Lateral pharyngeal fat pad pressure during breathing.

The purpose of this study was to test whether pressure in tissue lateral to the upper airway, the lateral pharyngeal fat pad, differs from atmospheric and pharyngeal pressure and whether it changes with breathing. We studied five male pigs by inserting a transducer-tipped catheter into their fat pad space using computed tomography (CT) scan guidance. We measured airflow with a pneumotachograph attached to a face mask and pharyngeal pressure with a balloon catheter. Fat pad pressure correlated positively with airflow and with pharyngeal pressure, decreasing during inspiration and increasing during expiration. Pressure in the fat pad differed from atmospheric pressure, generally exceeding it, and from pharyngeal pressure. We conclude that lateral pharyngeal fat pad pressure differs from atmospheric and pharyngeal pressure and that it changes with breathing.