Journal of Clinical Neuroscience 16 (2009) 366–372

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Journal of Clinical Neuroscience

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Review

Awake fibreoptic intubation in neurosurgery

R.A. Langford b, K. Leslie a,b,*

a Department of Pharmacology, University of Melbourne, Melbourne, Australiab Department of Anaesthesia and Pain Management, Royal Melbourne Hospital, Grattan Street, Parkville, Victoria 3050, Australia

a r t i c l e i n f o

Article history:Received 9 April 2008Accepted 27 May 2008

Keywords:Endotracheal intubationGeneral anaesthesiaNeurosurgeryFibreoptic intubation

0967-5868/$ - see front matter � 2008 Elsevier Ltd. Adoi:10.1016/j.jocn.2008.05.020

* Corresponding author. Tel.: +61 3 9342 7000; faxE-mail address: kate.leslie@mh.org.au (K. Leslie).

a b s t r a c t

Optimal airway management by the anaesthetist is particularly critical in neurosurgical patients. Stan-dard intubation attempts may fail or have deleterious effects on cerebral dynamics so awake fibreopticintubation is often the most suitable option for tracheal intubation. This review gives the neurosurgeoninsight into why the anaesthetist may choose this method and what to expect if an awake fibreoptic intu-bation method is selected for the patient. The difficult airway is more frequently seen in hypophyseal andcraniofacial surgery and in acute and chronic cervical spine pathology. Current practice and evidence forthe use of the technique are reviewed and contraindications and complications discussed. A descriptionof a typical awake fibreoptic intubation method is given with reference to the neurosurgical implicationsof local anaesthesia, sedation and the autonomic and neurophysiological responses that may occur.

� 2008 Elsevier Ltd. All rights reserved.

1. Introduction

Optimal airway management by the anaesthetist is particularlycritical in neurosurgical patients. Intracranial pathology often re-sponds poorly to even short periods of hypoxia1 or raised intracra-nial pressure, and patients with cervical spine lesions aresusceptible to both primary and secondary neurological injury dur-ing intubation. Conventional laryngoscopy is associated with agreater hypertensive response than awake fibreoptic intubation2

and can compromise cerebral dynamics in the setting of raisedintracranial pressure.3 In addition, airway management can bemore difficult in neurosurgical patients. Certain neurologicalpathology predisposes to difficult tracheal intubation, for example,in patients presenting for transphenoidal or spinal surgery. The useof fibreoptic tracheal intubation in the awake patient is probablythe safest option for intubating the neurosurgical patient with adifficult airway. However, this procedure is not without its ownrisks and is not the best technique in every situation.

Fibreoptic intubation is not uncommon in neurosurgery; thespecialty accounted for 17% of fibreoptic intubations in a reviewof 1612 cases, second only to ear, nose and throat surgery.4

There is little consensus on the definitions of the terms ‘‘difficultairway” and ‘‘difficult intubation”. We consider the AmericanSociety of Anesthesiologists’ definition of the difficult airwayacceptable: ‘‘the clinical situation in which a conventionallytrained anesthesiologist experiences difficulty with face mask ven-tilation of the upper airway, difficulty with tracheal intubation, or

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: +61 3 9342 7802.

both”.5 Difficult intubation has been defined in several waysincluding outright failure, Cormack and Lehane grade 3 or 4 laryn-goscopy, the need to use specialist equipment, more than 2 at-tempts or greater than 10 minutes of trying to intubate.6 Thelack of consensus for these definitions has obvious implicationswhen comparing airway-related studies and trials.

This review is intended to provide a practical focus for the clin-ical neurosurgeon into the practice of fibreoptic intubation andconfer a greater understanding of the factors considered by theanaesthetist when selecting this intubation technique. We describeneurosurgical and patient factors that may necessitate an awakeintubation and situations where awake intubation would not beappropriate. We hope to equip the neurosurgeon with the meansof predicting a difficult airway, so that they can inform their anaes-thetist early. Finally, we describe a technique for awake fibreopticintubation, with specific reference to topical airway anaesthesia,and discuss the neurosurgical implications for the patient.

2. Indications for awake fibreoptic intubation

2.1. Surgical factors

2.1.1. Cranial surgeryDifficult intubation has a reported incidence of 10% to 15% in

patients with acromegaly,7–9 compared to an incidence of around2% in the general surgical population.10 Historically, routine tra-cheostomy has even been advocated prior to surgery in these pa-tients.11 Several features associated with acromegaly cancontribute to a more difficult intubation: hypertrophy of the facialbones including the mandible, marked prognathism, macroglossia

R.A. Langford, K. Leslie / Journal of Clinical Neuroscience 16 (2009) 366–372 367

and hypertrophy of the lips and epiglottis, redundant pharyngealmucosa, stiff or partially paralysed vocal cords and narrowing ofthe subglottic area. Patient gender and tumour size do not affectthe incidence of difficult intubation.8 Acromegaly is also associatedwith a reduced cervical spine movement (e.g. one study of 128acromegalic patients found that 5% had reduced neck mobility).7

Of particular concern is that patients with acromegaly are morelikely to present with an unanticipated difficult laryngoscopy whena standard laryngoscope is used. The Mallampati score is a pre-operative airway screening test frequently used by anaesthetists.12

With the patient sitting and their mouth open as wide as possible,the airway is assigned a score between 1 and 4, depending uponthe degree of visibility of oral and pharyngeal structures. In gen-eral, scores of 1 and 2 (posterior pharyngeal wall visible includingall or part of the uvula) are usually associated with an easier viewat intubation.13,14 A review of 121 acromegalic patients revealedthat 10% were difficult to intubate. Of these, half had a Mallampatiscore of 1–2 (i.e. they should be easy to intubate according to theMallampati criteria).8

Nevertheless, pre-operative assessment is still of great value asa history of hoarseness, stridor and obstructive sleep apnoea (OSA)suggest periglottic or subglottic involvement. OSA, an independentrisk factor for difficult intubation, occurs in up to 70% of patientswith acromegaly.15 A history of prior difficult intubation shouldalways be taken seriously, as a difficult airway can become anunmanageable one as acromegaly progresses.

The transphenoidal surgical approach used for hypophysectomyin acromegalic patients prevents the use of a nasal endotrachealtube. Fibreoptic intubation, if indicated, will be required to takean oral route. There is no absolute indication for awake intubationin these patients and the conservative anaesthetist may elect tointubate all acromegalic patients in this manner. In practice, mostanaesthetists will evaluate the patient with particular regard to theaforementioned risk factors and make a clinical judgement basedon their own experience and skill. We could not find any publishedsurveys of current practice in this respect.

Patients with Cushing’s disease and non-functioning pituitarytumours do not appear to have an increased incidence of difficultintubation. This is despite a 20% to 30% incidence of OSA, centrip-etal obesity and fat deposits around the face typically found inCushing’s disease.16 Hypogonadism has been associated with anincreased incidence of unanticipated difficult intubation17 due toa narrower than expected tracheal diameter, but the laryngealview on laryngoscopy is not considered more difficult thannormal.

Pseudoankylosis of the temporomandibular joint can lead tosignificantly impaired mouth opening following temporal craniot-omy, with resultant difficulty in tracheal intubation.18 Pseudo-ankylosis is distinguished from true ankylosis in that the formerhas an extra-articular aetiology not related to the joint itself. Assuch, the capacity for forward subluxation of the jaw is generallymaintained in pseudoankylosis.19 It is due to contracture of thetemporalis muscle, either from the formation of connective scartissue or a Volkman’s ischaemic process, rather than muscle spasm.The degree of mouth opening may not increase after the adminis-tration of neuromuscular blocking drugs, so awake fibreoptic intu-bation has been advocated in such patients.19 The incidence ofpseudoankylosis in one study was 33% at 2 weeks and 20% at 12months post-surgery.18 The condition usually resolves over time;however, in some patients limited mouth opening may persistfor several years following surgery.20 Similarly, patients may havereduced jaw movement after skull base surgery when a transtem-poral surgical approach has been used.20 Inadequate jaw move-ment in recovering patients, especially if there is a compromisedlevel of consciousness, may result in contracture and shorteningof the temporalis muscle.

2.1.2. Craniofacial surgeryPatients with craniofacial abnormalities and associated difficult

intubation usually present for surgery in childhood, usually withsynostosis of cranial sutures. Intubation difficulty may relate tothe oral cavity itself (e.g. Pierre–Robin syndrome where difficultiesimprove with age as the jaw grows) or due to cervical spine pathol-ogy, such as fusion of cervical vertebrae (common in Goldenhar,Apert and Crouzon syndromes).

When considering patients with craniofacial tumours, carefulpre-operative imaging and consultation between the neurosurgeonand anaesthetist is required. Fibreoptic intubation may be thetechnique of choice in patients requiring a midline transfacial sur-gical approach as tumours of epithelial origin can significantlyimpair the view otherwise obtained during conventional laryngos-copy.21 However, awake fibreoptic intubation may not be thesafest approach. Obstructing laryngeal tumours can present aseverely abnormal upper airway that can be difficult to intubateconventionally. It can be difficult to provide adequate topicalanaesthesia and the fibreoptic endoscope itself can lead to com-plete airway obstruction – the ‘‘cork-in-a-bottle” effect.

Facial trauma needs careful consideration by the anaesthetistwhen determining the safest way to secure the airway. As wellas facial swelling, laryngotracheal injury and an obscured pharynxfrom swelling, blood or vomitus,22 two large reviews of patientspresenting with facial fractures indicated that the incidence ofcoexisting cervical spine injury was between 1.8% and 6.7%.23,24

Awake intubation is rarely used as a first-line approach in trau-ma;22 however, it can have unique advantages. Case reportsfollowing trauma include a transorbital intubating approach25

and awake fibreoptic intubation following a penetrating facialinjury with a crossbow bolt, in situ.26

2.1.3. Spinal surgeryThe awake fibreoptic approach is a reliable intubation tech-

nique in patients with acute and chronic cervical spine lesions.27

Cervical spine pathology such as ankylosing spondylitis, osteo-arthritis or advanced rheumatoid arthritis may result in an immo-bile stiff neck. An extreme example of this is seen with patients inhalo traction (upper airway access is an additional problem).

The second issue in spinal surgery concerns patients with anunstable spine, or where flexion or extension of the neck may re-sult in deterioration of neurological function such as patients withspinal tumours or following trauma.

One of the perceived advantages of awake intubation in cervicalsurgery patients is that a neutral neck position can be maintainedwhile securing the airway. A cadaveric study examining cervicalspine movement during six airway management techniques foundthat a destabilised C3 segment was least displaced with nasal fibre-optic tracheal intubation.28 Laryngeal reflexes are maintained dur-ing the procedure, which allows for continuous spontaneousventilation in patients where airway obstruction would be partic-ularly difficult to manage. Normal cervical muscle tone can splintthe damaged spine to provide additional protection,29 althoughthere is little evidence to support this. Once the airway has beensecured, a neurological assessment can ensure there has been nosecondary injury. A further advantage is that the neurosurgeoncan optimally position the patient for surgery prior to generalanaesthesia. Conventional laryngoscopy is often not possible there-after without moving the neck. Table 1 summarises the perceivedadvantages of awake fibreoptic intubation in spinal surgery.

Rheumatoid arthritis has a prevalence of 0.3% to 1.5% in theUSA. Estimates of cervical joint involvement, more commonlyfound in male patients, vary between 15% and 86%.30 The most fre-quent abnormality is anterior atlanto-axial subluxation. This isexacerbated by neck flexion, so direct laryngoscopy, which in-volves C1–C2 extension, has been advocated as an acceptable

Table 1Advantages of awake fibreoptic intubation in spinal surgery

Neutral head position is maintainedCervical muscle tone is preservedPost-intubation neurological assessment can be madePatient can be positioned prior to general anaesthesiaVisualisation of the larynx is still possible with an immobile spine

Table 2Patient factors indicating potentially difficult intubation

General indicatorsPrevious difficulty in securing the airwayA high aspiration riskCardiovascular instability when laryngoscopy is likely to be difficultContraindication to muscle relaxants (e.g. suxamethonium and high aspiration

risk)Inability to access the cricoid area if there were failure to intubate or oxygenateHistory of obstructive sleep apnoeaObesitySyndromesMucopolysaccharidoses - mostly in children, but can be present in adult patients

(e.g. Hurler-Scheie, Hunters, Maroteaux, Morquio)Oropharyngeal pathologySmall mouth (e.g. connective tissue disorders)Retrognathic - may be independent or part of an associated syndromeOral tumourOral traumaPrevious oral radiotherapy or surgeryTemporomandibular joint disease, including rheumatoid arthritis, trauma or

abscessNeck pathologyLimited mobility (e.g. seronegative arthritis, prior surgery)Instability (e.g. rheumatoid, Down syndrome, atlanto-axial subluxation, trauma)

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technique.30 Posterior atlanto-axial subluxation is uncommon andvertical atlanto-axial subluxation, observed in 10% to 20% of pa-tients, requires maintenance of a neutral head position. In thesesituations, a fibreoptic intubation technique is indicated. Subaxialsubluxation occurs in 10% to 20% of rheumatoid patients, most fre-quently at the C5–C6 level and can be managed in a similar mannerto traumatic cervical spine injuries. If the lesion cannot be fullyevaluated prior to anaesthesia, it is dangerous to assume stabilityof the cervical spine and an awake fibreoptic approach would beprudent.30

As rheumatoid disease progresses, ankylosis of the cervicalspine can occur, limiting neck movement. The emphasis shifts fromthe need to protect an unstable spine to the technical difficulties ofintubating the trachea of a patient with a fixed spine. Fibreopticintubation is strongly indicated. A study of 128 rheumatoid ar-thritic patients undergoing spinal surgery suggested a lower inci-dence of post-extubation stridor in patients receiving fibreopticintubation,31 thought to be due to a reduction in soft-tissuetrauma.

Difficult airway management is anticipated in trauma to thecervical spine. In a study of over 34,000 patients presenting withblunt trauma, cervical spine injuries were reported in 2.5%.32 Themost frequent level for fractures was C2 (24%) and for dislocationswas C5–C6 and C6–C7. Fractures of the vertebral body were themost frequent.

Optimal management of the airway in cervical spine trauma iscontroversial. Several techniques are advocated for tracheal intu-bation including direct laryngoscopy with manual in-line stabilisa-tion,33 cricothyroidotomy,34 use of the intubating laryngealmask,35,36 use of a lighted stylet37 and variations of a traditionallaryngoscope.38 In a study of 50 patients, difficult laryngoscopy(as defined by Cormack and Lehane grade 3 or 4) was reported in22% of patients stabilised with manual in-line immobilisationand in 64% of patients with collar, tape and sandbag immobilisa-tion.39 Despite the theoretical advantages of reduced cervical spinemovement when fibreoptic intubation is used, it has been difficultto realise this benefit clinically. The anaesthetist’s preference forawake fibreoptic intubation in cervical spine disease is evident. Itwas the preferred technique for patients with stable cervical spinedisease in a survey of 452 American Society of Anaesthesiologymembers.40 In another survey of 833 members of the CanadianAnesthesiologists’ Society, 67% preferred awake fibreoptic intuba-tion when presented with a patient with cervical cord compressionfor discectomy.41 Similarly, 78% of 472 members of the AmericanSociety of Anesthesiology expressed a preference for awake fibre-optic intubation in patients with cervical spine injury.42

In practice, small retrospective observational studies indicatevarying thresholds for awake fibreoptic intubation in cervical spineinjured patients.43 One of the key features of these studies is that,despite the variability in choice of airway management, the overallincidence of secondary cervical injury attributable to intubation isvery small. In an observational study of 327 patients with cervicalspine disease, 39% were intubated using an awake fibreopticapproach.29 Anaesthetists were more likely to use this techniqueif patients had myelopathy, unstable or fractured vertebrae orspinal canal stenosis. The authors consider these criteria suitablefor the use of awake fibreoptic intubation.

Neurological function can deteriorate following conventionaltracheal intubation after cervical spine injury.44,45 However, evenin these cases, it has been difficult to confidently attribute theinjury to the intubation. There are no published data to suggestthat awake fibreoptic intubation improves outcome in cervicalspine injured patients, compared to other intubation methods.Awake fibreoptic intubation may even be detrimental if attemptedby those without the necessary skills. Complete airway obstructionhas occurred during the fibreoptic intubation of two awake pa-tients with cervical spine injury.46

2.2. Patient factors

Non-neurosurgical reasons for awake fibreoptic intubation areoften related to the technical difficulty associated with conven-tional laryngoscopy. In patients at risk of aspiration of gastriccontents, preservation of the airway reflexes is advantageous ifrapid sequence induction is not possible. In addition, awakeintubation can produce less variability in cardiovascular parame-ters than standard anaesthetic induction if multiple or prolongedlaryngoscopy attempts are anticipated.47 The patient factorsassociated with a potentially difficult intubation are outlined inTable 2.

3. Contraindications to awake fibreoptic intubation

Strong contraindications to awake fibreoptic intubation includepatient refusal, allergy to local anaesthetic drugs and anticipatedlack of patient cooperation.

Blood in the airway will obscure the view during fibreopticintubation and can make effective topical anaesthesia difficult.Many anaesthetists would consider skull base fracture a contrain-dication to nasal intubation, although fibreoptic intubation is prob-ably safer than the blind placement of nasal tubes because the tubecan be guided through the nasopharynx under direct vision. Sincecoughing during the procedure is common, some anaesthetistsconsider raised intracranial pressure and penetrating eye injuryas relative contraindications.47

Stridor signifies airway narrowing and topicalisation of theairway or coughing can result in complete airway obstruction.48

Patients with airway tumours require careful evaluation asdiscussed previously. Contraindications are summarised in Table 3.

Table 3Contraindications to awake fibreoptic intubation

Patient refusalCombative patientReduced level of consciousnessHeavy airway soilingAllergy to local anaestheticStridor or impending airway obstructionRaised intracranial pressure (relative)Penetrating eye injury (relative)

Fig. 1. Nebulised lignocaine (4%) is used to anaesthetise the upper airway.

Fig. 2. The nose is anaesthetised using Cophenylcaine� Spray, a combinedpreparation of phenylephrine and lignocaine.

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The number of alternative airway devices available to anaesthe-tists has increased in recent years and alternatives to an awakefibreoptic intubation depend on the individual circumstances. Op-tions include classic rapid sequence induction (with the plan towake the patient if there is failure to secure the airway), inhala-tional (or gas) induction, use of alternative airway devices (e.g.the intubating laryngeal mask, Combitube or Bullard laryngoscope)or the pre-operative establishment of a tracheal stoma under localanaesthetic.

4. The technique of awake fibreoptic intubation inneurosurgical patients

4.1. Basic requirements

A cooperative patient is essential for this procedure and a fullexplanation of the technique to the patient is required. Awakefibreoptic intubation is unsuited to combative patients or for thosewith a reduced level of consciousness, such as for patients with se-vere head injury. Properly conducted awake intubation takes time:a study of 58 patients scheduled for cervical spine surgery under-going awake fibreoptic intubation revealed a mean intubation timeof 16 minutes including provision of airway anaesthesia.49

Another basic requirement is for the anaesthetist to have anadequate skill level. In a survey of 452 of American Society ofAnaesthesiology members conducted in 2003, only 59% reportedskill in the use of a bronchoscope,40 and some anaesthesia trainingschemes still define awake fibreoptic intubation as an additionalskill, rather than an essential one.50 More courses are beingprovided for trainees and specialists and the general level ofproficiency is increasing.51

4.2. Nasal or oral approach

The first step is to select either a nasal or an oral approach.Anaesthetists often find nasal fibreoptic intubation technically eas-ier, as there is a less acute angle to negotiate with the broncho-scope in the nasopharynx, compared to the oral approach. Onextubation, a nasal tube is generally better tolerated than an oralone, as the gag reflex is less likely to be provoked,52 so surges inintracranial pressure and arterial blood pressure are less likely.The endotracheal tube can also be left in the nasopharynx as anasopharyngeal airway until the full airway reflexes have returned.Nasal intubation is not always possible, for example, in pituitary orcraniofacial surgery or when the nares are not patent, and epistaxiscan be a problem. An oral endotracheal tube is used in suchsituations.

4.3. Airway anaesthesia

There are many safe and effective ways of achieving suitableairway topical anaesthesia and endotracheal intubation. We out-line just one method, simply to give neurosurgeons an idea of atypical sequence of events. Whichever methods are chosen, ade-

quate airway anaesthesia is the key to successful awake intubationand should not be rushed.

4.3.1. NasopharynxNebulised 4% lignocaine (about 4 mL) is administered first, to

provide some topical anaesthesia to the entire airway (Fig. 1). Thenthe nasopharynx is anaesthetised. The sensory innervation of thenasal cavity is by the trigeminal nerve. The anterior ethmoidalnerve is responsible for the anterior nose, while the posterior nasalcavity is innervated by branches of the maxillary nerve.53 Thepharynx is predominately innervated by the glossopharyngealnerve. A combined preparation of phenylephrine and lignocaine,such as Cophenylcaine�, instilled via the chosen nostril (usuallythe one the patient can ‘‘sniff” through the best) will provide bothtopical anaesthesia and vasoconstriction, lessening the likelihoodof epistaxis on passage of the endotracheal tube (Fig. 2). Cocainepaste will have a similar dual effect, although its use has declinedin recent years due to associated cardiac arrhythmia and myocar-dial infarction.54 Further nasal anaesthesia can be achieved bythe use of incremental sizes of nasopharyngeal airways coated lib-erally with 2% lignocaine paste. For an adult, one might start with asize 6 and then work up to a 7.5.

4.3.2. OropharynxMost of the oropharyngeal sensation is provided by the glosso-

pharyngeal nerve.53 Adequate topical anaesthesia can often be pro-vided by 3–4 actuations of 10% lignocaine spray. Care should be

370 R.A. Langford, K. Leslie / Journal of Clinical Neuroscience 16 (2009) 366–372

taken in the use of 10% lignocaine spray, as each press of the spraywill deliver 10 mg lignocaine. Further analgesia may be providedby 2–3 mL of 4% lignocaine via a mucosal atomiser device, localanaesthetic gargle or the use of local anaesthetic throat lozenges.

4.3.3. Larynx and tracheaSensory innervation to the larynx and trachea is from branches

of the vagus nerve. The internal branch of the superior laryngealnerve supplies the area above the vocal cords and the recurrent lar-yngeal nerve supplies the cords and below. Cough receptors in thelarynx and trachea also receive fibres from the vagus nerve.53 Top-ical anaesthesia of the infraglottic larynx can be achieved by inject-ing local anaesthetic agents directly into the trachea. Thecricothyroid membrane is punctured with a 25-G needle and2 mL to 3 mL of 4% lignocaine is injected directly into the airway(Fig. 3). This procedure is often associated with powerful coughingafter injection (which promotes subglottic anaesthesia) but doesnot usually provide adequate anaesthesia above the vocal cords.Further laryngeal anaesthesia can be achieved using a ‘‘spray-as-you-go” technique. Lignocaine (1 mL of 2%) is drawn up into a10 mL syringe, with 9 mL of air. This is then rapidly injected downthe suction port of the scope when the tip is positioned directlyover the larynx. The air serves to force all of the local anaestheticthrough the port of the scope and ensures maximal dispersion.Adequate airway anaesthesia is often heralded by changes in vocaltone. There are many descriptions of methods for blocking theindividual sensory laryngeal nerves. When individual nerve block-ade was compared with topical anaesthesia in neurosurgical pa-tients, there was no significant difference in time taken andsimilar physiological parameters were observed between groups.The authors did observe that the total lignocaine dose was twotimes greater if topical anaesthesia was used.55

4.4. Airway anaesthesia in neurosurgery patients

One of the difficulties of topical airway anaesthesia is determin-ing how much local anaesthetic is absorbed systemically from themucosa. The total dose of local anaesthetic agent given during thetopicalisation of the airway is high. Lignocaine doses of up to15 mg/kg have been studied with no systemic signs of toxicity,although in some patients plasma concentrations above the toxicthreshold have been recorded.56,57 The implications of this forthe neurosurgeon are two-fold. First, lignocaine toxicity is a possi-bility, with associated cardiovascular instability and neurotoxiceffects, including loss of consciousness, agitation and seizures.Second, there will be a significant impact upon the dose of local

Fig. 3. A transtracheal injection of lignocaine (2%) is made through a 22-Gintravenous cannula.

anaesthetic agent available for the neurosurgeon to administerduring surgery.

4.5. Endotracheal intubation

Once the airway is adequately anaesthetised, an endotrachealtube is threaded onto the lubricated fibreoptic bronchoscope. Ifthe nasal route is used, the scope is passed along the floor of thenasal cavity and directed inferiorly behind the soft palate (Fig. 4).The larynx will usually come into view and, at this point, furthertopical anaesthesia can be administered directly onto the larynxthrough the suction channel of the scope. The bronchoscope is thenadvanced into the trachea and, once the position is confirmed, theendotracheal tube is gently introduced into the trachea over thescope. Passage through the nasal cavity can be facilitated by ade-quate tube lubrication and softening of the tube in a flask of warmwater. In a large review, the rate of epistaxis requiring suction witha similar technique was 1.3%.4

For the oral intubation, an additional airway device is usuallyrequired as the oral cavity is larger than the nasal cavity and bitingon the scope can be a problem. The Berman and Ovassapian air-ways are devices that facilitate the passage of a fibreoptic scopeand endotracheal tube through the mouth. The endoscope ispassed through the airway to the back of the oral cavity and turnedinferiorly such that the operator can visualise the glottis.

Fig. 4. The operator may stand behind or in front of the patient to commencefibreoptic intubation.

Table 4Complications of awake fibreoptic intubation in neurosurgical patients

Increased intracranial pressureHypertensionHypotensionPatient movementTime consumingOver-sedationUnder-sedationLocal anaesthesia toxicityFailureEpistaxis

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4.6. Fibreoptic endotracheal intubation in neurosurgical patients

Inadequate airway analgesia prior to intubation will make theprocedure technically difficult and can cause significant rises inblood pressure and heart rate. This may be relevant to patients withcerebral aneurysms, where meticulous attention to perioperativehaemodynamics is important. Patients with arteriovenous malfor-mations seem at less risk than aneurysms in this respect.58 Withsufficient topical anaesthesia, hypertension is not necessarily aproblem. A study of 70 patients that compared conventional laryn-goscopy to awake fibreoptic laryngoscopy demonstrated a meandecrease in blood pressure of 9 mmHg in the group receiving fibre-optic intubation compared to an arterial pressure rise of 35 mmHgin patients receiving conventional laryngoscopy.2

Changes in intracranial pressure are of particular concern inpatients with poor intracranial compliance. The effects of fibreopticlaryngoscopy after topical anaesthesia have not been investigated,but fibreoptic bronchoscopy, a more invasive procedure, is associ-ated with a sustained rise in intracranial pressure. This was not ab-lated by midazolam, morphine or 3 mL of 4% nebulised lignocaine inone study.59 It is difficult to extrapolate these results to the morethoroughly anaesthetised airway encountered in fibreoptic laryn-goscopy. Surges in intracranial pressure have been reported duringthe Valsalva manoeuvre60 and, since coughing is likely during awakeintubation, this could have implications on cerebral perfusion.

A retrospective analysis of 1612 patients receiving fibreopticintubation cites a failure rate of 1.5%. The most frequent reasonscited were a lack of visualisation of the glottis and inability to passthe tube itself through the nose or vocal cords.4

4.7. Sedation

‘‘Awake intubation” is a misnomer, as many anaesthetists findthat patients tolerate ‘‘awake” intubation better under some seda-tion. Careful consideration should be given to the pros and cons ofproviding sedation in neurosurgery patients. Sedation can providea more tolerable experience for the patient, which is especiallyimportant if multiple procedures are required or the patient is par-ticularly anxious. Sedation can also reduce patient movement ifused appropriately. However, there are disadvantages: it can leadto hypoventilation, with resultant hypoxia and hypercarbia or air-way obstruction as a result of overdose. Many sedative agents,such as propofol, have a vasodilatory action at higher doses, result-ing in hypotension, which will affect cerebral perfusion in the set-ting of raised intracranial pressure. Sometimes patients canbecome disinhibited under sedation, leading to patient movementand potential secondary insult to unstable injuries. An ideal agentshould be predictable, short-acting, titratable and reversible. A lowdose propofol infusion or remifentanil infusion can be useful in thisrespect. Although remifentanil is not considered a hypnotic (it is apure opioid receptor agonist), it has the added benefit of bluntingthe laryngeal reflexes resulting in less coughing and improvedintubation conditions.61 A study that compared these two agents

found intubation conditions, endoscopy times and patient toler-ance scores to be better in the remifentanil group, despite a higherincidence of recall.62 The therapeutic windows for both theseagents are narrow, so care should be taken when using them, espe-cially on patients where airway difficulties are anticipated. Table 4summarises the complications associated with awake fibreopticintubation.

5. Conclusion

There are many reasons why the anaesthetist may choose anawake fibreoptic intubating technique for the neurosurgical pa-tient. Conditions such as acromegaly and rheumatoid arthritiscan make conventional intubation difficult or increase the risk ofsecondary injury. There are few absolute indications for awakeintubation and many areas where the theoretical advantages ofawake intubation have not been validated, such as in cervical trau-ma. Despite this, awake fibreoptic intubation is still the preferredmethod for intubation in cervical injury for most anaesthetists.Complications and undesirable effects are still possible with thetechnique and may be related to airway anaesthesia, the passageof the scope through the airway or patient sedation. The procedureitself is reliable in trained hands and through careful patient selec-tion, adequate topical anaesthesia and judicious use of sedation, isa safe method for securing the airway when conventional laryn-goscopy is likely to fail.

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