HEAR THAT BEAT!

Abstract

WHEN you were a student nurse, how long did it take you to learn how to take accurate blood pressure readings in the nursing arts laboratory? Were you confused by the muffled sounds coming through the stethoscope? Did you have to wait for the instructor to identify the various sounds for you? Were repeated demonstrations necessary before you or other members of your class could identify the sounds and record the readings accurately? We had these same problems in teaching our students how to take blood pressure readings at Beth Israel Hospital School of Nursing. They had difficulty in recognizing the different sounds; they could not hear them distinctly. The use of a standard stethoscope required individual demonstrations, which were trying for the students. They had to wait their turns patiently, while the instructors had to repeat the same instructions over and over again. The heart of the entire problem seemed to rest with the equipment we were using. The standard manometer and stethoscope both had their limitations as teaching aids. It seemed to us that if every member of the class could hear the beats clearly at the same time, and could simultaneously see the readings, these problems would be solved. With this thought in mind, we decided to construct an apparatus which would have two essential features: (1) a device to magnify the sounds; and (2) a kind of manometer that would be large enough for all the students to see at once. A single-channel sound reproduction system was devised, consisting of a small, sensitive microphone (about the size of a nickel), three amplifiers, a large, regular-sized microphone, and a loud-speaker. When the tiny microphone is placed against the brachial artery, in the same manner as a stethoscope, it picks up the blood pressure beats; these are then transmitted by the large microphone, magnified by the three amplifiers, and the sounds transmitted through the classroom by means of the loud-speaker. With the use of this amplifying system, the acoustical problem was solved, but our new teaching aid was not complete. The students still had to learn how to convert the sounds they heard into intelligible readings which they could analyze and com-