Determining the site of airway collapse in obstructive sleep apnea with airway pressure monitoring

Abstract

Twenty patients with obstructive sleep apnea (OSA) underwent complete polysomnography and simultaneous upper airway pressure monitoring with a custom-made, soft silicone-covered catheter measuring 2.3 mm in diameter. The catheter had four solid-state microtip pressure sensors positioned in the posterior nasopharynx, immediately caudal to the tip of the uvula, at the level of the hyoid bone, and in the midesophagus. The level(s) of airway collapse was determined by changes in the pressure patterns between transducers. In 14 of the 20 patients, airway collapse was confined or initiated at the oropharyngeal region. The obstruction extended to the base of tongue in 7 and to the entire collapsible upper airway in 2 patients. Four patients had collapse at the base of the tongue and 2 had collapse at the hypopharynx. The site of airway collapse remained fairly constant through various sleep stages and positions. Uvulopalatopharyngoplasty (UPPP) and postoperative polysomnography were performed in 4 patients (2 with hypopharyngeal, 1 with base of tongue, and 1 with oropharyngeal airway collapse). Two patients had a favorable response to UPPP.

Site of upper airway obstruction in obstructive apnoea and influence of sleep stage

“…In the study by SHEPARD and THAWLEY [5], oropharyngeal collapse is said to occur when pressure deflections are absent in two sensors: one located in the nasopharynx at the level of the soft palate and the other located just distal to the inferior margin of the soft palate, at the base of tongue. By contrast, in the study by KATSANTONIS et al [15], collapse of the oropharyngeal segment is defined as absence of pressure deflections in a sensor located at the posterior choanae. What is defined as nasopharyngeal collapse in our present study corresponds to the oropharyngeal collapse in the study of KATSANTONIS et al [15], and our definition of oropharyngeal collapse agrees with the definition of oropharyngeal collapse used by SHEPARD and THAWLEY [5].…”

“…By contrast, in the study by KATSANTONIS et al [15], collapse of the oropharyngeal segment is defined as absence of pressure deflections in a sensor located at the posterior choanae. What is defined as nasopharyngeal collapse in our present study corresponds to the oropharyngeal collapse in the study of KATSANTONIS et al [15], and our definition of oropharyngeal collapse agrees with the definition of oropharyngeal collapse used by SHEPARD and THAWLEY [5]. The use of different definitions for the UA emphasizes the need for a consensus at this point.…”

“…To our knowledge, the influence of sleep stage on the occurrence of obstruction at a particular site of the UA, has not been thoroughly investigated. In the study by KATSANTONIS et al [15], it is mentioned that the site of collapse remained constant throughout sleep stages and positions, but detailed data on this issue were not presented. SHEPARD and THAWLEY [5] studied nine patients during both rapid eye movement (REM) and nonREM (NREM) sleep and observed an extension of the collapse towards more caudal segments of the UA in seven patients.…”

“…UA pressure measurements provide information about UA dynamics in terms of changes in UA pressure before, during and after the appearance of respiratory events. Results from UA pressure measurements have been reported by several authors using different techniques varying from a fluid-filled catheter [5] to movable catheters [6,7], a bias flow catheter [8][9][10] and micropressure sensors [11][12][13][14][15]. Most studies were performed in a limited number of patients (n<20) except those of KATSANTONIS et al [15], SCATVEDT [13] and METES et al [7].…”

Evaluation of morphological changes in pharynx with dynamic CT and MRI in snoring patients

“…Many studies have demonstrated that the airway is anatomically smaller in snorers and OSAS patients. In many studies, the most affected area in patients with sleep apnea is the retropalatal region of the oropharynx [8][9][10] . It is stated in the study of Ahn et al one of the reasons of narrowness in retropalatal area was increase in volume of tongue 11 .…”