A novel method for conformity assessment testing of dialysis machines for post-market surveillance purposes

1.Introduction

According to the Food and Drug Administration (FDA) [1], dialysis machine is a medical device (MD) that is used as an artificial kidney system for the treatment of patients with renal failure or conditions and that consists of an extracorporeal blood system, a conventional dialyzer, a dialysate delivery system, and accessories. Blood from a patient flows through the tubing of the extracorporeal blood system and accessories to the blood compartment of the dialyzer, then returns through further tubing of the extracorporeal blood system to the patient. Dialysis machines are classified to classes based on risk. In the European Union, according to the Medical Device Regulation (MDR) [2], dialysis machines are classified as Class IIa. This classification determines regulatory scrutiny to which devices are subjected to before placing on the market. Generally, Class II determines a medical device with a moderate to high risk that requires special controls. Taking into account the nature of the substances involved, the relevant part of the body and the method of application, such devices are considered active therapeutic devices whose use can occur in a potentially dangerous manner.

Due to the fact that they circulate blood through the dialysis system and regulate pressure, temperature, treatment duration, and fluid evacuation, dialysis machines can be designated as medical devices with a measuring function (MDMF) [3]. Medical device measurements are made possible by sensors or measuring equipment inside the devices themselves. The effectiveness of MD’s sensors and measuring equipment has a direct impact on the overall standard of product quality. Each predefined setting for dialysis machines’ conductivity and temperature of the dialysis fluid, and the pressure of the measuring device serves a particular purpose. When dialysis machines fall short of their intended goal of purification of the patient’s blood, dangerous adverse outcomes may result. In this regard, the inspection of the dialysis machine will refer to measurements of the conductivity and temperature of the dialysis fluid, as well as the pressure of the measuring device, so the post-marketing supervision should be focused on the accuracy and safety of the delivered values of the specified measurement quantities.

The classification suggests that dialysis machines belong to the moderate to high risk category since their role is to filter and purify the blood, thus helping to maintain fluid and electrolyte balance when the kidneys cannot do their job. For this reason, it is crucial that the device performs its role at a high level of reliability. An extensive set of standards is used to demonstrate compliance with the essential safety and performance requirements of dialysis machines [4]. These standards can be grouped into three categories, general quality standards, electrical safety standards, special standards for dialysis machines. Even though dialysis machines are subjected to a variety of test prior to being placed on the market, there is a significant gap in their performance testing after they have been placed onto the market. As for all other devices, the performance of dialysis machines deteriorates significantly over time and due to the vital function they perform for patients in need, their non-compliant performance may result in severe adverse events.

This paper presents the novel methodology for conformity assessment of dialysis machines during usage taking into account the International Organisation of Legal Metrology (OIML) approach defined for other types of medical devices with measuring functions such as sphygmomanometers. Presented novel method can be used by national regulators as a gold standard in defining regulatory framework considering conformity assessment of devices used in healthcare.

2.Method

To present the novel methodology, the accepted concept of OIML guidelines for other medical devices with measuring functions such as thermometers or sphygmomanometer was followed [5]. The method, developed under OIML recommendations, is reported as a coherent structure, through the following parts:

During method validation, the performance assessment testing of dialysis machines was done by using two etalons, Fluke Biomedical ESA 620 electrical safety analyser [6] and MesaLabs 90XL Dialysis conductivity, pH, temperature & pressure metre [7]. Both of these devices were periodically calibrated in EN ISO 17025 accredited laboratories [8]. The novel method was validated during the 2018–2021 time period. The presented data was analysed using a statistical approach.

3.Results and discussion

The results are presented in two parts. The first part consists of reporting the novel methodology for conformity assessment testing of dialysis machines and the second part consists of the validation report of this methodology done in real-time by inspection bodies in Bosnia and Herzegovina and Republic of Serbia.

4.Conclusion

Access to health is fundamental human right. However, various adverse event involving medical devices pose a risk to patients’ safety and well-being. The importance of safe and compliant medical devices has been especially demonstrated during COVID-19 pandemics [10]. Lately, regulators have been working in improving post-market surveillance of medical devices to ensure that number of incidents and adverse events including medical devices is lowered. Specifically, in the European Union, Medical Device Regulation (MDR) introduces the EUDAMED database [11, 12] containing all information regarding the adverse events associated with medical devices and reported by the end users that may be physicians, medical technicians or patients themselves. However, current databases collect information for each database from both voluntary sources and mandatory reports. Judging by the number of reported incidents involving medical devices it can be concluded that the limitations of the databases are that the data submitted include “incomplete, inaccurate, untimely, unverified, or biased data.” In addition, many use errors stay underreported and data format unknown. Moreover, current databases are limited to administrative data only including manufacturers and distributor data, vigilance and clinical studies data, hence the surveillance is not taking its full capacity. Also, baseline evidence for medical device safety and performance cannot be established due to lack of traceable data.

This paper lays out a novel methodology for conformity assessment testing of dialysis machine for post-market surveillance purposes. The novel methodology was developed based on OIML guidelines for technical and metrological characteristics and performance evaluation. Developed methodology has been validated by the work of two inspection bodies for medical devices working under the legal metrology framework which has been adopted for medical devices in Bosnia and Herzegovina and Republic of Serbia [13, 14]. The introduction of standardized conformity assessment method for testing of safety and performance of dialysis machine produced traceable, accurate, complete, verified, nonbiased and standardized data. All data resulting from the inspection carried out by independent appointed inspection bodies has been entered in database specially developed for this purpose – eLab [15]. This practice showed that significant cost-effectiveness can be achieved in management of maintenance in healthcare institutions because standardized data showed certain patterns for healthcare institutions.

The work demonstrated how standardized method for conformity assessment testing produces complete, accurate, verified, traceable and unbiased data. Following the trend of digital transformation and application of artificial intelligence, the researchers investigated application of artificial intelligence on this database [16, 17, 18, 19, 20]. The hypothesis of predictive management of maintenance of medical devices has been set up. Indeed, as medicine is shifting toward personalized medicine clinical engineering should follow the path of predictive approach.