INCREASING BACKGROUND INSPIRATORY RESISTANCE CHANGES SOMATOSENSORY SENSATIONS IN HEALTHY MAN

The central purpose of the study was to investigate if increasing back ground inspiratory resistance, a circumstance which activated afferent s from the lungs and respiratory muscles, modified somatosensory and/o r auditory sensations in healthy individuals. Estimation of mechanical stimulations applied on the middle finger (somatosensory sensation) a nd unilateral sound-pressure stimulations (auditory sensation) was bas ed on the computation of Stevens' power function Psi = k.Phi(n), where Psi is the estimate and Phi is either the somatosensory stimuli or so und-pressures. This was studied during eupnoeic unloaded ventilation t hen during a 10-min period of loaded breathing followed by a 10-min re covery period. Loaded breathing significantly lowered the estimate of somatosensory stimuli (decreased it coefficient). This effect persiste d during the two first minutes of recovery period. By contrast, loaded breathing did not modify the perception of auditory stimulus. As some sthetic and respiratory afferents, but not auditory afferents, project on the same area in the sensory cortex we suggest the existence of ce ntral interactions which could explain clinical observations of the di fficulties to execute accurate tasks in patients suffering from obstru ctive lung disease independently from the alterations in their arteria l blood gases.