High‐molecular‐weight dissolved organic matter (HMW‐DOM, > 1,000 Daltons) is actively involved in the global biogeochemical cycling of many elements, but its carbon sources and detailed formation pathways are still not well understood. In this study, we measured bulk stable carbon and nitrogen isotopic ratios, lipid composition, and compound‐specific carbon isotopic ratios of HMW‐DOM samples collected from four U.S. estuaries (Boston Harbor/Massachusetts Bay, Delaware/Chesapeake Bay, San Diego Bay, and San Francisco Bay). Analytical results show (1) a fraction of HMW‐DOM (lipid associated) in estuarine and coastal waters is derived from bacteria and phytoplankton; (2) this fraction of HMW‐DOM is formed by various release processes of bacterial membrane components and bacterial reworking of phytoplanktonderived material; (3) this fraction of HMW‐DOM is generally present in all samples from different coastal systems despite variable organic matter inputs and environmental conditions, suggesting an important bacterial role in HMW‐DOM formation.
Purpose
Prior studies report that weekend admission to an intensive care unit is associated with increased mortality, potentially attributed to the organizational structure of the unit. This study aims to determine whether treatment of hypotension, a risk factor for mortality, differs according to level of staffing.
Methods
Using the Multiparameter Intelligent Monitoring in Intensive Care database, we conducted a retrospective study of patients admitted to an intensive care unit at Beth Israel Deaconess Medical Center who experienced one or more episodes of hypotension. Episode(s) were categorized according to the staffing level, defined as high during weekday daytime (7am–7pm) and low during weekends or nighttime (7pm–7am).
Results
Patients with a hypotensive event on a weekend were less likely to be treated compared to those that occurred during the weekday daytime (p=0.02). No association between weekday daytime versus weekday nighttime staffing levels and treatment of hypotension was found (RR 1.02; 95% CI 0.98–1.07).
Conclusion
Patients with a hypotensive event on a weekend were less likely to be treated than patients with an event during high-staffing periods. No association between weekday nighttime staffing and hypotension treatment was observed. We conclude that treatment of a hypotensive episode relies on more than solely staffing levels.
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