AJA Asian Journal of Anesthesiology

Advancing, Capability, Improving lives

Letter to the Editor
Volume 51, Issue 2, Pages 97-98
Chen-Hwan Cherng 1 , Zhi-Fu Wu 1 , Chun-Chang Yeh 1
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Outline



To the Editor,

The management of unanticipated difficult airway is always a big challenge to anesthesiologists. Even with a thorough preoperative evaluation, an unanticipated difficult airway may occasionally be encountered. Fiberscope-aided awake intubation with spontaneous breathing is recommended by many guidelines.123 However, if long-acting non-depolarizing neuromuscular blocking agents are used during induction, recovery of spontaneous breathing must be delayed. Here, we describe a two-person technique for fiberscope-aided nasotracheal intubation in an anesthetized patient.

Unanticipated difficult orotracheal intubation was encountered after receiving the non-depolarizing muscle relaxant, rocuronium 0.6 mg/kg, for induction of general anesthesia. The laryngeal view of the patient was Grade IV by the Cormack and Lehane classification. After two attempts of failed orotracheal intubation, the ventilation was maintained by the aid of an oropharyngeal airway. We thought that awaking the patient might not be the best choice for an alternative method of intubation, due to delayed recovery of spontaneous breathing by the rocuronium blockade. A two-person technique for fiberscope-aided nasotracheal intubation under anesthesia was thus decided. Assisted ventilation with 100% O2 via a face mask was continued during the transition period. After being lubricated with 2% lidocaine jelly, a 7.0 mm endotracheal tube was first inserted into the nostril until it hit the oropharynx, and then, a fiberscope was passed through the endotracheal tube. At this juncture, another anesthesiologist simultaneously implemented the direct laryngoscopy, so as to lift the tongue base and use the Magill forceps to pinch the tip of the endotracheal tube (Fig. 1). By adjusting the direction of the endotracheal tube tip toward the laryngeal inlet, the glottis and vocal cords could be easily identified by the fiberscope; the scope was then passed through the glottis and the endotracheal tube was smoothly slid into the trachea. After confirming the correct anchorage of the endotracheal tube by capnography and the fiberscope, the scheduled operations proceeded as planned. The intubation time (from endotracheal tube insertion to capnographic confirmation) was <1 minute and the peripheral oxygen saturation was maintained above 98% during the intubation period.

Fig. 1.
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Fig. 1. Diagram showing that, under direct laryngoscopy, a Magill forceps can hold the tip of an inserted endotracheal tube via the nasal route, which aids in directing the fiberscope into the laryngeal inlet.

Problems with difficult tracheal intubation remain the major cause of morbidity and mortality associated with anesthesia.4 Preanesthetic airway assessment should be routinely performed for all patients. Clinically, many tests have been used for difficult airway assessment,5 however, up until now, no test has provided enough specificity and sensitivity to predict difficult intubations. Many guidelines with algorithm concerning the management of difficult airway have been published.123 Awaking the patient was suggested when several attempts of tracheal intubation fail, and then alternative non-invasive approaches could be tried if the patient’s ventilation is adequate; awake fiberoptic intubation, LMA (laryngeal mask airway) as an intubation conduit, intubating stylet and light wand methods, retrograde intubation, and blind oral or nasal intubation, stand out as alternatives.1 Among these recommended alternative methods, none is perfect and most of the techniques require extra training. Besides, the consumption of time of these alternatives is another important factor to be considered during this critical moment. The two-person technique introduced here provides another practical choice, and from our experience, this technique is not difficult to implement. It takes little time to perform; in our case it took <1 minute for accomplishment. Fiberoptic tracheal intubation is a common and useful technique for difficult intubation.123 However, it is difficult to implement in anesthetized patients. The anatomical appearance of the oropharynx of conscious patients is different from that of anesthetized patients. In the conscious patients, there is tonus of the tongue, epiglottis, piriform fossa and oral muscles, which makes visualization of the laryngeal inlet easier by a fiberscope. However, in anesthetized patients, the tonus of the oral and pharyngeal muscles disappears,6 and subsequently constitutes airway obstruction. In such circumstances, the fiberscope-aided tracheal intubation may become more difficult and time consuming. Although the two-person technique described here cannot simultaneously provide ventilation, the intubation time is short enough to avoid hypoxemia. Fiberoptic intubation can be performed via the oral or nasal route. In our patient, we did not choose the oral route, because an acute angle was encountered while the tip of the fiberscope was entering the laryngeal inlet. This would make scope insertion difficult. On the contrary, through the nasal route, a smooth oblique angle emerged which facilitated approach of the fiberscope. Besides, the oropharyngeal space needs to be exposed, for the second person's manipulation in this two-person technique. Repeated attempts of direct laryngoscopic intubation should be avoided, because progressive laryngeal edema and hemorrhage may develop. This could hinder subsequent assisted mask ventilation.

In summary, if difficult intubation during induction of general anesthesia is encountered, we suggest that, as long as the patient's ventilation can be maintained by a face mask, the two-person technique described here is recommended to implement intubation, as it could be accomplished before recovery of spontaneous breathing and consciousness.


References

1
American Society of Anesthesiologists Task Force
Practice guidelines for management of the difficult airway. An updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway
Anesthesiology, 98 (2003), pp. 1269-1277
Article  
2
E.T. Crosby, R.M. Cooper, M.J. Douglas, D.J. Doyle, O.R. Hung, P. Labrecque, et al.
The unanticipated difficult airway with recommendations for management
Can J Anaesth, 45 (1998), pp. 757-776
3
J.J. Henderson, M.T. Popat, I.P. Latto, A.C. Pearce
Difficult Airway Society guidelines for management of the unanticipated difficult intubation
Anaesthesia, 59 (2004), pp. 675-694
4
F.W. Cheney, K.L. Posner, L.A. Lee, R.A. Caplan, K.B. Domino
Trends in anesthesia-related death and brain damage: a closed claims analysis
Anesthesiology, 105 (2006), pp. 1081-1086
5
T. Shiga, Z. Wajima, T. Inoue, A. Sakamoto
Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening test performance
Anesthesiology, 103 (2005), pp. 429-437
6
M. Sivarajan, R.B. Fink
The position and the state of the larynx during general anesthesia and muscle paralysis
Anesthesiology, 72 (1990), pp. 439-442

References

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