Are anatomical landmark measurements accurate for predicting endotracheal tube depth?

Abstract

Background: A traditional method for depth of intubation in adult patients is taping the endotracheal tube (ETT) at the upper incisors a distance of 21 or 23 cm for women and men respectively (21/23 method). A novel "topographical" measurement for estimating proper intubation depth has been suggested as a better depth predictor compared to the 21/23 method. Objectives:To compare the 21/23 method to topographical measurements.Methods: 100 ASA physical status I-II patients scheduled for elective surgery were enrolled. The 21/23 method was initially utilized for intubation and the ETT tip to carina distance was then fiberoptically measured. Anatomical (topographical) measurements were then obtained from each patient by adding the distance from the corner of the mouth to the mandibular angle to the distance from the mandibular angle to the center of the sternal notch and were recorded as the topographical intubation depth. Both measurements were assessed for percentage of ETTs that fell outside of our desired tip to carina range of 2-4 cm. Results:After the 21/23 method, 29% of ETTs fell outside our desired tip to carina range compared to 47% of ETTs with the topographical method (p=0.010). No correlation was found between the topographical measurements and airway length (upper incisors to vocal cords) (r=0.248). Conclusions:Topographical measurements were not re-confirmed as an accurate intubation method and were found to be less reliable than the 21/23 method. We maintain that regardless of ETT insertion method utilized, the gold standard to ensure accurate ETT placement is fiberoptic inspection.

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

“…Evron et al found good correlation between topographically measured length of airway and insertion depth (17). Manger et al, however, reported a 47% malposition rate using the same topographical method (10). We used the same anatomical structures but found that the difference between the measured topographical length and insertion depth varied by a large range (-2.0 cm to +9 cm).…”

“…The mark may also be inappropriate because the distance between the ETT tip and the carina cannot be predicted (9). Definitive methods to confirm ETT placement are chest radiograph and fibreoptic bronchoscopy examination, but they involve additional costs and intervention (10,11).…”

“…Other authors however, felt that predetermined distances are not good predictors for appropriate placement of ETT and their use may increase patient risk (10). Evron et al found good correlation between topographically measured length of airway and insertion depth (17).…”

“…By convention, the depth of ETT insertion is evaluated by auscultation for bilateral breath sounds and symmetric chest expansion, but they fall woefully short of being referred to as benchmarks, as high or low placement of the ETT won't be detected by them. Flexion of the neck from full extension may result in a 3-5 cm (mean 3.8 cm) caudal movement of the ETT toward the carina, while an extension of the neck may result mean 1.9 cm movement of the tip of ETT away from the carina (on manoeuvre of the head from neutral position to full extension) (9,10). To prevent ETT misplacement and main-stem bronchial intubation during head movement, the tip of the ETT should thus be located at least 3 cm cephalad to the carina and the proximal end of the ETT cuff should be at least 2 cm below the vocal cords to avoid cuff impingement on the vocal cords (1,13,14).…”

Chula Formula sebagai Prediktor Ketepatan Kedalaman Endotracheal Tube pada Intubasi Nasotracheal

“…3,5,6 Penempatan terlalu dangkal dapat menyebabkan jarak ETT terlalu dekat dengan pita suara sehingga balon ETT dapat menekan pita suara yang menyebabkan stimulasi simpatetik dan trauma pita suara, kompresi saraf laryngeal recurrent, dan meningkatkan risiko terlepasnya ETT. 3,5,7,8 Beberapa teknik telah dikemukakan untuk menentukan kedalaman posisi ETT, yaitu auskultasi 5 titik, palpasi balon ETT pada lekukan suprasternal, x-ray, capnography, dan ultrasound. Penelitian terbaru pengukuran kedalaman dilaksanakan dengan visualisasi langsung dari ujung ETT mempergunakan fiberoptic bronchoscope (FOB).…”