retro-mining to look for global metabolic changes that were not part of the original focus. This offers a way to strike the balance between targeted and untargeted approaches in one single experiment and address the two approaches' limitations. This simultaneous acquisition of hypothesis-led and discovery-led datasets allows scientists to gain more knowledge about biological systems in a single experiment.

Preliminary experience in laparoscopic distal pancreatectomy using the AEON™ endovascular stapler.

Background: The aim of this study is to investigate the effects of using a new innovative endovascular stapler, AEON™, on the pancreatic leak rates and other outcome measures. Methods: In a retrospective review of prospectively collected data from a secure tertiary unit registry, patients undergoing distal or lateral pancreatectomy were analyzed for any differences on pancreatic fistula rates, length of stay, comprehensive complication index (CCI), and demographics after using AEON™ compared with other commonly used staplers. Statistical significance was defined as <0.05. Results: There were no differences in the demographics between the two groups totaling 58 patients over 2 years from 2019 to 2021. A total of 43 and 15 patients underwent pancreatic transection using other staplers and AEON™ endovascular stapler, respectively. The comparison of the two groups revealed a significantly reduced rate of mean drain lipase at postoperative day 3 with AEON™ (446 U/L) versus the other staplers (4,208 U/L) (p = 0.018) and a subsequent reduction of postoperative pancreatic fistula (POPF) from 65% to 20%. A reduction in the mean CCI, from 13.80 when other staplers were used to 4.97 when AEON™ was used, was also observed (p = 0.087). Mean length of stay was shorter by 3 days in the AEON™ group compared with that in the other staplers (6 and 9 days, respectively; p = 0.018). Conclusion: AEON™ stapler when used to transect the pancreas demonstrated a significantly reduced pancreatic fistula rate, length of stay in hospital, and a leaning towards a reduced CCI. Its use should be further evaluated in larger cohorts with the encouraging results to determine whether this is possibly related to the technology used in the design of the AEON™ stapler.

A comparative study to evaluate the effect of various postoperative treatment protocols on dry eye and patient satisfaction after phacoemulsification.

Purpose: Foreign body sensation and irritation are common after cataract surgery, as is the exacerbation of dry eye disease if present. This study compared postoperative dry eye treatments and patient satisfaction. Methods: Age-related cataract patients undergoing phacoemulsification were recruited and were divided randomly into 4 postoperative treatment groups: Group A: Antibiotic + Steroids; Group B: Antibiotic + Steroids + Mydriatic; Group C: Antibiotic + Steroids + Mydriatic + Non-steroidal Ant-inflammatory drugs (NSAIDs); Group D: Antibiotic + Steroids + Mydriatic + NSAID + Tear substitute. Patients were assessed at 1, 3, and 5 weeks post-operatively for uncorrected distance and near vision, best corrected visual acuity (BCVA) for distance and near, Schirmer's-1 test, and Tear Film Break-Up Time test. At each visit, patients were assessed for dry eye-related subjective parameters using Ocular Surface Disease Index questionnaire. Results: Study participants numbered 163. (87 male and 76 female patients). No statistically significant difference was present in visual acuity for near and distance. The mean values of Schirmer's test and TFBUT were better in group D patients at each postoperative visit, with significant differences noted in comparison with other groups. The patient response to pain and dry eye symptoms was superior in groups C and D, with group D producing the best results. Compared to group A, patients in groups C and D were more satisfied with their vision and surgery. Conclusion: The addition of tear substitutes to steroids and NSAIDs has been associated with decreased dry eye-related symptoms and a better subjective feeling of vision, although no significant difference was noted in vision measured objectively.

Social determinants of diabetic retinopathy and impact of sight-threatening diabetic retinopathy: A study from Pune, India.

Purpose: Diabetes-related retinopathy is the leading cause of blindness in India. The study was carried out with the purpose of studying the association of sight-threatening diabetic retinopathy (STDR) with socioeconomic factors and demonstrating the impact of STDR on the affected individual. Methods: A mixed methods (quantitative and qualitative) research design was used. The study participants were divided into two groups for quantitative analysis. The control group consisted of non-sight-threatening diabetic retinopathy, whereas the study group consisted of sight-threatening diabetic retinopathy. Apart from demographics, data on comorbidities, type and duration of diabetes mellitus (DM), health insurance status, and socioeconomic data were collected from each individual. A statistical test (Chi-square) was performed to study the association between socioeconomic (SE) classes and STDR. For the qualitative part, a few people were chosen. Face-to-face interviews were conducted in depth. Results: A total of 207 individuals, were recruited, of which 69 had STDR and the remaining 138 had non-STDR. The incidence of STDR was high among patients with lower socioeconomic class (SEC) (upper lower and lower), and univariate analysis revealed a strong association between STDR and SEC, the presence of comorbidities, presence of health insurance, type and duration of DM, and P value <0.05. SEC, in contrast, emerged as an independent risk factor for STDR in multivariate analysis. STDR had a devastating effect on all patients interviewed. The financial impact was most likely the most severe. Conclusion: People with lower SEC are more likely to suffer from STDR-related vision loss. The impact of such vision loss on individuals is multifaceted, including a negative impact on social and work life, psychological well-being, and, most importantly, a significant financial impact.

A Comparison of the Celiacomesenteric Trunk in the Caribbean with Global Prevalence Calculated by a Systematic Review.

Background: Typically, the celiac trunk and superior mesenteric artery branch off separately from the anterior aspect of the abdominal aorta. The celiacomesenteric trunk (CMT) is a rare variant in which those arteries share a common origin. We sought to compare the prevalence of CMT in the Caribbean with the global prevalence as calculated by a systematic review. Methods: In this study, we evaluated all consecutive patients who had multiphase contrast-enhanced CT scans at two major referral centres in the Caribbean from August 30, 2017, to September 1, 2019. In patients with a CMT, we recorded demographic and anatomic details. We then conducted a systematic literature search and retrieved raw data to calculate the global prevalence (number of individuals with a CMT divided by the sum total of study samples). We compared CMT prevalence in our sample with the global prevalence using Pearson's chi-square and Fisher's exact tests. Statistical significance was considered to be present when the P value was <0.05. Results: From 832 CTs, 665 scans met the inclusion criteria. There were 16 (2.41%) CMTs: 3 (0.45%) classic CMTs, 12 (1.8%) hepato-mesenteric trunks, and 1 (0.15%) hepato-spleno-mesenteric trunk. Forty-two studies reported on CMTs in a total of 74,320 persons. The global CMT prevalence was comparable (3.88%; P = 0.054), but the incidence of hepato-mesenteric variants was significantly lower in our sample (1.8% vs. 3.24%; P = 0.0352). Conclusion: There was no difference in the prevalence of a classic CMT in the Caribbean compared to the global prevalence. However, the hepato-mesenteric trunk (incomplete CMT variant) was significantly less prevalent in the Caribbean. Advances in Knowledge: Healthcare professionals performing hepatobiliary interventions must be aware of these differences in order to minimize morbidity during their interventions.

Comparative study of anatomical and functional recovery of eye along with patient satisfaction score after small-incision cataract surgery and phacoemulsification cataract surgery.

Purpose: Functional recovery after cataract surgery depends on the anatomical recovery of the eye. This study compared the improvement in visual function parameters after uniocular manual small-incision cataract surgery (MSICS) and phacoemulsification cataract surgery. Methods: This study included 310 patients divided randomly into two groups: 155 who received MSICS (MSICS group) and 155 who underwent phacoemulsification (phaco group) for cataract treatment. Outcome measures assessed included vertical and horizontal keratometry reading. The mean corneal astigmatism tear function measured using Schirmer 1 test results were recorded preoperatively, and on postoperative day 1, day 7, and day 30. Optical coherence tomography (OCT) was done to record the average central macular thickness (µm) on day 7 and day 30. Results: The mean corneal astigmatism and anterior chamber inflammation were more in the MSICS group than in the phaco group immediately postoperatively. However, no statistically significant difference was found between the groups with respect to corneal sensation, mean corneal astigmatism, tear film function, and visual outcomes on postoperative day 30. Uncorrected visual acuity was better in the phacoemulsification group than in the manual SICS group on postoperative day 1, day 7, and day 30 (P < 0.001). Conclusion: Both phacoemulsification cataract surgery and manual small-incision sutureless cataract surgery (MSICS) are safe and effective for visual rehabilitation. Phacoemulsification is the preferred technique where resources are available with the advantages of less mean corneal astigmatism, less anterior chamber inflammation, and better uncorrected visual acuity (UCVA) in the immediate postoperative period.

Whipple's operation with a modified centralization concept: A model in low-volume Caribbean centers.

Conventional data suggest that complex operations, such as a pancreaticoduodenectomy (PD), should be limited to high volume centers. However, this is not practical in small, resource-poor countries in the Caribbean. In these settings, patients have no option but to have their PDs performed locally at low volumes, occasionally by general surgeons. In this paper, we review the evolution of the concept of the high-volume center and discuss the feasibility of applying this concept to low and middle-income nations. Specifically, we discuss a modification of this concept that may be considered when incorporating PD into low-volume and resource-poor countries, such as those in the Caribbean. This paper has two parts. First, we performed a literature review evaluating studies published on outcomes after PD in high volume centers. The data in the Caribbean is then examined and we discuss the incorporation of this operation into resource-poor hospitals with modifications of the centralization concept. In the authors' opinions, most patients who require PD in the Caribbean do not have realistic opportunities to have surgery in high-volume centers in developed countries. In these settings, their only options are to have their operations in the resource-poor, low-volume settings in the Caribbean. However, post-operative outcomes may be improved, despite low-volumes, if a modified centralization concept is encouraged.

Effects on ocular aberration and contrast sensitivity after implantation of spherical and aspherical monofocal intraocular lens - A comparative study.

Purpose: Phacoemulsification with intraocular lens (IOL) implantation is the standard of care for cataractous eyes. Monofocal IOLs are spherical or aspheric. The aspheric design of IOLs reduces the spherical and higher-order aberrations and impacts contrast sensitivity post cataract surgery. There are some studies, but data in the Indian setting with the IOLs we used is lacking. We aimed to compare the effect of implantation of spheric and aspheric foldable intraocular lenses on postoperative quality of vision, spherical aberration, and contrast sensitivity. Methods: This prospective observational study was conducted at a tertiary care hospital with an ophthalmology specialty, data collection from January 2017 to May 2018 in 100 patients. Patients meeting the inclusion criteria were selected. Their preoperative and postoperative data were collected and divided into groups based on whether spherical or aspheric IOL was implanted after cataract surgery. Variables assessed were visual acuity on days 7 and 30, spherical aberrations, and contrast sensitivity was assessed at 1-month postoperative. Results: The mean age of the patients in this study was 64 ± 8 years with a majority of patients (60%) being females. There is no significant difference in postoperative visual acuity between the two groups. Internal SA was significantly lower (~50%) in eyes implanted with aspheric IOLs (P value = 0.004, 0.0001) compared with the spherical group. Contrast sensitivity of patients of the aspheric group was significantly better (P value <0.05). Conclusion: The optical design of the aspheric IOLs reduced spherical aberrations and increased contrast sensitivity.

A fast-track surgery programme leads to timelier treatment and higher resection rates in pancreatic cancer.

BACKGROUND: The aim was to perform a propensity-matched comparison of patients with pancreatic cancer undergoing surgery, with and without biliary stenting and an intention to treat analysis of long-term survival between the two groups. METHODS: This was an observational study of a cohort of consecutive patients presenting with obstructive jaundice and undergoing pancreatoduodenectomy for pancreatic and periampullary malignancies between November 2015 and May 2019. RESULTS: In this study of 216 consecutive operable patients, 70 followed the fast-track pathway and 146 had pre-operative biliary drainage. All 70 patients in the FT group and 122 out of 146 in the PBD group proceeded to surgery (100% and 83.6% respectively, p = 0.001). Interval time from diagnostic CT scan to surgery and from MDT decision to treat to surgery was shorter in the FT group, (median 8 vs 43 days p < 0.001 and 3 vs 36 days p < 0.001 respectively) as was the overall time from diagnostic CT to adjuvant treatment (88 vs 121 days p < 0.001). Postoperative outcomes including complications, readmission and mortality rates were comparable in the two groups. There was no difference in survival. CONCLUSION: For a person with pancreatic cancer who is proceeding to surgery, the best approach is to avoid pre-operative biliary drainage.

Review of minimally invasive pancreas surgery and opinion on its incorporation into low volume and resource poor centres.

Pancreatic surgery has been one of the last areas for the application of minimally invasive surgery (MIS) because there are many factors that make laparoscopic pancreas resections difficult. The concept of service centralization has also limited expertise to a small cadre of high-volume centres in resource rich countries. However, this is not the environment that many surgeons in developing countries work in. These patients often do not have the opportunity to travel to high volume centres for care. Therefore, we sought to review the existing data on MIS for the pancreas and to discuss. In this paper, we review the evolution of MIS on the pancreas and discuss the incorporation of this service into low-volume and resource-poor countries, such as those in the Caribbean. This paper has two parts. First, we performed a literature review evaluating all studies published on laparoscopic and robotic surgery of the pancreas. The data in the Caribbean is examined and we discuss tips for incorporating this operation into resource poor hospital practice. Low pancreatic case volume in the Caribbean, and financial barriers to MIS in general, laparoscopic distal pancreatectomy, enucleation and cystogastrostomy are feasible operations to integrate in to a resource-limited healthcare environment. This is because they can be performed with minimal to no consumables and require an intermediate MIS skillset to complement an open pancreatic surgeon's peri-operative experience.

An Investigative Study of Hepatic Arterial Anomalies in a West Indian Population.

PURPOSE: There are many known variations in the arterial supply to the liver. We sought to document the incidence and details of anomalies of the extrahepatic arteries in an unselected population in the West Indies. METHODS: This study spanned 24 months. All 205 CT scans were evaluated at a hepatobiliary referral center in Trinidad and Tobago. We described the anomalies of the arterial supply to the liver using the conventional classification proposed by Michels. RESULTS: 205 CT scans were evaluated, and 112 persons (54.6%) had conventional Type 1 anatomy. However, compared to the incidence in the existing medical literature, we encountered a greater incidence of replaced right hepatic arteries (18.1% vs 11%; P 0.04) and a lower incidence of accessory right hepatic arteries (2.4% vs 7%; P 0.030). CONCLUSION: Although 54.6% of persons in this West Indian population have conventional hepatic arterial supply, the distribution of anatomic variants of the right hepatic artery is quite different to that seen in North American and European centers. We found a higher incidence of replaced right hepatic arteries and a lower incidence of accessory right hepatic arteries.

Anatomic variations of the intra-hepatic biliary tree in the Caribbean: A systematic review.

BACKGROUND: In the classic descriptions of the human liver, the common hepatic duct forms at the confluence of left and right hepatic ducts. Many authors have documented variations in the intra-hepatic ductal system, but to the best of our knowledge there has been no report on bile duct variations in Caribbean populations. AIM: To evaluate the variations in bile duct anatomy using magnetic resonance cholangiography (MRC) in unselected patients at a major hepatobiliary referral centre in the Eastern Caribbean. Knowledge of the intra-hepatic biliary anatomy is important to optimize service delivery for any physician treating liver and biliary disorders. METHODS: This study was carried out at a tertiary referral hospital for hepatobiliary diseases in the Eastern Caribbean. We retrospectively evaluated magnetic resonance cholangiograms in 152 consecutive patients at this facility over a two-year period from April 1, 2017 to March 31, 2019. Two consultant radiologists experienced in MRC interpretation reviewed all scans and described biliary anatomy according to the Huang's classification. A systematic review of published studies was performed and relevant data were extracted in order to calculate the global prevalence of each biliary variant. The variants in our population were compared to the global population. RESULTS: There were 152 MRCs evaluated in this study in 86 males and 66 females. There were 109 (71.7%) persons with "classic" biliary anatomy (type A1) and variants were present in 43 (28.3%) persons. There was no statistical relationship between the presence of anatomic variants and gender or ethnicity. We encountered the following variants: 29 (19.1%) type A2, 7 (4.6%) type A3, 6 (3.95%) type A4, 0 type A5 and a single variant (quadrification) that did not fit the classification system. Compared to the global prevalence, our population had a significantly greater occurrence of A1 anatomy (71.7% vs 62.6%; P = 0.0227) and A2 trifurcations (19.1% vs 11.5%; P = 0.0069), but a significantly lower incidence of A3 variants (4.61% vs 11.5%; P = 0.0047). CONCLUSION: There are significant differences in intra-hepatic biliary anatomy in this unselected Eastern Caribbean population compared to global statistics. Specifically, persons of Caribbean descent have a greater incidence of Huang A2 trifurcations and a lower incidence of Huang A3 variants.

Surgical relevance of anatomic variations of the right hepatic vein.

BACKGROUND: Variations in the anatomy of hepatic veins are of interest to transplant surgeons, interventional radiologists, and other medical practitioners who treat liver diseases. The drainage patterns of the right hepatic veins (RHVs) are particularly relevant to transplantation services. AIM: The aim was to identify variations of the patterns of venous drainage from the right side of the liver. To the best of our knowledge, there have been no reports on RHV variations in in a Caribbean population. METHODS: Two radiologists independently reviewed 230 contrast-enhanced computed tomography scans performed in 1 year at a hepatobiliary referral center. Venous outflow patterns were observed and RHV variants were described as: (1) Tributaries of the RHV; (2) Variations at the hepatocaval junction (HCJ); and (3) Accessory RHVs. RESULTS: A total of 118 scans met the inclusion criteria. Only 39% of the scans found conventional anatomy of the main hepatic veins. Accessory RHVs were present 49.2% and included a well-defined inferior RHV draining segment VI (45%) and a middle RHV (4%). At the HCJ, 83 of the 118 (70.3%) had a superior RHV that received no tributaries within 1 cm of the junction (Nakamura and Tsuzuki type I). In 35 individuals (29.7%) there was a short superior RHV with at least one variant tributary. According to the Nakamura and Tsuzuki classification, there were 24 type II variants (20.3%), six type III variants (5.1%) and, five type IV variants (4.2%). CONCLUSION: There was significant variation in RHV patterns in this population, each with important relevance to liver surgery. Interventional radiologists and hepatobiliary surgeons practicing in the Caribbean must be cognizant of these differences in order to minimize morbidity during invasive procedures.

Can the postoperative follow-up visit be deferred up to four weeks after an uneventful cataract surgery? - A randomized controlled trial.

Purpose: The aim of this study was to compare the postoperative visual outcome after a Day 0 examination in patients with two follow-ups, one between Day 3 to Day 7 and other between Day 25 to Day 30 to those with a single ophthalmic follow-up directly after 25-30 Days and to assess the safety of deferral of the first follow-up visit at 1 week. Methods: Randomized Controlled Trial was conducted at a tertiary eye care hospital, with 848 patients enrolled for the study. Patients meeting the inclusion criteria were selected. Their pre-operative and post-operative data was collected and the patients were divided into groups based on the type of cataract surgery and the postoperative follow-up protocol through randomization. Results: No significant difference was observed in the postoperative visual outcome in patients that underwent postoperative review at Day 3-7 and Day 25-30 as opposed to those that followed up directly at Day 25-30 after a mandatory Day 0 examination for all patients. Conclusion: In patients with no preexisting ocular or systemic comorbidity undergoing an uneventful cataract surgery, the postoperative follow-up visit can be safely deferred until 4 weeks, without any impact on the postoperative visual outcome, thereby conserving the available resources which can be deviated towards better eye care services.