Confirmatory tests for endotracheal tube insertion depth

To the Editor, McKay et al. used suprasternal tracheal palpation (TP) during endotracheal tube (ETT) insertion to ensure a midtracheal position of the distal tip. The advancing tip was never or barely felt in 15 of 92 subjects. Furthermore, Fig. 1 shows that the tip position was either too close to the carina (less than 2.5 cm) or too close to the vocal cords (more than 7.5 cm away from the carina) in 18 of the remaining 77 subjects in whom the tip was felt. Thus, this actually shows that the use of TP results in accurate midtracheal positioning in only 59 of the 92 subjects. Importantly, TP cannot be used to verify the depth in an existing ETT because the technique, as described by the authors, depends on progressively feeling the advancing tip during placement. As the authors correctly stated, it behooves anesthesiologists as well as other providers to use measures to guarantee a mid-tracheal placement of the ETT distal end to avoid mainstem intubation or accidental dislodgement with changes in the patient’s head and neck position. We prefer cuff ballottement to TP as this maneuver yields a high success rate. For the last ten years, we have used a slight modification to the original cuff ballottement maneuver with excellent results as verified by fibreoptic examination. We inject 5 mL of air rapidly while feeling the ETT cuff in the suprasternal notch using two fingers of the other hand. Because of its simplicity, this maneuver can be taught very easily to our trainees. In our experience, only very few situations could render our maneuver (and TP) difficult to interpret, e.g., massive obesity, huge thyroid tumours, and excessive neck scarring. It has also been suggested that inserting the ETT with the upper edge of the ETT cuff lying 2 cm below the vocal cords ensures mid-tracheal positioning of its tip, but this approach remains to be investigated. There is no doubt that fibreoptic and radiological confirmation are the most reliable confirmatory methods, but they are not simple to perform and require additional equipment that is not always convenient or immediately available. While we commend the authors for investigating a new technique that may enhance accurate ETT positioning, we also highlight the importance of using multiple confirmatory techniques to avoid any uncertainty due to the shortcomings that may be inherent in any single technique.