Usability and safety of ventricular assist devices: human factors and design aspects.

The purpose of this study was the investigation of the usability and ergonomics of ventricular assist devices (VADs) in everyday usage. Patients with four different VAD types were observed. After implantation, instruction, and discharge from the hospital, the patients returned on a regular basis to the outpatient clinic, where the investigation took place. Data collection took place in two phases. In phase I home-released VAD patients were asked about perceived problems with the system at home. Additionally health-care professionals were interviewed to gather information on frequent VAD inconveniences and shortcomings. This inquiry resulted in a standardized self-assessment questionnaire and a manual skill test, which were performed in phase II by the whole collective (16 patients and ongoing). As a result, 38% of the patients disconnected parts of their system unintentionally at least once. All of them ascribed this problem to their own carelessness. Thirty-eight percent had to replace a cable. Seventy-five percent desired an additional cable strain relief. Thirty-eight percent suffered from rubbing of parts on the body. Sixty-three percent used a separate repository aside from the factory-provided transportation systems. The overall noise emission (pump, ventilators, and alarms) annoyed 56%; however, for 32% the alarm signals were too quiet to wake them up. No correlation between the assessed manual skills and the number of adverse events was found. To conclude, this preliminary study revealed considerable potential for improvements in the usability of ventricular assist systems.