Air leak with intact cuff inflation system: A case report with brief review of literature.

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Sir, Tracheal re-intubation because of air leak after a successful tracheal intubation is not very uncommon in anaesthesia practice. The most common illustrated causes for air leaks are related to a defect in the cuff, inflation tube/lumen, pilot balloon, or the spring loaded inflation valve. Here, we report an unexpected product quality compromise leading to appreciable air leak without a defect in cuff inflation system. The trachea of a 38-year-old lady posted for elective transsphenoidal excision of pituitary adenoma was successfully intubated with a 7 mm internal diameter disposable flexometallic endotracheal tube (ETTfm) (Sterimed™) and was secured with elastic adhesive plaster at lip line corresponding to 21 cm on the ETTfm tube. A few minutes later while positioning the patient, we noticed audible air leak from the mouth. Hence, we followed a stepwise approach to ascertain and fix the cause. In the first step, we pushed 2 ml air (in addition to 5 ml air used to inflate the cuff initially) and found that the pilot balloon was holding the air that ensured an intact cuff and a competent inflation valve. However, the air leak was still audible from patient's oral cavity with each mechanised positive pressure breath. In the next step, we ascertained the correct position of tracheal tube with check laryngoscopy which confirmed that the entire cuff is below the vocal cord. In the final step, we presumed that the tube may be too small for the trachea of the patient. However auscultation over trachea was negative; but to give the benefit of doubt we re-intubated the patient with a new ETTfm tube and with this, there was no air leak. After uneventful completion of surgery and subsequent extubation, we re-examined and compared both the ETTsfm to localise the cause of air leak. On careful physical examination, we found a small defect near the insertion point of the inflation tube in the first ETTfm [Figure 1], suggesting air leak from the wall of the tube despite the pilot balloon appearing to be firmly inflated. Figure 1 The red in colour arrow pointing toward the oval defect in the wall of the flexometallic tube. The flexometallic endotracheal tube is straightened to make the defect more appreciable Normally, cuff leak or leak around the cuff can be identified by looking at pilot balloon, palpation of the cuff over suprasternal space, auscultation over trachea and bubbles coming out from the oral and nasal cavity if secretions are present. However, the leak from the wall of the ETTfm at the insertion point of pilot balloon is difficult to identify unless we look for it because the junction is situated 18 cm from tip of the ETTfm just behind the incisor and possibly much above the accumulated secretion if any, to form the bubbles. Literature search illustrated few more case reports implicating improper fixation of the tube by adhesive plaster,[1] repeated use and attempt to remove the adhesive plaster,[2] bitten notch on re-sterilised tube[3] and low product quality compliance[4] as the cause of unexpected air leak from after tracheal intubation. In all these reports, the recommended in vitro test failed to detect such type of occult leak.[5] However, one author reported that such occult leak can be detected if, the tube was examined by flexing it opposite to its natural curve immersed in a bowl of water.[6] Our case report along with the discussed literature re-affirms that air leaks may be present in all types of ETT (both flexometallic and polyvinyl chloride) irrespective of their trade mark. The structural defect leading to air leak may be there in a newly opened ETT or may be caused by repeated use of re-sterilised tube. The small cuts and holes on the convex surface of the ETTfm and near the entry point of the inflation tube usually go undetected by routine in vitro test. Considering the fact that a small air leak at the beginning of the surgery may become larger leading to dangerous inadequate ventilation, an ideal solution for this type of problem would be use of a magnifying glass to verify structural integrity of cuff, insertion point and pilot balloon. However, as it is practically not possible to check each and every tube using a magnifying glass, such problems do occur irrespective of manufacturer. Hence, anaesthesiologist should be aware of such possibilities, and this should be kept in the mind as a diagnosis of exclusion, for which the best solution is change of the tube. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.