[Preliminary report: observation by video laryngoscope of glottal narrowing due to cricoid pressure].
BACKGROUND
When the applied cricoid pressure is too strong, or the place or direction of the pressure application is not appropriate, glottal closure may occur, but its details are unclear.


METHODS
We evaluated possible changes in the size of the rima glottides due to backward pressure on the cricoid cartilage or backward pressure or backward, upward, and rightward pressure (BURP) on the thyroid cartilage using a video laryngoscope (Fine View' Laryngoscope, Tray Medical, Tokyo) in 6 adult males and 6 females with Cormack and Lehane grade 1.


RESULTS
The right-to-left distance of the rima glottides was 5.1 +/- 1.2 mm without pressure application but was reduced to 3.8 +/- 1.7, 3.5 +/- 1.8, 2.8 +/- 1.9, 2.4 +/- 1.8, and 2.6 +/- 1.2 mm by 20 N and 30 N backward pressure on the cricoid cartilage and 20 N and 30 N backward pressure and BURP on the thyroid cartilage, respectively. Compared with the absence of pressure application, 20 N and 30 N backward pressure and BURP on the thyroid cartilage significantly reduced it. It was reduced to 1 mm by 30 N backward cricoid pressure in 1 patient while glottal closure occurred due to 30 backward thyroid pressure in 1 patient.


CONCLUSIONS
The right-to-left distance of the rima glottides was significantly reduced by backward pressure or BURP on the thyroid cartilage, and was also markedly reduced by cricoid pressure in 1 of the 12 patients.
Oshima
Yoshiaki
Y
Department of Anesthesiology, Operating Room, Shimane Prefectural Central Hospital, Izumo.
Sasaki
Akira
A
Kajitani
Harumi
H
Sasaki
Atsuko
A
Niino
Norio
N
Matsubara
Yasuhiro
Y
D000328:Adult; D000368:Aged; D003413:Cricoid Cartilage / Q000502:physiology*; D005260:Female; D005931:Glottis / Q000473:pathology*; D006801:Humans; D007442:Intubation, Intratracheal / Q000009:adverse effects; D007828:Laryngoscopy; D007829:Laryngostenosis / Q000209:etiology* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011015:Pneumonia, Aspiration / Q000209:etiology / Q000517:prevention & control; D011312:Pressure / Q000009:adverse effects*; D014741:Video Recording