Anesthesiaworld

Success with fiberoptic guided airway management techniques is the result of multiple factors related to the patient, equipment, anaesthesiologist and environment. However, even with the best combination of above factors, outcome can be less than satisfactory in some situations.

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Prerequisites for a successful intubation with a fiberscope

1. Well prepared, cooperative patient
2. Appropriate size fiberscope
3. Appropriate intubation aids and other accessories
4. Adequate anesthesia of the airway or general anesthesia
5. Attention to details of the technique
6. Operator skills

We will review the different aspects of the procedure and how the best outcome can be achieved by overcoming the “traps”. Success results from the appropriate considerations for and management of patient factors, equipment, environment and the anaesthesiologists own experience and expertise.

Figure 1: FOB and accessories

I Patient selection

Not all patients can be ideal for fiberoptic guided airway management. Based on the type of difficult airway (DA), a patient can be easy to intubate, difficult to intubate or contraindicated for fiberoptic guided technique.

Easy patients

 Those who have DA, but the technique is straightforward and easy

1. Adult, cooperative patient
2. Adequate mouth opening (or minimal reduction in interincisor distance)
3. Physiologically stable
4. Mask ventilation is likely to be easy or moderately difficult only
5. No risk of aspiration

Examples include acquired temporomandibular joint ankyloses, sub mucous fibrosis, moderate micrognathia etc

Difficult patients

1. Physiologically unstable patients
2. Obesity
3. Congenital TMJ ankyloses
4. Patient with infraglottic pathology
5. Difficult mask ventilation
6. Distortion of airway anatomy, congenital or post-surgical
7. Uncooperative patient
8. Paediatric patient

Examples include syndromic patients, patients with Ludwig’s angina, tracheal stenosis etc

Figure 2: Difficult patients for fiberoptic techniques

Contraindications

1. Severely distorted airway anatomy
2. Oral tumors
3. Glottic tumours
4. Maxillofacial trauma
5. Blood in the airway region

With experience and expertise, one will be able to do more easily even the most difficult case.

How to succeed?

II Patient preparation

This is the first step and more time spent with the patient describing the technique and explaining the need for cooperation from the patient, more successful is the likely outcome. Other aspects of patient preparation are:

• Antisialogogue: Intramuscular glycopyrrolate or atropine, about 30min before the procedure
• Nasal vasoconstrictor drops to prevent nasal bleeding. Once bleeding starts, the visibility is significantly affected.
• Sedation: Awake fiberoptic guided technique is really not completely awake. Some sort of sedation produces anxiolysis and increase patient comfort, leading to smooth and successful technique. Though no single drug can be recommended for this purpose, broad principles are a) use a single drug, avoid polypharmacy b) use of lowest dose required c) initial small bolus followed by infusion or intermittent doses d) titrated rather than fixed dose of the drug e) monitoring of the patient continuously with ECG, SpO₂ and blood pressure and f) watch for airway obstruction due to excessive sedation. Drugs like fentanyl, propofol, midazolam or dexmedetomedine can be used.
• Airway anesthesia: Different options are available They include nerve blocks alone or combined with nebulization or use of atomizer (Enk fiberoptic atomizer set from Cook Co.) The latter is customized for “Spray-as-you- go” technique with intubation fiberscope. Nerve blocks include superior laryngeal nerve block and transtracheal injection of lignocaine. This can be supplemented by nebulization. Nerve blocks may be difficult/contraindicated in patients with short neck, thyroid swelling, neck contracture, obesity and in patients with partial airway obstruction or risk of aspiration.

Fiberoptic guided intubation need not be necessarily always performed under awake conditions. Alternately, general anesthesia with or without muscle relaxant can be used. This is particularly useful for training in a normal airway.

Figure 3: Airway Anaesthesia (Wearing gloves and using sterile technique is strongly recommended)

Techniques

The term fiberoptic guided airway management is preferred to fiberoptic intubation as the instrument, intubation fiberscope can be used for a) airway management other than intubation by different routes and techniques.

Role of intubation fiberscope in airway management

1. Endotracheal intubation
2. Confirmation of single and double lumen endotracheal tubes
3. Placement of Endobronchial tube and bronchial blockers
4. Diagnosis of airway pathology
5. Confirmation of positioning of a supraglottic airway device (SAD)
6. To assist percutaneous dilatational tracheostomy
7. To assist extubation
8. To assess vocal cord movement
9. Management of postop atelectasis by clearing of the secretions from the bronchi

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III Different ways endotracheal intubation can be accomplished with the help of intubation fiberscope

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1. Direct techniques: refer to techniques where the endotracheal tube is preloaded over the fiberscope and once the carina is visualized the tube is railroaded over the scope.

• Direct nasotracheal intubation: Conventionally the tube of appropriate size is loaded over the intubation fiberscope and the scope is passed into the trachea initially. This is referred to as “scope first” technique. Sometimes,
• Direct orotracheal intubation

1. Indirect techniques: refer to techniques where intubation is not done directly over the fiberscope, but the latter is used to identify the glottic opening or lower airway and also used to introduce an intubation aid. Subsequently endotracheal tube is passed over the intubation aid.

The intubation aids which can be used with a fiberscope are guidewire (through the working channel), bougie (by the side of fiberscope) and Aintree catheter or airway exchange catheter (both over the fiberscope). Yet another way of intubating using fiberscope by indirect technique is with a supraglottic airway devices.

Endotracheal intubation using these indirect techniques can be in two or three stages.

Figure 4: Two stage technique using supraglottic airway device. Easy to ventilate with SAD is not necessarily easy to intubate through fiberscope (see pic 3c, d and e)

Individual techniques:

Direct Nasotracheal intubation:

1. Prepare patient
2. Select appropriate size fiberscope: check for disinfection and integrity. The performer is expected to be familiar with the parts and use of fiberscope.
3. Lubricate the insertion cord, except the tip
4. Load the appropriate size and type of endotracheal tube
5. Choose the proper(wider) nostril
6. Pass the fiberscope under vision into the oral cavity through the nasopharynx. Identify the structures as you go on.
7. Look for epiglottis and underneath that the glottis opening. This will be helped by jaw thrust, pulling out tongue (both in unconscious or sedated patients) or by asking the patient to protrude the tongue out.
8. Enter the trachea and proceed further down the trachea till carina is visualized
9. Stabilize the fiberscope and railroad the endotracheal tube
10. While stabilizing the endotracheal tube, gently withdraw the fiberscope
11. Connect to breathing system and ventilate
12. Confirm with ETCO₂

Figure 5: various tip position of bronchoscope

Figure 6: avoid looping

Modifications:

• “tube first” instead of “scope first” approach. Conventionally the fiberscope is always advanced into the trachea first and then the tube is railroaded. However, when there is a difficulty in passing the scope through the nasopharynx, in spite of a gentle pressure. In this situations, the endotracheal tube can be passed into the oropharynx similar to blind intubation and then the fiberscope passed through that.
• Intubation fiberscope and the endotracheal tube can be passed through the two different nostrils, but it requires more experience.

Direct nasotracheal intubation may not be possible if the size of the endotracheal tube required and the fiberscope size do not match. Then different options are available, which form a part of what can be called indirect techniques.

• An Aintree catheter can be loaded on the fiberscope and it can be inserted into the trachea. Then the fiberscope is removed and the tube is loaded over the Aintree catheter.
• A guidewire can passed through the working channel and it is passed into the trachea through conventional technique described above. In the second step, an airway exchange catheter is passed over the guidewire to make it more rigid. In the third stage, an endotracheal tube is loaded over the airway exchange catheter into the trachea.

Direct Orotracheal intubation

• Prepare patient
• Select appropriate size fiberscope: check for disinfection and integrity. The performer is expected to be familiar with the parts and use of fiberscope.
• Lubricate the insertion cord, except the tip
• Load the appropriate size and type of endotracheal tube
• Anesthetize the patient and paralyze if required/ if not contraindicated. Orotracheal intubation can be done in awake state also.
• Insert a Berman or Ovassipian Airway Pass (fig – 6)
• Pass the fiberscope along the under surface of the tongue with a jaw thrust maintained
• Look for epiglottis and underneath that the glottis opening. This will be helped by jaw thrust,
• Enter the trachea and proceed further down the trachea till carina is visualized (fig – 7)
• Stabilize the fiberscope and railroad the endotracheal tube
• While stabilizing the endotracheal tube, gently withdraw the fiberscope
• Connect to breathing system and ventilate
• Confirm with ETCO₂

Figure 6: a. Berman airway b. Ovassipian Airway

Figure  7: a. epiglottis b. trachea

Fiberoptic guided techniques through a Supraglottic Airway Device:

This is performed either as a) primary technique in an anticipated difficult airway or b) as an alternate technique when there is an unanticipated difficulty in intubation.

Steps: Usually performed under anesthesia

1. Insert LMA under anaesthesia
2. Stabilize the patient in terms of ventilation, oxygenation and depth of anaesthesia
3. Load the fiberscope with appropriate size endotracheal tube. Special purpose made tube is used for intubating LMA.
4. Perform the procedure similar to the ortracheal intubation, described above.
5. In case the tube can’t be loaded over the fiberscope, a two stage technique using airway exchange catheter or Aintree catheter, as described above can be used