All that appears well is not well: A novel method to detect an unusual manufacturing defect of the endotracheal tube.

Sir,

We report an unusual manufacturing defect in a cuffed polyvinyl chloride endotracheal tube (ETT). After induction, a 12-year-old girl, was intubated with a prechecked (checked by inspection and cuff inflation), 5.5 mm cuffed, single use ETT. Following intubation, air leakage was audible, despite further air being injected into the cuff. Even after inserting a throat pack, air leak was still persistent, with the ventilator showing low expired tidal volume (Vte). As cause and site of the leak could not be identified, we replaced the ETT. This resulted in the disappearance of air leak and improvement in Vte.

Original tube was checked for integrity under water. On cuff inflation, no air bubbles were found, indicating that pilot balloon assembly, including cuff, was not defective. We then occluded the patient end of ETT with a needle cap and assisted ventilation at the other end using artificial manual breathing unit (AMBU). Air bubbles were apparent at the junction of cuff inflation tube and ETT shaft. On using magnifying glasses, a small hole at this site was identified [Figure 1].

Figure 1

Hole at the junction of cuff inflation tube and endotracheal tube

Routine inspection of ETT may fail to detect certain manufacturing defects.[1] There have been reports of defects in cuff,[2] kinking of ETT,[3] and intraluminal plastic films.[4] Lewer et al.[5] noted an elliptical defect in ETT wall on naked eye examination. We observed a similar defect, but it was too small to be visible to the naked eye. Hence, we invented a novel approach to detect such small defects that is, examination of ETT under water after occluding tip of ETT with a needle cap and AMBU ventilation at machine end; a method previously unreported.

To conclude, certain ETT manufacturing defects may go unnoticed. In addition to checking of ETT by inspection and cuff inflation, we recommend it's underwater testing prior to use. Though time-consuming, it will avoid unnecessary intraoperative problems arising due to defective ETTs.