Difficult Airway Management
Robert J. Sharpe BSc. M.D., FRCPC
Department of Anaesthesia & Perioperative Medicine
Department of Critical Care Medicine
Royal Columbian Hospital, New Westminster, B.C.
University of British Columbia
Airway Management
• First…
a few words of wisdom….
“Airway Management”
DOES
NOT
(NECESSARILY)
MEAN
INTUBATION
And… as we’ll see later…there’s
even an algorithm!
Catch all that???
• Excellent! Talk complete!
• Oh… well… maybe not so fast.
Airway Management:
Questions to Ask Yourself (while NOT PANICKING!)
1. WHY do we need to manipulate this
patient’s airway?
- indications
Airway Management:
Questions to Ask Yourself (while NOT PANICKING!)
2. WHEN do we need to do this?
- how urgent are the above indications
Airway Management:
Questions to Ask Yourself (while NOT PANICKING!)
3. WHAT are the risks and benefits of
manipulating this patient’s airway?
- trauma? C-spine?
Airway Management:
Questions to Ask Yourself (while NOT PANICKING!)
4. WHERE do we want to do this?
- not USUALLY a key issue in the PACU
itself, however…
- unless EMERGENT, avoid
manipulating the questionable airway in a
remote location (e.g. CT scanner, MRI,
wards, angio) - inadequate equipment,
inadequate backup personnel…. IN OTHER
WORDS…
THANK GOODNESS FOR THE
PACU
Airway Management:
Questions to ask yourself while NOT PANICKING!
HOW do I manipulate this patient’s airway?
- methods/means of mechanical ventilation
- medications
- what TOOLS do I need?
- bag/mask, oral airway, nasal trumpet, LMA, ETT etc…
- what MEDS do I need?
- sedation/topicalization, inotropes, pressors (anticipate
hemodynamic changes POST-intubation)
- have a plan. Then have a BACKUP plan!
WHO do I need to assist me?
-RT, nursing staff, anaesthesia?, ENT?
- sleeping ICU fellow?
Airway Management
WHY? Indications:
• Clinical
– upper airway obstruction
– respiratory distress (with hemodynamic instability
or impending respiratory collapse) / increased
“work of breathing”
– impaired airway protection (altered mentation:
“GCS less than 8? Go ahead and intubate.”)
– impaired ability to clear or high volume of
secretions/need for pulmonary toilet/lavage
Airway Management
WHY? Indications:
• Physiologic
– Hypoxemia
• persistent after O2 administration
– Hypercapnia
• PCO2 > 55 with pH <7.25
– vital capacity <15ml/kg with neuromuscular
disease
The Artificial Airway:
WHAT are the Risks and Benefits?
• Benefits:
• bypasses upper airway obstruction
• route for O2 and med. Administration
– NAVEL (naloxone, atropine, ventolin/versed, epinephrine,
lidocaine)
• allows mechanical/positive-pressure ventilation and
PEEP
• allows suctioning of secretions/pulmonary toilet
• allows fiberoptic bronchoscopy/lavage/biopsy
The Artificial Airway:
WHAT are the Risks and Benefits?
• Risks:
• trauma on insertion
• oropharyngeal/nasopharyngeal/tracheal
ulceration/trauma/perforation with chronic use
• tracheomalacia
• impaired cough
• increased aspiration risk*
• resistance/work of breathing
The Artificial Airway:
WHAT are the Risks (cont’d)?
• impaired mucociliary function
• increased infection risk (VAP)
• increased resistance/work of breathing
• Risks of mechanical ventilation in general
Don’t Panic,… but...
• Airway management
• single largest source for unfavourable outcomes in ASA closed-claims
study (34% of 1541 liability claims)
• 3 mechanisms of injury account for 75% of undesireable events:
– inadequate ventilation
– esophageal intubation
– difficult tracheal intubation
• recurrent patterns of management error or injury:
–
–
–
–
–
airway trauma
pneumothorax
airway obstruction
aspiration
bronchospasm
HOW do I minimize the Risk?
• thorough airway history and physical
examination
• management plan for supraglottic means of
ventilation
• management plan for subglottic means of
ventilation
• alternate plan & an alternate to your alternate
plan!
Basic Airway Anatomy:
• “airway” refers to the upper airway:
–
–
–
–
–
nasal and oral cavities
pharynx
larynx
trachea
principal bronchi
Basic Airway Anatomy
base of tongue
epiglottis
vocal cords
trachea
glottis
Insert tube here!
…NOT here
Basic Airway Anatomy:
• trachea suspended from cricoid cartilage by cricotracheal
ligament
• trachea roughly 15cm lenth in adults; supported by 17-18 Cshaped cartilages (open posteriorly; membranous aspect
overlies esophagus)
• 1st tracheal ring anterior to C6
• trachea ends at level of carina at T5
• right mainstem bronchus larger in diameter and deviates at
less acute angle than left (therefore aspiration or
endobronchial intubation usu. to right side)
The Airway Evaluation
• Easy (though not necessarily reliable) in the awake,
cooperative, cognitively intact patient
• (How often do you see awake, cooperative, cognitively intact
patients if respirator distress sets in, in the PACU???)
• quickly evaluate the urgency of the situation:
– Vital signs: SpO2, HR, BP
– is the patient protecting his/her airway?
– Is the patient fatigued/showing signs of respiratory
distress?
• Proceed to history, physical, labs as appropriate.. And …
•CALL for HELP!
Airway Management:
Evaluation of the Airway - History
• Full history that one considers if time permitting
• key points:
–
–
–
–
previous intubations and ease thereof?/tracheostomies?
known difficult airway?
full stomach?
chipped teeth, loose teeth, caps, crowns, bridges,
dentures?
– stridor, dysphagia, change in phonation, c-spine
pain/instability, upper extremity neuropathies?
– AMPLE
Airway Management - History
• In the PACU… the nature of the surgery may
be one of the most important factors, e.g.:
–
–
–
–
Carotid Endarterectomy
C-spine fusion
Microlaryngectomy
… basically any surgical manipulation of the head
and neck is a red flag for potentially difficult
airway management
Airway Management:
Evaluation of the Airway - Physical
• Basic areas of evaluation:
– TMJ
– TMD and submandibular soft-tissue compliance
– NROM - atlanto-occipital extension
– Mallampati/Samsoon & Young Classification
–
–
–
–
–
dentition
beard
identification of cricothiroid membrane
identification of (obvious) pharyngeal pathology
intraoperative Cormack & Lehane class (if
available)
What we like to see…
Sometimes the difficult airway is
obvious...
Sometimes it’s not quite so …
…at least… until direct
laryngoscopy…
obvious
Normal…
Complete obstruction…
Attempting to differentiate the
difficult from the not-sodifficult…
Mallampati Classification:
Airway Evaluation
• Mallampati/Samsoon & Young classification
– unfortunately neither significantly sensitive nor
specific
• in a trial of 675 patients, the index detected only 5 of
12 difficult airways and gave 139 false positives
So…
…we’ve determined this patient
needs airway intervention…
…we’ve evaluated this patient’s
airway…
...now we’re going to manage their
airway for them...
Airway Management:
HOW do I manage this patient’s airway?
• Preoxygenation
– aka denitrogenation
– replacement of N2 volume (>69% of
FRC) with O2
– provides reservoir of O2 for diffusion
into alveolar capillaries after onset of
apnea
– 100% O2 x 5 min yields 10 min. O2
reserve following apnea (w/o
cardiopulmonary disease and with
normal VO2)
Airway Management
How do we “free” this airway?
First, recall…
– any condition which increases O2 consumption
(VO2) or decreases O2 supply/diffusion will
dramatically decrease this reserve:
• e.g. obesity, sepsis, pregnancy, pulmonary
parenchymal disease, intrapulmonary/intracardiac
shunt, thryotoxicosis… etc… etc… etc...
Airway Management:
The HOW: PreOxygenate
• Faster alternative to 100% O2 x 5 minutes:
– 4 “vital capacity breaths” at 100% O2 over 30
seconds
• still, shorter time to desaturation that with 100% x 5
minutes, but more effective than room air (FiO2 =
21%) alone
– 8 “deep breaths” of FiO2 1.0 over 60 seconds
Preoxygenation cont’d
• “pre-oxygenation” implies ultimately, more
definitive securing of the airway
• pre-oxygenation may be active or passive
depending on patient status
– if patient awake and cooperative, attempt the
above deep breathing or vital capacity techniques
– if patient already apneic or once rendered apneic
with medications, bag/mask ventilate the patient
yourself
Face Mask Ventilation
• Positioning:
– sniffing position
• renders base of the tongue and the epiglottis more
anterior
• aligns axes of oral cavity, pharynx, and trachea (in
preparation for laryngoscopy)
The sniffing position aligns:
• the pharyngeal axis
• the laryngeal axis
• the oral axis
Laryngoscope technique:
• Grasp with the left hand
• Insert into right CORNER of patient’s mouth
• You want to SWEEP the tongue out of the way
• Follow the curve of the tongue with the tip of the
laryngoscope
• You do not want to push the tongue inward
• Lodge the tip of the laryngoscope at the base of the
epiglottis
• You do NOT want to trap the epiglottis under the blade, you
want it to move up as you compress its base
• PUSH
Laryngoscopy:
• That’s right – PUSH
• Push the tongue, mandible and epiglottis up toward
the far corner (wall to ceiling) of the room
• You should (regardless of size, age or medical
speciality) be able to lift the patient’s head off the bed
by simply pushing
Laryngoscopy…
• We TRY not to flex at the WRIST
• The push is from the arm, NOT FROM THE WRIST
• Remember
– Teeth are breakable!
– Teeth can be aspirated!
– Teeth are embarrassing on CXR and on rounds!
What you’ll see…
How we interpret what we see
with experience, in time…
Laryngeal Grade
Class I: the vocal cords are
visible
Class II the vocals cords are
only partly visible
Class III only the epiglottis is
seen
Class IV the epiglottis cannot be
seen
So, now what???
•
Plan A
– Insert ETT
• Size 7.0 – 8.0 female
• Size 7.5 – 8.5 male
• (Age/4) +4 for children
• +/- stylet
• But never forget… the previously manipulated airway (as
frequently the case in PACU) is ANGRY!!!
– While the “virgin” airway may tolerate a 7.5 just fine…
the inflamed, angry, post-op airway may need a 7.0, a 6.0
or “worse”
Plan B
• What if the tube won’t pass or you can only
see a “Grade III” tiny little opening?
– Regroup
– Try again
– TRY SOMETHING DIFFERENT each time
you try again – there’s no point in repeating your
initial mistake
– There’s LOTS available
Plan B (and Plan C… and Plan D
and…. Plans E through Z!)
•
•
•
•
•
Repositioning the head
Cricoid pressure/BURP
Stylet
Bougie
(lighted stylet, fiberoptic bronchoscope, LMA,
combitube, retrograde intubation, cricothyroidotomy, etc…
etc… etc…)
• REMEMBER: if you can just BAG and MASK
ventilate a patient, you may save their life with that
alone…
There’s even an algorithm…
… or a few of them…
…. (don’t worry about it)
…and remember what we said to
begin with…