TITLE: ANALYSIS OF A NEW FLEXIBLE ADJUSTABLE LARYNGOSCOPE IN COMPARISON WITH A MACINTOSH BLADE

AUTHORS: Paramdeep S. Bhasin, MD, Rajesh V. Patel, MD, Marcus Canas, MD, I Z. Yardeni, MD
AFFILIATION: University of Southern California, Los Angeles, CA.

INTRODUCTION: There are two essentials for a successful direct laryngscopy: 1. Epiglottis elevation by movement of hyoid bone with blade tip 2. A clear line of view to exposed larynx. In normal situation a Macintosh blade does exactly this. However in difficult situations like anterior displacement of larynx, disproportionately large tongue and restricted neck movement, upper teeth may inadvertently be used as a fulcrum. This new flexible tip device is designed to overcome this limitation by providing a dynamically bending yet instantaneously rigid blade.
METHODS: After institutional approval, 55 randomly selected ASA 1, 2 & 3 elective patients between ages 18 and 75 were studied. Every patient had a through preoperative airway exami- nation, which included Mallampati classification, Thyro-mental distance and Range of neck movement. Patients who required rapid sequence intubation were excluded from the study. Standard size sponge pillow of five-inch thickness was placed under the head of the patient. After induction of anesthesia, direct larnyngoscopy was done using a Macintosh blade, the layngo- scopic view was recorded using Cormack and Lehane classifi- cation. The flexible tip blade was then used to expose the larynx, the layngoscopic views obtained before and after the maneuver- ing the tip were also recorded using the same classification.
RESULTS: Except one in all 54 patients the view obtained by the Macintosh blade was similar to the one obtained before maneuvering the levering tip of the flexible blade. The results were recorded by the anesthesiologist included age, sex, weight, preoperative airway assessment.

The Cormack & Lehane Classification grade in flexible blade after levering the tip was less than that seen with the Macintosh blade.

DISCUSSION: These results clearly show that the new flexible blade helps to visualize the vocal cords in a grade 3 & 4 Cormack & Lehane classification. However, in grade 2 view it changed to grade 1 view in less than 50% of the patients.
CONCLUSION: The new flexible laryngoscope blade helped improve visualization of the vocal cords.
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2.) Cormack RS, Lehane J., "Difficult tracheal intubation in obstrtics"Anaesthesia1984; 39: 1105-11.

3.) McCoy E.P., Mirakhure R.K., "The levering laryngoscope." Anaesthesia 1993; 48: 516 -19.