We read with interest the article by Sanuki et al [1], and would like to comment on some issues regarding their study design. We agree with the authors that there are numerous methods to reduce the incidence of nasal mucosal trauma e.g. tracheal tube guidance, softening the tube and the use of vasoconstrictors. Previous studies have also shown that softening the tracheal tube in warm saline, choosing the more patent nostril, using a smaller size nasotracheal tube and nasal application of vasoconstrictors, may reduce the incidence of epistaxis [2-6]. We find it surprising, (at least from an ethical point of view), that the authors choose not to use any of the above methods, and conclude that the choice of nasotracheal tube may influence the reduction in nasal trauma more than the methods mentioned above. The reported incidence of epistaxis in their study was 35% for the conventional tube. 17% of these cases were described as severe.  The use of the Parker Flex tube reduced these complications to 9.8% and 2% respectively.

It is quite interesting to note that other studies [7, 8], which examine the incidence of epistaxis during nasotracheal intubation, also choose to follow a similar methodology. Thus, generating a smilar incidence of side-effects.

Smith & Reid [9] in their group of patients found a high incidence (68%) of intranasal pathologies that may make nasotracheal intubation difficult. These authors suggested using a fibrescope to select the most patent nostril. In our institute, we encourage the use of a fibreoptic scope to aid nasal intubation, as this allows the operator to not only choose the more patent nostril, but to inspect both nostrils for any obvious pathology. The fibreoptic scope also serves to guide the tube through the preferred pathway i.e. along the floor of the nose, below the turbinates [10]. We routinely prepare the nose with otrivine drops (xylometazoilne 0.1%) or 1% ephedrine drops, and restrict ourselves to using a size 6.0-6.5 mm  nasotracheal tube, which is soft and well lubricated. This technique has served us well over the years, and we have published two studies totalling 103 patients, where a two scope technique was used to study the incidence of impingement on nasotracheal intubation [11, 12]. In our studies, the use of the second “observing” scope allowed us to observe for complications such as epistaxis. We did not record a single incidence of moderate or severe epistaxis.

Thus, although the design of the tracheal tube may contribute to reducing the incidence of nasal mucosal trauma, attention to detail should not be ignored. Nasotracheal intubation may result in epistaxis and cause fatal airway complications. This is rightly emphasised by certain authors in their discussion  [13- 15].

Mridula Rai

Alex Marfin

Nuffield Department of Anaesthetics

Oxford Radcliffe NHS Trust

Oxford, UK

E-mail:mridula.rai@btinternet.com

References

1. Sanuki T, Hirokane M, Matsuda Y, et al^. The Parker Flex-Tip™ tube for nasotracheal intubation: the influence on nasal mucosal trauma. Anaesthesia 2010; 65: 8-11.

2. Lee Jong-Hwan, Kim Chang-Hee, Bahk Jae-Hyon, et al. The influence of endotracheal tube tip design on nasal trauma during nasotracheal intubation: Magill –Tip Versus Murphy Tip. Anesthesia and Analgesia 2005; 101: 1226-9.

3. Kim YC, Lee SH, Noh GJ, et al. Thermo softening treatment of nasotracheal tube before intubation can reduce epistaxis and nasal damage.  Anesthesia and Analgesia 2000; 91: 698-701.

4. O’Hanlon J, Harper KW. Epistaxis and nasotracheal intubation-prevention with a vasoconstrictor spray. Irish Journal of Medical Science 1994; 163: 58-60.

5. Tong JL. Smaller is better through the nose. Anesthesia and Analgesia. 2008; 106: 1925.

6. Smith JE, Reid AP.Identifying the more patent nostril before nasotracheal intubation. Anaesthesia 2001; 56:258-62.

7. Kihara S, Komatsuzaki T, Brimacombe J, et al. A silicone-based wire reinforced tracheal tube with a hemispherical bevel reduces nasal morbidity for tracheal intubation. Anesthesia and Analgesia 2003; 97: 1488-91.

8. Coe T R, Human M. The peri-operative complications of nasal intubation: a comparison of nostril side. Anaesthesia 2001; 56: 447-450.

9. Smith JE, Reid AP. Asymptomatic intranasal abnormalities influencing the choice of nostril for nasotracheal intubation. British Journal of Anaesthesia 1999:83: 882-6.

10. Ahmed-Nusrath A, Tong J L, Smith JE. Pathways through the nose for nasal intubation: a comparison of three endotracheal tubes. British Journal of Anaesthesia 2008; 100: 269-74.

11. Rai M R, Scott S H, Marfin A, Get al.A comparison of a flexometallic tracheal tube with the intubating laryngeal mask tracheal tube for nasotracheal fibreoptic intubation using the two-scope technique. Anaesthesia2 009; 64: 1303-1306.

12. Marfin A G, Iqbal R, Mihm F, et al. Determination of the site of tracheal tube impingement during nasotracheal fibreoptic intubation. Anaesthesia 2006; 61: 646-650.

13. Piepho T, Thierbach A, Werner C. Look before you leap. British Journal of Anaesthesia 2005; 94: 859-60.

14. Hall C, Shutt L E. Nasotracheal intubation for head and neck surgery. Review article. Anaesthesia 2003; 58: 249-256.

15. Williams M, Onslow J. Airway difficulties associated with severe epistaxis. Anaesthesia
1999; 54: 812-813.

We appreciate the comments by Rai & Marfin regarding our study. They questioned our decision not to use certain techniques, such as nasal application of vasoconstrictors and softening the tracheal tube in warm saline, to reduce the incidence of epistaxis.  Why did we omit those techniques from our study design?

It is well known that topical vasoconstrictors have been associated with life-threatening complications [1-3].  For this reason, some anaesthetists routinely avoid topical vasoconstrictors for nasotracheal intubation [4].  Thermosoftening of tubes also carries risks, such as tube distortion and tube kinking, especially if the temperature of the saline is not tightly controlled and is too hot [5]. Some conventional tubes are very stiff and seem to require thermosoftening treatment prior to intubation [6].  Xue et al point out that if intubation with a thermosoftened tube is not accomplished very quickly, the tube will cool to the ambient temperature of the room and become stiffer [7], thereby increasing the risk of epistaxis and nasal damage [8]. 

Rai & Marfin recommend the use of a fiberoptic scope to inspect both nostrils for pathology before intubation, and to guide the tube through the preferred nasal pathway.  However, especially in urgent circumstances, such uses of a fiberoptic scope for nasotracheal intubation are frequently not practical or possible.

As several of the techniques recommended by Rai & Marfin to reduce the incidence of epistaxis are not risk-free, convenient, or always available, these techniques are not routinely employed for nasotracheal intubation by all medical personnel who perform endotracheal intubation.  Therefore, any tube which is able to accomplish less traumatic nasotracheal intubation than a conventional tube, without relying on these supplementary techniques, would offer a practical, clinical advantage.  We wanted to determine if there is any such clinical advantage to using the Parker tube compared to a conventional tube.  Therefore, we designed our study using no other special equipment or topical medication, (except for routine lubrication of the tube), to determine if the Parker Flex-Tip tube may significantly reduce the incidence of nasal mucosal trauma, and also reduce the severity of nasal pain during nasotracheal intubation when compared to a conventional tip tracheal tube. Our results convinced us that the Parker tube does accomplish these goals.

T. Sanuki

S. Sugioka

J. Kotani

Department of Anaesthesiology, Osaka Dental University

Osaka, JAPAN

E-mail: odu9847@yahoo.co.jp

References