Respiratory sound energy and its distribution patterns following clinical improvement of congestive heart failure: a pilot study

Respiratory sounds throughout the respiratory cycle were captured using an acoustic-based imaging technique. Twenty-three consecutive CHF patients were imaged at the time of presentation to the emergency department and after clinical improvement. Digital images were created (a larger image represents more homogeneously distributed vibration energy of respiratory sound). Geographical area of the images and respiratory sound patterns were quantitatively analyzed. Data from the CHF patients were also compared to healthy volunteers.The median (interquartile range) geographical areas of the vibration energy image of acute CHF patients without and with radiographically evident pulmonary edema were 66.9 (9.0) and 64.1(9.0) kilo-pixels, respectively (p < 0.05). After clinical improvement, the geographical area of the vibration energy image of CHF patients without and with radiographically evident pulmonary edema were increased by 18 ± 15% (p < 0.05) and 25 ± 16% (p < 0.05), respectively.With clinical improvement of acute CHF exacerbations, there was more homogenous distribution of lung vibration energy, as demonstrated by the increased geographical area of the vibration energy image.Congestive heart failure (CHF) is one of the leading causes of frequent visits to the emergency department (ED) with a prevalence of 1-2% in the general population and a five year mortality rate after diagnosis reported at 60% in males and 45% in females [1]. Several methods are used to assess and monitor CHF patients during therapy including clinical symptoms, physical examination, echocardiography, brain natriuretic peptide (BNP) and chest radiography [2]. Since the advent of the stethoscope, clinicians have routinely listened to the sounds produced by a patient's internal organs, such as the heart and lungs, as a means of assessment and to diagnose pathology. Lung sounds (lung vibrations) are produced by airflow in and out of the lungs. In the past decade, there have been attempts to refine n