To the Editor:
I read with great interest the recent case report by Duma et al. 1regarding tube-in-tube emergency airway management after a bitten endotracheal tube (ETT) caused by repetitive transcranial electrical stimulation during spinal cord surgery. This is indeed a favorable rescue airway measure for the ETT perforation by patient biting or electrical surgical instrument,2–4especially when the ETT exchange is difficult or impossible because of patient position, space limit, device deficiency, and others. The authors stated that this method was a new strategy to manage the ETT rupture during surgery. In fact, Peskin and Sachs2used a tube-in-tube technique to manage a partially severed nasotracheal tube during orthognathic surgery in 1986. Moreover, in this article, the tube-in-tube study in table 1 gives the best sizes for the inner tubes that correspond to the sizes for the outer tubes. It has been shown that the outer diameter of the ETT for a given internal diameter from different manufacturers varies because of differences in wall thickness.5Therefore, these results may be only suitable for the ETTs tested by the authors.
Just as the authors have found, a main disadvantage of the tube-in-tube technique is increased resistance to ventilation because of small internal diameter of an inner tuber. We had used a modified method to establish emergency airway after a size 7.5-wire-reinforced ETT was perforated by biting in a patient undergoing face and neck scar resection under the lateral position. The destructed wire-reinforced ETT and a size 5.0 cuffed polyvinyl chloride ETT (used as an inner tube) are cut at 0.5–1.0 cm distal to the site of attachment of the external inflation tube of the cuff (figs. 1A and B). The shortened inner tube is adequately lubricated and inserted into the destructed wire-reinforced ETT until the midpoint of the cuff of the inner tube is located at the damage site of the wire-reinforced ETT (fig. 1C). Subsequently, the cuff of the inner tube is inflated, and the inner tube is connected to the circle breathing system by the standard connector. During the intermittent positive pressure ventilation with a tidal volume of 10 ml/kg, a ventilatory frequency of 10 breaths/min, an inspiratory time-respiratory cycle time ratio of 1:2, and a fresh gas flow of 2.5 l/min, the mean and peak airway pressures observed were 9 cm H2O and 21 cm H2O in this patient.
As compared with methods reported by Duma et al. 1and Peskin and Sachs,2we consider that this modified technique has some possible advantages. First, removing the tube connector and the proximal part of destructed wire-reinforced ETT may facilitate insertion of an inner tube. Second, except for the radius of the ETT and density of gas, the length of the ETT is another important contributing factor to airflow resistance.6Therefore, shortening the length of the inner tube can significantly decrease ventilation resistance. Third, inflating the cuff of the inner tube can firmly secure stabilization of the two tubes together and avoid airway leakage without requiring any auxiliary maneuver or tool.
Finally, it must be emphasized that when ETT perforation or rupture accidentally occurs during surgery, the tube-in-tube technique can only be used as a temporary rescue airway measure, especially for the patients with a large body weight. If the tear in the ETT is small and it may be possible to approximate the damage site of the ETT, moreover, sealing the leak with gauze,7nylon ties, adhesive tape, or finger4are also alternatives to emergency airway management to obtain a functional ETT. However, once this condition is allowed, the ETT exchange should be performed as soon as possible.4
*Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China. firstname.lastname@example.org