<p>Quantitative Morphometric Measurements of the Oropharynx in Obstructive Sleep Apnea Syndrome Using a Laser Depth Measurement Module</p>

Abstract

Introduction Current diagnostic routines in obstructive sleep apnea syndrome (OSAS), including drug-induced sleep endoscopy (DISE), provide qualitative data. Quantitative morphometric measurements of oropharyngeal structures remain challenging. This study aims to introduce a special linear laser projection device that can facilitate computer-assisted digitalized analysis and provide important quantitative information for OSAS prediction. Materials and Methods We used a single-wavelength green three-linear laser to provide the scaling reference, with one at an angle of 8.5 degrees with the other two which were parallel. The oropharyngeal images were divided into two groups: the non-OSAS and OSAS group, after polysomnography. A minimum of three evaluations were carried out to determine the maximum cross-sectional area of the oropharyngeal inlet (CSAOI) and the retropalatal depth. Results A total of 132 subjects were enrolled in this study, with 76 subjects in the non-OSAS group and 56 cases in the OSAS group. In the non-OSAS group, the CSAOI was significantly larger in males than in females. There was a trend toward deeper retropalatal region in men than in women (14.25 vs 11.76 mm). Correlation analysis revealed that retropalatal depth is significantly related to body height and the CSAOI. The body weight and BMI of patients with OSAS were significantly higher than those of participants without OSAS. The retropalatal depth and CSAOI were significantly decreased in OSAS patients as compared to those without OSAS. Our new parameter, the oropharyngeal index, showed the most outstanding discrimination by ROC analysis to predict OSAS. Conclusion Our innovative module can provide reference parameters, which make it possible to directly estimate the objective absolute values of relevant oropharyngeal structures. Our non-invasive approach can be used for outpatient screening, since it allows the identification of potential OSAS patients who should be referred for polysomnography, as many patients do not require DISE early in their evaluation.

Quantitative Measurement of Throat and Larynx After Endotracheal Intubation for Palatoplasty

“…The pre-operative and post-operative retropalatal depth and CSAOI were automatically identified and calculated, as shown in our previous work ( 6 ). With a specially designed angle laser line ( Figure 2 ), the depth can be calculated by our module (θ = 8.5 degrees) and can provide the scaling reference to determine the CSAOI.…”

“…However, drug-induced sleep endoscopy is more invasive and depends on the clinicians' subjective judgment. The real size of the oropharynx, including the retropalatal depth and CSAOI, was not quantitatively analyzed in the past, until a recent study introduced endoscopic morphometric measurement with a laser module ( 6 ). This oropharyngeal laryngoscopy can easily and automatically measure the retropalatal depth and CSAOI with the laser module ( Figure 2 ).…”

“…As in our previous report ( 5 , 6 ), our module comprised a rigid 70° endoscope, laser pointers, and a reflection lens. Two parallel laser beams, with a distance of 1 mm, were obtained from a laser excitation apparatus (H435151D/R, 515 nm).…”

“…The two parallel laser beams can provide the scaling reference for further image analysis ( Figure 1A ). To measure the oropharyngeal structure, laryngoscopy was performed with a device which composed of a rigid straight endoscope, three laser pointers and a grating sheet ( 6 ). The dot laser was transformed to a liner laser by the grating sheet, and provided the scaling reference.…”

“…Accordingly, we are committed to finding a real-time and low invasive alternative, that can be implemented immediately in an outpatient setting. We have once introduced a new device composed of a rigid laryngoscope and laser pointers, which was the first report to measure the absolute values of the laryngeal and oropharyngeal structures ( 5 , 6 ). Although there is evidence that this type of outpatient screening is quite convenient and provides objective quantitative information, the applicability of the device in patients after surgery with endotracheal general anesthesia is still unclear.…”