Measurement of Pressure between Upper Airway Tract and Laryngoscope Blade during Orotracheal Intubation with Film of Microcapsules

The measurement system for the pressure between the blade of a laryngoscope and the upper airway tract during orotracheal intubation has been investigated with a film of microcapsules. Two types of the laryngoscope were used in the study: WisForegger and Mac-Intosh. The film is attached on the surface of the blade of the laryngoscope. The measurement was applied to 20 cases of the orotracheal intubation. In the pressed part of the film, the microcapsules burst and release chemicals, which react with chemicals out of microcapsules and show a red color. The color density was photoelectrically measured, and converted to the pressure value in three regions on the blade; the epiglottis, the tongue, and the upper incisor. The results show that the pressures are 1.2±0.6 MPa on the epiglottis, 0.8±0.4 MPa on the tongue, and (11±3)×10 MPa on the upper incisor, and that the pressures on the epiglottis are 2.0±0.3 MPa in bled cases, and 0.8±0.4 MPa in non-bled cases.