We do not believe that all endolaryngeal examinations can be done advantageously under general anesthesia. However for those cases requiring general anesthesia, such as those which involve certain endolaryngeal operative maneuvers, or biopsies, we have studied what type of anesthesia is best suited.
It seems to be the common practice to do general anesthesia for laryngoscopy using the so called “apneic method”. However, we have found the disadvantages of this method are 1) the definite limitation of time for observing the larynx and 2) the danger of aspiration of blood, etc., into the larynx.
To date we have collected 74 cases of endolaryngeal examinations or operative maneuvers requiring general anesthesia, using a smaller caliber cuffed endotracheal tube (# 23-21 French size).
The advantages and disadvantages of this method were evaluated (Fig. 1).
The adequacy of respiratory exchange especially alveolar Co2 concentration was proven, using a Godat Capnograph in healthy subject. The alveolar Co2 concentration in these healthy subjects stayed within normal limits for more than 30 minutes under general anesthesia using our method of a smaller caliber endotracheal tube (Fig. 2).
