An observational study to determine whether alignment of endotracheal tube indicator line with the vocal cords results in appropriate depth of intubation

Abstract

Background: Inappropriate endotracheal tube placement depth may be associated with complications. Objective: To determine whether the accurate alignment of the indicator ring on the endotracheal tube at the level of the vocal cords, results in its appropriate placement. Design: Prospective observational study. Patients: 98 adult patients scheduled for general anesthesia with orotracheal intubation. Interventions: The indicator band mark on the endotracheal tube was accurately placed at the vocal cords level under video-laryngoscope view. The tube length at the right upper incisor and the distance between its tip and the carina was measured using fibreoptic bronchoscope. Data to validate methods to predict insertion depth was collected and evaluated. Main Outcome: To determine the distance between the tip of the endotracheal tube and the carina. Results: The endotracheal tube tip depth was inap- propriate in 46.94% cases and was <3 cm above the carina in 41.64% cases. This difference in this distance was similar (p = 0.246) in the two genders. A correlation was noted between topographic length and insertion depth in females only (r2 = 0.201 and p = 0.001). The mean tracheal length was 12.66 + 1.35 cm in males and 12.04 + 1.26 cm in females. Conclusion: We found a high incidence of endo- tracheal tube tip malposition despite the accurate placement of the indicator band at the vocal cords level. We suggest that international endotracheal tube design standards be defined and endotracheal tube manufacturers modify the standard intratracheal length.

Characteristics of lower airway parameters in an adult Asian population related to endotracheal tube design: a cadaveric study

“…The strength of this study is that it enabled subglottic measurements, which cannot typically be obtained using plain chest radiography or fiberoptic confirmation after intubation. Unlike most published studies that focused on Tip-Carina distance 2 , 4 , 7 , 12 , 14 – 16 , we found that the rate of cuff in the glottis ranged from one-fourth to approximately 100% with most of the ETTs (Fig. 3 A).…”

“…This is particularly challenging during the intraoperative period owing to the lack of routine radiographic confirmation. Variations in the tracheal length have been reported in multiple studies with different racial populations 1 , including Indian 2 – 4 , Asian 5 – 8 , and Caucasian 9 . The length of vocal cord-to-carina (VC-Carina) in males were larger than females, and also correlated with height 5 – 7 ; however, the current practice of ETT selection takes only sex and airway diameter into account.…”

“…However, despite guidance from VCmarking, inappropriate placement still occurs. Up to 30–50% of the patients who were intubated were reported to be at risk of endobronchial intubation as Tip-Carina distance < 3 cm 2 , 4 . Kang et al also reported that 6.7% of the patients had cuff displacement beyond the cricoid cartilage after head and neck extension for thyroidectomy 17 .…”