CONTROL OF THE LOWER ESOPHAGEAL SPHINCTER USING ACOUSTIC-SIGNALS

An original method is described for graphic display of sounds araising from the cardia during the swallowing of saliva or water. Two dynamic microphones were placed on the skin of epigastric xyphoid area and si multaneously on the latero-cervical position. The following conditions must be filled: position of the subject (upright or lying), correct a pplication of microphone with pressure (2 kPa), specially for the xyph oid situation. For graphic restitutions from magnetic signal, a time-r ecording paper was used, on line or off line, with an analogical devic e including Butterworth band active filter (optimal frequency range 0. 8-1.2 kHz), amplifier and integrator (tau = 2 s). Occurence of typical cardia sounds were 86-97 % for saliva and 95-100 % for water in two n ormal subjects for the evaluation of reproductibility (one man and one woman 35 and 47 years old respectively n = 234 sequencies, interval 2 0 s). Using the distance between the upper and lower microphones, the esophageal time transit can be measured. The signal was more unconstan tly recorded for saliva 40 +/- 44 % in adults (n = 10) and 76 +/- 17 % in children (n = 7), than for 80 et 87 % for water respectively. The optimal interval between two swallows appeared to be 15-25 s. In patie nts with presumption of achalasia (n = 8), the two phonic signals were recorded during esophageal pressure measurement. The presence of esop hageal sounds seems to be the sign of absence of achalasia.