Alterations in the respiratory movements may consist in a change in the rate, rhythm or amplitude of the respirations or in the expiratory position of the chest, or in several of these combined. The factors that influence the rate, rhythm and amplitude of the respirations have been carefully studied by numerous investigators, and the subject has been thoroughly reviewed by Haldane,1 Gesell2 and Means,3 but the factors that alter the expiratory position of the chest have received less study.
Changes in the expiratory position of the chest were encountered during a study of oxygen debt after muscular work in patients with hyperthyroidism. The consumption of oxygen as determined by the closed circuit method increased rapidly during work, whereas immediately after work it decreased to or below the previous basal level, so that a lack of oxygen was not demonstrable. The respiratory quotient declined during work to 0.7