Biomedical Instrumentation and Technology最新文献

Mechanical respirators typically use a plastic circuit apparatus to pass gases from the ventilator to the patient. Structural integrity of these circuits is crucial for maintaining oxygenation. Anesthesiologists, respiratory therapists, and other critical care professionals rely on the circuit to be free of defects. The American Society for Testing and Materials maintains standards of medical devices and had a standard (titled Standard Specification for Anesthesia Breathing Tubes) that included circuits. This standard, which was last updated in 2008, has since been withdrawn. Lack of a defined standard can invite quality fade-the phenomenon whereby manufacturers deliberately but surreptitiously reduce material quality to widen profit margins. With plastics, this is often in the form of thinner material. A minimum thickness delineated in the breathing circuit standard would help ensure product quality, maintain tolerance to mechanical insults, and avert leaks. Our impression is that over the recent years, the plastic in many of the commercially available breathing circuits has gotten thinner. We experienced a circuit leak in the middle of a laminectomy due to compromised plastic tubing in a location that evaded the safety circuit leak check that is performed prior to surgery. This compromised ventilation and oxygenation in the middle of a surgery in which the patient is positioned prone and hence with a minimally accessible airway; it could have resulted in anoxic brain injury or death. The incident led us to reflect on the degree of thinness of the circuit's plastic.

This article reports on the development of usability engineering recommendations for next-generation integrated interoperable medical devices. A model-based hazard analysis method is used to reason about possible design anomalies in interoperability functions that could lead to use errors. Design recommendations are identified that can mitigate design problems. An example application of the method is presented based on an integrated medical system prototype for postoperative care. The AAMI/UL technical committee used the results of the described analysis to inform the creation of the Interoperability Usability Concepts, Annex J, which is included in the first edition of the new ANSI/AAMI/UL 2800-1:2019 standard on medical device interoperability. The presented work is valuable to experts developing future revisions of the interoperability standard, as it documents key aspects of the analysis method used to create part of the standard. The contribution is also valuable to manufacturers, as it demonstrates how to perform a model-based analysis of use-related aspects of a medical system at the early stages of development, when a concrete implementation of the system is not yet available.

Validating a thermal disinfection process for the processing of medical devices using moist heat via direct temperature monitoring is a conservative approach and has been established as the A0 method. Traditional use of disinfection challenge microorganisms and testing techniques, although widely used and applicable for chemical disinfection studies, do not provide as robust a challenge for testing the efficacy of a thermal disinfection process. Considerable research has been established in the literature to demonstrate the relationship between the thermal resistance of microorganisms to inactivation and the A0 method formula. The A0 method, therefore, should be used as the preferred method for validating a thermal disinfection process using moist heat.

The ability to adequately ventilate a patient is critical and sometimes a challenge in the emergency, intensive care, and anesthesiology settings. Commonly, initial ventilation is achieved through the use of a face mask in conjunction with a bag that is manually squeezed by the clinician to generate positive pressure and flow of air or oxygen through the patient's airway. Large or small erroneous openings in the breathing circuit can lead to leaks that compromise ventilation ability. Standard procedure in anesthesiology is to check the circuit apparatus and oxygen delivery system prior to every case. Because the face mask itself is not a piece of equipment that is associated with a source of leak, some common anesthesia machine designs are constructed such that the circuit is tested without the mask component. We present an example of a leak that resulted from complete failure of the face mask due to a tiny tear in its cuff by the patient's sharp teeth edges. This subsequently prevented formation of a seal between the face mask and the patient's face and rendered the device incapable of generating the positive pressure it is designed to deliver. This instance depicts the broader lesson that deviation from clinical routines can reveal unappreciated sources of vulnerability in device design.