A recent letter outlined two cases where the intubating laryngeal mask airway tracheal tube (ILMATM; Intavent Orthofix, Maidenhead, UK) kinked following an awake fibre optic intubation. [1]
We wish to report a similar case occurring with another brand of intubating laryngeal mask tracheal tube following submental intubation.The procedure was open reduction and internal fixation of complex pan facial fractures. A FastrachTM tracheal tube (The Laryngeal Mask Company Limited, Mahe, Seychelles) was used for an initial oral intubation with direct laryngoscopy. This was subsequently converted to a submental airway [2], as the pattern of injury and requirement for intra-operative maxillomandibular fixation precluded nasal and regular oral routes of intubation during the case.
Several hours into the surgery, there was difficulty with ventilation and a loss of thr capnograph trace. With direct laryngoscopy it was seen that the tracheal tube had migrated proximally, and so was advanced under direct vision. At this point chest expansion was visible, there was an abnormal capnograph trace and the patient's oxygen saturation was rapidly declining. Ventilation was confirmed visually and by auscultation by two further anaesthetists.However the patient's oxygen saturation declined further, with haemodynamic instability. Exhaled carbon dioxide appeared only intermittently and the trace was abnormal.
An attempt to confirm tracheal tube position with a fibreoptic bronchoscope failed. The tracheal tube was replaced via direct laryngoscopy, using a bougie passed alongside the submental tracheal tube, with subsequent improvement in haemodynamics and oxygenation. The FastrachTM tracheal tube was removed, closely inspected and found to be normal. It seems that the tube had initially migrated proximally, then kinked at the distal soft end when advanced.
An important difference in this case to the cases previously described [1], is that there was no obvious leak caused by disruption of the seal between cuff and tracheal wall. We believe that this led to dynamic gas trapping, with inspiration occurring at high pressure via the Murphy's eye and little or no expiration possible.This would explain the anaesthetists hearing air entry and seeing the chest rise when squeezing the bag, but the capnography trace being absent or abnormal.
One factor, which may be contributory, is the recent change from the multi use FastrachTM tracheal tube to a single use device. (Fig 1)
The tip of the single use tracheal tube is thinner and on manual manipulation is easier to deform.
As the intubating laryngeal mask airway tracheal tube is commonly used in cases of difficult intubation, we think it is important for all anaesthetists to be aware of the potential for obstruction at the distal silicone tip with this type of tube.
For a submental airway, a tracheal tube which is reinforced, with a Murphy's eye and with a detachable connector is ideal e.g. WelcareTM reinforced cuffed endotracheal tube (Welford Manufacturing ,Selangor, Malaysia)
D. Moore
B. Hockey
D. Williams
Royal Melbourne Hospital
Melbourne, Australia
Email: d.moore@mh.org.au
No external funding and no competing interests declared.
References
1. F. E. Kelly, J.J.Gatward, B.W. Howes, T. H. Gould. Kinking of intubating laryngeal mask tracheal tubes following fibreoptic intubation. Anaesthesia 2010; 65: 646.
2. F.H. Altemir. The submental route for endotracheal intubation: a new technique. Journal of Maxillofacial Surgery 1986; 14: 64-5.
