Airway Management Flashcards
Where is the larynx located in relation to cervical vertebrae in adults?
C4-6 (maybe C3 in women)
1st tracheal ring at C6
How many cartilages make up the larynx?
9
- 3 single (epiglottic, thyroid, cricoid)
- 3 pairs (arytenoid, corniuclate, cuneiform)
What is the approximate length of the trachea?
15cm
Where is the carina located in relation to thoracic vertebrae in adults?
T5
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.
What nerves provide sensory and motor innervation to the pharynx?
Sensory = glossopharyngeal (IX) posterior 2/3 of tongue
Motor = accessory (XI)
Which nerves innervate the larynx?
Superior and recurrent laryngeal (X)
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
What areas/muscles of the larynx does the external branch of the superior laryngeal nerve provide motor innervation?
cricothyroid muscle –> tenses the vocal cords
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.
What nerve injury is associated with hoarseness?
Unilateral recurrent laryngeal nerve
What nerve injury is associated with respiratory distress?
Bilateral recurrent laryngeal nerve
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)
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
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
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
What factors may predict difficult mask ventilation?
Obesity BMI >30 Mallampati 3-4 Beard Edentulous Limited mouth opening Snoring/OSA Age >55
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
What are some drugs used for tracheal intubation under spontaneous ventilation?
Sevo - fast onset, minimal irritation
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?
- Alternative to mask or ETT either by type of case or difficult intubation/mask ventilation
- Reactive airway disease (less stimulating/trauma)
- 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?
- 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
