Evaluation of a new method for determining tracheal tube length in children

Abstract

SummaryMost paediatric tracheal tubes are marked in centimetres from the tip. In 105 children, nasotracheal tube length was set at the level of the vocal cords such that all 3.0 and 3.5mm internal diameter tubes were placed with the 3 cm mark at the cords, all 4.0 and 4.5 tubes were set at 4 cm at the cords and all 5.0 and 5.5 tubes were set at 5 cm at the cords. Subsequent chest X ray showed that 79% of the tracheal tubes were in the ideal midtracheal position, one tube was marginally short and 20% of the tubes were marginally long. Neither bronchial intubation nor accidental extubation occurred in any subject. This is an effective method to determine tracheal tube length which may be used for both oral and nasal intubation.

A Comparative Study of Endotracheal Tube Positioning Methods in Children: Safety from Neck Movement

“…Freeman et al (4) reported that the midtracheal positioning of the ETT could be achieved in 79% of patients aged 0 -14 yr by setting the tube length at the level of the vocal cord, such that an ETT with an internal diameter of 3.0 and 3.5 could be set 3 cm from the tip at the cords, 4.0 and 4.5 tubes at 4 cm, and 5.0 and 5.5 tubes at 5 cm. The advantage of this technique is that it is easily remembered and setting the tube length at the level of the vocal cord reduces the variability due to the length of the upper airway.…”

“…The ETT can be displaced as a result of the neck movement causing accidental endobronchial intubation or extubation from the trachea (1,4). Therefore, it is extremely important to accurately place the ETT to a predetermined depth to ensure safety during neck movement.…”

“…There are simple methods for positioning the ETT, which consider the patient's age or ETT size (4). However, these methods are less accurate than CXR or FOB, and there does not appear to be a strong relationship between tracheal length and these previously described methods (4a).…”

Ischemic subglottic damage following a short-time intubation

“…Thus, the cuff would lie in the subglottic space, between the vocal cords, or even in the supraglottic space if the tubes are placed either according to radiological criteria or to an age-related formula for predicting depth of tube insertion [1,9,10]. Excessive subglottic pressure can cause mucosal ischemia, fibrosis, and lead to stenosis by compression of the mucosa against the nonexpandable cricoid cartilage [1].…”

Assessment and Management of the Pediatric Airway

“…As the assistant removes the orotracheal tube, the nasotracheal tube is gently advanced through the vocal cords; the Magill forceps should not be used to advance the tracheal tube through the vocal cords, as this may cause trauma to the glottis. Several methods of estimating the depth of insertion of nasotracheal tubes have been described [189][190][191], although the following formula [190] works well for children up to 4 years of age:…”