Department of Anaesthesia, University Hospital Birmingham, Selly Oak Hospital, Birmingham B29 6JD, UK*Corresponding author
Accepted for publication: March 13, 2001
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Br J Anaesth 2001; 87: 20711
Keywords: intubation tracheal, technique; equipment, fibreoptic laryngoscope
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
Methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Each patients airway was assessed preoperatively and the Mallampati score and thyromental distance were recorded. Electrocardiogram, indirect arterial pressure, arterial oxygen saturation, and carbon dioxide concentrations were monitored. Glycopyrrolate 200400 µg was administered i.v. and the patient was given 100% oxygen. Anaesthesia was induced with fentanyl 1 µg kg1 and propofol 2.5 mg kg1 followed by atracurium 0.5 mg kg1 and the patients lungs were ventilated with isoflurane in oxygen, using a face mask attached to a circle system, until muscle relaxation was complete.
Upper airway endoscopies were performed using an Olympus LF2 fibreoptic laryngoscope attached to an endoscopic video camera system and a videotape recorder. Videotape recordings of the endoscopies were made following General Medical Council guidelines. The investigation team comprised an anaesthetist experienced in fibreoptic endoscopy (VKD or JPM) and two assistants. The first assistant, another anaesthetist (JES), stood on the patients right-hand side and the second assistant, a trained operating department assistant, stood on the patients left-hand side. The assistants were blinded from the television screen and were unaware of the findings during the endoscopy. Three airway manoeuvres were carried out on each patient and all the patients acted as their own control.
The patients head rested on a single pillow and the atlanto-occipital joint was extended. The first assistant applied firm jaw thrust, keeping the patients mouth open, and the operator then advanced the fibrescope, onto which had been threaded a tracheal tube, into the mouth along the dorsum of the tongue. Airway clearance at the level of the soft palate was assessed by observing whether or not the uvula, or uvula and soft palate, were in contact with the dorsum of the tongue. The fibrescope was then advanced into the oropharynx and airway clearance at epiglottic level was assessed by observing whether or not the epiglottis was in contact with the posterior pharyngeal wall. If the uvula, or the uvula and base of uvula, touched the tongue or if the sides of the epiglottis touched the posterior pharyngeal wall, the airway was classified as partially obstructed at the respective levels. If the whole of the soft palate was in contact with the tongue or if the sides and tip of the epiglottis were in contact with the posterior pharyngeal wall, the airway was classified as completely obstructed at the respective levels. If these structures were not in contact, the airway was classified as clear at the respective levels.
The fibrescope was then removed and the first assistant applied a large-sized Duvals lung forceps to the tongue and carefully lifted the tongue anteriorly until minimal resistance was felt. Lingual traction was applied in the vertical plane so that the lower incisors did not make contact with the ventral surface of the tongue. The forceps were then held in the second assistants left hand while his right hand maintained extension of the atlanto-occipital joint. The fibrescope was advanced into the mouth and oropharynx and airway clearance at soft palate and epiglottic level was assessed as before.
The fibrescope was removed from the mouth again and the first assistant applied jaw thrust, keeping the mouth open, in addition to the lingual traction. The fibrescope was again advanced into the mouth and oropharynx and airway clearance was assessed as described. The fibrescope was advanced through the vocal cords, into the trachea and down to the carina. The Duvals forceps were removed and the tracheal tube was passed over the fibrescope into the trachea to complete the intubation. The dorsal and ventral surfaces of the tongue were examined for any signs of injury. Anaesthesia and surgery then proceeded as usual. The videotape recording was later reviewed to validate the observations. A maximum time of 90 s was allowed for the investigation. If the observations could not be completed within this time limit, the patient was withdrawn from the trial and intubated immediately. All patients were visited next day and asked if they had a sore throat or sore tongue, and the tongue was again examined.
Airway clearance when using jaw thrust and lingual traction at soft palate and epiglottic level were compared using Fishers exact test. The associations between airway clearance, when using both jaw thrust and lingual traction, and the patients Mallampati scores were analysed using Fishers exact test.
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
|
|
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
As fibreoptic endoscopy relies on clear airspace ahead of the fibrescope tip, increasing airway obstruction may cause increasing difficulty. At pharyngeal level, apposition of the uvula base to the tongue did not usually cause undue difficulty as the fibrescope could be passed to one side of it. However, in the two patients with both uvula and soft palate apposed to the tongue, it was difficult to obtain a view of the larynx and several blind attempts had to be made before the epiglottis was seen. At epiglottic level, when the sides of the epiglottis only were apposed to the posterior pharyngeal wall, with careful manipulations, it proved possible to pass the fibrescope beneath the tip of the epiglottis in all patients. No patient in our series had the tip of the epiglottis apposed to the posterior pharyngeal wall, but our previous experience suggests that when this circumstance does arise, endoscopy is particularly difficult.
Our figures also demonstrated that with jaw thrust, patients with Mallampati 2 or 3 scores had more incidents of obstruction at soft palate level than patients with Mallampati 1 scores. Also, the only patient with a Mallampati 3 score in our series had obstruction with both jaw thrust and lingual traction at both airway levels. Hence, potentially difficult conventional direct laryngoscopy may be associated with difficult fibreoptic laryngoscopy. When both manoeuvres were applied simultaneously, however, the airway was fully cleared. It would be useful to know whether the combined manoeuvre works as well in patients with possible or confirmed difficult laryngoscopy. Further work would be required to investigate this possibility. The combined technique is particularly helpful in fibreoptic training as inexperienced personnel have greater difficulty in performing endoscopy when airway clearance is less than perfect.
During general anaesthesia, posterior displacements of the tongue, soft palate, and epiglottis tend to close the airway.25 The primary manoeuvres used to clear the airway comprise chin lift, extension of the atlanto-occipital joint and anterior displacement of the mandible. These manoeuvres may be further refined by allowing the lips and teeth to separate slightly (triple airway manoeuvre)3 23 so that exhalation is not impeded. Considerably more mouth opening is needed during fibreoptic instrumentation and this may partly explain why partial or complete airway obstruction was seen in some of our patients. It is recognized that the mouth open position may compromise airway patency.3 24
When electing to perform oral fibreoptic intubation without intubating airways, or if satisfactory airway clearance cannot be secured when an intubating airway is being used, perhaps the first manoeuvre to try is jaw thrust with the mouth open, as this is the simplest and least invasive approach. If this does not help because of apposition of the tongue and soft palate, then lingual traction might be applied by a trained assistant as there is a good chance that this manoeuvre will successfully treat this type of airway obstruction. A better alternative, if a second anaesthetist is present and familiar with the techniques, is to apply both manoeuvres simultaneously. The efficacy of the combined manoeuvre is one of the reasons why a known or suspected difficult intubation being managed under general anaesthesia should involve two anaesthetists. At present, it is not known whether using intubating airways or applying jaw thrust and lingual traction simultaneously is the more reliable way of clearing the airway in fibreoptic orotracheal intubation of patients known to be a difficult intubation.
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 Safar P, Escarraga LA, Chang F. Upper airway obstruction in the unconscious patient. J Appl Physiol 1959; 14: 7604[ISI]
3 Morikawa S, Safar P, DeCarlo J. Influence of the head-jaw position upon upper airway patency. Anesthesiology 1961; 22: 26570[ISI]
4 Boidin MP. Airway patency in the unconscious patient. Br J Anaesth 1985; 57: 30610[Abstract]
5 Nandi PR, Charlesworth CH, Taylor SJ, Nunn JF, Dore CJ. Effect of general anaesthesia on the pharynx. Br J Anaesth 1991; 66: 15762[Abstract]
6 Berman RA. A method for blind intubation of the trachea or oesophagus. Anesth Analg 1977; 56: 8667[ISI][Medline]
7 Ovassapian A. A new fiberoptic intubating airway. Anesth Analg 1987 (Suppl); 66: S132
8 Ovassapian A, Yelich SJ. Learning fiberoptic intubation. Anesthesiology Clin N Am 1991; 9: 17585
9 Mason RA. Learning fibreoptic intubation: fundamental problems. Anaesthesia 1992; 47: 72931[ISI][Medline]
10 Morris IR. Continuing medical education: fibreoptic intubation. Can J Anaesth 1994; 41: 9961008[Abstract]
11 Erb T, Hampl KF, Schurch M, Kern CG, Marsch SCU. Teaching the use of fiberoptic intubation in anesthetized spontaneously breathing patients. Anesth Analg 1999; 89: 12925
12 Roberts JT. Preparing to use the flexible fiber-optic laryngoscope. J Clin Anesth 1991; 3: 6475[Medline]
13 Schaefer HG, Marsch SCU. Comparison of orthodox with fibreoptic orotracheal intubation under total I.V. anaesthesia. Br J Anaesth 1991; 66: 60810[Abstract]
14 Hartley M, Morris S, Vaughan RS. Teaching fibreoptic intubation. Effect of alfentanil on the haemodynamic response. Anaesthesia 1994; 49: 3357[ISI][Medline]
15 Lucas DN, Yentis SM. A comparison of the intubating laryngeal mask tracheal tube with a standard tracheal tube for fibreoptic intubation. Anaesthesia 2000; 55: 35861[ISI][Medline]
16 Witton TH. An introduction to the fiberoptic laryngoscope. Can J Anaesth 1981; 28: 47580
17 Smith JE, Mackenzie AA, Scott-Knight VCE. Comparison of two methods of fibrescope-guided tracheal intubation. Br J Anaesth 1991; 66: 54650[Abstract]
18 Cole AFD, Mallon JS, Rolbin SH, Ananthanarayan C. Fiberoptic intubation using anesthetized, paralyzed, apneic patients: Results of a residency training program. Anesthesiology 1996; 84: 11016[ISI][Medline]
19 Hakala P, Randell T, Valli H. Laryngoscopy and fibreoptic intubation in acromegalic patients. Br J Anaesth 1998; 80: 3457
20 Hakala P, Randell T. Comparison between two fibrescopes with different diameter insertion cords for fibreoptic intubation. Anaesthesia 1995; 50: 7357[ISI][Medline]
21 Randell, Valli H, Hakal P. Comparison between the Ovassapian intubating airway and the Berman intubation airway in fibreoptic intubation. Eur J Anaesth 1997; 14: 3804[ISI][Medline]
22 Aoyama K, Seto A, Takenaka I. Simple modification of the Ovassapian fiberoptic intubating airway. Anesthesiology 1999; 91: 897[ISI][Medline]
23 Benumof JL. Nonintubation management of the airway: mask ventilation. In: Benumof JL, ed. Airway Management: Principles and Practice. St Louis: Mosby, 1996; 233
24 Meurice JC, Marc I, Carrier G, Series F. Effects of mouth opening on upper airway collapsibility in normal sleeping subjects. Am J Respir Crit Care Med 1996; 153: 2559[Abstract]