Biomedical subjects

L E Stevens

Publications and source records attributed to L E Stevens.

At least 19 recordsLinked to original sources

PubMed2006

Adaptation of USP types II and IV controlled release assays for sparingly soluble compounds by direct eluent HPLC analysis.

Measurement of drug release of a sparingly soluble drug by conventional methods proceeds very slowly without the aid of surfactants. Two preliminary automated methods were developed that increase sensitivity and accelerate such studies by working at very small reservoir volumes. All high pressure liquid chromatography (HPLC) equipment components were commercially available. Results are presented for the drug release of a single pellet of the sparingly soluble drug Eliprodil in two types of drug release experiments using (1) a stirred cell and (2) a flow-through method. Release rates measured from each method were comparable.

Algorithms↗

PubMed2004

Dissolution of anecortave acetate in a cylindrical flow cell: re-evaluation of convective diffusion/drug dissolution for sparingly soluble drugs.

Steady-state drug release rates were measured from a model cylindrical implant, comprised mainly of the sparingly soluble drug anecortave acetate, suspended as an obstacle in a cylindrical flow cell. Dissolution medium was delivered at a steady, slow flow rate (0.05-0.7 mLs/min) using an HPLC pump, and samples from the outflow were analyzed by direct injection onto an HPLC column. Release rates were determined as a function of flow rate for three different implant orientations--vertical, elevated to the center of the dissolution cell; horizontal, elevated; and horizontal, resting directly upon the flat porous inlet frit. Release rates were ranked as follows: horizontal, floor >> horizontal, elevated>vertical, elevated. The steady, laminar flow enabled use of the finite element method (FEM) to simulate the dissolution process using convective diffusion/drug dissolution theory. Simulations predicted the absolute magnitude of the release rate to within < 10% for all situations, and predicted the power law exponent of the dependence of release rate on flow rate with great accuracy. The current method is more general than compendial methods that provide a dissolving surface that is uniformly accessible to the dissolution medium, or a shear rate that is uniform across the entire dissolving surface. The current approach may be utilized to provide estimates of dissolution rates for any geometry and set of hydrodynamic conditions that can be numerically calculated.

Algorithms↗

PubMed1998

Delirium in hospital: does it increase length of stay?

OBJECTIVE: To determine the effect of delirium, as a comorbid diagnosis in hospitalised patients, on patient length of stay (LOS). METHOD: Prospective study comparing LOS of delirious patients with controls matched by age, gender, principal diagnosis and date of admission. Medical and surgical inpatients of Westmead Hospital with delirium were identified from a Consultation Liaison (CL) psychiatry database and were matched with controls from the hospital medical records. RESULTS: Delirious patient LOS was found to be significantly longer (2.2-fold; 95% confidence interval 1.5-3.3) than matched controls. CONCLUSIONS: Delirium, as a comorbid diagnosis in general hospital patients, is associated with an increased use of resources. Its early diagnosis may limit this and morbidity.

Adolescent↗

PubMed1995

A large randomized clinical trial of a silver-impregnated urinary catheter: lack of efficacy and staphylococcal superinfection.

PURPOSE: The antibacterial activity of silver-containing compounds has recently been employed in constructing medical devices, such as vascular and urinary catheters, that may be effective in blocking infection. The present study was designed to evaluate the efficacy of a silver oxide-coated urinary catheter. PATIENTS AND METHODS: A total of 1,309 hospitalized patients who required placement of an indwelling urinary catheter for 24 hours or longer were randomly assigned to receive either a silicone catheter coated externally with 5% silver oxide or a standard silicone elastomer-coated latex catheter. Daily catheter-urine specimens were collected aseptically and catheter-care violations were monitored daily for the duration of the catheterization. RESULTS: Bacteriuria developed in 85 of 745 patients (11.4%) in the silver-coated catheter group and in 73 of 564 patients (12.9%) in the control group (P = 0.45). In women who did not receive antibiotics, the rates were 29.3% and 30.4%, respectively (P = 0.98). In men who did not receive antibiotics, the rate of bacteriuria was significantly higher with the silver-coated catheter (29.4% compared to 8.3%, respectively, P = 0.02). Staphylococcal species were isolated more often from the silver-coated catheter group than from the control group (25% versus 8% of all isolates, respectively, P = 0.002). CONCLUSIONS: This study, the largest ever reported evaluating any silver-impregnated device, has not only failed to demonstrate the efficacy of silver in prevention of catheter-associated bacteriuria, as suggested in prior studies, but it has also shown a significantly increased incidence of bacteriuria in male patients and a significantly increased occurrence of staphylococcal bacteriuria. These results suggest the need for caution and for similar large-scale trials before silver-containing compounds are widely used for preventing device-associated infections, both in vascular and urinary catheters.

Bacteriuria↗

PubMed1994

HELP the next generation: a new client-server architecture.

A new client-server based system which is centered around a lifetime data repository (LDR) is under construction. The goal of the new system is to maintain the patient centered decision support aspects of the existing HELP* system while providing an open architecture that supports faster application development and allows execution of applications to be distributed across many computers. These goals are achieved by implementing the system with software components that are commercially available or by adhering to national and international standards for software integration. Keys to successful integration include the use of MS-DOS @, OS/2#, and UNIX Section as operating systems, Microsoft OLE 2.0 as a standard interface to the clinical database, the use of TUXEDO as a transaction/communication manager, and the use of ORACLE [symbol: see text] RDBMS as the underlying database management system.

Computer Communication Networks↗

PubMed1993

Prospective surveillance of imipenem/cilastatin use and associated seizures using a hospital information system.

OBJECTIVE: To develop computerized methods to monitor and recommend dosage changes for patients treated with excessive dosages of imipenem/cilastatin (I/C) and to determine the incidence of I/C-associated seizures in our patient population. DESIGN: Prospective observational and interventional study of all patients admitted to LDS Hospital and treated with I/C from May 1, 1987, through June 30, 1991. SETTING: LDS Hospital, Salt Lake City, UT, a 520-bed, tertiary care center associated with the University of Utah School of Medicine. PATIENTS: Using a hospital information system we developed computerized algorithms to identify and monitor patients receiving I/C. These algorithms screened the computer-stored medical records of all inpatient admissions for I/C prescription orders. Computer-decision support algorithms estimated the renal function of each I/C-treated patient and provided suggestions when dosages were determined to be excessive. Additional computer-generated alerts identified patients who were receiving anticonvulsants concomitantly with I/C or whose therapy reflected dosage changes in the previous 24 hours. A list of all I/C-treated patients with alerts was reviewed daily by a clinical pharmacist and prescribing physicians were contacted if the computer-generated suggestions were clinically relevant. MAIN OUTCOME MEASURE: The number and characterization of I/C-associated seizures. RESULTS: From May 1, 1987, through June 30, 1991, we prospectively monitored 107,600 patients of whom 1951 were treated with I/C. The following risk factors for I/C-associated seizures were observed in the I/C-treated population: CNS disease (6 percent), seizure disorders (0.6 percent), and abnormal renal function (70 percent). The observational and interventional methods employed in this study resulted in 79 percent of the patients receiving I/C dosages appropriate for their corresponding renal function. During the 50-month study period, we detected four seizures (0.20 percent) in the I/C-treated patients. All 4 patients were receiving I/C dosages that were excessive with respect to their renal function. CONCLUSIONS: Our rate of seizure (0.2 percent) was lower than the 1-2 percent rate reported in the literature despite the fact that more than 70 percent of the patients who received I/C had risk factors for seizure. We believe that appropriate dosing of I/C results in a low rate of associated seizures. Computer-assisted monitoring of I/C dosages in relation to renal function resulted in a reduced incidence of seizures.

Adolescent↗

PubMed1993

Using a hospital information system to assess the effects of adverse drug events.

The most common adverse events experienced by hospitalized patients are drug related. While numerous studies have described the incidence and types of adverse drug events (ADEs), the actual effect of these events on patient outcomes have only been estimated. The studies that have described the effects of ADEs on patient outcomes have not stratified patients by severity of illness and hospital costs were estimated based on a percent of hospital charges. We designed a study to utilize the resources of our hospital information system to assess the attributable effects of ADEs on hospital length of stay and cost of hospitalization. This approach emphasized the difference between study patients and their matched control patients rather than overall differences between patients with and without ADEs. In addition, we used nursing acuity data to help adjust severity of illness within DRG groups and actual hospital costs were used instead of estimated costs. This study found that while the average length of stay for patients with ADEs was 8.19 days compared to 4.36 days for matched control patients, the attributable difference due to the ADEs was 1.94 days. Similar methods found that patients with ADEs had an average cost of hospitalization of $10,584 compared to $5,350 for those without and the attributable difference due to ADEs was $1,939. This indicates that the 569 ADEs at our hospital during 1992 resulted in an additional 1,104 extra patient days at a cost of $1,103,291.

Adverse Drug Reaction Reporting Systems↗

PubMed1992

Drug release profiles of ophthalmic formulations. 1. Instrumentation.

An experimental method is described for measuring time-release profiles of drugs from various ophthalmic dosage forms. This in vitro method is carried out under conditions nearly representative of those observed in vivo. Specifically, we have reproduced in vitro the small volume and the slow exchange rate of the human precorneal tear reservoir. Volumes on the order of 8-30 microL are achievable. The concentration of drug downstream from the sample reservoir is analyzed nearly continuously and the entire release profiles are appropriate for modeling. This analytical system has been used to study drug release kinetics from controlled release formulations such as gels and suspensions. The method is compared with alternative techniques.

Calibration↗

PubMed1992

Biochemical parameters which may be useful in improving organ viability after storage.

Biochemical methods that accurately detect ischemic damage in livers stored by flush cooling would be useful in the efficient development of new storage solutions. This study compares UW and Collins' solutions to evaluate those biochemical parameters which may be useful in assessing the reversibility of ischemic damage and the efficiency of organ storage solutions. Livers stored in UW solution showed higher levels of adenine nucleotides at all storage times studied. This increase in adenine nucleotides averaged 29% and was statistically significant. There was also a significant increase in the NAD levels in organs stored in UW solutions; however, the ATP levels were not significantly different after storage in either solution. Storage of livers in UW solution also decreased the amount of DNA damage which occurs with storage as compared to storage in Collins' solution, becoming statistically significant after 48 hr of storage. This suggests that these biochemical parameters may be useful in designing improved storage solutions since they reflect the extent of ischemic damage to the organ and can be determined on a small section of liver taken by biopsy.

Adenine Nucleotides↗

PubMed1992

Computerized identification of patients at high risk for hospital-acquired infection.

Surveillance for hospital-acquired infections is required in U.S. hospitals, and statistical methods have been used to predict the risk of infection. We used the HELP (Health Evaluation through Logical Processing) Hospital Information System at LDS Hospital to develop computerized methods to identify and verify hospital-acquired infections. The criteria for hospital-acquired infection are standardized and based on the guidelines of the Study of the Efficacy of Nosocomial Infection Control and the Centers for Disease Control. The computer algorithms are automatically activated when key items of information, such as microbiology results, are reported. Computer surveillance identified more hospital-acquired infections than did traditional methods and has replaced manual surveillance in our 520-bed hospital. Data on verified hospital-acquired infections are electronically transferred to a microcomputer to facilitate outbreak investigation and the generation of reports on infection rates. Recently, we used the HELP system to employ statistical methods to automatically identify high-risk patients. Patient data from more than 6000 patients were used to develop a high-risk equation. Stepwise logistic regression identified 10 risk factors for nosocomial infection. The HELP system now uses this logistic-regression equation to monitor and determine the risk status for all hospitalized patients each day. The computer notifies infection control practitioners each morning of patients who are newly classified as being at high risk. Of 605 hospital-acquired infections during a 6-month period, 472 (78%) occurred in high-risk patients, and 380 (63%) were predicted before the onset of infection. Computerized regression equations to identify patients at risk of having hospital-acquired infections can help focus prevention efforts.

Cross Infection↗

PubMed1992

Risk factors for epidemic Xanthomonas maltophilia infection/colonization in intensive care unit patients.

OBJECTIVE: To determine risk factors for and modes of transmission of Xanthomonas maltophilia infection/colonization. DESIGN: Surveillance and cohort study. SETTING: A 470-bed tertiary trauma-referral community hospital. PATIENTS: From January 1, 1988 to March 17, 1989, 106 intensive care unit patients developed X maltophilia infection/colonization. We defined a case as any intensive care unit patient who, from July 15, 1988, through March 17, 1989 (epidemic period), had X maltophilia infection/colonization greater than or equal to 48 hours after intensive care unit admission. We identified 45 case patients and 103 control patients (persons in the shock-trauma intensive care unit for greater than or equal to 72 hours during the epidemic period who had no X maltophilia-positive culture). RESULTS: Cases were significantly more likely to occur in the shock-trauma intensive care unit than in all other intensive care units combined. Mechanical ventilation, tracheostomy, being transported to the hospital by airplane, and receipt of a higher mean number of antimicrobials were risk factors for X maltophilia infection/colonization. Risk of X maltophilia infection/colonization was significantly greater among cases exposed to a patient with a X maltophilia surgical wound infection than among those without such exposure (relative risk = 1.3, p = .03). Animate and inanimate cultures revealed X maltophilia contamination of the hospital room of a patient with an X maltophilia surgical wound infection, of respiratory therapy equipment in this patient's room, of respirometers shared between patients, and of shock-trauma intensive care unit personnel's hands. Related environmental and clinical isolates were serotype 10. CONCLUSIONS: Mechanically ventilated patients receiving antimicrobials in the shock-trauma intensive care unit were at increased risk of X maltophilia infection/colonization. Patients with draining X maltophilia surgical wound infections served as reservoirs for X maltophilia, and contamination of the respirometers and the hands of shock-trauma intensive care unit personnel resulted in patient-to-patient transmission of X maltophilia.

Cohort Studies↗

PubMed1992

Randomized trial of meatal care with silver sulfadiazine cream for the prevention of catheter-associated bacteriuria.

A randomized, controlled, prospective clinical trial involving 696 hospitalized patients was undertaken to determine the effectiveness of 1% silver sulfadiazine cream applied twice daily to the urethral meatus in preventing transurethral catheter-associated bacteriuria. The overall incidence of bacteriuria was 11.4% (38/332) in the treated group and 13.2% (48/364) in the untreated group (P = .56; odds ratio, 0.85; 95% confidence interval, 0.53-1.37). Cox proportional hazards analysis identified female sex, lack of antibiotic use, and a positive initial meatal culture (but not treatment randomization or lack of urinemeter use) as independent variables associated with an increased risk of bacteriuria. Survival curve analysis of subgroups stratified by sex and antibiotic use failed to detect an effect of silver sulfadiazine on the rate of bacteriuria. Meatal care with silver sulfadiazine cream did not prevent the development of catheter-associated bacteriuria in short-term catheterized patients.

Administration, Topical↗

PubMed1992

The development of a virtual database to provide on-line access to a large archive of clinical data.

The archival database of the HELP Hospital Information System at LDS Hospital is too large to be stored on line. The archival data are important for clinical and research applications. Demountable disk packs have been used to store the archival database. This method of storage has four significant disadvantages. A virtual database was developed to overcome the limitations of this data-management scheme. This virtual database enables the transparent use of appropriate low-cost network-based storage technology to provide on-line availability of the entire archive of clinical data. The virtual database successfully resolves the problems associated with disk packs, and opens the door to enhanced use of the data for clinical and research applications.

Computer Storage Devices↗

PubMed1992

Clinical trial of junction seals for the prevention of urinary catheter-associated bacteriuria.

BACKGROUND: Preconnected catheter systems with sealed junctions have been associated with reduced rates of bacteriuria and mortality. A clinical trial was undertaken to evaluate the effectiveness of a junction seal applied after catheter insertion for preventing bacteriuria and reducing mortality. METHODS: Patients undergoing transurethral catheterization at a community hospital were randomized within 24 hours of catheter insertion to receive either a tape seal applied to the catheter-drainage tubing junction or no tape seal. Catheter urine cultures and catheter care violations were monitored daily until catheter removal or patient discharge. RESULTS: Overall, 124 (13.7%) of 903 patients in the group receiving a junction seal acquired bacteriuria, compared with 125 (14.9%) of 837 patients in the control group (P = .52, odds ratio = 0.91, 95% confidence interval, 0.69 to 1.20). Multivariate analysis revealed that only female gender and lack of systemic antibiotic use independently correlated with the development of bacteriuria; neither junction treatment randomization nor disconnection of the junction was associated with bacteriuria. Survival curve analysis of patients stratified by gender and antibiotic use revealed no significant differences in the rate of bacteriuria between treatment groups. The overall mortality in the tape seal group was less than that in the control group (6.6% vs. 8.0%, respectively), but not to a statistically significant extent despite stratification by antibiotic use. CONCLUSIONS: The use of a tape seal applied to the catheter-drainage tubing junction within 24 hours of catheter insertion was not associated with significantly lower rates of bacteriuria and mortality in patients undergoing short-term catheterization.

Bacteriuria↗

PubMed1991

The HELP system and its application to infection control.

The HELP system is a comprehensive hospital information system that is linked to an allied financial data base. The clinical data base integrates information from areas such as admitting, pharmacy, radiology, surgery, pathology, nursing, respiratory therapy, and the clinical laboratories, including microbiology. This allows for the creation of an electronic medical record that contains all the clinical and financial data for each patient. The HELP system combines both communication and advice features through the use of data- and time-driven algorithms. We have used the HELP system to automate the surveillance and analysis of hospital-acquired infections and to identify patients at high risk for nosocomial infection. The expert system features have also been used to suggest alternatives for patients receiving inappropriate antimicrobial therapy, to improve the timing of antibiotic prophylaxis in surgery, and to curtail unnecessarily prolonged prophylaxis. Automated hospital information systems such as HELP can facilitate the investigation of a broad range of infection control, quality improvement, and cost-containment issues.

Cross Infection↗

PubMed1991

Prevention of catheter-associated bacteriuria: clinical trial of methods to block three known pathways of infection.

The simultaneous use of methods to block all three known pathways of bacterial entry into the bladders of catheterized patients has been suggested because of the limited effectiveness of individual methods that block single pathways. We conducted a randomized controlled trial to assess the prevention of bacteriuria in patients, using a three-way system that included a hydrophilic polymer-coated and preconnected sealed catheter system, daily catheter care, and disinfection of the outflow tube of the drainage bag with povidone-iodine (i.e., methods to block bacterial entry at the urethral insertion site, at the catheter drainage tube junction, and at the outflow tube). Among treated patients, 14 (4.7%) of 300 acquired bacteriuria as compared with 15 (4.9%) of 306 who did not receive the protocol treatments. Only 3 of 29 episodes of bacteriuria occurred in patients whose meatal cultures did not contain gram-negative bacilli or enterococci; thus migration of bacteria in the periurethral mucous sheath appeared to be the most common pathway by which bacteria gained entry into the bladder in this study. Catheter care and disinfection of the drainage bag outflow tube as used in this study remain unproven methods of preventing catheter-associated bacteriuria. Preconnected catheters with junction seals were used in both treated and untreated patients and, on the basis of previous studies, appear to be effective in reducing junction disconnections and bacteriuria. Therefore we conclude that the use of several simultaneous measures to prevent catheter-associated urinary infections is no more effective than the use of preconnected catheters with junction seals alone and is clearly more expensive.

Bacteriuria↗

PubMed1991

Daily meatal care for prevention of catheter-associated bacteriuria: results using frequent applications of polyantibiotic cream.

OBJECTIVE: To determine the efficacy of meatal treatment with a polyantibiotic cream in the prevention of bacteriuria during transurethral bladder catheterization. DESIGN: Randomized controlled trial. SETTING: Community teaching hospital. PATIENTS: Adult patients who underwent closed urinary catheter drainage for short and intermediate durations (two to 30 days). INTERVENTION: Polyantibiotic cream containing polymyxin B sulfate, neomycin sulfate, and gramicidin was applied to the urethral meatus-catheter interface three times daily from the first day of catheterization until bacteriuria was found. The onset of bacteriuria was defined as the day the colonizing species first achieved a colony count of greater than or equal to 1000 colonies/ml. Patients randomized to the control group received routine meatal care with cleansing of the meatal surface during daily bathing. RESULTS: Among 2,923 patients who were randomly allocated to receive either the protocol meatal care or routine care, the evaluable study population consisted of 747 patients who were nonbacteriuric and who remained catheterized for more than two days. Overall, 26 (6.8%) of 383 patients given the polyantibiotic treatment acquired bacteriuria, as compared to 37 (10.1%) of 364 patients not given this treatment (p = .167). A Cox proportional hazards regression analysis showed that, among putative risk factors including lack of meatal care, only female gender, a meatal swab culture yielding gram-negative rods or enterococci, and lack of antibiotic use during catheterization were independently associated with the development of bacteriuria. CONCLUSIONS: The adverse effect of meatal care noted in earlier studies of a disinfectant ointment applied twice daily was not found in this study of an antimicrobial preparation in a cream vehicle applied three times daily. However, the results do not support meatal care as an efficacious method to prevent catheter-associated bacteriuria in all patients.

Aged↗

PubMed1991

Surveillance for quality assessment: IV. Surveillance using a hospital information system.

Hospital surveillance for infection control purposes is a well-accepted method of following nosocomial infections in U.S. hospitals. However, hospital surveillance is being increasingly performed for nosocomial events in noninfectious areas, such as quality assurance and other areas of outcomes research. For the continued development of hospital surveillance in all these areas, dramatic growth in the amount of information collected will occur. To accommodate this growth and to validate new approaches in these areas, large amounts of data collection will be necessary. Collection of these data will be quite difficult without the creation of clinical hospital data bases in which large amounts of information are collected as a routine part of patient care, not as an elaborate addition to patient care. Automated hospital information systems, such as the HELP system, can facilitate the conduct of ongoing hospital surveillance not only in infection control but also in a broad range of areas, such as quality improvement outcomes research and cost-containment areas.

Cross Infection↗