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LETTER TO THE EDITOR

Introducer Catheter for Fiberoptic Intubation Does Exist

Department of Anesthesiology and Critical Care, St. Louis University Hospital St. Louis, MO, govind_r{at}hotmail.com, rajang{at}slu.edu

In Response:

We thank Craker et al. for their interest in our technique but disagree with their claim that Aintree intubating catheter (AIC) (Cook Critical Care, Bloomington, IL) provides a reliable and safe means of airway exchange during difficult airway emergencies. In addition, because the AIC has a non-taper tip design, it cannot reliably be railroaded over a guide wire and hence, as we correctly stated, cannot be used in the course of transoral wire-guided endotracheal intubation. In our experience, the Aintree intubating catheter is too short to allow reliable exchange of an adult laryngeal mask airway (LMA) with an adult endotracheal tube (ETT). The catheter is only 56 cm long. The usual adult 7-mm or 8-mm internal diameter ETT is at least 31–33 cm long. That leaves us with 23 cm of overall length. One needs at least 5–6 cm of the exchanger besides what is needed for safe loading of the ETT tube while the distal tip of the exchanger is securely maintained in position well distal to the vocal cords in the trachea. Because the AIC is thin-walled, it is prone to kinking, especially when used with relatively stiff polyvinyl chloride (PVC) ETT. One must keep in mind that during over-the-fiberoptic intubation, even when the ETT tube and the bronchoscope diameter are well matched, this may require significant manipulation and force, which, if used with the AIC, may lead to catheter dislodgement and esophageal intubation. Dr. Genzwuerker, while evaluating ETT exchange using the Aintree Catheter in patients who were not difficult to intubate, reported a 10% rate of catheter dislodgement leading to esophageal intubation (1).

We also disagree with their statement that an endotracheal tube of any size can be inserted over the AIC. These catheters are marketed in two lengths (56 and 80 cm), and one cannot pass ETT sizes smaller than 7 mm ID over them (2). Recently, the Arndt Airway Exchange Catheter (Cook Critical Care) has been marketed; this is similar in concept to our modification for exchange of ETT for an LMA using the wire-guided approach (Fig. 1) (2,3). It is 70 cm long with a tapered distal end and a proximal end that can accept a specially designed adaptor to institute jet ventilation during emergency airway management. ETT greater than 5 mm ID can be railroaded over this catheter.

View larger version (74K): [in this window] [in a new window]   Figure 1. Arndt Airway Exchange Catheter designed for transoral wire guided exchange of the laryngeal mask airway for endotracheal tube using fiberoptic bronchoscopy. (A) Distal tapered end of the catheter introducer, (B) the Rapifit Adaptor which accepts 22-mm female connector and (C) an adaptor with Luer lock connector.

The need for switching the LMA for ETT is primarily observed in scenarios where the LMA has been placed to provide rescue ventilation either during inadvertent difficult intubation after induction of anesthesia in the operating room or during emergency difficult airway management outside the operating room. Under both circumstances, LMA is usually placed after multiple failed attempts at direct laryngoscopy and intubation that can be associated with significant airway bleeding, glottic edema, excessive secretions, and inadequate oxygenation and ventilation. Attempting bronchoscopy using a pediatric bronchoscope under such circumstances could be a very challenging task because lighting, resolution, and ability to suction blood and secretions are significantly inferior compared with adult bronchoscopes.

In our opinion simple modification and prudent application of available products has made significant contribution to the field of anesthesia, especially in the area of airway management. The use of the Fogarty balloon catheter for lung isolation, modified TwistLock^TM Adaptor (Arrow International, Reading, PA) to provide secure air tight seal (4), and the use of large-bore IV cannula for transtracheal jet ventilation are excellent examples of products that have been modified and used for indications other than that for which they were designed.

References

1. Genzwuerker HV, Vollmer T, Ellinger K. Fibreoptic tracheal intubation after placement of the laryngeal tube. Br J Anaesth 2002;89:733–8.[Abstract/Free Full Text]
2. Cook Critical Care. Available at: http://www.cookcriticalcare.com/discip/pdf/C-DAB-0212-210-02GB.pdf. Accessed May 30, 2005.
3. Rajan GR. Fiberoptic wire-guided transoral and through the LMA intubation technique using modified gum elastic bougie. Anesth Analg 2005;100:599–600.[Free Full Text]
4. Rajan GR. An improved technique of placing a coaxial endobronchial blocker for one-lung ventilation. Anesthesiology 2000;93:1563–4.[Web of Science][Medline]

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