The changes of endotracheal tube cuff pressure by the position changes from supine to prone and the flexion and extension of head

BACKGROUND The proper cuff pressure is important to prevent complications related to the endotracheal tube (ETT). We evaluated the change in ETT cuff pressure by changing the position from supine to prone without head movement. METHODS Fifty-five patients were enrolled and scheduled for lumbar spine surgery. Neutral angle, which was the angle on the mandibular angle between the neck midline and mandibular inferior border, was measured. The initial neutral pressure of the ETT cuff was measured, and the cuff pressure was subsequently adjusted to 26 cmH2O. Flexed or extended angles and cuff pressure were measured in both supine and prone positions, when the patient's head was flexed or extended. Initial neutral pressure in prone was compared with adjusted neutral pressure (26 cmH2O) in supine. Flexed and extended pressure were compared with adjusted neutral pressure in supine or prone, respectively. RESULTS There were no differences between supine and prone position for neutral, flexed, and extended angles. The initial neutral pressure increased after changing position from supine to prone (26.0 vs. 31.5 ± 5.9 cmH2O, P < 0.001). Flexed and extended pressure in supine were increased to 38.7 ± 6.7 (P < 0.001) and 26.7 ± 4.7 cmH2O (not statistically significant) than the adjusted neutral pressure. Flexed and extended pressure in prone were increased to 40.5 ± 8.8 (P < 0.001) and 29.9 ± 8.7 cmH2O (P = 0.002) than the adjusted neutral pressure. CONCLUSIONS The position change from supine to prone without head movement can cause a change in ETT cuff pressure.