Role of routine blood cultures in detecting unapparent infections during continuous renal replacement therapy.

OBJECTIVE: Continuous renal replacement therapy (CRRT) is frequently employed in the management of renal failure in unstable intensive care patients. At some centers, blood cultures are performed routinely while on CRRT to monitor for occult bacteremia. We questioned the role of routine blood cultures (RBC) in diagnosing underlying infections in these often afebrile patients. DESIGN: Retrospective cohort study (1998-2003). SETTING: Medical, surgical and pediatric intensive care units in a tertiary care teaching hospital. METHODS/MEASUREMENTS: We undertook a retrospective chart review of all 101 episodes of CRRT performed in our hospital since 1998. The primary endpoint of the study was the number of positive cultures that changed patient management. For each positive result, documented infection and parameters of sepsis were noted. RESULTS: There were 101 treatments of CRRT in 98 patients. A total of 698 routine RBC bottles were drawn, a mean of 7.2+/-7 per patient; of those, 29 (4%) were positive in 17patients, documenting 11 bacteremias. Six positive cultures represented contaminants. In all but one case, infection was known or signs of sepsis were present prior to receipt of the culture result. CONCLUSIONS: For patients on CRRT, RBC are rarely positive, and do not detect occult infection in the absence of clinical evidence of infection for the majority of patients. Because routine cultures utilize significant resources, and can result in false-positive results, RBC should not be performed in these patients. Careful clinical monitoring, with blood cultures performed at the first clinical suggestion of an infection, should detect all clinically relevant infections.

Effects of forested floodplain soil properties on phosphorous concentrations in two Chesapeake Bay sub-watersheds, Virginia, USA.

Aquatic ecosystems are known to undergo fluctuations in nutrient levels as a result of both natural and anthropogenic processes. Changes in both extrinsic and intrinsic fluvial dynamics necessitate constant monitoring as anthropogenic alterations exert new pressures to previously stable river basins. In this study, we analyzed stream water and riparian zone soil phosphorous (P) dynamics in two third-order sub-watersheds of the lower Chesapeake Bay in Virginia, USA. The Ni River is predominantly forested (70 % forested), and Sugarland Run is a more human impacted (>45 % impervious surfaces) sub-watershed located in the suburbs of Washington D.C. Total stream P concentrations were measured during both high and low flows and Mehlich-3 methods were used to evaluate potential P fluxes in riparian soils. The results show total stream P concentrations in Sugarland Run ranged from 0.002 to 0.20 ppm, with an average of 0.054 ppm. In contrast, the forested Ni River had typical stream P concentrations <0.01 ppm. Total soil P was significantly higher in the more urbanized Sugarland Run basin (23.8 ± 2.1 ppm) compared to the Ni River basin (16 ± 3.7 ppm). Average stream bank erosion rates and corresponding cut-bank P flux rates were estimated to be 7.98 cm year(-1) and 361 kg P year(-1) for Ni River and 9.84 cm year(-1) and 11,600 kg P year(-1) for Sugarland Run, respectively. The significantly higher values of total P in the stream water and floodplain cut-banks of Sugarland Run suggests erosion and resuspension of previously deposited legacy sediments is an important processes in this human-impacted basin.

A multiple discriminant analysis of vessel accidents.

A large sample of 936 vessel accident cases occurring between 1979 and 1987 on the lower Mississippi River were cluster analyzed to generate four groups relatively unique in their respective attribute values. The attributes used to cluster the accidents included participation in the U.S. Coast Guard's New Orleans Vessel Traffic Service (NOLA-VTS), type of accident, river stage traffic level, system utilization, accident location, weather conditions, and time of accident. The four-group cluster solution resulted in logical groupings, given the realities of navigating the lower Mississippi River. The four groups resulting from the cluster analysis were characterized as Group 1: Danger Zone (224 cases), 100% NOLA-VTS participants whose accidents occurred primarily on the most dangerous part of the river; Group 2: Bad Conditions for Good Navigators (230 cases), characterized by a high rate of participation and unserious accidents occurring in treacherous navigating conditions; Group 3: Probably Preventable (134 cases), characterized by a low participation rates and serious accidents occurring in not the worst navigating conditions; and Group 4: Accidents That Should Not Have Happened (345 cases), characterized by zero participation and serious accidents occurring in reasonable navigating conditions. Significant marginal participation rates for the marine tracking technology across the four accident clusters (100% for Group 1, 67% for Group 2, 37% for Group 3, and 0% for Group 4) effectively distinguishes between casualty groups. In the subsequent discriminant analysis, three discriminant functions correctly classified 96% of the total accidents, including 100% of Group 1 and Group 4, 90% of Group 2, and 88% of Group 3. The variables contributing most to overall group differentiation were participation in the system, overall system utilization, river stage, traffic level, time and location of accidents. The three discriminant functions were statistically significant, with each individual function accounting for a large relative percentage of the variance between the groups. In order of decreasing discriminating power, the functions could be characterized as (1) System Participation and Utilization, (2) Navigating Conditions, and (3) Time and Place.

Operationalizing a comprehensive neurobehavioral plan.

The formulation and implementation of a workable and effective plan of care for the complex rehabilitation patient are nursing challenges. Even more challenging, however, is putting the plan into operation over a 24-hour period. Staffing variations, patients' circadian rhythms, and visiting hours are only a few of the factors that require consideration when formulating a viable plan of care. The purpose of this article is to discuss strategies that have been effective in providing consistent, safe, therapeutic care for the patient population on a 39-bed neurobehavioral unit that treats mostly individuals with traumatic brain injuries.

Identity of V factor in culture medium used for prior growth of two strains of Staphylococcus aureus.

Staphylococcus aureus ATCC 12598 and ATCC 25923 were starved of pyridine nucleotides and precursors and then grown in a semidefined medium containing [carbonyl-14C]nicotinamide. Samples of medium from late-exponential-phase and stationary-phase cultures were analyzed for 14C-metabolites. In all cases, V factor was present primarily as NAD.