Predictors of Admission in Adult Unscheduled Return Visits to the Emergency Department.

Introduction: The 72-hour unscheduled return visit (URV) of an emergency department (ED) patient is often used as a key performance indicator in emergency medicine. We sought to determine if URVs with admission to hospital (URVA) represent a distinct subgroup compared to unscheduled return visits with no admission (URVNA). Methods: We performed a retrospective cohort study of all 72-hour URVs in adults across 10 EDs in the Edmonton Zone (EZ) over a one-year period (January 1, 2015 - December 31, 2015) using ED information-system data. URVA and URVNA populations were compared, and a multivariable analysis identified predictors of URVA. Results: Analysis of 40,870 total URV records, including 3,363 URVAs, revealed predictors of URVA on the index visit including older age (>65 yrs, odds ratio [OR] 3.6), higher disease acuity (Canadian Emergency Department Triage and Acuity Scale [CTAS] 2, OR 2.6), gastrointestinal presenting complaint (OR 2.2), presenting to a referral hospital (OR 1.4), fewer annual ED visits (<4 visits, OR 2.0), and more hours spent in the ED (>12 hours, OR 2.0). A decrease in CTAS score (increase in disease acuity) upon return visit also increased the risk of admission (-1 CTAS level, OR 2.6). ED crowding at the index visit, as indicated by occupancy level, was not a predictor. Conclusion: We demonstrate that URVA patients comprise a distinct subgroup of 72-hour URV patients. Risk factors for URVA are present at the index visit suggesting that patients at high risk for URVA may be identifiable prior to admission.

Monomolecular pyrenol-derivatives as multi-emissive probes for orthogonal reactivities.

Photoacids on the basis of pyrenol have been extensively studied in the past 60 years. As their photophysical properties strongly depend on the substituents at the aromatic scaffold, we introduced two reactive moieties with different electronic coefficients thus creating multi-wavelength fluorescent probes. One probe is capable of monitoring two orthogonal transformations by four fluorescence colors, distinguishable even by the naked human eye. Another derivative can act as a three-color sensor for a wide range of different pH values. Both the presented compounds allow for mimicking of fundamental and advanced two-input logic operations due to the multi-wavelength emission. Furthermore, these compounds can process information in a logically reversible way (Feynman gate).

Biexponential photon antibunching: recombination kinetics within the Förster-cycle in DMSO.

Time-resolved experiments with pulsed-laser excitation are the standard approach to map the dynamic evolution of excited states, but ground-state kinetics remain hidden or require pump-dump-probe schemes. Here, we exploit the so-called photon antibunching, a purely quantum-optical effect related to single molecule detection to assess the rate constants for a chemical reaction in the electronic ground state. The measurement of the second-order correlation function g((2)), i.e. the evaluation of inter-photon arrival times, is applied to the reprotonation in a Förster-cycle. We find that the antibunching of three different photoacids in the aprotic solvent DMSO significantly differs from the behavior in water. The longer decay constant of the biexponential antibunching tl is linked to the bimolecular reprotonation kinetics of the fully separated ion-pair, independent of the acidic additives. The value of the corresponding bimolecular rate constant, kp = 4 × 10(9) M(-1) s(-1), indicates diffusion-controlled reprotonation. The analysis of tl also allows for the extraction of the separation yield of proton and the conjugated base after excitation and amounts to approximately 15%. The shorter time component ts is connected to the decay of the solvent-separated ion pair. The associated time constant for geminate reprotonation is approximately 3 ± 1 ns in agreement with independent tcspc experiments. These experiments verify that the transfer of quantum-optical experiments to problems in chemistry enables mechanistic conclusions which are hardly accessible by other methods.

Monofluorination and Trifluoromethylation of BODIPY Dyes for Prolonged Single-Molecule Detection.

Electrophilic monofluorination with Selectfluor and nucleophilic trifluoromethylation with the Ruppert-Prakesh reagent of dimethyl-, tetramethyl- and pentamethyl-substituted boron dipyrromethenes (BODIPY) are investigated. Monofluorinated dyes are synthesized with low yields (<30%), however trifluoromethyl derivatives are obtained in moderate to high yields (≈40-90%). All compounds are characterized by steady-state and time-resolved fluorescence spectroscopy, the photostability is investigated with fluorescence correlation spectroscopy (FCS) and total internal reflection fluorescence microscopy (TIRF). Monofluorination hardly affects the spectroscopic parameters of the unsubstituted parent compounds, but distinctly enhances the photostability, whereas trifluoromethylation leads to a hypsochromic shift by up to 17 nm in both absorption and emission, slightly enhanced intersystem crossing, and higher photostability. Further development of soft fluorination and trifluoromethylation methods is therefore highly desired.

Photon Antibunching in a Cyclic Chemical Reaction Scheme.

The direct observation of chemical reactions on the single-molecule level is an ultimate goal in single-molecule chemistry, which also includes kinetic analyses. To analyze the lifetime of reaction intermediates, very sophisticated excitation schemes are often required. Here we focus on the kinetic analysis of the ground-state proton transfer within the photocycle of a photoacid. In detail, we demonstrate the determination of the bimolecular rate constant of this process with nanosecond resolution. The procedure relies on the exploration of a purely quantum-optical effect, namely, photon antibunching, and thus on evaluating interphoton arrival times to extract the reaction rate constant.

Highly photostable "super"-photoacids for ultrasensitive fluorescence spectroscopy.

The photoacid 8-hydroxypyren-1,3,6-trisulfonic acid (HPTS, pyranine) is a widely used model compound for the examination of excited state proton transfer (ESPT). We synthesized five "super"-photoacids with varying hydrophilicity and acidity on the basis of HPTS. By chemical modification of the three sulfonic acid substituents, the photoacidity is enhanced by up to more than five logarithmic units from pK*≈ 1.4 to ∼-3.9 for the most acidic compound. As a result, nearly quantitative ESPT in DMSO can be observed. The novel photoacids were characterized by steady-state and time-resolved fluorescence techniques showing distinctively red shifted spectra compared to HPTS while maintaining a high quantum yield near 90%. Photostability of the compounds was checked by fluorescence correlation spectroscopy (FCS) and was found to be adequately high for ultrasensitive fluorescence spectroscopy. The described photoacids present a valuable palette for a wide range of applications, especially when the properties of HPTS, i.e. highly charged, low photostability and only moderate excited state acidity, are limiting.

Tracking emergency department overcrowding in a tertiary care academic institution.

Despite the release of a national report describing key markers of emergency department (ED) overcrowding, limited linear data using these markers have been published. We sought to report the degree and trends of ED overcrowding in a typical academic hospital and to highlight some of the key markers of ED patient flow and care. We conducted a prospective study in a large Canadian urban tertiary care teaching hospital that receives approximately 55,000 annual adult ED visits. A database captured demographic and real-time process of care data for each patient from 2000 to 2007. Descriptive data are reported using Canadian Triage and Acuity Scale (CTAS) scores. Over the study period, the ED patient visit volume and presentation times remained predictable. Emergent cases (CTAS levels 1-2) doubled from 8 to 16.6%, and urgent cases (CTAS level 3) increased from 40.2 to 50.3%. Moreover, semi-urgent presentations (CTAS level 4) decreased from 42.4 to 28.8%, and non-urgent cases (CTAS level 5) dropped from 9.4 to 4.3%. The median wait time from triage to bed location increased from two minutes (inter-quartile range [IQR] 1, 46) in 2000 to 27 minutes (IQR 2, 110) in 2007, while the median time from bed location to physician remained constant (29 minutes in 2001 versus 28 minutes in 2007). Overall, admissions increased from 20.4 to 23%. Semi-urgent and non-urgent admissions dropped from 11.5 to 7.4% and 3.2 to 1.8%, respectively. Admitted patients "boarding" in the ED increased from 70,955 hours in 2002 to 118,741 hours in 2007, while the number of emergent and urgent patients leaving without being seen increased by more than 400%. ED overcrowding in a tertiary care hospital is primarily a result of access block due to boarding admitted patients, a situation that poses serious risks to the majority of patients who have emergent or urgent conditions that cannot be managed appropriately in the waiting room.