A Smart-Phone App for Fluid Balance Monitoring in Patients with Heart Failure: A Usability Study

Background: For a long time, fluid balance monitoring has been one of the most difficult problems in the management of patients with heart failure (HF). There is considerable interest in technology-facilitated fluid balance monitoring. However, little is known about patient acceptance and the use of mobile technology for fluid balance monitoring. Objective: The aim of this study was to develop a mobile app for technology-facilitated fluid balance monitoring and to determine its usability. Methods: A mixed-methods study was conducted in a tertiary hospital in Shanghai, China. A mobile app named I-Self-Care was developed through a best practice implementation project. Patients and nurses both completed the System Usability Scale (SUS, 0-100) and participated in semistructured interviews. Results: I-Self-Care includes patients' daily fluid intake and output (I&O), symptoms, hospitalization, and diuretic records. It can automatically calculate food water content and perform real-time analysis of I&O. The average SUS scores were 81.74 (SD 5.44) among 36 patients and 80.80 (SD 13.26) among 28 nurses (scale 0-100, with 100 being the best usability), which means that I-Self-Care has high usability for both patients and nurses. Semistructured interviews about the usability of the app were conducted with 17 participants. During the interviews, the patients expressed the high ease of use of I-Self-Care, their expectations for a continuously updated database, and improved self-management behaviour. The nurses thought that family support and repeated operation demonstrations were needed for patients to use the app. The nurses also expressed the convenience of this app for nursing work and the information security of patients. Conclusion: With participant feedback, we confirmed the usability of I-Self-Care for fluid balance monitoring in patients with HF. Continuously updated databases, family support, repeated operation demonstrations, and information security are important for HF patients to use I-Self-Care.