Acoustic analysis of snoring and the site of airway obstruction in sleep related respiratory disorders. Acta Otolaryngol (Stockh) 1998; Suppl 537: 47 -51.Seventy-five adult patients with sleep related respiratory disorders were examined by polysomnography with simultaneous recordings of the intraluminal pressure of the upper airway and snoring sound. Obstructed sites in the upper airway during sleep were determined by comparing the amplitude of respiratory fluctuation of the pressures in the epipharynx, mesopharynx, hypopharynx and esophagus. A definite correlation existed between the intensity of snoring sound and the amplitude of respiratory fluctuation of the intraesophageal pressure. Based on the results of the intraluminal pressure partitioning, the subjects were divided into the soft palate type (28), the tonsil/tongue base type (14), the combined type (27) and the larynx type (6). The average value of fundamental frequency (ff) was 102.8 9 34.9 Hz in the soft palate type, 331.7 9144.8 Hz in the tonsil/tongue base type, 115.79 58.9 Hz in the combined type and around 250 Hz in the larynx type.

To analyze the facial patterns of obstructive sleep apnea syndrome (OSAS) patients, we took lateral cephalograms of 31 OSAS patients and 26 non-OSAS controls and utilized Ricketts' method. In addition, we measured the hyoid bone position, the length of mandibular plane to Hpoint, the length of soft palate, and lower pharynx. The facial patterns of OSAS patients were dolico, the hyoid bone was positioned low, the soft palate was longer and the width of the airway was narrower than that of the non-OSAS controls.

The influence of sleep position and the degree of obesity were examined in 257 subjects with sleep apnea. Subjects were divided into three groups according to obesity: normal weight (body mass index (BMI) under 24.0 kg/m 2 ), mild obese (BMI 24.0-26.4 kg/m 2 ) and obese group (BMI 26.4 kg/m 2 and heavier). The apnea + hypopnea index (AHI), the intraesophageal pressure and the lowest oxygen saturation became significantly worse according to the degree of obesity. The subjects were also divided into two groups according to the reduction in the AHI by lateral position: good responders showed 50% or more reduction of AHI in lateral position and poor responders indicated less than 50% reduction. The percentage of good responders to sleep position change was 90.9% in normal weight group, 74.0% in mild obese group and 57.4% in the obese group. The ratio of the subjects who had indicated two or more obstructive sites in normal weight group was 36.0% in good responders and 40.0% in poor responders. The ratio in the mild obese group was 51.8% in good responders and 66.7% in poor responders. In the obese group, the ratio was 59.4% in good responders and 78.9% in poor responders.

Oxygen saturation was measured in 37 patients with sleep-related breathing disorders over 2 nights: after alcohol intake and under control conditions. Both the number of 3% oxygen desaturation per hour (ODI3) and the lowest saturation (LSAT) were significantly aggravated after alcohol ingestion. Oxygen saturation was degraded in 28 cases after alcohol intake. In 69% of the cases in which ODI3 increased after alcohol ingestion, the aggravation during the alcohol metabolism time was noted. No correlation was found between the quantity of alcohol and oxygen desaturation following alcohol ingestion. Our study revealed that alcohol aggravates sleeprelated breathing disorders.

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