Morphologic analyses of mandible and upper airway soft tissue by MRI of patients with obstructive sleep apnea hypopnea syndrome.

STUDY OBJECTIVES: To evaluate the morphological features of the mandible and the volume of the upper airway soft tissues in determining the anatomical risk factors for the upper airway in Japanese male patients with obstructive sleep apnea hypopnea syndrome (OSAHS). METHODS: Five morphological parameters of the mandible at the mandibular base plane and three volumetric parameters of the upper airway soft tissue were analyzed using three-dimensional (3D) magnetic resonance imaging software in 31 OSAHS and 20 controls. RESULTS: There were no significant differences between the two groups in mandibular internal width (the distance between the internal right and left gonia [IRG and ILG]) and mandibular bony thickness. However, the patients with OSAHS had a significantly wider mandibular divergence (the angle between the spina mentalis (SM)- IRG line and SM- ILG line), a smaller mandibular internal length (the perpendicular distance from SM to the RG- LG line), and a smaller area than the normal subjects at the mandibular base plane. There were no significant differences in these morphological parameters for the mandible between obese and nonobese OSAHS patients. The volumes of the tongue, soft palate, and lateral pharyngeal walls were not significantly different between the OSAHS and the control groups. CONCLUSIONS: Japanese male OSAHS patients had specific anatomical features in the bottom part of the mandible; however, obesity seemed to be a less significant risk factor. Investigators and clinicians must realize that ethnicity may modify the effects of obesity and abnormal craniofacial anatomy as risk factors for the pathogenesis of OSAHS.

Digital recording and analysis of esophageal pressure for patients with obstructive sleep apnea-hypopnea syndrome.

To evaluate sleep-related obstructive breathing events in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS), we developed a technique for digital recording and analysis of esophageal pressure (Pes) and elucidated the Pes parameters. Pes was recorded overnight with a microtip-type pressure transducer in 74 patients with OSAHS. Simultaneously, in all patients digital polysomnography was recorded. The mean nadir end-apneic Pes swing (Pes Nadir) ranged from -20.2 to -147.4 cmH(2)O, with a mean of -53.6+/-2.9 cmH(2)O. Correlation of the mean Pes Nadir indicated a linear relationship with the mean ratio of maximal Pes swing to apnea duration (r(2)=0.70) and the mean area of the Pes (Pes Area) (r(2)=0.82). Significant correlations were noted between the mean Pes Nadir and apnea-hypopnea index (AHI, ranging from 7.9 to 109.5 per hour; r(2)=0.66), minimum SpO(2) (r(2)=0.60), oxygen desaturation index (ODI) of more than 3 (r(2)=0.65), arousal index (r(2)=0.54), and between the mean Pes Area and AHI (r(2)=0.63), minimum percutaneous arterial oxygen saturation (SpO(2); r(2)=0.57), ODI (r(2)=0.69), and arousal index (r(2)=0.41). Pes parameters were found to be significant in the evaluation of the severity of the respiratory effort during the sleep-related obstructive breathing events for patients with OSAHS.

The effect of upper airway structural changes on central chemosensitivity in obstructive sleep apnea-hypopnea.

We examined the efficiency of upper airway structural changes in uvulopalatopharyngoplasty and/or tonsillectomy on central chemosensitivity, and whether the outcome of such surgeries can be predicted by the central chemosensitivity in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients. In 11 patients with OSAHS group, the average of the hypercapnic ventilatory response (HCVR) slope was 1.93 +/- 0.20 L/min/mm Hg preoperatively and 1.78 +/- 0.22 L/min/mm Hg postoperatively. The average of the mouth occlusion pressure at 0.1 second after the onset of inspiration (P (0.1)) slope was 0.47 +/- 0.06 cm H (2)O/mm Hg and 0.44 +/- 0.08 cm H (2)O/mm Hg, before and after surgery, respectively. There were no significant differences before and after treatment, although OSAHS was improved by these surgeries. In control group with 5 patients, the HCVR slope and P (0.1) slope also showed no significant difference before and after the procedure. When we divided the 11 OSAHS patients into 7 responders (apnea-hypopnea index < 20 events/h and > 50% reduction) and 4 poor responders, there was a significant difference between the average HCVR slope of responders (1.59 +/- 0.21 L/min/mm Hg) and that of poor responders (2.52 +/- 0.20 L/min/mm Hg). We saw no significant difference in physiologic (age, body mass index, one-piece tonsil weight), blood gas values, cephalometric, spirometric, or sleep parameters.