Non-invasive method for semiquantitative measurement of neck volume

Abstract

A method of semiquantitatively measuring a subject's neck volume includes the steps of providing an extensible conductor in the form of a loop having a predetermined height; providing a signal variably responsive in value to changes in the inductance of the conductor; calibrating the signal by determining reference signal values obtained with the conductor disposed about at least two known volumes and using the reference signal values to establish the relationship between signal value and the volume enclosed by the conductor; disposing the conductor in close encircling relationship about the subject's neck; calibrating the signal for intrapleural pressure by using an invasive technique as a reference for determining a plurality of intrapleural pressures for the subject and simultaneously determining the signal value for each such intrapleural pressure measurment, thereby establishing the relationship between intrapleural pressure and signal value; discontinuing the reference technique; determining the signal value with the subject's airway closed, correlating the closed airway signal value with intrapleural pressure based on the established relationship between intrapleural pressure and signal value; and correlating intrapleural pressure obtained in accordance with the previous correlating step with the volume enclosed by the conductor based on the established relationship between signal value and enclosed volume.