Awake fibreoptic intubation (AFOI) is an established and recommended method for difficult airway cases [1]. The method provides a wide margin of safety during intubation, as conscious patients are able to maintain their own patent airway and breathe spontaneously. To achieve effective and stress-free tracheal intubation under such conditions, sufficient comfort and painlessness should be ensured using various forms of local anaesthesia and sedation [2, 3, 4].

The present report describes three cases of awake fibreoptic intubations.

CASE REPORTS

Case 1

A 40-year-old male patient (ASA II) was scheduled for bariatric surgery due to morbid obesity (BMI 55 kg m-2). The patient suffered from hiatus hernia and obstructive sleep apnoea syndrome managed with nocturnal non-invasive lung ventilation. Preoperative assessment of intubation conditions revealed: the short neck, 55 cm in circumference, width of mouth opening − 6 cm, thyromental distance – 8 cm, Mallampati score – 2, upper lip bite test score − 1, good mobility of the atlanto-occipital joint. Arterial blood saturation with oxygen in the sitting position was 91% (when breathing with air) and decreased to 85% in the recumbent position. 

Case 2

An 18-year-old man (ASA II) with the Silver-Russel syndrome (short stature, disproportion between the faciocranium and cerebrocranium, small and triangular face, micrognathia, congenital heart defects, mental retardation, hypoglycaemia, predisposition to some cancers) was scheduled for tympanoplasty. Before surgery, the patient reported difficult tracheal intubations during previous anaesthetic procedures (no medical records). The physical examination revealed congenital anomaly of the facial skeleton (disproportion between the size of faciocranium and cerebrocranium, and micrognathia). The mouth opening size (the distance between incisors) was 3 cm, the thyromental dimension – 8 cm; Mallampati score − 3, upper lip bite test score – 2; the mobility in the atlanto-occipital joint was markedly impaired.

Case 3

A 32-year-old male patient (ASA I), with the history of failed attempts of tracheal intubation, was scheduled for nucleus pulposus hernia repair in the lumbar spine. According to the information provided by the patient, dentists who treated him stressed markedly impaired mouth opening. The assessment of intubation conditions demonstrated: mouth opening (distance between incisors) of 3 cm, the thyromental dimension of 8 cm, full range of motion in the apical-occipital joint; the Mallampati score was 3 whereas the upper lip bite score – 2.

METHOD

In all patients, the decision to use a fibroscope for tracheal intubation was taken during preoperative anaesthetic visits. The essential element conditioning the successful procedure was the conversation with patients during which all information about the stages of procedure was provided and written informed consent was obtained.

One hour before surgery, patients were premedicated with 7.5 mg of oral midazolam. With the patient on the operating table in the semi-sitting position, monitoring of vital signs was initiated (SAP/DAP, HR, SpO2, f) and the peripheral vein cannulated. Once iv atropine 0.5 mg was injected, topical airway anaesthesia was initiated with 2% lidocaine solution in the volume of 4 mL administered through the face mask nebulizer (Cirrus nebulizer adult mask kit with nose clip, Intersurgical Ltd., UK). After 15 min 0.1% xylometazoline hydrochloride was instilled into both nostrils, 2 drops each, to constrict the mucosal vessels; the tongue and throat were sprayed with 10% lidocaine (4 doses, 4.8 mg each).

The nostril for introduction of the fibroscope was also anaesthetized topically; the three-way stop-cock was attached to the 20 G cannula, whose one arm was connected to the oxygen dispenser with the gas flow of 2 L min-1, whereas the other one to the syringe filled with 3 mL of 2% lignocaine solution with the addition of adrenaline, 10 µg mL-1. During slow injection of the liquid with the oxygen flow turned on, the aerosol formed, which penetrated all recesses of the nasal cavity.

After the completion of oropharyngeal mucosa anaesthesia, the patient was placed in the recumbent position and administered iv midazolam 1-2 mg and fentanyl 0.05-0.1 mg.

During tracheal intubation, the flexible bronchoscope was used, 5.2 cm diameter and 65 cm working length. An epidural catheter was introduced to the fibroscope working channel with its distal end reaching the channel outlet. The proximal end was connected to the three-way stopcock, whose one arm was attached to the oxygen dispenser (2 L min-1) and 4-5 syringes filled with 2% lignocaine solution, 2 mL each, were successively attached to the other one. Once the armoured tracheal tube was placed over, the fibroscope was inserted through the anaesthetized nostril under the inferior nasal concha. Whenever needed, the lignocaine solution was injected through the epidural catheter, sprayed with a strong oxygen stream over further anatomical structures.

The fibroscope was navigated under visual control. Once the superior aperture the larynx was passed, the fibroscope was advanced with its distal end positioned 2-3 cm above the tracheal bifurcation. The intubation tube placed over the fibroscope and coated with 4% lignocaine gel was gently slid down by rotating along its long axis counter clockwise. Before withdrawal of the fibroscope, the placement of the intubation tube was re-assessed and the capnograph sensor attached to the tube to confirm the presence of CO2 in the expired air. When the proper placement was confirmed, the induction of general anaesthesia was initiated.

DISCUSSION

In each of the cases described, the risk of difficult intubation was verified after the initiation of general anaesthesia using the direct laryngoscopy method. In patient 1, the degree of difficult intubation evaluated according to the Cormack-Lehane scale was 2, in the other two – 3. Preoperatively, the suspected difficult airway in the first patient was based entirely on morbid obesity and large neck circumference; evaluation using appropriate tests did not show the risk of difficult tracheal intubation. Therefore, it has been assumed that obesity per se is likely to be a risk factor for difficult tracheal intubation [5, 6], particularly when accompanied by large neck circumference [7]. Moreover, in this case, desaturation accompanying the body position changes (from sitting to recumbent) and hiatus hernia inclined to fibroscope intubation. In the patient with Silver-Russel syndrome, information on previous difficult intubations, visible anomalies in the facial skeleton and the tests performed suggested explicitly difficult intubation conditions. In our third patient, tracheal intubation with a laryngoscope was infeasible due to markedly limited mouth opening.

Classical tracheal intubation may be difficult and dangerous. In the majority of cases, a decrease in blood saturation observed during such a procedure results from deliberately induced muscle relaxation and apnoea. With conscious patients, such a risk is reduced and the time of tracheal intubation is not limited. Moreover, during the insertion of a fibroscope through the nose, patients breathe with oxygen-enriched air (flow − 3 L min-1) administered to the oral cavity. Such management markedly increases the patients` safety margin in potentially dangerous situations [2, 3, 4].

Many authors emphasize the cardiovascular stability during awake fibreoptic intubation [2, 3, 4]. Our experiences confirm such observations, as pharmacological interventions due to cardiovascular abnormalities were not necessary in any of the cases presented. This method of intubation is considered optimal for patients with severe cardiac diseases. In awake patients, despite premedication and anaesthesia, the procedure induces certain emotions, which, however, manifest themselves as slightly accelerated heart rate and slightly elevated arterial pressure. 

Our patients tolerated well this method of tracheal intubation. The history taken in the postoperative period disclosed that awake fibreoptic intubation was not a traumatic experience for the patients and they were ready to re-undergo such procedures if need be. This is confirmed by literature data demonstrating that skilled combination of local anaesthesia and analgosedation minimizes discomfort and complaints accompanying fibroscopy [8, 9, 10].

The procedure discussed is time-consuming – lasting about 20-30 min. About 80% of this time is taken by accurate anaesthesia of the mucous membranes of the nose, oral cavity and throat, particularly of the sensitive and richly innervated region of the larynx, vocal cords and trachea. Haste and the resulting lack of accuracy during topical anaesthesia may lead to severe consequences, e.g. lack of patient`s cooperation during intubation or spasm of the glottis, etc. For these reasons, the method in question is not recommended for emergency cases.

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REFERENCES

1.     American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway. An updated report. Anesthesiology 2003; 95: 1269–1277.

2.     Popat M: Practical fibreoptic intubation. Butterworth-Heinemann, Reed Educational and Professional Publishing Ltd, Oxford, 2001.

3.     Sudheer P, Stacey MR: Anaesthesia for awake intubation. Br J Anaesth  CEPD Rev 2003; 3: 120-123.

4.     Walker K, Smith A: Promoting fiberoptic intubation. Bulletin of The Royal College of Anaesthetists 2007; 46: 2329-2333.

5.     Brodsky JB, Lemmens HJ, Brock-Utne JG, Vierra M, Saidman LJ: Morbid obesity and tracheal intubation. Anesth Analg 2002; 94: 732–736.

6.     Voyagis GS, Kyriakis KP, Dimitriou V, Vrettou I: Value of oropharyngeal Mallampati classification in predicting difficult laryngoscopy among obese patients. Eur J Anaesthesiol 1998; 15: 330–334.

7.     Benumof JL: Obstructive sleep apnea in the adult obese patient: implications for airway management. J Clin Anesth 13; 2001: 144–156.

8.     Woodall NM, Harwood RJ, Barker GL: Complications of awake fibreoptic intubation without sedation in 200 healthy anaesthetists attending a training course. Br J Anaesth 2008; 100: 850-855.

9.     Mingo OH, Ashpole KJ, Irving CJ, Rucklidge MW: Remifentanil sedation for awake fibreoptic intubation with limited application of local anaestetic in patients for elective head and neck surgery. Anaesthesia 2008; 63: 1065-1069.

10.    Puchner W, Egger P, Puhringer F, Lockinger A, Obwegeser J, Gombot Z: Evaluation of remifentanil as single drug for awake fibreoptic intubation. Acta Anaesth Scand 2002; 46: 350-354.

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address:

*Paweł Andruszkiewicz
ul. Dźwiękowa 13, 02-857 Warszawa
tel.: +48 602 100 798
e-mail: pawel_andruszkiewicz@cyberia.pl

received: 21.04.2010
accepted: 13.07.2010