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

ObjectiveRespiratory-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.MethodsRREP potentials were examined in 10 OSA and in 12 non-apnoeic awake subjects by means of the NEP technique.ResultsAll controls showed a cortical response to all pressure stimuli. All OSA subjects showed responses to −5 and −10 cmH2O whereas six of them showed no responses to −1 cmH2O. 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 cmH2O stimuli. We found no significant differences in latencies.ConclusionsAwake OSA subjects had a raised threshold to pressure stimuli and blunted respiratory-related evoked potentials.SignificanceThese data indicate a deficit in afferent activity in the UA.

► A deficit in afferent activity is supposed to be present in obstructive sleep apnoea subjects, affecting the reflex mechanisms necessary to promote airway patency and stabilize the upper airway. ► Awake obstructive sleep apnoea subjects had a raised threshold to pressure stimuli and blunted respiratory-related evoked potentials. ► The negative expiratory pressure technique is a reliable neurophysiological method with which to detect reduced afferent traffic from the upper airway.