Faculty Bibliography

Let A and B be two sets of points in R^d, where | A| = | B| = n and the distance between them is defined by some bipartite measure dist(A,B). We study several problems in which the goal is to translate the set B, so that dist(A,B) is minimized. The main measures that we consider are (i) the diameter in two and higher dimensions, that is diam(A,B)=max{d(a,b)∣a∈A,b∈B}, where d(a, b) is the Euclidean distance between a and b, (ii) the uniformity in the plane, that is uni(A,B)=diam(A,B)-d(A,B), where d(A,B)=min{d(a,b)∣a∈A,b∈B}, and (iii) the union width in two and three dimensions, that is union_width(A,B)=width(A∪B). For each of these measures, we present efficient algorithms for finding a translation of B that minimizes the distance: For diameter we present near-linear-time algorithms in R² and R³ and a subquadratic algorithm in R^d for any fixed d≥ 4 , for uniformity we describe a roughly O(n^{9 / 4}) -time algorithm in the plane, and for union width we offer a near-linear-time algorithm in R² and a quadratic-time one in R³.

BACKGROUND:In the absence of overt infectious signs, clinical criteria for early intervention in patients with ureteral stones are poorly defined. We aimed to develop a model that can identify patients who are at risk for developing sepsis if discharged home from the emergency department (ED). MATERIALS AND METHODS/METHODS:We retrospectively reviewed patients between January 2010 and December 2019 who were discharged from the ED after diagnosis of ureteral stones. The primary outcome was sepsis requiring urgent surgical decompression. We used multivariable logistic regression to identify predictors of sepsis. We refined the model using backwards stepwise regression with a threshold p-value 0.05. RESULTS:We identified 1,331 patients who were discharged from the ED with ureteral stones. Of these patients, 22 (2%) subsequently developed sepsis requiring urgent decompression. In the initial multivariable model, female gender (OR 2.82, p=0.039) and urine white blood cells (WBC) (OR 1.02 per cell count, p<0.001) were predictive of sepsis. After performing backwards stepwise regression, female gender, urine WBC, and leukocytosis (WBC > 15,000/mm3) met criteria for inclusion in the model. A logistic model including these variables predicted sepsis with an internally cross-validated area under the curve of 0.79. Among patients with urine cultures completed in the ED, rates of sepsis were 9% in patients with positive cultures and 1% in patients with negative cultures (p<0.001). Antibiotic usage was not protective against developing sepsis. CONCLUSIONS:Sepsis is a rare complication among patients with ureteral stones selected for conservative management. The presence of elevated urine WBC and female gender can help identify patients who are at risk of developing sepsis. Patients with risk factors should be managed with an increased index of suspicion for infection and may benefit from early intervention to reduce the risk of sepsis. Sepsis is more common in patients with positive urine cultures.

INTRODUCTION/BACKGROUND:Nutritional status has been increasingly recognized as an important predictor of prognosis and surgical outcomes for cancer patients. We evaluated the effect of preoperative malnutrition on the development of surgical complications and mortality after radical nephroureterectomy (RNU) for upper tract urothelial carcinoma (UTUC). MATERIALS AND METHODS/METHODS:Using data from the American College of Surgeons National Surgical Quality Improvement Program, we evaluated the association of poor nutritional status with 30-day postoperative complications and overall mortality after RNU from 2005 to 2015. The preoperative variables suggestive of poor nutritional status included hypoalbuminemia (< 3.5 g/dL), weight loss within 6 months before surgery (> 10%), and a low body mass index. RESULTS:A total of 1200 patients were identified who had undergone RNU for UTUC. The overall complication rate was 20.5% (n = 246), and mortality rate was 1.75% (n = 21). On univariate analysis, patients who experienced a postoperative complication were more likely to have hypoalbuminemia (25.0% vs. 11.4%; P < .001) and weight loss (3.7% vs. 1.0%; P = .003). After controlling for baseline characteristics and comorbidities, hypoalbuminemia was found to be a significant independent predictor of postoperative complications (odds ratio, 2.09; 95% confidence interval, 1.29-3.38; P = .003). Hypoalbuminemia was also a significant independent predictor of mortality (odds ratio, 4.31; 95% confidence interval, 1.45-12.79; P = .008) on multivariable regression analysis. CONCLUSION/CONCLUSIONS:Our results have shown that hypoalbuminemia is a significant predictor of surgical complications and mortality after RNU for UTUC. This finding supports the importance of patients' preoperative nutritional status in this population and suggests that effective nutritional interventions in the preoperative setting could improve patient outcomes.

BACKGROUND:Ileostomies are a routine part of the care of patients with rectal cancer, but are associated with significant risk for dehydration, readmission, and acute kidney injury. Telemedicine has proven beneficial in decreasing readmission in chronic medical illnesses, but its utility in patients with an ileostomy is not well studied. OBJECTIVE:The purpose of this study was to evaluate the feasibility of televideoconferencing in the assessment of ileostomy output. DESIGN/METHODS:An institutional review board-approved, prospective clinical trial was conducted at a single institution from November 2014 through December 2015. SETTINGS/METHODS:The study was conducted in a single, large academic medical center. PATIENTS/METHODS:Patients >18 years of age undergoing surgery with plans for ileostomy were eligible. INTERVENTIONS/METHODS:Televideoconference assessments of ileostomy output and the need for medical intervention were conducted during the postoperative stay and compared with in-person assessment. MAIN OUTCOME MEASURES/METHODS:The primary end point of the trial was the feasibility of using teleconferencing to assess the need for medical intervention, defined as 90% agreement between telemedicine and in-person assessments. Secondary end points included patient/provider satisfaction, and correlative studies examined dehydration events and readmission. RESULTS:Twenty-seven patients underwent 44 teleconferencing assessments of ileostomy output. Compared with in-person treatment decisions, there was a 95% match (95% CI, 85%-99%). The readmission rate for the study participants was 31%, and 18% experienced dehydration events. Both patients and faculty responded favorably to surveys regarding the use of telemedicine in the perioperative period. LIMITATIONS/CONCLUSIONS:The study is limited by its in-hospital use of technology and small sample size. CONCLUSIONS:Televideoconference evaluation is a feasible, reliable means of assessing ileostomy output with high patient and physician acceptance. Our pilot study provides rationale for further study in the postdischarge setting for patients with ileostomies. The incorporation of televideoconference assessment within a teledischarge program may enable early intervention to improve patient outcomes. See Video Abstract at http://links.lww.com/DCR/A455.

OBJECTIVE: To evaluate the association of body mass index (BMI) and spermatic vein diameters (SVDs) in men treated for varicocele. SUBJECTS AND METHODS: One hundred fourteen men who underwent scrotal color duplex ultrasounds prior to microsurgical varicocelectomy were classified as normal (BMI = 18.5-24.9), overweight (25-29.9), or obese (>/=30). SVDs were measured with and without Valsalva, standing and supine. SVD, pre- and postoperative semen analyses (SA) were compared. RESULTS: Forty-six (40.4%) men had normal BMI, 54 (47.3%) were overweight, and 14 (12.3%) were obese. Higher BMI was associated with smaller left testis volume and larger left SVD when supine (with and without Valsalva). The association was absent when standing. Men with higher BMI had smaller differences between their left SVD Valsalva diameters when standing vs supine. There were no differences among BMI classes for right SVD measurements, preoperative SA, and postoperative SA improvement. CONCLUSION: Increased BMI is associated with larger left SVD while supine, suggesting that increased abdominal pressure while recumbent may contribute to varicocele pathology in this population. Interestingly, as in the general population, a majority of the men were overweight.

Multiphoton microscopy (MPM) enables real-time imaging of various cellular processes at submicron resolution. MPM is currently being used in neuroscience, oncology, and immunology. MPM has demonstrated promising results in urology. MPM has been used in the identification of spermatogenesis, evaluation of bladder cancer, and tissue identification in prostate cancer surgery. MPM has allowed the visualization of seminiferous tubules within the testis in a rat model and identified areas of spermatogenesis. MPM could potentially improve the efficacy of testicular sperm extraction. In bladder cancer evaluation, MPM has proven to be an effective imaging tool in identifying areas suspicious for malignancy. The imaging technology could be utilized in the future to provide urologists with an immediate impression of extracted bladder tissue, or as part of a cystoscopic device to evaluate the bladder in real time. Similarly, MPM has proven to be a useful imaging technique to evaluate prostate cancer. MPM could be utilized during a prostatectomy to help differentiate prostate from cavernous nerves that are closely adherent to the prostate. MPM uses a laser and safety studies will need to be performed prior to its utilization in the clinical setting.