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Using the bubble inclinometer to measure laryngeal tilt and predict difficulty of laryngoscopy
J T Roberts1, H H Ali, G D Shorten
1Department of Anesthesia, Massachusetts General Hospital, Boston 02114.
Study Objective:
To evaluate a simple device, the bubble inclinometer, to measure degrees of laryngeal tilt (LT) for predicting difficulty of direct laryngoscopy using a Macintosh #3 laryngoscope.
Design:
Randomized, double-blind study.
Setting:
Inpatient surgery center at a university medical center.
Patients:
50 renal lithotripter patients.
Interventions:
Patients were measured with the bubble inclinometer and the laryngeal indices caliper. A sleep dose of thiopental sodium (4 mg/kg) and a muscle-relaxing dose of succinylcholine (1 mg/kg) were then given to each patient.
Measurements And Main Results:
LT was measured by both methods (directly and indirectly). Difficulty of laryngoscopy was graded as follows: Grade 1 = all of vocal cords seen; Grade 2 = part of vocal cords seen; Grade 3 = no part of vocal cords seen.
Conclusions:
The bubble inclinometer accurately and reproducibly measures relative LT, and the anterior tilt of the larynx directly correlates with the ability to see the laryngeal opening during direct laryngoscopy with a Macintosh #3 laryngoscope.