[Changing from spontaneous to volitional regulation of respiration decreases dyspnea]

The objective of the investigation was to assess whether volitional control of respiration can influence the intensity of dyspnoea. In 17 volunteers the author assessed, using Borg's method, the intensity of dyspnoea during breathing with an added dead space of 600 ml and with a flow resistance. The experiments were made in two sessions. During the first session when the examined subjects breathed spontaneously the author recorded spirographically the respiratory volume during control ventilation and after inclusion of the dead space and resistance. During the second session the experimental subjects were asked to attempt to imitate during inclusion of the dead space and resistance, as closely as possible, the respiratory pattern from the first session. In both instances the author assessed the partial pressure of CO2 in the air at the end of the expiration (P(ET)CO2). During the first session the tested subjects evaluance the dyspnoea: it had an average grade of 5.9 +/- 1.9. Volitional regulation of breathing led not only to a significant decline of the sensation of dyspnoea to 3.4 +/- 1.5 points of Borg's scale but also to a decline of the CO2 partial pressure (on average by 0.4 kPa). The author selected therefore among the tested subjects only those who were able to imitate closely the respiratory pattern from the first session (they had the same P(ET)CO2 in both instances). Also in these 8 subjects the intensity of dyspnoea during volitional control of ventilation declined from 6.5 +/- 1.8 grade to 3.8 +/- 1.5 grade according to Borg. The change from spontaneous to volitional regulation of breathing thus reduced the intensity of dyspnoea.