Evaluation of the vascular reaction in pharyngeal mucosa

The patency of the upper airways during inspiration is maintained by reflexogenic muscular dilation, mediated by afferent nerves. Our hypothesis is that a local disturbance in these nerves might explain the increased tendency of upper airways to collapse in patients with obstructive sleep apnea. The vascular reaction in the mucosal microcirculation is regulated by afferent nerves. To investigate this, we developed the laser Doppler perfusion monitoring method and electrical nerve stimulation for investigations of the soft palatal mucosa in non-snoring subjects. A 12 cm probe with integrated bipolar electrodes and a special probe-holder were designed. The bandwidths 12 and 24 kHz were compared and the latter was better able to detect a high blood-flow. A dose response relation was found between the voltage stimulation level and percentage increase in blood-flow. Three series of stimuli (40 V) in 10 subjects caused reproducible vascular reactions. In conclusion, this method seems to be safe, tolerable and valuable for investigations of patients with obstructive sleep apnea or other pharyngeal disorders, e.g. dysphagia, in the search for local nerve lesions.