[Acoustic frequency analysis of auscultation findings in neonates]

The authors analyzed 280 auscultation findings of 35 neonates with birth weights of 1800-4500 g and 65 pathological neonates with birth weights of 1150-3600 g. For recording of the auscultation findings an electronic phonendoscope EST 40 (Bosch) was used and the finding was recorded on a microtape recorder (Olympus). The frequency analysis was made on a Sonagraf analyzer (Kay Elemetric), using a 45 Hz filter a time range of 2.4 sec. From the results of the work ensues that in physiological neonates two basis types of sonagrams can be detected: 1. the record presenting itself as a continuous zone of noise with maximal cumulation of acoustic energy up to 500 Hz where the ratio of acoustic energy is equal in both stages of the respiratory cycle. The clinical correlate is "alveolar respiration". 2. a record with a discontinuous zone of noise with a more expressive ratio of acoustic energy up to 2500 Hz during inspiration. The clinical correlate is "sharper bronchoalveolar respiration". In the group of pathological neonates with different pneumopathies further sonagraphic phenomena were detected: a) "rales" as discontinuous acoustic phenomena persisting for 7-35 msec with a frequency range up to 3000 Hz, without a harmonious structure, present during inspiration as well as expiration, b) "transmitted phenomena"--discontinuous acoustic phenomena persisting for 75-150 msec with a frequency range up to 6000 Hz, without a harmonious structure, c) "wheezing"--continuous acoustic phenomena with a clearly marked harmonious acoustic structure lasting 540 +/- 240 msec with a frequency of the basic sound of 500 +/- 240 msec.(ABSTRACT TRUNCATED AT 250 WORDS)