AWAKE FIBER-OPTIC BRONCHOSCOPY

DR. MANISHA

MODERATOR-DR. MAMTA SHARMA

Introduction Providing anesthetic care to the patient with

a difficult airway provokes anxiety as well as interest in anesthesiologist’s mind.

In the situation where the airway must be controlled and anesthesia must be delivered via an endotracheal route, intubation through the use of a flexible fiberoptic bronchoscope is a commonly chosen method.

INDICATIONSdiagnostic purpose: To visualize and to observe the lesions of the

tracheobronchial tree To collect specimen for biopsy and culture (e.g. by curettage or

brushing

For therapeutic purpose: For Endotracheal Intubation To remove foreign body in the tracheobronchial tree by forceps

or baskets To remove malignant tumors by laser (laser

photoresection) To frozen surface skin lesion (e.g. cryotherapy) To destroy malignant tumors by radiation (e.g. brachytherapy),

by electricity (e.g. electrocautery) or by chemicals (e.g. photodynamic therapy)

WHY WE ANESTHESIOLOGIST’S NEED IT Difficult airways !!

1. small mouth 2. Receding jaw3. Reduced mouth opening due to radiation therapy4. Jaw fracture5. Previous head and neck surgery6. Difficulty in neck extension due to prior cervical fusion or advanced

osteoarthritis7. Neck extension is contraindicated in patients with unstable cervical

spines due to fx., rheumatoid arthritis, Down syndrome, etc.8. Patients who cannot be intubated using direct laryngoscopy due to

anatomical variations, even though their airway exam appears normal.

Eyepiece

Control knob

Working channel

Video connection

Biopsy port with cap

Suction port

Insertion tube

Light source and camera

Light transmitting glass fiber bundle

Viewing glass fiber bundle

WORKING PRINCIPALTransmission of light in bronchoscope is based on total

internal reflectionWhen light is incident upon a medium of lesser index of

refraction (ni>nt), the ray is bent away from the normal. such reflection is commonly called "internal reflection"

The exit angle will then approach 90° for some critical incident angle θc, and for incident angles greater than the critical angle there will be total internal reflection

For fiberoptic bronchoscope, images are brought back to eyepiece using this principle

Innervation of the Airway The airway is divided into:1. Nasal cavities2. Oral cavities3. Pharynx ( consisting of the naso-, oro-, and

hypopharynx)4. Larynx5. Trachea

Innervation of the Airway –Nose - The nasal cavity is entirely innervated by fibers

carried by branches of the trigeminal nerve.

PHARYNX- Mainly innervated by glossopharyngeal nerve

LARYNX –

1. The superior laryngeal nerve dividing into internal and external branch

2. Recurrent laryngeal nerve

The airway reflexesThe aforementioned nerves participate in

several brainstem-mediated reflex arcs.1.gag reflex – triggered by mechanical and chemical

stimulation of areas innervated by the glosso-pharyngeal nerve, and the efferent motor arc is provided by the vagus nerve and its branches to the pharynx and larynx.

2.glottic closure reflex – elicited by selective stimulation of the superior laryngeal nerve, and efferent arc is the recurrent laryngeal nerve.– exaggeration of this reflex is called laryngospasm.

3.cough – the cough receptors located in the larynx and trachea receive afferent and efferent fibers form the vagus nerve.

Preprocedural preparation of the patient Check emergency medication/ equipment

Explanation

Sedation

Anti-sialagogue

Remove artificial denture

Explanation

1.The reasons for proceeding with an awake fiberoptic intubation

2.The potential complications3.The type of airway anesthesia that will be

provided4.Possible alternatives to the proposed

anesthetic

SedationAdequate sedation is important and

advantageous in both the anesthetizing of the airway as well as during the intubation.

A calm and comfortable patient is much more likely to cooperate with the anesthesiologist during the procedures.

Agents used to produce sedation generally fall into 2 group: benzodiazepines and opioids.

Anti-sialagoguesDecreasing oral secretions will aid in the

placing and effectiveness of topical agents.Fiberoptic intubation is much easier if excess

secretions are not obscuring the operator’s view.

For these purpose, glycopyrrolate is the one that is most commonly used due to its lack of CNS effects and relatively lesser likelihood of producing tachycardia.

Commonly Used Medications and DosagesWith Their Reversal Agents

MedicationDosage and

RouteEffect

Reversal Agent

Atropine0.5–1 mg IV,

IMAntisialogogue N/A

Glycopyrrola

te

0.2–0.4 mg IV, IM

Antisialogogue N/A

Dexmedetomidine

Loading dose: 1 mcg/kg/min over 10 min Infusion: 0.2–

0.7 mcg/kg/min

Sedative N/A

Midazolam 0.5–4 mg IV Sedative Flumazenil

Fentanyl 10–100 mcg IV Opioid Naloxone

Alfentanil100–1000 mcg

IVOpioid Naloxone

Local anesthetics There are three most often used local

anesthetic with or without the use of vasoconstrictors:

1. Cocaine2. Benzocaine3. Lidocaine +/- vasoconstrictors

Goals of anesthesia before FOB

To decrease the mucosal

senstivity

To obtund the airway reflexes

Anesthesia For Awake IntubationAnesthesia of the Nasal Mucosa and

Nasopharynx (Nasal Intubation)· SPHENOPALATINE GANGLION and

ETHMOID NERVE Anesthesia of the Mouth, Oropharynx

and Base of Tongue · GLOSSOPHARYNGEAL NERVE BLOCK · SUPERIOR LARYNGEAL NERVE BLOCK Anesthesia of the Hypopharynx, Larynx

and Trachea · RECURRENT LARYNGEAL NERVE BLOCK

Anesthesia of the Nasal Mucosa and NasopharynxDrugs: 4% Lidocaine with epinephrine (or

cocaine is a 4% solution – max. 200 mg in adult), or mixture of Lidocaine 3%(max dose 4-5mg/kg without epinephrine and 6-7 mg/kg with epinephrine) and Phenylephrine 0.25%

Patient Position: Patient is most comfortable when

head of bed is elevated approximately 30 degree

Technique: *Application of long cotton-tipped applicators or wide cotton string threaded pledgets soaked in the local solution

one applicator is placed along the inferior turbinate to the posterior nasopharyngeal wall

a second applicator is placed in a cephalad angulation along the middle turbinate, back to the mucosa covering the sphenoid bone (most important )

a third applicator may be placed along the superior turbinate, resting against the cribiform plate and posterior nasopharyngeal wall, providing anesthesia to the anterior ethmoid nerve

applicators are then left in place for 5 minutes, and the pledgets for 2-3 minutes

nasal airways, in increasing sizes, can be lubricated with Lidocaine 2-5% jelly, and passed into the nostril being intubated for additional patient comfort

Anesthesia of the Mouth and OropharynxDrugs: Cetacaine spray (mix of 14%

Benzocaine and 2% Tetracaine), Lidocaine spray 10% ( max 200mg or 20 spray), Lidocaine gel 2-5%, Viscous lidocaine 2%, Tetracaine .5% soln, Lidocaine 4% soln.

Patient Position: SupineTechniques: 1. Non-invasive2. invasive

NON INVASIVE TECHNIQUESLidocaine gel can be placed on tongue blade and

patient "sucks" on this for several minutes4cc of 4% Lidocaine or 0.5% Tetracaine can be

placed in a nebulizer. The patient then inhales the nebulized local anesthetic for 5-7 min, or the tongue and posterior pharynx are sprayed with the atomizer

Cetacaine spray (tetracaine and benzocaine combination) may also be used to provide anesthesia to the tongue and posterior pharynx.

I. toxic dose of benzocaine - 100 mg II. toxic dose of Tetracaine - 100 mg (but toxicity has been reported at

40 mg).

Viscous lidocaine 2-4 ml may also be used as a gargle (swish and swallow) for approx. 30 sec.

INVASIVE TECHNIQUES

GLOSSOPHARYNGEAL NERVE BLOCK is performed when topical techniques are not completely effective in obliterating the gag reflex.

This is performed with the anesthetist standing contralateral to the side to be blocked and the patient’s mouth wide open

The palatopharyngeal fold (posterior tonsillar pillar) is identified and a tongue blade, held with the non-dominant hand, is introduced into the mouth to displace the tongue medially (contralateral side) creating a gutter between the tongue and the teeth

A 25 G spinal needle is inserted into the membrane near the floor of the mouth at the base of the cul-de-sac and advanced slightly (0.25-0.5 cm).

aspiration test is performedIf air is aspirated, the needle has passed

through the membrane (through and through). If blood is aspirated, the needle is redirected

more medially. 2 ml of 1% Lidocaine can be injected into the

anterior tonsillar pillar 0.5 cm lateral to the base of the tongue blocks the lingual branch

This block is painful, may result in a persistent hematoma. Methemoglobinemia – occurs when the ferrous molecule in

hemoglobin is changed to its ferric state with essentially ionic bonds by oxidation

SUPERIOR LARYNGEAL NERVE (SLN) BLOCK

Drugs: 2-4 ml of Lidocaine 1% or 2% lidocaine, with or without epinephrine

Patient Position: Supine, with head slightly extended

Techniques:  (Non-invasive) Patient is asked to open the mouth widely, and the

tongue is grasped using a guaze pad or tongue blade. A right angle forcep (e.g., Jackson-Krause) is covered with anesthetic-soaked guaze and is slid over the lateral tongue and down into the pyriform sinuses

Cotton swabs are held in place for 5 minutes

Depicting the Vagus nerve branching into Superior Laryngeal and Recurrent Laryngeal nerve.

Note the insertion of Superior Laryngeal Nerve into ThyroHyoid Membrane

Tracheal anatomy depicting Superior Laryngeal Nerve with ascending and descending branches.

Invasive position - ipsilateral side of the neck Technique- The cornu of the hyoid bone is palpated

transversally with the thumb and the index finger on the side of the neck immediately beneath the angle of the mandible and anterior to the carotid artery.

To facilitate its identification, the hyoid bone is displaced toward the side being blocked.

One hand displaces the carotid artery laterally and posteriorly.

With the other hand, a 22 or 23 guage - 25 mm needle is "walked off" the cornu (cartilage) of the hyoid bone in an anterior caudad direction, aiming in the direction of the thyroid ligament, until it can be passed through the ligament.

Superior Laryngeal Nerve Block – showing displacement technique

At a depth of 1-2 cm, 2 ml of 2% lidocaine with epinephrine is injected (after negative air and blood aspiration) into the space between the thyrohyoid membrane and the pharyngeal mucosa.

An additional 1 ml is injected as needle is withdrawn. The block is repeated on the other side.

Technique Tips! Firmly displace the hyoid bone towards the side to be

blocked, even if it causes the patient some minor discomfort. Exercise caution - not to insert the needle into the thyroid

cartilage, injection of local anesthetic at the level of vocal cords may cause edema and airway obstruction.

    If air is aspirated, laryngeal mucosa has been pierced, and the needle needs to be retrieved.

    If blood is aspirated (superior laryngeal artery or vein), the needle needs to be redirected more anteriorly. Pressure should be applied to avoid hematoma formation

RECURRENT LARYNGEAL NERVE BLOCK – (TRANSTRACHEAL or TRANSLARYNGEAL BLOCK)3-4 ml of Lidocaine 4 % is used. Also, 1% or 2%

lidocaine, with or without epinephrine.Patient Position: Supine, with neck hyperextended (or

pillow removed and extended)Technique place index and third fingers of the non-dominant hand

in the space between the thyroid and cricoid cartilages (identifying the cricothyroid membrane)

The trachea can be held in place by placing the thumb and third finger on either side of the thyroid cartilage.

The midline should then be identified and injected lightly to create a local skin wheal (using a 22-guage or smaller needle).

Placement of fingers to identify the midline of the cricothyroid membrane

A 10 ml syringe containing 4% lidocaine (or other desired concentration), is mounted on a 22-guage, 35 mm plastic catheter over a needle, and is introduced into the trachea.

The catheter is advanced into the lumen, midline thru the cricothyroid membrane, at an angle of 45 degrees, in a caudal direction

a loss of airway resistance and aspiration of air confirms placement, and the needle is removed from the catheter

this usually cause patient to first inhale to catch his or her breath and then forcefully cough, spreading the lidocaine over the trachea

This area is nearly devoid of major vascular structures

Placement of the needle for the Transtracheal or Recurrent Laryngeal Nerve Block.

Transtracheal spread of local anesthetic with coughing

Technique Tips!

If a regular needle is used to inject (rather than a catheter), the lidocaine is injected rapidly and the needle is removed immediately!!! Surrounding structures, including the posterior tracheal wall can be damaged if the needle is not stabilized during injection of the local anesthetic and then be removed immediately!

The catheter should bet in place until the intubation is completed for the purpose of injecting more local anesthetic, if necessary, and to decrease the likelihood of subcutaneous emphysema

patient is then asked to take a deep breath and then asked to exhale forcefully. At the end of the expiratory effort, 3-4 ml of local anesthetic solution is rapidly injected into and over the back of the trachea.

COMPLICATIONSGastric Aspiration -decrease the risk, by decreasing risk of coughing and gag reflex

during intubation

Risk of Coughing -Contraindicated in patients diagnosed with an unstable neck,Vascular injury Structural injuries -posterior tracheal wall and vocal cords can be damaged,

especially if the needle is not stabilized during injection of the local anesthetic, or not removed immediately

Systemic toxicity Intravascular injection

Equipment setup and preliminary checksConnect and switch on the light-source and suction.

Check the patency of working channel by instilling saline. Clean the tip of the scope with a cotton gauze. Focus the

scope using the diopter ring while looking through the view finder at some fine printed matter or palmer crease.

Check the suction by pressing the suction knob and sucking normal saline from a bowl with the tip of the scope dipped into the saline.

Thread the appropriate enotracheal tube over the scopeEstablish standard monitoring and Intravenous access.Watch out for absolute or relative contraindications like

coagulopathy, refractory hypoxemia, unstable hemodynamics, myocardial infarction in last 6 weeks

Handling the scopeRight handed person will find it easier to advance and

maneuver the main cord with the right hand and use the left hand to hold the handle with the index finger over the suction knob and the thumb over the lever for controlling the scope tip.

The black cursor (triangular marker) in the viewfinder should

be at the 12 O’clock position during insertion. This cursor describes the plane of movement of the tip of scope.

The lever and scope tip moves in opposite directions; pushing

the lever down moves the tip upwards (anteriorly) and pushing it up angulates the tip downwards (posteriorly).

In order to angulate the tip to the left or right, the scope is rotated so that the cursor moves to 9 O’clock or 3 O’clock position respectively and then the lever is pushed down.

The entire procedure requires only three movements: flexion of the tip of the scope along the plane of the cursor, rotation of the entire scope to the left or right and advancement or withdrawal of the scope.

The goal is to keep the point of interest (uvula, epiglottis, tracheal opening) in the centre of the field.

i. If the point of interest is at the bottom of the field and you want to move it up towards the centre, move the lever up.

ii. If the point of interest is at the right edge of the field and you wish to center it, rotate the wrist to right so that the cursor moves to 3` O clock position then press the lever down.

iii. For centering a point of interest located at the left edge of the field, rotate the wrist to the left so that the cursor moves to 9` O clock and then move the lever down.

Whenever the point of interest is at the centre of the field the scope can be advanced with the right hand.

TECHNIQUE

The procedure can be done either standing at the head-end facing the patient’s feet or standing on the side facing the patients face.

Stand tall to avoid bending the main cord that may damage fiber optic bundles.

The assistant is instructed regarding the application of jaw thrust or head extension if required.

Oral approach:An intubating airway like the Ovassapian airway or a

mouth guard is inserted to protect the main cord from being damaged by the patient’s teeth.

The lubricated scope is inserted down the airway using the right hand.

The right thumb, index and middle fingers hold the distal end of the scope for insertion while the little finger rests on the patient’s face for stability.

The uvula is visualized and the scope is maneuvered beneath it.

Once beyond the uvula, angulate the tip anteriorly by pushing the lever down and advance until the epiglottis comes into view.

This sharp angulation at the uvula makes the oral FOB difficult as compared to the nasal approach where a gentle curve is encountered.

Nasal approach:The tip of the nose is elevated and the scope is

introduced through the more patent nostril.

It is inserted along the inferior turbinate.

Stay in the centre of the lumen and avoid scraping

the mucosa that may precipitate bleeding.

After entering the nasopharynx gently angulate the

scope anteriorly and advance to visualize the

epiglottis

APPROACH AFTER EPIGLOTTIS VISUALIZATIONAdvance the scope below the epiglottis to visualize

the glottic opening. If passage beneath the epiglottis is difficult ask the assistant to extend the head of the patient or execute jaw thrust.

Keep the vocal cords in the centre of the field by up-down angulation or clockwise, counter clockwise rotationof the scope.

If anatomy is lost at any stage, withdraw the scope until the anatomy becomes identifiable again. When withdrawing the scope, remove finger from the lever that controls the tip.

The scope commonly impinges at the anterior commissure or the anterior laryngeal wall. Angulate posteriorly while advancing between the cords to enter the trachea.

The trachea is recognized by the C shaped cartilages anteriorly (12 O’clock position). Keep the tracheal opening in the centre of the field and advance the scope until the carina comes into the view.

Endotracheal tube (previously loaded over the FOB) is threaded into the trachea and FOB is withdrawn keeping the tip straight to avoid damage

Care of the FOBImmediately after removal from patient, exterior of

FOB should be wiped with disinfectantAll channels should be flushed with water or an

enzymatic detergentFiberscope should be immersed in enzymatic solution

with water resistant cap over video connector Allow to soak for 2-5 min and then cleaned and rinsed

with sterile water / tap water and the alcoholEndoscope should be hung vertically to allow any

remaining fluid to drain outDisinfectant used – gluteraldehyde / hydrogen peroxideGas sterlization can be used

Topicalization is the simplest method for anesthetizing the airway.

Local anesthetic can be sprayed directly onto the desired mucosa.

Nebulization of lidocaine 2–4% via face mask or oral nebulizer for 15–30

minutes can achieve highly effective anesthesia of the oral cavity and

trachea for intubation.

Atomization is ideal for airway topicalization during nasotracheal

intubations.

Density of anesthesia is variable and often requires supplementation to

facilitate intubation.

Anesthetic-soaked cotton can be applied to targeted mucosal surfaces for

5–15 minutes to effect selective blockade of underlying nerves.

Vasoconstrictors such as epinephrine (1:200,000) or phenylephrine (0.05%)

can be added to the solution to reduce mucosal bleeding.

Adequate time allocation is needed to achieve optimal conditions.

 

Ask the patient to protude the tongue. The assistant will hold it gently with the gauge and pull gently out. This will help elevate the epiglottis

Classical indication for nasal route

Restricted mouth opening

LARGE TONGUE

Short and thick neck

Tumor/mass in oral cavity