• Ichiro Takenaka, Kazuyoshi Aoyama, and Tamao Iwagaki.
• Department of Anaesthesia, Nippon Steel Yawata Memorial Hospital, 1-1-1 Harunomachi, Yahatahigashi-ku, Kitakyushu 805-8508, Japan. takenaka.i@ns.yawatamhp.or.jp
• Eur J Anaesthesiol. 2012 Aug 1;29(8):380-5.

ContextAlthough a life-threatening complication, pulmonary aspiration of gastric contents caused by vomiting or regurgitation during induction of anaesthesia cannot be prevented. It may be prevented if the mouth is placed more inferiorly than the larynx and tracheal bifurcation by the use of head-down tilt and head-neck positioning.ObjectiveWe aimed to determine the head-down tilt required to prevent aspiration in the neutral, simple extension, sniffing and full cervical spine extension (Sellick) positions and to investigate the relationship between pulmonary aspiration and the vertical height of the mouth, larynx and tracheal bifurcation.DesignObservational study.SettingOperating theatre at Nippon Steel Yawata Memorial Hospital.PatientsManikins with coloured fluid in the oesophagus and 30 adult volunteers.InterventionsUse of head-down tilt between 0° and 50° in 5° increments in four head-neck positions (neutral, simple extension, sniffing and Sellick).Main Outcome MeasuresAspiration of oesophageal contents (coloured fluid) from the oesophagus into the trachea and bronchi. Measurement of the mouth-arytenoid angle (manikin and volunteers) and the mouth-carina angle (manikin).ResultsThe head-down tilts required to protect both the trachea and bronchi from aspiration were 45°, 35° and 10° in the neutral, simple extension and Sellick positions, respectively, which coincided with the mouth-arytenoid angle in those positions. The maximum tilt used in this study was not adequate to prevent aspiration in the sniffing position. The head-down tilt required to level the mouth with the tracheal bifurcation (mouth-carina angle) protected the bronchi from aspiration but not the trachea.ConclusionA head-down tilt equal to the mouth-arytenoid angle (levelling the mouth with the larynx) was necessary to completely prevent aspiration. This angle of tilt was within clinically relevant ranges only with the Sellick position.

22 keywords...

hide…