Biomedical Instrumentation and Technology最新文献

The temperature of the water used in vacuum pumps of steam sterilizers has the potential to cause failures in sterilization processes due to reduced efficiency and compromised vacuum levels. This study measured the impact of water temperature on a liquid ring vacuum pump (monobloc design) in a steam sterilizer. A sterilizer with a 566-L chamber was used for the tests. The water temperatures tested were 10°C, 20°C, 30°C, 40°C, and 50°C, and the following outcomes were analyzed: vacuum depth achieved in the drying phase (mbar), total cycle time (min), vacuum rate in the conditioning phase (mbar/s), and water consumption (L). Water temperature influenced the performance of the vacuum pump in all outcomes analyzed. Considering total cycle times, the performance with water at 10°C can be up to 50% better compared with performance with water at 50°C. The highest vacuum rates were obtained with water between 10°C and 20°C (up to 13 and 20.24 mbar/s, respectively). In cycles performed at 10°C, average water consumption was 33.3 L. In contrast, for cycles carried out at 50°C, the average water consumption increased to 94.2 L. The temperature of the water used in vacuum pumps influences the efficiency of sterilization cycles, which can result in longer cycles and higher water consumption.

Protein assays commonly used to evaluate reusable device cleanliness do not always accurately measure the low concentrations of protein that are expected on reusable medical devices after processing. Methods often are adapted to provide an estimation of protein concentration; however, sensitivity issues in the portion of standard curves at the acceptance criteria of 6.4 μg/cm² protein have been reported. Using analytical validation criteria, method improvements for the micro-bicinchoninic acid assay for protein residuals are demonstrated by incorporating a standard addition method, increasing the well volume, and changing the working reagent ratio. These improvements increased method sensitivity and accuracy in the reliable detection of protein levels for device cleaning validations.

Saturated steam (SS) is used for sterilizing many medical devices. Exposure to SS for appropriate temperature/time combinations creates a microbicidal environment that renders product sterile. Superheated steam (SHS) has been heated beyond its saturation point and is less microbicidal, compromising process efficacy. Sterilization monitoring systems should detect SHS. One method is to use biological indicators (BIs; e.g., rapid-readout self-contained BIs [RRSCBIs]). The purpose of this study was to determine if RRSCBIs can detect SHS. Pressurizing the boiler to 4,700 mB, manifold to 4,000 mB, and chamber jacket to 3,600 mB and heating the viewing window to 150°C in a 10-L BI evaluation resistometer vessel allowed approximately 12°C and 4.5°C of superheat in a nominal 121.75 ± 0.25°C and 132.5 ± 0.25°C cycle, respectively, to be reproducibly achieved. Replicate tests using multiple RRSCBIs from different batches were exposed vertically (cap up), inverted (cap down), and horizontally to SS and SHS. RRSCBI viability was determined using a fluorescent readout method. RRSCBIs exposed to SS at 121.75 ± 0.25°C for 7 or 14 minutes were negative. A total of 135 type A RRSCBIs were exposed to SHS (12°C) at 121.75 ± 0.25°C for 14 minutes. Zero of 45 RRSCBIs mounted vertically showed a positive fluorescent result, 26 of 45 mounted inverted were positive, and 45 of 45 mounted horizontally were positive. A total of 135 type B RRSCBIs were exposed to SHS (12°C) at 121.75 ± 0.25°C for 7 minutes. Twenty-four of 45 mounted vertically were positive, 41 of 45 mounted inverted were positive, and 45 of 45 mounted horizontally were positive. RRSCBIs detected SHS, but this was orientation dependent. Further work is required to establish the application of these findings in healthcare facility settings.

Endotoxins are high-molecular-weight complexes that contain lipopolysaccharide, protein, and phospholipid originating from the outer membrane of gram-negative bacteria. As gram-negative bacteria are naturally present in a variety of sources, endotoxins are commonly identified as contaminants in manufacturing environments. In industrial applications, endotoxin often is considered difficult to inactivate and to have a strong affinity with surfaces resulting from its hydrophobic chemical structure. This article describes the investigation of the true affinity of endotoxin, from various microbial sources in solution, for medical device material surfaces. In addition, endotoxin reduction was investigated with commonly used sterilization methods such as those based on ionizing radiation, dry and moist heat, and ethylene oxide sterilization. Endotoxin activity was found to be reduced following exposure to a range of sterilization modalities with the degree of activity reduction related to the source of endotoxin and the substrate material upon which it was present.

Polytetrafluoroethylene (PTFE) is a common polymer used in medical devices due to its exceptional properties (e.g., biocompatibility, inertness, chemical stability, low coefficient of friction). However, as a result of molecular weight reduction caused by the process of chain scission, it is known to be susceptible to radiation exposure and can rapidly lose strength and integrity. In this design of experiments study, the goal was to determine whether an operating window of conditions exist for electron beam (E-beam) radiation sterilization in which the degradation of PTFE is acceptably low. PTFE was tested for yield stress after exposure to radiation under different parameters (total dose [15-60 kGy], packaging atmosphere [air/nitrogen], and poststerilization accelerated aging [real-time equivalent of 1 and 3 years]). The results showed that total dose and packaging atmosphere were significant factors and indicated that the use of modified atmosphere packaging (vacuum sealing with nitrogen gas purge) can be a useful approach in increasing the stability of PTFE toward E-beam sterilization.

While selecting the test variables for a cleaning validation for reusable medical devices, the manufacturer must provide a simulative and clinically representative challenge for the device. An appropriate challenge must be identified with care so as not to overchallenge the cleaning process by selecting the worst case for every variable, thus leading to an impossible validation or unrealistic processing requirements. To appropriately select the testing variables, an understanding of the challenge to the cleaning process is important. The relationship among device material, test soil, and application method was investigated by testing 140 variable combinations, including seven materials (stainless steel, polyoxymethylene, polyether ether ketone, nitinol, aluminum, titanium, and silicone), four test soils (defibrinated blood soil, coagulated blood, modified coagulated blood, and Miles soil), and five soil application methods (pipetting neat, pipetting spreader, painting, handling with soiled gloves, and immersion). Stainless steel was the only material that showed consistent soil application in a thickness (at ~6 μL/cm²) that fully covered the test surface without some element of pooling, cracking, flaking, or soil migration with all test soils and application methods. The data collected using solubility testing indicated that a complex relationship for material adherence may exist between device materials and test soil. Stainless steel was the most challenging material tested.

Parametric release, which relies on use of process data for product release, provides many benefits. However, adoption by the sterilization industry has been slow, with release typically involving biological indicator (BI) growth responses/ dosimetry readings. The current article highlights how the data provided by the process (described through examples for ethylene oxide [EO], vaporized hydrogen peroxide [VHP], and radiation) may be better used to inform parametric release implementation. The examples involving EO and VHP demonstrated the ability of the sterilization equipment to deliver validated parameters repeatedly after the load presented was validated. For instances in which load variability has not been addressed in performance qualification, BI testing or even measurement of EO concentration cannot reliably or fully inform the impact of such variance on the validated process. "Direct" monitoring of EO concentration is a current requirement in ISO 11135:2014. Nonetheless, the findings presented here show that EO and VHP concentrations can be determined by the calculated method, rendering the use of a concentration measurement probe somewhat superfluous. In alignment with European Union good manufacturing practice Annex 17, a key requirement of parametric release is to have sufficient data to demonstrate the repeatability of the validated process. Similar to gas technologies, radiation processing strives to implement parametric release but is limited by the currently available means of measuring all critical parameters, such as photon delivery.

The identification of worst-case device (or device set) features has been a well-established validation approach in many areas (e.g., terminal sterilization) for determining process effectiveness and requirements, including for reusable medical devices. A device feature approach for cleaning validations has many advantages, representing a more conservative approach compared with the alternative compendial method of testing the entirety of the device. By focusing on the device feature(s), the most challenging validation variables can be isolated to and studied at the most difficult-to-clean feature(s). The device feature approach can be used to develop a design feature database that can be used to design and validate device cleanliness. It can also be used to commensurately develop a quantitative cleaning classification system that will augment and innovate the effectiveness of the Spaulding classification for microbial risk reduction. The current study investigated this validation approach to verify the efficacy of device cleaning procedures and mitigate patient risk. This feature categorization approach will help to close the existing patient safety gap at the important interface between device manufacturers and healthcare facilities for the effective and reliable processing of reusable medical devices. A total of 56,000 flushes of the device features were conducted, highlighting the rigor associated with the validation. Generating information from design features as a critical control point for cleaning and microbiological quality will inform future digital transformation of the medical device industry and healthcare delivery, including automation.

When approaching an ethylene oxide (EO) sterilization validation, medical device manufacturers traditionally have two choices. They can use biological indicators (BIs) to monitor each production run or establish a parametric release process in which sterile release is based on the monitoring and control of physical process parameters that ensure process specifications are met. In ISO 11135:2014, parametric release was brought to the forefront as an acceptable release method; however, a perception exists that implementing parametric release is challenging and time consuming. This article will demonstrate that the opposite is true. It presents a streamlined approach in which parametric release is addressed through the various stages of validation: product definition, process definition, performance qualification, routine release, and process control. Considerations for establishing specifications directly from validation versus "run and record" and trending critical process parameters (e.g., relative humidity, temperature, EO concentration) are discussed. In addition, the benefits of parametric release (active monitoring) over BI release (passive monitoring), including improvements to turnaround time, process control, risk mitigation, reduction of resource investment, and elimination of microbiological release testing, are highlighted. With multiple benefits, parametric release should be the gold standard for EO sterilization processes. It is not novel and has been widely accepted by regulatory agencies globally and notified bodies. The article further describes how the data collection and process capability that is central to process control and parametric release is more powerful than the information provided by a BI, which is merely a catastrophic indicator when used in routine processing.

Background: Continuous physiologic monitoring commonly is used in pediatric medical-surgical (med-surg) units and is associated with high alarm burden for clinicians. Characteristics of pediatric patients generating high rates of alarms on med-surg units are not known. Objective: To describe the demographic and clinical characteristics of pediatric med-surg patients associated with high rates of clinical alarms. Methods: We conducted a cross-sectional, single-site, retrospective study using existing clinical and alarm data from a children's hospital. Continuously monitored patients from med-surg units who had available alarm data were included. Negative binomial regression models were used to test the association between patient characteristics and the rate of clinical alarms per continuously monitored hour. Results: Our final sample consisted of 1,569 patients with a total of 38,501 continuously monitored hours generating 265,432 clinical alarms. Peripheral oxygen saturation (SpO₂) low alarms accounted for 57.5% of alarms. Patients with medical complexity averaged 11% fewer alarms per hour than those without medical complexity (P < 0.01). Patients older than 5 years had up to 30% fewer alarms per hour than those who were younger than 5 years (P < 0.01). Patients using supplemental oxygen averaged 39% more alarms per hour compared with patients who had no supplemental oxygen use (P < 0.01). Patients at high risk for deterioration averaged 19% more alarms per hour than patients who were not high risk (P = 0.01). Conclusion: SpO₂ alarms were the most common type of alarm in this study. The results highlight patient populations in pediatric medical-surgical units that may be high yield for interventions to reduce alarms. Most physiologic monitor alarms in pediatric medical-surgical (med-surg) units are not informative and likely could be safely eliminated to reduce noise and alarm fatigue.^1-3 However, identifying and sustaining successful alarm-reduction strategies is a challenge. Research shows that 25% of patients in pediatric med-surg units produce almost three-quarters of all alarms.⁴ These patients are a potential high-yield target for alarm-reduction strategies; however, we are not aware of studies describing characteristics of pediatric patients generating high rates of alarms. The patient populations seen on pediatric med-surg units are diverse. Children of all ages are cared for on these units, with diagnoses ranging from acute respiratory infections, to management of chronic conditions, and to psychiatric conditions. Not all patients on pediatric med-surg units have physiologic parameters continuously monitored,⁴ but among those who do, understanding patient characteristics associated with high rates of alarms may help clinicians, healthcare technology managemen