QUANTITATIVE IMPROVEMENT IN LARYNGOSCOPIC VIEW BY OPTIMAL EXTERNAL LARYNGEAL MANIPULATION

Study Objective: To determine the improvement in laryngoscopic view ob tained (sing both the Macintosh and Miller blades by applying optimal external laryngeal manipulation (OELM). Design: Prospective, with each patient serving as his or her own control. Setting: Inpatient operati ng rooms of a University Medical Center. Patients: 181 informed and co nsenting adult nonpregnant patients requiring general anesthesia and t racheal intubation. The only exclusion criteria was the need to apply cricoid pressure to prevent aspiration of gastric contents. Interventi ons: Anesthetized, paralyzed patients under(vent laryngoscopy without external laryngeal manipulation and the laryngoscopic view was graded (''A'') according to visualized structures [1.0-1.9 = all (1.0) or par t of the vocal cords (90% = 1.1 and 10% = 1.9; 2 = just the arytenoids ; 3 = just the epiglottis; 4 = just the soft palate] The larynx was th en quickly manipulated by the thumb and index and middle fingers of th e laryngoscopist's right hand in both cephalad and posterior direction s over the hyoid, thyroid, and cricoid cartilages until it was determi ned which vector and spot produced the optimal laryngoscopic view (''B ''). Measurements and Main Results: It was found that in every patient with a ''A'' greater than 1.0, OELM improved the view; i.e., ''B'' de creased relative to ''A.'' For both the Macintosh blade patients and M iller blade patients with an ''A'' equal to 2, ''B'' decreased by one whole laryngoscopic grade in all patients. For both the Macintosh and Miller blade patients with an ''A'' equal to 3, ''B'' decreased by at least one whole laryngoscopic grade in all patients and by two laryngo scopic grades in most patients. No patients had an ''A'' equal to 4. T he distribution of optimal-external-laryngeal-manipulation (OELM) spot s for all patients was 1%, 40%, 48%, and 11% for the hyoid, high thryo id, low thyroid, adn cricoid cartilages, respectively, and the distrib ution was not significantly different for either the Macintosh and Mil ler blade groups or for the ''A'' and ''B'' subgroups (i.e., ''A'' < 1 .9, = 2 or = 3). Conclusions: We conclude that OELM can improve the la ryngoscopic view by at least one whole grade, that the best way to det ermine OELM for an individual patient is on an empirical basis by mani pulation of the larynx with the laryngoscopist's right hand, and that OELM should be an instinctive and reflex response to any ''A' of 2, 3, or 4.