We present a multimodal catheter for characterizing airway collapse in obstructive sleep apnea (OSA) during in-vivo sleep studies. Traditionally, diagnosis focusses on identifying the presence of apnea rather than the underlying cause of obstruction, and current methods of detecting airway collapse are not able to identify a specific patient's contributing factors. It is considered that a simple method to establish the primary site and mechanism for upper airway collapse would improve the ability of clinicians to distinguish which patients would benefit from one of the variety of treatments currently available. By introducing a newly developed manometry catheter into in-vivo studies of known OSA sufferers we can provide the means to determine the location of the site(s) of collapse, the degree of occlusion that occurs, the severity of reduced air flow, the associated anatomical features, and mechanism of collapse. The device consists of 13 discrete pressure and temperature sensing elements and a micro-video camera that collectively enable simultaneous recording of pressure, temperature, and visualization of the point of collapse. The sensors use fiber Bragg gratings (FBGs) spaced on a 10mm pitch which is sufficient to provide an accurate interpolated image of both pressure and temperature along the upper airway (above the epiglottis), whilst the use of paired FBGs effectively removes the temperature artefact. We present results from recent in-vivo studies that demonstrate the viability of the device to identify and characterize occlusive events in the upper airway and the potential to better guide subsequent therapeutic interventions.