3. THE DECISION TO INTUBATE
ASSESS Need for intubation
Urgency of situation
Difficult airway
DECIDE Best method to intubate
Medications to use
Rescue technique (if fail)
4. INDICATION FOR INTUBATION
• Is there a failure of airway maintenance or protection?
• Is there a failure of ventilation or oxygenation?
• What is the anticipated clinical course?
6. L – Look externally
E – Evaluate 3-3-2
M - Mallampati
O – Obstruction/Obesity
N – Neck mobility
M – Mask seal
O – Obesity
A – Age > 55
N – No teeth
S – Stiff lung
R – Restricted mouth
opening
O – Obstruction
D – Distorted anatomy
S – Stiff lung, short
thyromental
S – Surgery
M – Mass
A – Anatomy
R – Radiation
T - Tumour
DIFFICULT
AIRWAY
DIMENSIONS
DIFFICULT
LARYNGOSCOPY/
INTUBATION
DIFFICULT BAG
MASK
VENTILATION
DIFFICULT EGD DIFFICULT
SURGICAL
AIRWAY
11. DIFFICULT
LARYNGOSCOPY
L – Look externally
E – Evaluate 3-3-2
M - Mallampati
O – Obstruction/Obesity
N – Neck mobility
What are the signs of upper
airway obstruction?
13. DIFFICULT BVM
M – Mask seal/Mallampati/Male
O – Obesity
A – Age > 55
N – No teeth
S – Stiff lung
14. DIFFICULT BVM
M – Mask seal/Mallampati/Male
O – Obesity
A – Age > 55
N – No teeth
S – Stiff lung
15. DIFFICULT BVM
M – Mask seal/Mallampati/Male
O – Obesity
A – Aged
N – No teeth
S – Stiff lung
16. DIFFICULT BVM
M – Mask seal/Mallampati/Male
O – Obesity
A – Age > 55
N – No teeth
S – Stiff lung
17. DIFFICULT BVM
M – Mask seal/Mallampati/Male
O – Obesity
A – Age > 55
N – No teeth
S – Stiff lung
18. FAILED AIRWAY
• Failure to maintain acceptable oxygen
saturation during or after one or more failed
laryngoscopic attempts (CICO) or
• Three failed attempts at orotracheal
intubation by an experienced intubator,
even when oxygen saturation can be
maintained or
• The single “best attempt” at intubation fails
in the “Forced to Act” situation (see below).
The decision to intubate is the first step
in emergency airway management, and sets in motion a complex series of actions
required of the clinician, before performing the actual intubation::
- Rapidly assess the patient’s need for intubation and the urgency of the situation.
Determine the best method of airway management based on assessment of the
patient’s predicted difficulty and pathophysiology.
Decide which pharmacologic agents are indicated, in what order, and in what
doses.
Prepare a plan in the event that the primary method is unsuccessful, know in
advance how to recognize when the planned airway intervention has failed or
will inevitably fail, and clearly lay out the alternative (rescue) technique(s).
A. Is there a failure of airway maintenance or protection?
Without a patent airway and intact protective reflexes, adequate oxygenation
and ventilation may be difficult or impossible and aspiration of gastric contents
can occur. Both expose the patient to significant morbidity and mortality.
-Difference between maintaining airway (eg use OPA in morphine overdose or PSA cx) and protecting airway (definitive)
Don’t use gag reflex to indicate airway protection
Anticipated clinical course
These are the patients for whom intubation is
likely or inevitable because their conditions, and airways, are predicted to
deteriorate from dynamic and progressive changes related to the presenting
pathophysiology or because the work of breathing will become overwhelming in
the face of catastrophic illness or injury. For example, consider the patient who
presents with a stab wound to the midzone of the anterior neck and a visible
hematoma. At presentation, the patient may have perfectly adequate airway
maintenance and protection and be ventilating and oxygenating well. The
hematoma, however, provides clear evidence of significant vascular injury.
Ongoing bleeding may be clinically occult because the blood often tracks down
the tissue planes of the neck (e.g., prevertebral space) rather than demonstrating
visible expansion of the hematoma. Furthermore, the anatomical distortion caused
by the enlarging internal hematoma may well thwart a variety of airway
management techniques that would have been successful if undertaken earlier. The
patient inexorably progresses from awake and alert with a patent airway to a state
in which the airway becomes obstructed, often quite suddenly, and the anatomy is
so distorted that airway management is difficult or impossible.
Not every trauma patient or every patient with a serious medical disorder
requires intubation. However, in general, it is better to err on the side of
performing an intubation that might not, in retrospect, have been required, than to
delay intubation, thus exposing the patient to the risk of serious deterioration.
Although there is no absolute cutoff for oxygen saturation or CO2 that dictates
intubation, a saturation that cannot be sustained above 80%, a RR > 30 or a
CO2 > 100 has strong associations with intubation.
L—Look externally: Although a gestalt of difficult intubation is not particularly
sensitive (meaning that many difficult airways are not readily apparent
externally), it is quite specific, meaning that if the airway looks difficult, it
probably is. Most of the litany of physical features associated with difficult
laryngoscopy and intubation (e.g., small mandible, large tongue, large teeth, and
short neck) are accounted for by the remaining elements of LEMON and so do
not need to be specifically recalled or sought, which can be a difficult memory
challenge in a critical situation. The external look specified here is for the
“feeling” that the airway will be difficult. This feeling may be driven by a
specific finding, such as external evidence of lower facial disruption and
bleeding that might make intubation difficult, or it might be the ill-defined
composite impression of the patient, such as the obese, agitated patient with a
short neck and small mouth, whose airway appears formidable even before any
formal evaluation (the rest of the LEMON attributes) is undertaken. This
“gestalt” of the patient is influenced by patient attributes, the setting, and
clinician expertise and experience, and likely is as valid for VL as for DL.
O—Obstruction/Obesity: Upper airway obstruction is a marker for difficult
laryngoscopy. The four cardinal signs of upper airway obstruction are muffled
voice (hot potato voice), difficulty swallowing secretions (because of either pain
or obstruction), stridor, and a sensation of dyspnea. The first two signs do not
ordinarily herald imminent total upper airway obstruction in adults, but critical
obstruction is much more imminent when the sensation of dyspnea occurs.
Stridor is a particularly ominous sign. The presence of stridor is generally
considered to indicate that the airway has been reduced to <50% of its normal
caliber, or to a diameter of 4.5 mm or less. The management of patients with
upper airway obstruction is discussed in Chapter 36. Although it is controversial
whether obesity per se is an independent marker for difficult laryngoscopy or
whether obesity simply is associated with various difficult airway attributes,
such as high Mallampati score or failure of the 3-3-2 rule, obese patients
frequently have poor glottic views by DL or VL, and obesity, in itself, should be
considered to portend difficult laryngoscopy.
1.Muffled or “hot potato” voice (as though the patient is speaking with a mouthful of hot food)
2.Inability to swallow secretions, because of either pain or obstruction
3.Stridor
4.Dyspnea
The first two signs do not necessarily herald imminent total
upper airway obstruction; stridor, if new or progressive, usually
does, and dyspnea also is a compelling symptom.
Neck mobility: The ability to position the head and neck is one of the key factors
in achieving the best possible view of the larynx by DL. Cervical spine
immobilization for trauma, by itself, may not create a degree of difficulty that
ultimately leads one to avoid RSI after applying the thought processes of the
difficult airway algorithm. However, cervical spine immobilization will make
intubation more difficult and will compound the effects of other identified
difficult airway markers. In addition, intrinsic cervical spine immobility, as in
cases of ankylosing spondylitis or rheumatoid arthritis, can make intubation by
DL extremely difficult or impossible and should be considered a much more
serious issue than the ubiquitous cervical collar (which mandates inline manual
immobilization). VL requires much less (or no) head extension, depending on
blade shape, and provides a glottic view superior to that by DL when head
extension or neck flexion is restricted. Other devices, such as the Airtraq or the
Shikani optical stylet, discussed elsewhere in this manual, also may require less
cervical spine movement than DL although image size and clarity are far inferior
to that obtained with VL.
In the “Forced to Act” scenario, airway difficulty is apparent, but the clinical conditions (e.g., combative, hypoxic, rapidly deteriorating
patient) force the operator’s hand, requiring administration of RSI drugs in an attempt
to create the best possible circumstances for tracheal intubation, with immediate
progression to failed airway management if that one best attempt is not successful
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