Journal of Anaesthesiology Clinical Pharmacology

: 2013  |  Volume : 29  |  Issue : 3  |  Page : 408--409

Kinking of a patent flexometallic tube due to dislodgement of reinforcing spirals

Surya Kumar Dube, Mihir Prakash Pandia, Varun Jain 
 Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi, India

Correspondence Address:
Mihir Prakash Pandia
Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi - 110 029

How to cite this article:
Dube SK, Pandia MP, Jain V. Kinking of a patent flexometallic tube due to dislodgement of reinforcing spirals.J Anaesthesiol Clin Pharmacol 2013;29:408-409

How to cite this URL:
Dube SK, Pandia MP, Jain V. Kinking of a patent flexometallic tube due to dislodgement of reinforcing spirals. J Anaesthesiol Clin Pharmacol [serial online] 2013 [cited 2020 Sep 29 ];29:408-409
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A 37-year-old male (weighing 59 kg) with fourth ventricle choroid plexus tumor was scheduled for craniotomy and tumor excision. After intravenous induction of anesthesia using fentanyl and thiopentone and achieving neuromusular blockade with rocuronium, tracheal intubation was performed with an 8.5-mm cuffed flexometallic tube (FMT) [Portex® Reusable Reinforced Tracheal tube, Smith Medical ADS INC., U.S.A]. The FMT appeared normal on routine checking and a stylet could easily be passed through it. Few seconds after the patient was connected to the ventilator, we noticed a sudden increase in the peak airway pressure (PAP) from 14 mmHg to 53 mmHg along with an upward sloping of ETCO 2 curve. On careful examination, no deficiency was found with the anesthesia circuit, machine, or ventilator. There were no signs of inadequate anesthetic depth, endobronchial intubation, or abnormal breath sounds. During the investigation of this difficulty, when we lifted the breathing circuit, PAP decreased to 19 mmHg and the capnograph became normal. Inspection of the FMT at this stage revealed an acute kinking at the angle of mouth. The PAP returned to the baseline after the FMT was changed. The rest of the intraoperative course remained uneventful. On close examination of the tube, we found that few spirals of the FMT were dislocated at around 20 cm from the patient end [Figure 1].{Figure 1}

Metal or nylon spirals are embedded in the walls of the FMT for its reinforcement and to give it a kink-resistant framework. [1] Because of the kink-resistant framework and flexibility, FMT are preferred in various head and neck procedures. There are various reports of kinking and obstruction of the FMT because of tube bites and deformation of spirals. The deformity of spirals results in the loss of its support and the FMT becomes prone for kinking and obstruction. [2],[3]

In our case, the spirals were loosened from the tube wall not due to manufacturing defect but probably because of reuse. So, the FMT maintained its shape and appeared normal on gross inspection and a stylet could be easily passed through it, leaving the defect unnoticed. Subsequently, some of the spirals get dislodged and, immediately after intubation, when the tube remained straight, the patency of the tube was maintained despite the detached spirals. But when weight of the breathing circuit resulted in bending of the tube, there was kinking and obstruction. Our case illustrates that, with reuse, the spirals of the FMT can be loosened (and subsequently dislodged), which can easily be missed by gross visual inspection and a stylet can easily be passed through it. This also demonstrates that, in presence of loosened spirals, a FMT may not show any evidence of kinking as long as it is kept straight, which may give a false sense of security. Therefore, we suggest that the reusable FMT should specifically be inspected for presence of dislodgement of its spirals before use and in presence of high airway pressure, the possibility of kinking of the FMT due to dislodged reinforcing spirals should always be suspected.


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