A modified tracheal tube with curvature-control function for blind nasotracheal intubation.

Sir,

Patients with restricted mouth opening are unique challenges in preoperative airway management. In the absence of specialized devices, such as flexible fiber-optic scope, or lighted intubated stylets, and others, blind nasal intubation has been widely practiced for intubating such patients. All blind intubation techniques depend on the operator's skill in manipulating the tip of the tube, and recognizing the alignment with the larynx. Specialized tubes like the Endoflex endotracheal tubes[1] and Endotrol tubes,[2] are extremely useful for oral and nasal intubations, without the need for additional airway adjuncts. We created a similar tube by using an 80 cm long 1–0 silk thread (Ethicon, Johnson and Johnson Company, Somerville, N.J., U.S.A.), which was inserted through the proximal end of the standard polyvinyl chloride cuffed tracheal tube, taken out through the distal end, reinserted into the tube via the murphy eye, and brought out through the proximal end [Figure 1]. Pulling the proximal ends of the thread resulted in decreasing the radius of curvature of the tube, and anterior placement of the tube tip [Figure 2]. We used this modified tracheal tube for blind nasal intubation in 5 adult male patients with restricted mouth opening. Equipment and personnel to deal with an airway mishap were always kept ready. Distance from the tip of the nose to the tragus, and then down till the suprasternal notch (signifying the final depth of tube insertion) was measured for all the patients, and vasoconstrictor drops were instilled in both nostrils. Anesthesia was induced with 4%–6% sevoflurane in oxygen, and the patients were allowed to breathe spontaneously. After adequate depth had been attained, the well-lubricated tube was inserted through the more patent nostril, with the patient's head in sniffing position. A sidestream CO2 airway adapter was attached to the tube. After pushing the tube beyond the nasopharynx, the curvature was manipulated by pulling on the thread, and the tube advanced toward the larynx, guided continuously by the capnographic waveform on the monitor. After pushing till the desired depth, tube position was reconfirmed by 5-point auscultation. The thread was then removed completely by gently pulling out one of the ends. The tube was fastened, neuromuscular blockade achieved, ventilation commenced, and the surgery was allowed to proceed.

Figure 1

The simple looping of the thread at the tip of the tube, which allows its easy removal after intubation

Figure 2

A prolonged-exposure photograph showing the tube-tip movements on pulling the thread

We found the device convenient to use, and the technique easy to master. The average intubation time (from insertion of the tube through the nostril till confirmation of tracheal position by auscultation and capnography) was 36 s, and was less than 1 min in all the patients. This is acceptable in most clinical scenarios. The problems associated with metal stylets, namely, calculating the bend, their removal, and the risk of trauma, were absent with this technique. The use of the device can safely be extrapolated for oral intubations also. We present the technique for wider appraisal by the esteemed readers.