Benjamin Vekhter

Sleep-disordered breathing and postoperative outcomes after elective surgery: analysis of the nationwide inpatient sample.

BACKGROUND Systematic screening and treatment of sleep-disordered breathing (SDB) or obstructive sleep apnea (OSA) in presurgical patients would impose a significant cost burden; therefore, it is important to understand whether SDB is associated with worse postoperative outcomes. We sought to determine the impact of SDB on postoperative outcomes in patients undergoing four specific categories of elective surgery (orthopedic, prostate, abdominal, and cardiovascular). The primary outcomes were in-hospital death, total charges, and length of stay (LOS). Two secondary outcomes of interest were respiratory and cardiac complications. METHODS Data were obtained from the Nationwide Inpatient Sample database. Regression models were fitted to assess the independent association between SDB and the outcomes of interest. RESULTS The cohort included 1,058,710 hospitalized adult patients undergoing elective surgeries between 2004 and 2008. SDB was independently associated with decreased mortality in the orthopedic (OR, 0.65; 95% CI, 0.45-0.95; P = .03), abdominal (OR, 0.38; 95% CI, 0.22-0.65; P = .001), and cardiovascular surgery groups (OR, 0.54; 95% CI, 0.40-0.73; P < .001) but had no impact on mortality in the prostate surgery group. SDB was independently associated with a small, but statistically significant increase in estimated mean LOS by 0.14 days (P < .001) and estimated mean total charges by

Cooperative phenomena in Jahn-Teller crystals

860 (P < .001) in the orthopedic surgery group but was not associated with increased LOS or total charges in the prostate surgery group. In the abdominal and cardiovascular surgery groups, SDB was associated with a significant decrease in adjusted mean LOS of 1.1 days and 0.35 days, respectively (P < .001 for both groups), and adjusted mean total charges of

Sex disparities in diagnosis of bladder cancer after initial presentation with hematuria: A nationwide claims-based investigation

3,814 and

Modeling self-assembling of proteins: Assembled structures, relaxation dynamics, and phase coexistence

4,592, respectively (P < .001 for both groups). SDB was independently associated with a significantly increased OR for emergent intubation and mechanical ventilation, noninvasive ventilation, and atrial fibrillation in all four surgical categories. Emergent intubation occurred significantly earlier in the postoperative course in patients with SDB. In the subgroup of patients requiring emergent intubation, LOS, total charges, pneumonias, and in-hospital death were significantly higher in those without SDB. CONCLUSIONS In this large national study, despite the increased independent association of SDB with postoperative cardiopulmonary complications, the diagnosis of SDB was not independently associated with an increased rate of in-hospital death. SDB had a mixed impact on LOS and total charges by surgical category.

Phase coexistence in clusters: An “experimental” isobar and an elementary model

A comprehensive study of the microscopic theory of structural phase transitions and the cooperative Jahn-Teller effect, for scientists, engineers, and students interested in any aspect of phase transformation. The volume contains six chapters: the Jahn-Teller effect; interaction of Jahn-Teller cente

Vibrational relaxation of clusters: Relation to potential surface topography

Women have disproportionately higher mortality rates relative to incidence for bladder cancer. Multiple etiologies have been proposed, including delayed diagnosis and treatment. Guidelines recommend ruling out malignancy in men and women presenting with hematuria. This study sought to determine the difference in timing from presentation with hematuria to diagnosis of bladder cancer in women versus men.

Demonstration of the Weighted-Incidence Syndromic Combination Antibiogram: An Empiric Prescribing Decision Aid

A string-of-beads model used previously to describe folding of a polypeptide into a β-barrel is transformed into four-strand model of a self-assembling system, which also produces a β-barrel. In molecular dynamics (MD) simulations, both isothermal and variable-temperature (annealing), the system behaves much like a typical small cluster, insofar as it exhibits the dynamic coexistence of several phase-like forms over ranges of temperature. A three-state analytic model, then a four-state model, supplemented by degeneracies inferred from the MD simulations, yield partition functions and phase diagrams that reproduce the simulations rather well.

Financial Responsibility of Hospitalized Patients Who Left Against Medical Advice: Medical Urban Legend?

This work examines the temperature dependence of the coexistence ratios of phaselike forms of atomic clusters of two kinds, a homogeneous cluster bound by pairwise Lennard–Jones forces that simulates Ar55, and a binary, ionic cluster simulating (KCl)32. Two methods have been used: isothermal molecular dynamics and a simple analytical model based on highly simplified densities of states. The phase behavior of the alkali halide cluster is well represented by a two-level density of states, a nondegenerate lower level, and a highly degenerate upper level. The phase behavior of the argon cluster needs an intermediate level of moderate degeneracy to reproduce the three-phase behavior of the simulations.

Simulation of mutation: Influence of a “side group” on global minimum structure and dynamics of a protein model

Simulations by isothermal and isoergic molecular dynamics show that vibrationally-cold clusters, initially at some high-energy point on their potential surfaces, relax monotonically down to low-lying minima where they are trapped. The most significant point regarding this relaxation is that species with sawtoothlike and staircaselike potentials show the same qualitative behavior, equilibrating their vibrations after each major saddle crossing. This result justifies the use of transition state kinetics for constructing coarse-grained master equations to describe the well-to-well flow of population distributions on complex potential energy surfaces, even in cases such as (KCl)32 and some protein models which have staircase topographies in which large drops in potential energy from one well to the next might suggest nonthermal kinetics could occur.

MP22-01 GENDER DISPARITIES IN DIAGNOSIS OF BLADDER CANCER AFTER INITIAL PRESENTATION WITH HEMATURIA: A NATIONWIDE CLAIMS-BASED INVESTIGATION

OBJECTIVE Healthcare providers need a better empiric antibiotic prescribing aid than the traditional antibiogram, which supplies no information on the relative frequency of organisms recovered in a given infection and which is uninformative in situations where multiple antimicrobials are used or multiple organisms are anticipated. We aimed to develop and demonstrate a novel empiric prescribing decision aid. DESIGN/SETTING This is a demonstration involving more than 9,000 unique encounters for abdominal-biliary infection (ABI) and urinary tract infection (UTI) to a large healthcare system with a fully integrated electronic health record (EHR). METHODS We developed a novel method of displaying microbiology data called the weighted-incidence syndromic combination antibiogram (WISCA) for 2 clinical syndromes, ABI and UTI. The WISCA combines simple diagnosis and microbiology data from the EHR to (1) classify patients by syndrome and (2) determine, for each patient with a given syndrome, whether a given regimen (1 or more agents) would have covered all the organisms recovered for their infection. This allows data to be presented such that clinicians can see the probability that a particular regimen will cover a particular infection rather than the probability that a single drug will cover a single organism. RESULTS There were 997 encounters for ABI and 8,232 for UTI. A WISCA was created for each syndrome and compared with a traditional antibiogram for the same period. CONCLUSIONS Novel approaches to data compilation and display can overcome limitations to the utility of the traditional antibiogram in helping providers choose empiric antibiotics.