EFFECTS OF VOLUNTARY CHANGES IN BREATHING FREQUENCY ON RESPIRATORY COMFORT

Previous experiments on voluntary breathing have suggested that sponta neous breathing is partly determined by the minimization of respirator y sensations. However, during instructed breathing, respiratory sensat ions may be confounded with difficulty in achieving the prescribed pat tern. In the present experiment, we tested the hypothesis that the sub jective assessment of respiratory comfort and the difficulty in follow ing breathing instructions are closely related. A total of 15 subjects adjusted breathing frequency to prescribed values ranging from 40 to 250% of individual spontaneous levels. Then, they scored the difficult y of this task and the discomfort associated with the target frequency . Difficulty scores sharply increased above 100% (spontaneous level) a nd discomfort scores displayed a similar shape. A significant positive correlation between discomfort and difficulty was found, thus suggest ing a possible influence of the difficulty to follow ventilatory instr uctions on respiratory sensation scores. (C) 1998 Elsevier Science B.V . All rights reserved.