Accidental intraoperative avulsion of external inflation tubing of armored endotracheal tube.

Sir,

We report a case of intraoperative accidental disruption of inflation line assembly of an armored tube. A 70-kg, 30-year-old woman, in ASA I, was scheduled for subtotal thyroidectomy. She was administered anesthesia as per the standard protocol followed at our institute. Endotracheal intubation was done using 7-mm ID armored endotracheal tube (ETT) (Unoflex, Unomedical, Kedah, Malaysia). After securing the ETT, head rolls were placed under the interscapular area to achieve adequate neck extension. We suddenly noticed that the inflation line assembly of the ETT lying on the floor. Peritracheal cuff leak was also present [Figure 1]. Direct laryngoscopy was done and ETT was changed with a fresh one. Rest of the intraoperative and postoperative course was uneventful.

Figure 1

Patient with endotracheal tube without infltaion assembly

Various complications with the use of armored ETT have been reported, including visible bite injuries, tube malposition, and normal appearing tubes causing life-threatening obstruction.[1-3] Higher complication rate has been reported with the use of reused ETT.[2] We reuse the silicone armored ETT up to 20 times after autoclaving in our institute. As compared to normal polyvinylchloride ETT, the inflation tube is attached more proximally to machine end of armored ETT. This increased length of inflation tube of the ETT may increase the chances of accidental pulling and disruption of inflation system [Figure 2].

Figure 2

Avulsed inflation assembly and endotracheal tube

The ASTM/ISO standard requires that the external diameter of inflation tube of the ETT does not exceed 2.5 mm and recommends that it be attached to the tube at a small angle.[4] The standard also specifies the distance from the tip of the tube to where inflation tube is attached and requires that there should be at least 3 cm distance between the machine end of the inflation tube and the pilot balloon.

In this case, the avulsion of inflation tube was probably caused by accidental pulling during positioning of the head and neck. One contributing factor may be the weakening of inflation tube due to repeated autoclaving of the tube. This tube had been used four times before this case. It is a standard practice in our institute to strap the external inflation tube with proximal end of ETT to avoid any accidental pulling of the inflation tube from the inflation lumen but unfortunately strapping was not done in this case. Even after strapping, an accidental knotting of inflation tube can occur. Different methods of fixation have been suggested.[5]

One should be vigilant during head and neck manipulation in intubated patients. It is advisable to strap the external inflation tube around the proximal end of ETT, so that it moves as a single unit. In addition to regular cuff checking, the external inflation tube should also be checked for continuity and damage.