The Hooded Hypopharyngeal Videoendoscope: A New Channel for Continuous Airflow

Abstract

Focusing problems during hypopharyngeal fiberscopy can be caused by membranes (red-ball phenomenon) or secretions (white-ball phenomenon) present at a distance shorter than the fiberscope's minimum focusing distance.
In order to resolve these problems, we have developed a hooded hypopharyngeal videoendoscope in the earlier version (PENTAX^®), and reported on hypopharyngeal fiberscopy using this scope in combination with a continuous airflow through a rotary T-shaped adapter, with a valve to prevent backflow (adapted to the inlet of the instrument channel) in our last paper. Although the image of this scope was extremely sharp without the occurrence of the red-ball phenomenon, suctioning in the lumen of the esophagus was insufficient. This problem was completely resolved by the new channel for continuous airflow with a diameter of 0.6 mm without the enlargement of the diameter of the scope.
The white-ball phenomenon which occurred in the supine position (also as reported in our last paper) disappeared by changing the posture of the patient to the sitting position. Furthermore, it was ascertained that a continuous airflow of 200∼300 ml/min was enough to open the inlet of the esophagus using a flowmeter set at 2 l/min.
The hypopharyngeal fiberscope must be alternately inserted from both sides of the recess piriformises, because the opposite side cannot be observed when the scope is only inserted on one side.