Airway Management Flashcards by Jon Johnson

Where is the larynx located in relation to cervical vertebrae in adults?

C4-6 (maybe C3 in women)

1st tracheal ring at C6

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How many cartilages make up the larynx?

3 single (epiglottic, thyroid, cricoid)
3 pairs (arytenoid, corniuclate, cuneiform)

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What is the approximate length of the trachea?

15cm

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Where is the carina located in relation to thoracic vertebrae in adults?

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What are the most significant difference in the anatomy of the airway between kids and adults?

larynx is at C3-C4
narrowest part of the airway is = cricoid cartilage
epiglottis is longer, narrower and stiffer
vocal folds have a more anterior angle.

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What nerves provide sensory and motor innervation to the pharynx?

Sensory = glossopharyngeal (IX) posterior 2/3 of tongue

Motor = accessory (XI)

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Which nerves innervate the larynx?

Superior and recurrent laryngeal (X)

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What areas/muscles of the larynx does the recurrent laryngeal nerve provide motor and sensory innervation?

all the intrinsic muscles of the larynx, except for the cricothyroid muscle

sensory below the vocal folds and trachea

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What areas/muscles of the larynx does the external branch of the superior laryngeal nerve provide motor innervation?

cricothyroid muscle –> tenses the vocal cords

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What areas/muscles of the larynx does the internal branch of the superior laryngeal nerve provide sensory innervation?

vocal cords
posterior surface of the epiglottis
aryepiglottic folds
arytenoids.

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What nerve injury is associated with hoarseness?

Unilateral recurrent laryngeal nerve

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What nerve injury is associated with respiratory distress?

Bilateral recurrent laryngeal nerve

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What is the purpose or pre-oxygenation?

Replace nitrogen in lungs with oxygen –> FRC will be an O2 reservoir

Allows patient to tolerate apneic period without desaturating (O2 consumption ~250ml/min)

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If unable to mask ventilate after induction, what is the next step?

Reassess patient positioning and masking technique

2 handed mask

oral or nasal airway

LMA

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Name 4 advantages to doing an awake intubation

maintain spontaneous ventilation
decreased likelihood of airway obstruction
decreased risk of aspiration (depending on the block technique used)
performing a neurological examination after intubation if needed

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What is the definition of a difficult airway?

the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with face mask ventilation, difficulty with tracheal intubation, or both

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What factors may predict difficult mask ventilation?

Obesity BMI >30
Mallampati 3-4
Beard
Edentulous
Limited mouth opening
Snoring/OSA
Age >55

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Name some techniques available for difficult intubation

different laryngoscope blades
awake intubation
blind oral or nasal
fiberoptic
video laryngoscopy
intubating stylet or tube changes
rigid bronchoscope
lightwand
supraglottic airways as intubating conduits

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What are some drugs used for tracheal intubation under spontaneous ventilation?

Sevo - fast onset, minimal irritation

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What are keys to successful awake intubation?

Explain procedure
Develop rapport
Topical airway anesthesia
Anxiolysis w/ dex, ketamine, midaz, propofol, fentanyl

List some techniques in topical airway anesthesia

Nebulizers
Topical sprays
Gels
Transtracheal injection of local
Nerve blocks

What is the purpose of retrograde intubation?

Wire/catheter through cricothyroid membranr - pass tube over and advanced

Means to establish definitive airway when conventional techniques have failed

When might a Miller blade be considered a better option for intubation?

Laryngeal lesions
hypoplastic mandible
large, floppy epiglottis

What are the 5 elements of a cuffed endotracheal tube?

Valve - prevent air loss after inflation
Pilot balloon
Inflating tube
Cuff
Murphy eye - opening just proximal to tip to allow gas flow if distal tip obstructed

Why are high volume/low pressure cuffs more commonly used than high pressure?

Less complications - stenosis, TE fistula, ischemic injury, edema, rupture

What is the perfusion pressure of the tracheal mucosa and how should a HVLP cuff be filled?

48cm H2O Fill until air leak is just prevented cuff pressures 25-30cmH2O (15-20 in kids)

What gas has a tendency to diffuse into the cuff and increase cuff pressures?

Nitrous oxide

What are the advantages and disadvantages of using a cuffed ET tube vs. uncuffed?

Advantages - reduced risk of aspiration - decreased need for tube exchange - better ETCO2 monitoring - smaller air leaks with reduced potential for insufficient ventilation - reduced loss of volatile gases into the environment - lower gas flows Disadvantages - choosing a tube ½ a size smaller than an uncuffed tube - possibly more difficulty with suctioning and ventilation - greater expense.

What are some factors affecting maintenance of cuff pressure?

nitrous oxide inflation volume type of tube used diameter of the cuff in relation to the trachea tracheal cuff compliance intrathoracic pressure (e.g. coughing), and inspiration (and expiration) pressures

What is the advantage of using a Lanz valve?

pressure-regulation system preventing rapid changes in cuff volume

What is the limit to cuff pressure of an LMA?

20cmH2O

What are some consequences of of overinflation of an LMA?

trauma to hypopharynx or arytenoids may --> tongue necrosis from compression of blood vessels. malposition --> compression of the lingual or hypoglossal nerve --> transient or prolonged nerve palsy.

What two factors account for the most failures of LMA placement?

Folding of the distal LMA cuff Displacement of epiglottic downward May be alleviated by partial cuff inflation

When is the ideal time to remove an LMA?

Either deep or after protective reflexes have returned

What are some consequences for poor LMA placement?

Gastric fluid aspiration Neuropraxia Sore Throat

What is the difference between a classic LMA and a Proseal?

Pro seal - additional drain port from distal end of cuff to atmosphere --> allows for passive (regurgitation) and active (gastric tube insertion) emptying of the stomach

What are 3 indications for use of an LMA?

1. Alternative to mask or ETT either by type of case or difficult intubation/mask ventilation 2. Reactive airway disease (less stimulating/trauma) 3. Conduit for ETT - 6.0 ETT can be passed through an LMA 3 o 4

What is the primary contraindication for use of an LMA?

Potential aspiration of gastric contents - Significant GERD - hiatal hernia - intestinal obstruction - delayed gastric emptying - full stomach

What are some relative contraindications to using LMAa?

``` poor lung compliance high airway resistance glottic or supraglottic airway obstruction limited mouth opening morbid obesity ```

LMA inserted, cuff inflated but with PPV there is no chest rise, etCO2 and leak is heard at

LMA distal tip has folded over With a leak you should still get some gas exchange

Young healthy 80kg male induction with 200mg propofol, easy LMA placement but O2 drops to 85% and no etCO2. What is your next step?

Laryngospasm - young healthy males may need closer to pediatric dose of propofol - PPV or deepen anesthetic - Succ or Roc if no improvement

What are two signs that the GEB is correctly placed in the trachea?

1. Clicks or bumps along tracheal rings | 2. Distal hold up sign - lodged against carina or small bronchus

In the hospital setting, what is the most common indication for the use of a Combitube device?

difficult airways caused by massive regurgitation or massive upper GI bleeding (i.e. situations in which it is difficult to visualize the glottic opening due to material entering the oropharynx from the GI tract).

Is the LT device safe in patients with a latex allergy?

Yes Combitube = latex

When is a flexible fiberoptic bronchoscope used?

predicted or known difficult intubation unstable cervical spine in the setting of performing an awake intubation after multiple failed intubations

What are the indications for securing the airway with a retrograde wire intubation (RWI) technique?

``` inability to visualize the glottic opening due to blood or secretions in the airway unstable cervical spine fractured or traumatized mandible upper airway malignancy severe anatomic variations ```

Why are the outcomes for patients undergoing emergent cricothyroidotomy poor?

late timing at which the procedures are initiated

What is the major risk of TTJV when the patient suffers from upper airway obstruction?

upper airway must remain patent; if not, the injected pressure does not dissipate from air entrainment, and barotrauma can ensue Max pressure 50PSI

Age cricothyrotomy is contraindicated in children