Chest computed tomography for staging renal tumours: validation and simplification of a risk prediction model from a large contemporary retrospective cohort.

OBJECTIVES: To externally validate a nomogram recently proposed by Larcher et al. (BJU Int. 2017; 120: 490) and to develop a simplified model with comparable accuracy to guide on the need for staging chest computed tomography (CT) for patients with new renal masses. PATIENTS AND METHODS: We analysed the data of 1082 consecutive patients with unilateral enhancing renal masses referred to urology multidisciplinary team meetings at two centres between 2011 and 2017. All patients underwent a staging chest CT at diagnosis. We fitted multivariable logistic regression models and tested the Larcher model performance using area under the receiver-operating curve (AUC), calibration and decision curve analysis. RESULTS: Forty-two patients (3.9%) had a positive chest CT. The Larcher nomogram had an AUC of 83.8% (95% confidence interval [CI] 77.1-90.6), but was only moderately well calibrated (calibration-in-the-large = -0.61, slope = 0.82). Specifically, the nomogram overestimated the risk of positive chest CT, and the magnitude of miscalibration increased with increasing predicted risks. Using a stepwise backward approach, a new model was developed including tumour size, nodal stage and systemic symptoms. Compared with the Larcher model, the new model had a similar AUC (82.7% [95% CI 75.5-90.0]), but improved calibration and clinical net benefit. The predicted risk of positive chest CT was <1% in the low-risk group and 1.9-79.9% in the high-risk group. CONCLUSION: The Larcher nomogram is an accurate prediction tool that was moderately well calibrated with our dataset. However, our simplified model has similar accuracy and uses more objective variables available from referral, so may be easier to incorporate into clinical practice. The low-risk group from our model (tumour size ≤4 cm and no systemic symptoms) had a risk of positive chest CT <1%, suggesting these patients may forego chest CT.

Increasing the Reliability of Fully Automated Surveillance for Central Line-Associated Bloodstream Infections.

OBJECTIVE: To increase reliability of the algorithm used in our fully automated electronic surveillance system by adding rules to better identify bloodstream infections secondary to other hospital-acquired infections. METHODS: Intensive care unit (ICU) patients with positive blood cultures were reviewed. Central line-associated bloodstream infection (CLABSI) determinations were based on 2 sources: routine surveillance by infection preventionists, and fully automated surveillance. Discrepancies between the 2 sources were evaluated to determine root causes. Secondary infection sites were identified in most discrepant cases. New rules to identify secondary sites were added to the algorithm and applied to this ICU population and a non-ICU population. Sensitivity, specificity, predictive values, and kappa were calculated for the new models. RESULTS: Of 643 positive ICU blood cultures reviewed, 68 (10.6%) were identified as central line-associated bloodstream infections by fully automated electronic surveillance, whereas 38 (5.9%) were confirmed by routine surveillance. New rules were tested to identify organisms as central line-associated bloodstream infections if they did not meet one, or a combination of, the following: (I) matching organisms (by genus and species) cultured from any other site; (II) any organisms cultured from sterile site; (III) any organisms cultured from skin/wound; (IV) any organisms cultured from respiratory tract. The best-fit model included new rules I and II when applied to positive blood cultures in an ICU population. However, they didn't improve performance of the algorithm when applied to positive blood cultures in a non-ICU population. CONCLUSION: Electronic surveillance system algorithms may need adjustment for specific populations.

Preliminary Results on the Feasibility of Using ARFI/SWEI to Assess Cutaneous Sclerotic Diseases.

In this study, acoustic radiation force impulse (ARFI) and shear wave elasticity imaging (SWEI) were applied to the skin to investigate the feasibility of their use in assessing sclerotic skin diseases. Our motivation was to develop a non-invasive imaging technology with real-time feedback of sclerotic skin disease diagnosis. This paper shows representative results from an ongoing study, recruiting patients with and without sclerosis. The stiffness of the imaged site was evaluated using two metrics: mean ARFI displacement magnitude and bulk shear wave speed inside the region of interest (ROI). In a subject with localized graft versus host disease (GVHD), the mean ARFI displacement inside sclerotic skin was 61% lower (p < 0.01) and shear wave speed 128% higher (p < 0.005) compared to those in normal skin-indicating stiffer mechanical properties in the sclerotic skin. This trend persisted through disease types. We conclude ARFI and SWEI can successfully differentiate sclerotic lesions from normal dermis.

Comparison of Acoustic Radiation Force Impulse Imaging Derived Carotid Plaque Stiffness With Spatially Registered MRI Determined Composition.

Measurements of plaque stiffness may provide important prognostic and diagnostic information to help clinicians distinguish vulnerable plaques containing soft lipid pools from more stable, stiffer plaques. In this preliminary study, we compare in vivo ultrasonic Acoustic Radiation Force Impulse (ARFI) imaging derived measures of carotid plaque stiffness with composition determined by spatially registered Magnetic Resonance Imaging (MRI) in five human subjects with stenosis > 50%. Ultrasound imaging was implemented on a commercial diagnostic scanner with custom pulse sequences to collect spatially registered 2D longitudinal B-mode and ARFI images. A standardized, multi-contrast weighted MRI sequence was used to obtain 3D Time of Flight (TOF), T1 weighted (T1W), T2 weighted (T2W), and Proton Density Weighted (PDW) transverse image stacks of volumetric data. The MRI data was segmented to identify lipid, calcium, and normal loose matrix components using commercially available software. 3D MRI segmented plaque models were rendered and spatially registered with 2D B-mode images to create fused ultrasound and MRI volumetric images for each subject. ARFI imaging displacements in regions of interest (ROIs) derived from MRI segmented contours of varying composition were compared. Regions of calcium and normal loose matrix components identified by MRI presented as homogeneously stiff regions of similarly low (typically ≈ 1 µm) displacement in ARFI imaging. MRI identified lipid pools > 2 mm(2), found in three out of five subjects, presented as softer regions of increased displacement that were on average 1.8 times greater than the displacements in adjacent regions of loose matrix components in spatially registered ARFI images. This work provides early evidence supporting the use of ARFI imaging to noninvasively identify lipid regions in carotid artery plaques in vivo that are believed to increase the propensity of a plaque to rupture. Additionally, the results provide early training data for future studies and aid in the interpretation and possible clinical utility of ARFI imaging for identifying the elusive vulnerable plaque.

Multicenter evaluation of computer automated versus traditional surveillance of hospital-acquired bloodstream infections.

OBJECTIVE: Central line-associated bloodstream infection (BSI) rates are a key quality metric for comparing hospital quality and safety. Traditional BSI surveillance may be limited by interrater variability. We assessed whether a computer-automated method of central line-associated BSI detection can improve the validity of surveillance. DESIGN: Retrospective cohort study. SETTING: Eight medical and surgical intensive care units (ICUs) in 4 academic medical centers. METHODS: Traditional surveillance (by hospital staff) and computer algorithm surveillance were each compared against a retrospective audit review using a random sample of blood culture episodes during the period 2004-2007 from which an organism was recovered. Episode-level agreement with audit review was measured with κ statistics, and differences were assessed using the test of equal κ coefficients. Linear regression was used to assess the relationship between surveillance performance (κ) and surveillance-reported BSI rates (BSIs per 1,000 central line-days). RESULTS: We evaluated 664 blood culture episodes. Agreement with audit review was significantly lower for traditional surveillance (κ [95% confidence interval (CI) = 0.44 [0.37-0.51]) than computer algorithm surveillance (κ [95% CI] = 0.58; P = .001). Agreement between traditional surveillance and audit review was heterogeneous across ICUs (P = .01); furthermore, traditional surveillance performed worse among ICUs reporting lower (better) BSI rates (P = .001). In contrast, computer algorithm performance was consistent across ICUs and across the range of computer-reported central line-associated BSI rates. Conclusions: Compared with traditional surveillance of bloodstream infections, computer automated surveillance improves accuracy and reliability, making interfacility performance comparisons more valid.

Feasibility of near real-time lesion assessment during radiofrequency catheter ablation in humans using acoustic radiation force impulse imaging.

BACKGROUND: Visual confirmation of radiofrequency ablation (RFA) lesions during clinical cardiac ablation procedures could improve procedure efficacy, safety, and efficiency. It was previously shown that acoustic radiation force impulse (ARFI) imaging can identify RFA lesions in vitro and in vivo in an animal model. This is the "first-in-human" feasibility demonstration of intracardiac ARFI imaging of RFA lesions in patients undergoing catheter ablation for atrial flutter (AFL) or atrial fibrillation (AF). METHODS AND RESULTS: Patients scheduled for right atrial (RA) ablation for AFL or left atrial (LA) ablation for drug refractory AF were eligible for imaging. Diastole-gated intracardiac ARFI images were acquired using one of two equipment configurations: (1) a Siemens ACUSON S2000™ ultrasound scanner and 8/10Fr AcuNav™ ultrasound catheter, or (2) a CARTO 3™ integrated Siemens SC2000™ and 10Fr SoundStar™ ultrasound catheter. A total of 11 patients (AFL = 3; AF = 8) were imaged. ARFI images were acquired of ablation target regions, including the RA cavotricuspid isthmus (CTI), and the LA roof, pulmonary vein ostia, posterior wall, posterior mitral valve annulus, and the ridge between the pulmonary vein and LA appendage. ARFI images revealed increased relative myocardial stiffness at ablation catheter contact sites after RFA and at anatomical mapping-tagged RFA treatment sites. CONCLUSIONS: ARFI images from a pilot group of patients undergoing catheter ablation for AFL and AF demonstrate the ability of this technique to identify intra-procedure RFA lesion formation. The results encourage further refinement of ARFI imaging clinical tools and continued investigation in larger clinical trials.

Acoustic radiation force impulse imaging (ARFI) on an IVUS circular array.

Our long-term goal is the detection and characterization of vulnerable plaque in the coronary arteries of the heart using intravascular ultrasound (IVUS) catheters. Vulnerable plaque, characterized by a thin fibrous cap and a soft, lipid-rich necrotic core is a precursor to heart attack and stroke. Early detection of such plaques may potentially alter the course of treatment of the patient to prevent ischemic events. We have previously described the characterization of carotid plaques using external linear arrays operating at 9 MHz. In addition, we previously modified circular array IVUS catheters by short-circuiting several neighboring elements to produce fixed beamwidths for intravascular hyperthermia applications. In this paper, we modified Volcano Visions 8.2 French, 9 MHz catheters and Volcano Platinum 3.5 French, 20 MHz catheters by short-circuiting portions of the array for acoustic radiation force impulse imaging (ARFI) applications. The catheters had an effective transmit aperture size of 2 mm and 1.5 mm, respectively. The catheters were connected to a Verasonics scanner and driven with pushing pulses of 180 V p-p to acquire ARFI data from a soft gel phantom with a Young's modulus of 2.9 kPa. The dynamic response of the tissue-mimicking material demonstrates a typical ARFI motion of 1 to 2 microns as the gel phantom displaces away and recovers back to its normal position. The hardware modifications applied to our IVUS catheters mimic potential beamforming modifications that could be implemented on IVUS scanners. Our results demonstrate that the generation of radiation force from IVUS catheters and the development of intravascular ARFI may be feasible.

Development, Implementation and Use of Electronic Surveillance for Ventilator-Associated Events (VAE) in Adults.

Mechanical ventilation provides an important, life-saving therapy for severely ill patients, but ventilated patients are at an increased risk for complications, poor outcomes, and death during hospitalization.1 The timely measurement of negative outcomes is important in order to identify potential issues and to minimize the risk to patients. The Centers for Disease Control and Prevention (CDC) created an algorithm for identifying Ventilator-Associated Events (VAE) in adult patients for reporting to the National Healthcare Safety Network (NHSN). Currently, the primarily manual surveillance tools require a significant amount of time from hospital infection prevention (IP) staff to apply and interpret. This paper describes the implementation of an electronic VAE tool using an internal clinical data repository and an internally developed electronic surveillance system that resulted in a reduction of labor efforts involved in identifying VAE at Barnes Jewish Hospital (BJH).

Harmonic tracking of acoustic radiation force-induced displacements.

Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse-inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse-inversion techniques. The method is implemented with acoustic radiation force impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8-MHz harmonic images created using a band-pass filter approach and the fully sampled pulse-inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower- and higher-frequency methods suggests that any improvement resulting from the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse-inversion harmonic ARFI images. Within the lumen, the harmonic tracking methods improved the discrimination of the blood­vessel interface, making it easier to visualize plaque boundaries. Improvements in harmonic ARFI images in vivo were consistent with suppressed clutter supported by improved contrast and contrast-to-noise ratio (CNR) in the matched harmonic B-mode images compared with the fundamental B-mode images. These results suggest that harmonic tracking methods can improve the clinical utility and diagnostic accuracy of ultrasound-based elasticity imaging methods.

Fluid balance and cardiac function in septic shock as predictors of hospital mortality.

INTRODUCTION: Septic shock is a major cause of morbidity and mortality throughout the world. Unfortunately, the optimal fluid management of septic shock is unknown and currently is empirical. METHODS: A retrospective analysis was performed at Barnes-Jewish Hospital (St. Louis, Missouri). Consecutive patients (n = 325) hospitalized with septic shock who had echocardiographic examinations performed within 24 hours of shock onset were enrolled. RESULTS: A total of 163 (50.2%) patients with septic shock died during hospitalization. Non-survivors had a significantly larger positive net fluid balance within the 24 hour window of septic shock onset (median (IQR): 4,374 ml (1,637 ml, 7,260 ml) vs. 2,959 ml (1,639.5 ml, 4,769.5 ml), P = 0.004). The greatest quartile of positive net fluid balance at 24 hours and eight days post-shock onset respectively were found to predict hospital mortality, and the greatest quartile of positive net fluid balance at eight days post-shock onset was an independent predictor of hospital mortality (adjusted odds ratio (AOR), 1.66; 95% CI, 1.39 to 1.98; P = 0.004). Survivors were significantly more likely to have mild left ventricular dysfunction as evaluated by bedside echocardiography and non-survivors had slightly elevated left ventricular ejection fraction, which was also found to be an independent predictor of outcome. CONCLUSIONS: Our data confirms the importance of fluid balance and cardiac function as outcome predictors in patients with septic shock. A clinical trial to determine the optimal administration of intravenous fluids to patients with septic shock is needed.

Clostridium difficile infection: a multicenter study of epidemiology and outcomes in mechanically ventilated patients.

OBJECTIVES: Clostridium difficile is a leading cause of hospital-associated infection in the United States. The purpose of this study is to assess the prevalence of C. difficile infection among mechanically ventilated patients within the ICUs of three academic hospitals and secondarily describe the influence of C. difficile infection on the outcomes of these patients. DESIGN: A retrospective cohort study. SETTING: ICUs at three teaching hospitals: Barnes-Jewish Hospital, Mayo Clinic, and Creighton University Medical Center over a 2-year period. PATIENTS: All hospitalized patients requiring mechanical ventilation for greater than 48 hours within an ICU were eligible for inclusion. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 5,852 consecutive patients admitted to the ICU were included. Three hundred eighty-six (6.6%) patients with development of C. difficile infection while in the hospital (5.39 cases/1,000 patient days). Septic shock complicating C. difficile infection occurred in 34.7% of patients. Compared with patients without C. difficile infection (n = 5,466), patients with C. difficile infection had a similar hospital mortality rate (25.1% vs 26.3%, p = 0.638). Patients with C. difficile infection were significantly more likely to be discharged to a skilled nursing or rehabilitation facility (42.4% vs 31.9%, p < 0.001), and the median hospital (23 d vs 15 d, p < 0.001) and ICU length of stay (12 d vs 8 d, p < 0.001) were found to be significantly longer in patients with C. difficile infection. CONCLUSIONS: Clostridium difficile infection is a relatively common nosocomial infection in mechanically ventilated patients and is associated with prolonged length of hospital and ICU stay, and increased need for skilled nursing care or rehabilitation following hospital discharge.

Acoustic radiation force elasticity imaging in diagnostic ultrasound.

The development of ultrasound-based elasticity imaging methods has been the focus of intense research activity since the mid-1990s. In characterizing the mechanical properties of soft tissues, these techniques image an entirely new subset of tissue properties that cannot be derived with conventional ultrasound techniques. Clinically, tissue elasticity is known to be associated with pathological condition and with the ability to image these features in vivo; elasticity imaging methods may prove to be invaluable tools for the diagnosis and/or monitoring of disease. This review focuses on ultrasound-based elasticity imaging methods that generate an acoustic radiation force to induce tissue displacements. These methods can be performed noninvasively during routine exams to provide either qualitative or quantitative metrics of tissue elasticity. A brief overview of soft tissue mechanics relevant to elasticity imaging is provided, including a derivation of acoustic radiation force, and an overview of the various acoustic radiation force elasticity imaging methods.

Catheter removal versus retention in the management of catheter-associated enterococcal bloodstream infections.

BACKGROUND: Enterococci are an important cause of central venous catheter (CVC)-associated bloodstream infections (CA-BSI). It is unclear whether CVC removal is necessary to successfully manage enterococcal CA-BSI. METHODS: A 12-month retrospective cohort study of adults with enterococcal CA-BSI was conducted at a tertiary care hospital; clinical, microbiological and outcome data were collected. RESULTS: A total of 111 patients had an enterococcal CA-BSI. The median age was 58.2 years (range 21 to 94 years). There were 45 (40.5%) infections caused by Entercoccus faecalis (among which 10 [22%] were vancomycin resistant), 61 (55%) by Enterococcus faecium (57 [93%] vancomycin resistant) and five (4.5%) by other Enterococcus species. Patients were treated with linezolid (n=51 [46%]), vancomycin (n=37 [33%]), daptomycin (n=11 [10%]), ampicillin (n=2 [2%]) or quinupristin/dalfopristin (n=2 [2%]); seven (n=6%) patients did not receive adequate enterococcal treatment. Additionally, 24 (22%) patients received adjunctive gentamicin treatment. The CVC was retained in 29 (26.1%) patients. Patients with removed CVCs showed lower rates of in-hospital mortality (15 [18.3%] versus 11 [37.9]; P=0.03), but similar rates of recurrent bacteremia (nine [11.0%] versus two (7.0%); P=0.7) and a similar post-BSI length of hospital stay (median days [range]) (11.1 [1.7 to 63.1 days] versus 9.3 [1.9 to 31.8 days]; P=0.3). Catheter retention was an independent predictor of mortality (OR 3.34 [95% CI 1.21 to 9.26]). CONCLUSIONS: To the authors' knowledge, the present article describes the largest enterococcal CA-BSI series to date. Mortality was increased among patients who had their catheter retained. Additional prospective studies are necessary to determine the optimal management of enterococcal CA-BSI.

HISTORIQUE: Les entérocoques constituent une cause importante de bactériémies liées à un cathéter veineux central (CVC). On ne sait pas s'il est nécessaire de retirer le CVC pour réussir la prise en charge de ce type de bactériémie. MÉTHODOLOGIE: Les auteurs ont mené une étude rétrospective de cohorte de 12 mois auprès d'adultes ayant une bactériémie liée à un CVC dans un hôpital de soins tertiaires. Ils ont colligé des données cliniques, des données microbiologiques et des données d'issue. RÉSULTATS: Au total, 111 patients étaient atteints d'une bactériémie à entérocoque liée à un CVC. Ils avaient un âge médian de 58,2 ans (plage de 21 à 94 ans). Les chercheurs ont constaté 45 infections (40,5 %) causées par l'Enterococcus faecalis (dont 10 [22 %] résistantes à la vancomycine), 61 infections (55 %) causées par l'Enterococcus faecium (dont 57 [93 %] résistantes à la vancomycine) et cinq (4,5 %) causées par d'autres espèces d'Enterococcus. Les patients ont été traités au linézolide (n=51 [46 %]), à la vancomycine (n=37 [33 %]), à la daptomycine (n=11 [10 %]), à l'ampicilline (n=2 [2 %]) ou à la quinupristine-dalfopristine (n=2 [2 %]). Sept patients (n=6 %) n'ont pas reçu de traitement convenable contre les entérocoques. De plus, 24 patients (22%) ont reçu un traitement d'appoint à la gentamicine. Vingt-neuf patients (26,1 %) ont conservé leur CVC. Les patients à qui on l'avait retiré présentaient des taux de mortalité hospitalière plus faibles (15 [18,3 %] par rapport à 11 [37,9]; P=0,03), mais des taux similaires de bactériémie récurrente (neuf [11,0 %] par rapport à deux (7,0 %); P=0,7) et une durée d'hospitalisation similaire après la bactériémie (jours médians [plage]) (11,1 [1,7 à 63,1 jours] par rapport à 9,3 [1,9 à 31,8 jours]; P=0,3). Le maintien du cathéter était un prédicteur indépendant de mortalité (RRR 3,34 [95 % IC 1,21 à 9,26]). CONCLUSIONS: En autant que le sache les auteurs, le présent article décrit la plus grosse série de bactériémies liées à un CVC. La mortalité était plus élevée chez les patients qui conservaient leur cathéter. D'autres études prospectives s'imposent pour déterminer la prise en charge optimale de la bactériémie à entérocoque liée à un CVC.

Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis.

Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI imaging could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was<1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI imaging are orders of magnitude lower than the stresses associated with blood pressure.

Septic shock attributed to Candida infection: importance of empiric therapy and source control.

BACKGROUND: Delayed treatment of candidemia has previously been shown to be an important determinant of patient outcome. However, septic shock attributed to Candida infection and its determinants of outcome have not been previously evaluated in a large patient population. METHODS: A retrospective cohort study of hospitalized patients with septic shock and blood cultures positive for Candida species was conducted at Barnes-Jewish Hospital, a 1250-bed urban teaching hospital (January 2002-December 2010). RESULTS: Two hundred twenty-four consecutive patients with septic shock and a positive blood culture for Candida species were identified. Death during hospitalization occurred among 155 (63.5%) patients. The hospital mortality rate for patients having adequate source control and antifungal therapy administered within 24 hours of the onset of shock was 52.8% (n = 142), compared to a mortality rate of 97.6% (n = 82) in patients who did not have these goals attained (P < .001). Multivariate logistic regression analysis demonstrated that delayed antifungal treatment (adjusted odds ratio [AOR], 33.75; 95% confidence interval [CI], 9.65-118.04; P = .005) and failure to achieve timely source control (AOR, 77.40; 95% CI, 21.52-278.38; P = .001) were independently associated with a greater risk of hospital mortality. CONCLUSIONS: The risk of death is exceptionally high among patients with septic shock attributed to Candida infection. Efforts aimed at timely source control and antifungal treatment are likely to be associated with improved clinical outcomes.

Institutional perspective on the impact of positive blood cultures on the economic and clinical outcomes of patients with complicated skin and skin structure infections: focus on gram-positive infections.

BACKGROUND: Traditionally, skin and skin structure infections (SSSIs) have been viewed as having a lower risk of mortality, morbidity, and cost compared with other types of infection. The influence of secondary bacteremia on the medicoeconomic outcomes of patients with SSSIs has not been well described. OBJECTIVE: The goal of this study was to evaluate the impact of bacteremia complicating SSSIs on length of hospital stay and costs. METHODS: This was a retrospective cohort study involving 579 patients with culture-positive SSSIs who were admitted to Barnes-Jewish Hospital, a major academic medical center, between April 1, 2005, and December 31, 2007. The outcomes evaluated in this analysis included hospital mortality, length of stay, hospital costs, and hospital readmission. RESULTS: Secondary bacteremia was present in 277 (47.8%) patients. Hospital mortality was statistically greater among patients with bacteremia (7.9% vs 1.0%; P < 0.001). The unadjusted median length of stay in bacteremic patients was 7.1 days compared with 2.8 days in those without bacteremia (P < 0.001 by log-rank test). This finding correlated with total hospital costs, which were greater in patients with bacteremia (median values: $14,623 vs $5841.50; P < 0.001). In a Cox model controlling for multiple confounders, bacteremia independently correlated with hospital duration (adjusted hazard ratio [HR], 1.820; 95% CI, 1.654-2.003; P < 0.001) and hospital costs (adjusted HR, 1.895; 95% CI, 1.723-2.083; P < 0.001). Hospital readmission within 30 days of discharge was also significantly more common among patients with SSSIs complicated by bacteremia (24.5% vs 12.9%; P < 0.001). CONCLUSIONS: Bacteremia complicating SSSIs occurred in almost 50% of patients infected with gram-positive bacteria in our institution. Beyond its impact on mortality, bacteremia is associated with increased length of stay, hospital costs, and readmission. However, these data are from a single academic medical center and may not be adjusted for all applicable confounders.

Electronic surveillance for healthcare-associated central line-associated bloodstream infections outside the intensive care unit.

BACKGROUND: Manual surveillance for central line-associated bloodstream infections (CLABSIs) by infection prevention practitioners is time-consuming and often limited to intensive care units (ICUs). An automated surveillance system using existing databases with patient-level variables and microbiology data was investigated. METHODS: Patients with a positive blood culture in 4 non-ICU wards at Barnes-Jewish Hospital between July 1, 2005, and December 31, 2006, were evaluated. CLABSI determination for these patients was made via 2 sources; a manual chart review and an automated review from electronically available data. Agreement between these 2 sources was used to develop the best-fit electronic algorithm that used a set of rules to identify a CLABSI. Sensitivity, specificity, predictive values, and Pearson's correlation were calculated for the various rule sets, using manual chart review as the reference standard. RESULTS: During the study period, 391 positive blood cultures from 331 patients were evaluated. Eighty-five (22%) of these were confirmed to be CLABSI by manual chart review. The best-fit model included presence of a catheter, blood culture positive for known pathogen or blood culture with a common skin contaminant confirmed by a second positive culture and the presence of fever, and no positive cultures with the same organism from another sterile site. The best-performing rule set had an overall sensitivity of 95.2%, specificity of 97.5%, positive predictive value of 90%, and negative predictive value of 99.2% compared with intensive manual surveillance. CONCLUSIONS: Although CLABSIs were slightly overpredicted by electronic surveillance compared with manual chart review, the method offers the possibility of performing acceptably good surveillance in areas where resources do not allow for traditional manual surveillance.

Resistance to empiric antimicrobial treatment predicts outcome in severe sepsis associated with Gram-negative bacteremia.

BACKGROUND: Gram-negative bacteria are an important cause of severe sepsis. Recent studies have demonstrated reduced susceptibility of Gram-negative bacteria to currently available antimicrobial agents. METHODS: We performed a retrospective cohort study of patients with severe sepsis who were bacteremic with Pseudomonas aeruginosa, Acinetobacter species, or Enterobacteriaceae from 2002 to 2007. Patients were identified by the hospital informatics database and pertinent clinical data (demographics, baseline severity of illness, source of bacteremia, and therapy) were retrieved from electronic medical records. All patients were treated with antimicrobial agents within 12 hours of having blood cultures drawn that were subsequently positive for bacterial pathogens. The primary outcome was hospital mortality. RESULTS: A total of 535 patients with severe sepsis and Gram-negative bacteremia were identified. Hospital mortality was 43.6%, and 82 (15.3%) patients were treated with an antimicrobial regimen to which the causative pathogen was resistant. Patients infected with a resistant pathogen had significantly greater risk of hospital mortality (63.4% vs 40.0%; P < 0.001). In a multivariate analysis, infection with a pathogen that was resistant to the empiric antibiotic regimen, increasing APACHE II scores, infection with Pseudomonas aeruginosa, healthcare-associated hospital-onset infection, mechanical ventilation, and use of vasopressors were independently associated with hospital mortality. CONCLUSIONS: In severe sepsis attributed to Gram-negative bacteremia, initial treatment with an antibiotic regimen to which the causative pathogen is resistant was associated with increased hospital mortality. This finding suggests that rapid determination of bacterial susceptibility could influence treatment choices in patients with severe sepsis potentially improving their clinical outcomes.

Noninvasive assessment of wall-shear rate and vascular elasticity using combined ARFI/SWEI/spectral Doppler imaging system.

The progression of atherosclerotic disease is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesized that measurements of cardiovascular stiffness and wall-shear rate (WSR) may provide important information regarding vascular remodeling, endothelial function and the growth of soft lipid-filled plaques that could help a clinician better predict the occurrence of clinical events such as stroke. Two novel ARFI based imaging techniques, combined on-axis/off-axis ARFI/Spectral Doppler Imaging (SAD-SWEI) and Gated 2D ARFI/Spectral Doppler Imaging (SAD-Gated), were developed to form co-registered depictions of B-mode echogenicity, ARFI displacements, ARF-excited transverse wave velocity estimates and estimates ofwall-shear rate throughout the cardiac cycle. Implemented on a commercial ultrasound scanner, the developed techniques were evaluated in tissue-mimicking and steady-state flow phantoms and compared with conventional techniques, other published study results and theoretical values. Initial in vivo feasibility of the method is demonstrated with results obtained from scanning the carotid arteries of five healthy volunteers. Cyclic variations over the cardiac cycle were observed in on-axis displacements, off-axis transverse-wave velocities and wall-shear rates.

Development and validation of a Clostridium difficile infection risk prediction model.

OBJECTIVE: To develop and validate a risk prediction model that could identify patients at high risk for Clostridium difficile infection (CDI) before they develop disease. DESIGN AND SETTING: Retrospective cohort study in a tertiary care medical center. PATIENTS: Patients admitted to the hospital for at least 48 hours during the calendar year 2003. METHODS: Data were collected electronically from the hospital's Medical Informatics database and analyzed with logistic regression to determine variables that best predicted patients' risk for development of CDI. Model discrimination and calibration were calculated. The model was bootstrapped 500 times to validate the predictive accuracy. A receiver operating characteristic curve was calculated to evaluate potential risk cutoffs. RESULTS: A total of 35,350 admitted patients, including 329 with CDI, were studied. Variables in the risk prediction model were age, CDI pressure, times admitted to hospital in the previous 60 days, modified Acute Physiology Score, days of treatment with high-risk antibiotics, whether albumin level was low, admission to an intensive care unit, and receipt of laxatives, gastric acid suppressors, or antimotility drugs. The calibration and discrimination of the model were very good to excellent (C index, 0.88; Brier score, 0.009). CONCLUSIONS: The CDI risk prediction model performed well. Further study is needed to determine whether it could be used in a clinical setting to prevent CDI-associated outcomes and reduce costs.