Smartphone for heart sound measurement in hospital: which factors affect heart sound quality?

Abstract

Abstract Background Smartphone has recently been utilized to measure heart sounds in general population, but not in hospitalized patients. Purpose To explore the factors affecting the quality of heart sounds collected from the patients using smartphone in hospital. Methods An App was developed for Android smartphone to use the built-in microphone for measuring heart sounds on cardiac apex for 20 – 30 seconds in patients. Heart sounds were visually assessed for the presence of the first and second heart sounds and categorized into good, uncertain or bad quality. The factors affecting the percentage of good-quality heart sound recordings were analyzed, including the patients’ baseline characteristics, medical history and blood test. Results Among the 296 patients enrolled, 267 (90%) patients had a good-quality heart sound recording. Good-quality heart sounds were less recorded in emergency room (76%), cardiac care unit (82%), intensive care unit (87%) and neurosurgical intensive care unit (88%). Sex, body mass index, body position (supine vs. sitting), heart rate, medical history of atrial fibrillation, coronary artery disease, heart failure or chronic obstructive pulmonary disease, did not significantly affect heart sound quality (all P > 0.05). An advanced age was related to a lower percentage of good-quality heart sounds (< 60 vs. ≥ 60 years: 94% vs. 87%, P = 0.048). Heart sound quality significantly decreased with red blood cell count, hemoglobin level and hematocrit (all P < 0.001). Conclusions Smartphone can be used in hospital settings for measuring heart sounds in good quality, but factors such as department of hospitalization, age and blood indicators need to be considered.Central illustration