2. “The best preparation for
managing the difficult airway is
being excellent at the
management of routine airways.
Patients are not harmed by
inadequate intubation but rather
inadequate ventilation”
Nagelhout 4th ed. p. 441
4. Airway A & P: the nose
The nose comprises a large surface area. It helps to warm,
humidify & filter but provides 2/3 of the resistance to breathing
Branches of
3 arteries
supply the
mucosa:
Facial
Opthalmic
Maxillary
Branches of the
facial nerve
innervate the
nose;
sensory is from
divisions of the
trigeminal
nerve.
Sympathetic stimulation results in vasoconstriction of nasal
tissue. Depression of the SNS by general anesthesia may
produce engorged nasal tissue which may bleed easily with
tube insertions.
5. Airway A & P: the mouth
The hard palate is
stationary.
The soft palate is
able to rise, but also
may become more
movable
(obesity,age..) and
fall against the nasal
passages during
sleep producing
obstruction.
The uvula
protects the
oropharynx.
The large,
space
occupying,
muscular
tongue may
obstruct the
airway when
it relaxes.
6. Airway A & P: the nasopharynx
Lies anterior to C1
Superior border: base of skull
Inferior border: soft palate
Adenoid tonsils and eustachian tubes are within the
nasopharynx. Maxillary nerve provides sensory innervation.
7. Airway A & P: the oropharynx
Lies anterior to C12-C3
Superior border: soft palate
Inferior border: epiglottis
Opens into the mouth through the tonsillar pillars
8. Airway A & P: the hypopharynx
Lies posterior to the larynx
Superior border: epiglottis
Inferior border: cricoid cartilage (C5-C6)
The upper esophageal sphincter, which helps prevent conscious
regurgitation, lies at the inferior border. The sphincter arises from the
cricopharyngeal muscle.
9. Airway A & P: the pharynx
Gag reflex diagram
Afferent/sensory
stimuli is carried by
glossopharyngeal
(IX)
to the medulla
Synapse occurs in the medulla with the
vagus (X) & spinal accessory (XI)
Efferent /motor
response returns
through the
vagus (X) causing
the pharyngeal
muscles to
constrict and
elevate -“gag”
10. Airway A & P: the pharynx
SLN & RLN
Superior Laryngeal nerve:
Internal →sensory above cords
External→motor to cricothyroid muscle
Recurrent Laryngeal nerve:
Sensory→below glottis
Motor→ all other muscles of larynx
Branches off the vagus and
loops around the aorta
(design flaw or developmental
physiology?)
Loops
around the
innominate
artery
11.
12. Anesthesia concerns with the RLN
Damage to the RLN interferes with airway control.
Acute bilateral injury → unopposed tension→ vocal cord adduction →stridor
Unresolved stridor leads to respiratory distress and possibly death.
14. Airway A & P: the larynx
Valeculla – the
space above the
epiglottis.
The Macintosh
intubating blade is
placed into this
space.
The blade lifts
structures to view
the glottis.
1 bone (hyoid) + 9 cartilages
Cricoid cartilage is the only complete ring
Tracheal rings are incomplete posteriorly to
accommodate food in the esophagus
18. Oxygen administration –
spontaneously breathing patient
The simple oxygen mask administers
40-60% FIO2 (assuming normal
respiration) by increasing the
anatomic reservoir.
The nasal cannula administers
24-40% FIO2 (assuming
normal respiration).
A 4% increase in FIO2 for each liter (except the 1st which is 3%)
ex. 1 lpm =24%, 2 lpm=28% , 3 lpm = 32%...
21. Proper positioning
The sniffing position
– the
tragus/auditory
meatus of the ear
aligns with the
sternal notch
The sniffing position + hyperextension align the axis
23. Preoxygenation
Administration of 100% oxygen is intended to replace
nitrogen (denitrogenation) in the FRC with the goal of
increasing the safe apneic period.
Techniques:
Normal tidal volume breaths with high flow 100 % oxygen for 3 mins.
8 vital capacity breaths with 100% oxygen over 1 minute.
4 vital capacity breaths with 100% oxygen over 30 secs.(less effective)
24. Concept of Desaturation
The FRC is the “reservoir.”
Preoxygenation fills the “reservoir”.
Oxygen consumption empties the “reservoir”.
FRC (or 35ml/kg in adult)
Oxygen consumption
(or 3 ml/kg for an adult)
2500 ml
250 ml/min
(Need to also consider closing capacity)
25. SaO2 vs time (after succinylcholine)
Anesthesiology 1997 87:979-982
26. Mask Ventilation Technique-
a vital skill for an airway expert
1.Establish a snug fit over the bridge of nose and at the chin.
2.The left thumb and forefinger create a “C” over the mask
pressing down towards the floor.
3.The remaining fingers rest on the mandible. They may secure
and lift loose tissue onto the mandible.
4. To improve ventilation, repositioning, hyperextension or an oral
airway may be required.
28. Oral* and Nasal Airways
•Used to facilitate ventilation
•Always size before inserting
•Consider the risk vs. benefit
•Risks include:
damage to teeth
tissue trauma → bleeding
laryngospasm
eliciting a gag reflex →vomiting
further obstruction
*Are not bite blocks!
30. Supraglottic Airways-LMA’s
DO NOT prevent aspiration, or stomach inflation (keep
inflation pressure <20 cm H2O)
Are easily inserted blindly
Laryngeal Mask Airways (LMA’s) were introduced in 1989
Is properly positioned in the hypopharynx, above the
epiglottis
With overinflation, may open the upper esophageal
sphincter
With malposition, may produce airway obstruction
33. Endotracheal Intubation
• The gold standard for airway management and protection.
• It’s usually facilitated by direct laryngoscopy.
• Indications include:
a full stomach
a high risk for aspiration
critically ill pts.
significant lung abnormalities
lung isolation
surgical need for prolonged muscle relaxation
a difficult airway
pt. positioning
44. Confirmation of ETT placement
Visualization of tube passing through the glottis
With first breath, observe chest rise
Observe condensation in the ETT
Observe for a sustained normal capnogram (>3 breaths)
Listen for equal bilateral breath sounds
Listen for absence of gurgling over the epigastrum
45. Intubation Risks
•trauma to mouth and/or teeth
•endobronchial or esophageal intubation
•aspiration
•perforation of the pharnyx or trachea
•endotracheal tube (ET)obstruction: kinking biting,
tissue, secretions
•ET ignition/fire
•laryngospasm
•Croup
•Sore throat
46. Trauma to mouth/teeth
•Assess the mouth and teeth preop and post extubation.
•All attempts must be made to find fragments before aspiration.
•Consider a chest x-ray to find missing fragments.
47. Esophageal/Endobronchial intubation
Ensure endotracheal intubation by confirming
placement.
Visualize the ET cuff pass through the glottis.
Observe for condensation and chest rise with the first
manual breath.
Observe for sustained end tidal carbon dioxide
capnogram.
Listen for equal bilateral breath sounds and absence of
gurgling over stomach.
Further confirmation may include CXR or fiberoptic
scope
48. Aspiration
Remains a significant cause of morbidity and mortality in obstetrics.
Prophylaxis goals are to decrease the contents (<25 ml) and change
the pH of the contents (<2.5)
use non-particulate antacids (Bicitra)
gastrokinetics (metoclopramide)
H2 antagonists or proton pump inhibitors
Use a rapid sequence induction (RSI) technique for any at risk patient
full stomach
obstructed bowel
diabetic
trauma
severe, ongoing pain
obesity
obstetrics
50. Laryngospasm
Reflex constriction of the laryngeal muscles producing spasmodic
closure of the glottis.
Causes include secretions on the cords and extubation in a light
plane of anesthesia
Identify & eliminate the stimulus
Insert oral/nasal airway
Administer positive pressure ventilation with 100% oxygen
Perform jaw thrust with concomitant pressure of laryngeal notch
Deepen anesthetic level with propofol
Consider succinylcholine
51. Sore Throat
The most common postoperative complaint.
Factors may include:
ET size
irritation from instrumentation
female gender
52. 4 skill areas
1.Note the time in the room.
2.Move the “pt/student” from the
stretcher to the table.
3.Apply monitors.
4.Properly position “pt” for intubation.
5.Apply mask and administer air.
6.Properly position table height.
7.Instruct “pt” in preoxygenation.
Attempt mask ventilation.
Oral airway insertion.
Nasal airway insertion.
LMA insertion
Intubation.
Editor's Notes
Everybody wants to learn how to intubate but an excellent mask ventilation technique is the mark of an airway expert.
The turbinates increase surface area
Soft palate is the posterior third to half of the oral cavity
We will start by breaking up the pharynx into 3 parts
Tonsillar pillars are the glossopalatine muscle covered by the mucus membrane of the mouth/orophraynx.
Aka the laryngo pharynx
One of the things that concerns us is the gag response. All muscles of the pharynx, larynx & soft palate are innervated by the Glossopharyngeal (IX) Vagus (X) Spinal Accessory (XI) cranial nerves
Damage may include intubation traction, surgical traction, tumors, trauma, dissecting aortic aneurysms. Unilateral damage produces hoarseness. The unnopposed tension is from the SLN innervating the crycothroid muscle. Damage to the vagus leaves both nerves damaged and the cords are flaccid. Eventually becomes compensated for and leaves a hoarse voice. SLN damage doesn’t do anything, stimulation causes laryngospasm.
You can never get enough views of the larynx. I’m showing this because it illustrates even with a good view -Grade 1- it can still be difficult to align a device. Also illustrates oxygenation, proper positioning, suction, fasiculation with succ, use of the bougie and the larnyx.
4% increase for every liter except the 1st which is 3%
Get in the habit of properly positioning every potentially unconscious patient. BEST viewed from the side.
This needs to be done in the awake or unconscious patient. Can we properly preoxygenate an awake pt. with a simple oxygen mask? Consider maximum oxygen delivery of 60% with a simple mask. You aren’t being kind to the anxious patient by skipping this step. The art of anesthesia.
I speculate this is the reason why the woman in “just a routine operation” video desaturated so fast- premedication produced shallow respirations and lack of preoxygenation. Oxygen consumption is based on metabolic needs. Why some anesthesia machine oxygen flowmeters do not shut down to zero.
This illustrates desaturation time
Sensory stimulation of the SLN causes laryngospasm.
For general anesthesia, the rule of thumb is an internal diameter 7mm for women, 8 mm for men.
Backward, upward rightward pressure
“Its all fun and games until somebody loses a tooth”
Prevalent in children but can happen to anyone. The jaw thrust at the “laryngeal notch” ( the condyle at the mandible and the mastoid process) causing an intense painful stimulus can end laryngospasm by arousing the pt/activating sympathetic pathways.
