Blunted respiratory-related evoked potential in awake obstructive sleep apnoea subjects: a NEP technique study

Respiratory-related evoked potentials (RREP) elicited by transmural pressure in obstructive sleep apnoea (OSA) subjects have reported conflicting data. Different features of pressure stimuli and/or in the timing of stimuli application seem to account for these contradictory results. The negative expiratory pressure (NEP) technique, highly reproducible in terms of rise time and pressure values, allows to minimize the methodological confounding factors. We determined whether the afferent activity from the upper airway (UA) is altered in OSA subjects.

RREP potentials were examined in 10 OSA and in 12 non-apnoeic awake subjects by means of the NEP technique.

All controls showed a cortical response to all pressure stimuli. All OSA subjects showed responses to -5 and -10 cmH(2)O whereas six of them showed no responses to -1 cmH(2)O. The amplitude of the P22, N45 and P85 components of the RREP was significantly reduced in OSA with respect to the controls in response to both the -5 and -10 cmH(2)O stimuli. We found no significant differences in latencies.

Awake OSA subjects had a raised threshold to pressure stimuli and blunted respiratory-related evoked potentials.

These data indicate a deficit in afferent activity in the UA.