Human Factors Validation Testing for the Peripal System; a Manual Connection Assist Device for Peritoneal Dialysis Devices

The growth in the renal replacement therapy population is primaryly in the elderly age group, a population with a high frailty and comorbidity burden. Facilitating PD in this group of patients requires improved PD technology with greater accessibility tailored to patient needs. Following evaluation of specific barriers to the use of PD including feedback from established PD patients, a novel connection-assist device has been developed.

As part of the CE marking authorization, the connection device has been evaluated for safety and ease of use in a study at University Hospitals Birmingham NHS Foundation Trust involving 24 patients and carers.

The evaluated device is designed to assist peritoneal dialysis patients performing their daily dialysis treatment either for APD or for CAPD. The device facilitates the connection and disconnection of the dialysis line to the PD catheter transfer set. The connections are performed inside the device in a protected area, and the patient does not need to touch the transfer set or the dialysis line while they are unprotected. In addition, the breaking of the dialysis line frangible and the clamping of the dialysis line are replaced by pushing a button.

The operating procedure of the device consists of multiple tasks including preparing and loading the transfer set and dialysis line into the device, performing the handling steps related to the PD therapy with the device and finally unloading the used material from the device. Each task comprises several handling steps. During the study, the operating procedure with the device was simulated and the subjects were connected to a dummy catheter, which was attached to an apron.

This study recruited established PD patients and carers involved in the delivery of PD. Carers included healthcare professionals and lay carers.

The study design was divided into three one hour long parts. Firstly, a training session introduced the operation of the device. Secondly, a break of one hour allowed relaxation and recovery. Thirdly, a test was carried out to determine whether the subject could use the device independently with the aid of a quick start guide and the device manual.

The training consisted of two cycles in which the moderator guided the subject and three cycles in which the subject guided the moderator through the complete handling of the device. After the break, the subjects were asked to carry out a complete handling cycle themselves. Subjects could use the quick start guide and the device manual as help. After the unsupported handling cycle, subjects were asked to complete the NASA Task Load Index (N-TLX) questionnaire. In the meantime, the moderator left the room to obtain information on observed use errors. In a final semi-structured interview, the subjects were asked about the reasons for the observed use errors.

For each subject, one moderator and one observer were involved in the study. The moderator was the interface between the subject and the device both in training and in testing. This person was employed by an external agency to avoid any influence on the subject. The observer saw the handling with the help of a live feed from a separate room. He evaluated the handling steps in the categories of "safe use" and "use error" according to IEC 62366-1. For each use error, the observer described the observed situation from his point of view. In addition to evaluating the effectiveness of the task performance, the subjects were interviewed in a semi structured way. Here the observations of technique errors were discussed with the subjects in order to identify the specific causes. In this interview, the subjects were also asked for their feedback on the general ease of use of the device.

In addition, the subjects were asked about the task load in six different dimensions in the standardized N-TLX. Task load is a hypothetical construct that represents the cost incurred by a human operator to achieve a particular level of performance. The dimensions of the N-TLX are mental, physical and temporal demands as well as performance, effort and frustration in the task. Each dimension is evaluated on a 20-point scale. This scale is then transferred to the task load index, which is a scale between 0 and 100 points. To classify the results of the N-TLX, Eitrheim and Fernandes (2016) state "Workload levels below 50 were perceived as acceptable."

Fifteen patients and nine carers volunteered in this study, ranging from 23 to 86 years in age and from 0.3 to 24 years in experience in the PD therapy.