A Multisensor Solid‐State Pressure Manometer to Identify the Level of Collapse in Obstructive Sleep Apnea

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Abstract
The cause of failure after uvulopalatopharyngoplasty (UPPP) in idiopathic obstructive sleep apnea (OSA) is poorly understood, but has been speculated to be due, in part, to persistent collapse in the lower oropharynx. In order to determine the specific level of upper airway obstruction during sleep, a multisensor pressure catheter has been developed with five solid-state ultraminiature sensors. Four sensors in the pharynx simultaneously measure multiple pressure levels, with no need to move the catheter during sleep. One distal esophageal port measures the respiratory effort. To evaluate the use of this catheter, manometry in twelve patients was reviewed and compared to simultaneous videoendoscopy. The initial site of obstruction was the palate in nine patients (75%) and the tongue base in three (25%). Three patients with initial obstruction at the palate manometrically demonstrated distal obstruction on subsequent occluded breaths. Furthermore, simultaneous videoendoscopy in four patients with a palatal level of obstruction also identified marked near-total visual collapse without obstruction of the lower oropharynx that was not identified by pharyngeal manometry. The endoscopy revealed that at the initial site of obstruction, collapse appeared to have occurred passively during expiration and not on inspiration. Inferior to the site of mano-metric obstruction, collapse occurred during inspiration associated with increased negative inspiratory pressures. These results demonstrate that a multisensor pressure catheter can objectively identify the level of obstruction during sleep. However, manometry does not identify visually observed collapse at nonobstructive segments of the upper airway. Because such collapse and the associated increases in resistance may contribute to the pathology of airway obstruction in OSAS, manometry may miss pathologic segments of the upper airway in OSAS.