[Measurement of human laryngeal mucosal blood volume]

To the best of our knowledge little if any information is available concerning human laryngeal mucosal blood volume presumably because the larynx is an anatomical position which renders the measurement of blood flow there difficult. With the advent of a reflectance spectrophotometer, however, studies of tissue blood flow have been facilitated to a great extent. As a result, attempts have been made to determine mucosal blood volume in various organs and tissues including the gastric mucosa. Recently, an ultra-thin fiber probe (1.8 m min diameter) for measurement of tissue blood volume has been developed. Using a laryngeal flexible fiberscope attached with this newly developed probe in the opening for the forceps, an attempt was made to measure laryngeal mucosal blood volume by the method of reflectance spectrophotometry, determining IHb and ISO2 the former of which is a parameter of hemoglobin in the tissue blood vessels and the latter, a parameter of hemoglobin oxygen saturation in the tissue blood vessels. IHb of the vocal folds is significantly low, about half those of the false folds and arytenoid region, whereas ISO2 is significantly higher in the false folds and arytenoid region than in the vocal folds. The hemodynamics in the vocal folds as a high-speed vibrator are specific, unlike in other laryngeal regions. We have plans to determine laryngeal tissue blood volume at more sites so as to investigate the laryngeal tissue distribution of blood volume in greater detail. Furthermore, tissue blood volume in morbid conditions will also be determined for information which will be of value in clinical applications.