Sensory detection of threshold intensity resistive loads in severe obstructive sleep apnoea.

Respiratory related evoked potentials (RREPs) were used to investigate whether sensory detection of small mid-inspiratory resistive loads (≈1.2-6.2 cmH2 OL-1 s), delivered during wakefulness, was impaired in obstructive sleep apnoea (OSA). It was reasoned that impaired detection of minor airway patency challenge may lead to difficult-to-remedy further collapse. There was a significant reduction in OSA (n=16) vs. control (n=17) participants in the slope of the relationship between the P1 RREP component amplitude, which reflects arrival of somatosensory information at the cortex, and stimulus intensity, expressed as change in epiglottic pressure (mean [95% confidence intervals]: -0.50 [-0.97, -0.03] vs. -1.78 [-2.54, -1.02]; P=0.004), suggesting a reduction in sensitivity to small respiratory loads. However there was no significant difference in sensitivity after background Pepi was taken into account (P=0.268). Additionally, there were no significant group differences in the threshold of the P1 amplitude/stimulus intensity relationship, or in the P1 latency. These results indicate a reduced sensitivity to detection of small upper airway negative pressure stimuli in OSA related to a reduction in mechanoreceptor activation (likely related to increased airway resistance in OSA vs. controls; P=0.002) rather than defective mechanosensory function.