ABSTRACT
OBJECTIVE: Patients seen in emergency departments (EDs) not requiring admission are typically discharged with appropriate follow-up. Sometimes hospitals indirectly refer, or redirect, patients to a different hospital's ED. Anecdotally, indirect referrals are commonly received in safety-net hospitals. This study characterizes the types of patients and hospitals affected and the cost of indirect referral in the orthopaedic trauma population. METHODS: A retrospective cross-sectional chart review was conducted of 1,162 consecutive adult patients receiving orthopaedic care in an urban public hospital ED over a six-month period in 2011. Multivariable logistic regression analysis compared patients who were indirectly referred with those presenting primarily. RESULTS: One in five (N=236) patients treated for orthopaedic injury was indirectly referred from neighboring hospitals with orthopaedists available; 209 (88.6%) of these patients were uninsured (OR 3.69; CI 1.85-7.34). Nonprofit hospitals initially treated 107 (64.1%) of these patients. Costs for largely uncompensated care at the public hospital were $1.77 million.
Subject(s)
Emergency Service, Hospital/statistics & numerical data , Medically Uninsured/statistics & numerical data , Orthopedics/statistics & numerical data , Patient Transfer/statistics & numerical data , Safety-net Providers/statistics & numerical data , Adult , Age Factors , Cross-Sectional Studies , Emergency Service, Hospital/economics , Female , Humans , Male , Middle Aged , Orthopedics/economics , Patient Transfer/economics , Retrospective Studies , Safety-net Providers/economics , Socioeconomic Factors , Uncompensated Care/economics , Wounds and Injuries/economics , Wounds and Injuries/surgeryABSTRACT
The effects of natural organic matter (NOM), ferrozine, and AQDS (anthraquinone-2,6-disulfonate) on the reduction of hematite (alpha-Fe2O3) by Shewanella putrefaciens CN32 were studied. It has been proposed that NOM enhances the reduction of Fe(III) by means of electron shuttling or by Fe(II) complexation. Previously both mechanisms were studied separately using "functional analogues" (AQDS for electron shuttling and ferrozine for complexation) and are presently compared with seven different NOMs. AQDS enhanced hematite reduction within the first 24 h of incubation, and this had been ascribed to electron shuttling. Most of the NOMs enhanced hematite reduction after 1 day of incubation indicating that these materials could also serve as electron shuttles. The effect of ferrozine was linear with concentration, and all of the NOMs exhibited this behavior. Fe(II) complexation only enhanced hematite reduction after sufficient Fe(II) had accumulated in the system. Fe(II) complexation appeared to alleviate a suppression of the hematite reduction rate caused by accumulation of Fe(II) in the system. Addition of Fe(II) to the hematite suspension, prior to inoculation with CN32, significantly inhibited hematite reduction and greatly diminished the effects of all of the organic materials, although some enhancement was observed due to addition of anthroquinone-2,6-disulfonate. These results demonstrate that NOM can enhance iron reduction by electron shuttling and by complexation mechanisms.
Subject(s)
Ferric Compounds/chemistry , Iron/chemistry , Shewanella putrefaciens/physiology , Biodegradation, Environmental , Electrons , Ferrozine/chemistry , Iron Chelating Agents/chemistry , Organic Chemicals , Oxidation-ReductionABSTRACT
Natural organic matter (NOM) enhancement of the biological reduction of hematite (alpha-Fe2O3) by the dissimilatory iron-reducing bacterium Shewanella putrefaciens strain CN32 was investigated under nongrowth conditions designed to minimize precipitation of biogenic Fe(II). Hydrogen served as the electron donor. Anthraquinone-2,6-disulfonate (AQDS), methyl viologen, and methylene blue [quinones with an Ew0 (pH 7) of 0.011 V or less], ferrozine [a strong Fe(II) complexing agent], and characterized aquatic NOM (Georgetown NOM or Suwannee River fulvic acid) enhanced bioreduction in 5-day experiments whereas 1,4-benzoquinone (Ew0 value = 0.280 V) did not. A linear relationship existed between total Fe(II) produced and concentrations of ferrozine or NOM but not quinones, except in the case of methylene blue. Such a linear relationship between Fe(II) and methylene blue concentrations could be due to the systems being far undersaturated with respect to methylene blue or the loss of the thermodynamic driving force. A constant concentration of AQDS and variable concentrations of ferrozine produced a linear relationship between total Fe(II) produced and the concentration of ferrozine. Enhancement effects of both AQDS and ferrozine were additive. NOM may serve as both an electron shuttle and an Fe(II) complexant; however, the concentration dependence of hematite reduction with NOM was more similar to ferrozine than quinones. NOM likely enhances hematite reduction initially by electron shuttling and then further by Fe(II) complexation, which prevents Fe(II) sorption to hematite and cell surfaces.
