The Experts below are selected from a list of 1107 Experts worldwide ranked by ideXlab platform
William R. Jarvis - One of the best experts on this subject based on the ideXlab platform.
-
an outbreak of gram negative bacteremia in Hemodialysis patients traced to Hemodialysis Machine waste drain ports
Infection Control and Hospital Epidemiology, 1999Co-Authors: Susan A. Wang, Loretta A. Carson, M J Arduino, Michele L. Pearson, R B Levine, T Killar, F G Grillo, William R. JarvisAbstract:OBJECTIVE To investigate an outbreak of gram-negative bacteremias at a Hemodialysis center (December 1, 1996-January 31, 1997). DESIGN Retrospective cohort study. Reviewed infection control practices and maintenance and disinfection procedures for the water system and dialysis Machines. Performed cultures of the water and dialysis Machines, including the waste-handling option (WHO), a drain port designed to dispose of saline used to flush the dialyzer before patient use. Compared isolates by pulsed-field gel electrophoresis. SETTING A Hemodialysis center in Maryland. RESULTS 94 patients received dialysis on 27 Machines; 10 (11%) of the patients had gram-negative bacteremias. Pathogens causing these infections were Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 4), and Escherichia coli (n = 2); two patients had polymicrobial bacteremia. Factors associated with development of gram-negative bacteremias were receiving dialysis via a central venous catheter (CVC) rather than via an arterio-venous shunt (all 10 infected patients had CVCs compared to 31 of 84 uninfected patients, relative risk [RR] undefined; P<.001) or dialysis on any of three particular dialysis Machines (7 of 10 infected patients were exposed to the three Machines compared to 20 of 84 uninfected patients, RR = 5.8; P = .005). E cloacae, P aeruginosa, or both organisms were grown from cultures obtained from several dialysis Machines. WHO valves, which prevent backflow from the drain to dialysis bloodlines, were faulty in 8 (31%) of 26 Machines, including 2 of 3 Machines epidemiologically linked to case-patients. Pulsed-field gel electrophoresis patterns of available dialysis Machine and patient E cloacae isolates were identical. CONCLUSIONS Our study suggests that WHO ports with incompetent valves and resultant backflow were a source of cross-contamination of dialysis bloodlines and patients' CVCs. Replacement of faulty WHO valves and enhanced disinfection of dialysis Machines terminated the outbreak.
-
An outbreak of gram-negative bacteremia in Hemodialysis patients traced to Hemodialysis Machine waste drain ports.
Infection Control & Hospital Epidemiology, 1999Co-Authors: Susan A. Wang, Loretta A. Carson, M J Arduino, Killar T, Michele L. Pearson, William R. JarvisAbstract:OBJECTIVE To investigate an outbreak of gram-negative bacteremias at a Hemodialysis center (December 1, 1996-January 31, 1997). DESIGN Retrospective cohort study. Reviewed infection control practices and maintenance and disinfection procedures for the water system and dialysis Machines. Performed cultures of the water and dialysis Machines, including the waste-handling option (WHO), a drain port designed to dispose of saline used to flush the dialyzer before patient use. Compared isolates by pulsed-field gel electrophoresis. SETTING A Hemodialysis center in Maryland. RESULTS 94 patients received dialysis on 27 Machines; 10 (11%) of the patients had gram-negative bacteremias. Pathogens causing these infections were Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 4), and Escherichia coli (n = 2); two patients had polymicrobial bacteremia. Factors associated with development of gram-negative bacteremias were receiving dialysis via a central venous catheter (CVC) rather than via an arterio-venous shunt (all 10 infected patients had CVCs compared to 31 of 84 uninfected patients, relative risk [RR] undefined; P
Susan A. Wang - One of the best experts on this subject based on the ideXlab platform.
-
an outbreak of gram negative bacteremia in Hemodialysis patients traced to Hemodialysis Machine waste drain ports
Infection Control and Hospital Epidemiology, 1999Co-Authors: Susan A. Wang, Loretta A. Carson, M J Arduino, Michele L. Pearson, R B Levine, T Killar, F G Grillo, William R. JarvisAbstract:OBJECTIVE To investigate an outbreak of gram-negative bacteremias at a Hemodialysis center (December 1, 1996-January 31, 1997). DESIGN Retrospective cohort study. Reviewed infection control practices and maintenance and disinfection procedures for the water system and dialysis Machines. Performed cultures of the water and dialysis Machines, including the waste-handling option (WHO), a drain port designed to dispose of saline used to flush the dialyzer before patient use. Compared isolates by pulsed-field gel electrophoresis. SETTING A Hemodialysis center in Maryland. RESULTS 94 patients received dialysis on 27 Machines; 10 (11%) of the patients had gram-negative bacteremias. Pathogens causing these infections were Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 4), and Escherichia coli (n = 2); two patients had polymicrobial bacteremia. Factors associated with development of gram-negative bacteremias were receiving dialysis via a central venous catheter (CVC) rather than via an arterio-venous shunt (all 10 infected patients had CVCs compared to 31 of 84 uninfected patients, relative risk [RR] undefined; P<.001) or dialysis on any of three particular dialysis Machines (7 of 10 infected patients were exposed to the three Machines compared to 20 of 84 uninfected patients, RR = 5.8; P = .005). E cloacae, P aeruginosa, or both organisms were grown from cultures obtained from several dialysis Machines. WHO valves, which prevent backflow from the drain to dialysis bloodlines, were faulty in 8 (31%) of 26 Machines, including 2 of 3 Machines epidemiologically linked to case-patients. Pulsed-field gel electrophoresis patterns of available dialysis Machine and patient E cloacae isolates were identical. CONCLUSIONS Our study suggests that WHO ports with incompetent valves and resultant backflow were a source of cross-contamination of dialysis bloodlines and patients' CVCs. Replacement of faulty WHO valves and enhanced disinfection of dialysis Machines terminated the outbreak.
-
An outbreak of gram-negative bacteremia in Hemodialysis patients traced to Hemodialysis Machine waste drain ports.
Infection Control & Hospital Epidemiology, 1999Co-Authors: Susan A. Wang, Loretta A. Carson, M J Arduino, Killar T, Michele L. Pearson, William R. JarvisAbstract:OBJECTIVE To investigate an outbreak of gram-negative bacteremias at a Hemodialysis center (December 1, 1996-January 31, 1997). DESIGN Retrospective cohort study. Reviewed infection control practices and maintenance and disinfection procedures for the water system and dialysis Machines. Performed cultures of the water and dialysis Machines, including the waste-handling option (WHO), a drain port designed to dispose of saline used to flush the dialyzer before patient use. Compared isolates by pulsed-field gel electrophoresis. SETTING A Hemodialysis center in Maryland. RESULTS 94 patients received dialysis on 27 Machines; 10 (11%) of the patients had gram-negative bacteremias. Pathogens causing these infections were Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 4), and Escherichia coli (n = 2); two patients had polymicrobial bacteremia. Factors associated with development of gram-negative bacteremias were receiving dialysis via a central venous catheter (CVC) rather than via an arterio-venous shunt (all 10 infected patients had CVCs compared to 31 of 84 uninfected patients, relative risk [RR] undefined; P
Elvinia Riccobene - One of the best experts on this subject based on the ideXlab platform.
-
Integrating formal methods into medical software development : the ASM approach
'Elsevier BV', 2018Co-Authors: Paolo Arcaini, Atif Mashkoor, Silvia Bonfanti, Angelo Gargantini, Elvinia RiccobeneAbstract:Medical devices are safety-critical systems since their malfunctions can seriously compromise human safety. Correct operation of a medical device depends upon the controlling software, whose development should adhere to certification standards. However, these standards provide general descriptions of common software engineering activities without any indication regarding particular methods and techniques to assure safety and reliability. This paper discusses how to integrate the use of a formal approach into the current normative for the medical software development. The rigorous process is based on the Abstract State Machine (ASM) formal method, its refinement principle, and model analysis approaches the method supports. The Hemodialysis Machine case study is used to show how the ASM-based design process covers most of the engineering activities required by the related standards, and provides rigorous approaches for medical software validation and verification
-
how to assure correctness and safety of medical software the Hemodialysis Machine case study
Lecture Notes in Computer Science, 2016Co-Authors: Paolo Arcaini, Silvia Bonfanti, Angelo Gargantini, Elvinia RiccobeneAbstract:Medical devices are nowadays more and more software dependent, and software malfunctioning can lead to injuries or death for patients. Several standards have been proposed for the development and the validation of medical devices, but they establish general guidelines on the use of common software engineering activities without any indication regarding methods and techniques to assure safety and reliability. This paper takes advantage of the Hemodialysis Machine case study to present a formal development process supporting most of the engineering activities required by the standards, and provides rigorous approaches for system validation and verification. The process is based on the Abstract State Machine formal method and its model refinement principle.
-
ABZ - How to Assure Correctness and Safety of Medical Software: The Hemodialysis Machine Case Study
Lecture Notes in Computer Science, 2016Co-Authors: Paolo Arcaini, Silvia Bonfanti, Angelo Gargantini, Elvinia RiccobeneAbstract:Medical devices are nowadays more and more software dependent, and software malfunctioning can lead to injuries or death for patients. Several standards have been proposed for the development and the validation of medical devices, but they establish general guidelines on the use of common software engineering activities without any indication regarding methods and techniques to assure safety and reliability. This paper takes advantage of the Hemodialysis Machine case study to present a formal development process supporting most of the engineering activities required by the standards, and provides rigorous approaches for system validation and verification. The process is based on the Abstract State Machine formal method and its model refinement principle.
Leif Sörnmo - One of the best experts on this subject based on the ideXlab platform.
-
Detection of ventricular premature beats based on the pressure signals of a Hemodialysis Machine.
Medical engineering & physics, 2017Co-Authors: Mattias Holmer, Frida Sandberg, Bo Olde, Juan Pablo Martinez, Eduardo Gil, Leif SörnmoAbstract:Abstract Monitoring of ventricular premature beats (VPBs), being abundant in Hemodialysis patients, can provide information on cardiovascular instability and electrolyte imbalance. In this paper, we describe a method for VPB detection which explores the signals acquired from the arterial and the venous pressure sensors, located in the extracorporeal blood circuit of a Hemodialysis Machine. The pressure signals are mainly composed of a pump component and a cardiac component. The cardiac component, severely overshadowed by the pump component, is estimated from the pressure signals using an earlier described iterative method. A set of simple features is extracted, and linear discriminant analysis is performed to classify beats as either normal or ventricular premature. Performance is evaluated on signals from nine Hemodialysis treatments, using leave-one-out crossvalidation. The simultaneously recorded and annotated photoplethysmographic signal serves as the reference signal, with a total of 149,686 normal beats and 3574 VPBs. The results show that VPBs can be reliably detected, quantified by a Youden’s J statistic of 0.9, for average cardiac pulse pressures exceeding 1 mmHg; for lower pressures, the J statistic drops to 0.55. It is concluded that the cardiac pressure signal is suitable for VPB detection, provided that the average cardiac pulse pressure exceeds 1 mmHg.
-
Cardiac signal estimation based on the arterial and venous pressure signals of a Hemodialysis Machine.
Physiological measurement, 2016Co-Authors: Mattias Holmer, Frida Sandberg, Kristian Solem, Bo Olde, Leif SörnmoAbstract:Continuous cardiac monitoring is usually not performed during Hemodialysis treatment, although a majority of patients with kidney failure suffer from cardiovascular disease. In the present paper, a method is proposed for estimating a cardiac pressure signal by combining the arterial and the venous pressure sensor signals of the Hemodialysis Machine. The estimation is complicated by the periodic pressure disturbance caused by the peristaltic blood pump, with an amplitude much larger than that of the cardiac pressure signal. Using different techniques for combining the arterial and venous pressure signals, the performance is evaluated and compared to that of an earlier method which made use of the venous pressure only. The heart rate and the heartbeat occurrence times, determined from the estimated cardiac pressure signal, are compared to the corresponding quantities determined from a photoplethysmographic reference signal. Signals from 9 complete Hemodialysis treatments were analyzed. For a heartbeat amplitude of 0.5 mmHg, the median absolute deviation between estimated and reference heart rate was 1.3 bpm when using the venous pressure signal only, but dropped to 0.6 bpm when combining the pressure signals. The results show that the proposed method offers superior estimation at low heartbeat amplitudes. Consequently, more patients can be successfully monitored during treatment without the need of extra sensors. The results are preliminary, and need to be verified on a separate dataset.
-
Extracting a Cardiac Signal From the Extracorporeal Pressure Sensors of a Hemodialysis Machine
IEEE Transactions on Biomedical Engineering, 2015Co-Authors: Mattias Holmer, Frida Sandberg, Kristian Solem, Eglė Grigonytė, Bo Olde, Leif SörnmoAbstract:Although patients undergoing Hemodialysis treatment often suffer from cardiovascular disease, monitoring of cardiac rhythm is not performed on a routine basis. Without requiring any extra sensor, this study proposes a method for extracting a cardiac signal from the built-in extracorporeal venous pressure sensor of the Hemodialysis Machine. The extraction is challenged by the fact that the cardiac component is much weaker than the pressure component caused by the peristaltic blood pump. To further complicate the extraction problem, the cardiac component is difficult to separate when the pump and heart rates coincide. The proposed method estimates a cardiac signal by subtracting an iteratively refined blood pump model signal from the signal measured at the extracorporeal venous pressure sensor. The method was developed based on simulated pressure signals, and evaluated on clinical pressure signals acquired during Hemodialysis treatment. The heart rate estimated from the clinical pressure signal was compared to that derived from a photoplethysmographic reference signal, resulting in a difference of 0.07 ± 0.84 beats/min. The accuracy of the heartbeat occurrence times was studied for different strengths of the cardiac component, using both clinical and simulated signals. The results suggest that the accuracy is sufficient for analysis of heart rate and certain arrhythmias.
Michael Butler - One of the best experts on this subject based on the ideXlab platform.
-
validating the requirements and design of a Hemodialysis Machine using iuml b bmotion studio and co simulation
ABZ 2016 Proceedings of the 5th International Conference on Abstract State Machines Alloy B TLA VDM and Z - Volume 9675, 2016Co-Authors: Thai Son Hoang, Colin Snook, Lukas Ladenberger, Michael ButlerAbstract:We present a formal specification of a Hemodialysis Machine HD Machine using Event-B. We model the HD Machine using iUML-B state-Machines and class diagrams and build a corresponding BMotion Studio visualisation. We focus on validation using i diagrams to aid the modelling of the sequential properties of the requirements, and ii ProB-based animation and visualisation tools to explore the system's behaviour. Some of the safety properties involve dynamic behaviour which is difficult to verify in Event-B. For these properties we use co-simulation tools to validate against a continuous model of the physical behaviour.
-
ABZ - Validating the Requirements and Design of a Hemodialysis Machine Using iUML-B, BMotion Studio, and Co-Simulation
Lecture Notes in Computer Science, 2016Co-Authors: Thai Son Hoang, Colin Snook, Lukas Ladenberger, Michael ButlerAbstract:We present a formal specification of a Hemodialysis Machine HD Machine using Event-B. We model the HD Machine using iUML-B state-Machines and class diagrams and build a corresponding BMotion Studio visualisation. We focus on validation using i diagrams to aid the modelling of the sequential properties of the requirements, and ii ProB-based animation and visualisation tools to explore the system's behaviour. Some of the safety properties involve dynamic behaviour which is difficult to verify in Event-B. For these properties we use co-simulation tools to validate against a continuous model of the physical behaviour.