2. Components of spinal motor control
system
• Spinal neurons
• Motor unit
• Muscle spindles
• Golgi tendon organs
3. Upper motor neuron
of extrapyramidal tract Upper motor
Dorsal root neuron of
ganglion cell corticospinal tract
α-motor neuron in
the spinal cord
Neuro muscular
junction
α-mn is directly
Muscle responsible for
spindle generation of
force by muscle muscle
Golgi Tendon organ
4. 50 muscles of the
Figure 5.28
arm innervated
from spinal
segments C3-T1
Page 173
Cervical Cervical
cord nerves Vertebrae
Muscles of the leg
innervated from
spinal segments
L1-S3
Thoracic
Thoracic nerves
cord
Lumbar
Lumbar nerves Cauda
cord equina
Sacral
Sacral nerves
cord
Coccygeal
nerve
5. Cell body of White matter Gray matter
efferent neuron
Interneuron
Cell body of
afferent neuron Dorsal root
Dorsal root
Efferent fiber ganglion
From receptors
To effectors
Ventral root
Spinal nerve
Figure 5.29
Page 174
6. Figure 5.31 Page 176
Dorsal horn (cell bodies of interneurons
on which afferent neurons terminate)
Central Lateral horn (cell bodies of autonomic
canal efferent nerve fibers)
Ventral horn (cell bodies of somatic
efferent neurons)
7. Motor neuron pool of a muscle.
• Those motor neurons innervating a single
muscle
• The motor neuron pools are segregated into
longitudinal columns extending through two to
four spinal segments.
• The longitudinal orientation of motor neurons
and their dendrites matches that of primary
afferent terminals in that zone.
• Thus impulses in a given afferent axon tend to
be distributed to motor neurons innervating the
same muscle or muscles with similar function.
8. Figure 8.15
Page 269
Spinal cord
= Motor unit 1
A motor unit is one motor
= Motor unit 2
neuron and the muscle
= Motor unit 3 fibers it innervates
9. The size principle: the orderly
recruitment of motor units
• The first motor units to be activated are those
with smallest motor axons;
– these motor units generate the smallest contractile
forces
– and allow the initial contraction to be finely graded.
• As more motor units are recruited,
– the alpha motor neurons with progressively larger
axons become involved
– and generate progressively larger amounts of tension
12. Whole muscle tension depends on
• the size of the muscle,
• the extent of motor unit recruitment,
• the size of each motor unit.
• The number of muscle fibers varies among
different motor units.
– Muscles performing refined, delicate movements
have few muscle fibers per motor unit.
– Muscles performing coarse, controlled movements
have a large number of fibers per motor unit.
– The asynchronous recruitment of motor units
delays or prevents muscle fatigue.
13. • One group of motor neuron pools is
located in the medial part of the ventral
horn, and the other much larger group lies
more laterally.
14. Somatotopic organization of spinal cord motor neuron
trunk extremities
α-mn: the flexors
final common
pathway
extensor
The ventral root s
15. Functional rule
• The motor neurons located medially project to
axial muscles (muscles of the neck and back):
those located more laterally project to limb
muscles (arms and legs).
• Within the lateral group the most medial motor
neuron pools tend to innervate the muscles of
the shoulder and pelvic girdles, while motor
neurons located more laterally project to distal
muscles of the extremities and digits.
• In addition the motor neurons innervating the
extensor muscles tend to lie ventral to those
innervating flexors.
17. Motor neurons
• Alpha motor neuron
– Thick myelinated fast conducting axons
– Motor end plate of extrafusal skeletal muscle
fibers
• Gamma motor neuron
– Thin myelinated slower conducting axons
– Supply the intrafusal fibers of Muscle spindles
in skeletal muscles
γ-static
γ-dynamic
18. Spinal interneurons
• Points of convergence for
– most of the input of the brain descending
tracts
– Sensory afferents & collaterals of LMN axons
• Intersegmental; same side of spinal cord
• Commissural: cross midline
19. Spinal reflexes
• Contribute to
• Muscle tone
• Body posture
• Locomotion
20. Muscle spindles
• Lie parallel to regular muscle fibers
• contain nuclear bag and nuclear chain
intrafusal muscle fibers.
21. Capsule
Alpha motor
neuron axon Intrafusal (spindle)
muscle fibers
Gamma motor
neuron axon Contractile end portions
of intrafusal fiber
Noncontractile
Secondary (flower-spray) central portion
endings of afferent of intrafusal
fibers fiber
Primary (annulospiral)
Extrafusal (“ordinary”) endings of afferent fibers
muscle fibers
22. Muscle spindles
• Can be stimulated by 2 ways
• Stretching the entire muscle
• Causing contraction of intrafusal fibers
while extrafusal fibers remain at the same
length.
23. Muscle spindles
• Group Ia afferent fibers form primary
endings on nuclear bag and chain fibers,
• Group II fibers form secondary endings on
nuclear chain fibers.
• Dynamic motor axons end on nuclear bag
fibers and static motor axons on nuclear
chain fibers.
24. Muscle spindles
• Primary endings demonstrate both static
and dynamic responses, which signal
muscle length and rate of change in
muscle length.
• Secondary endings demonstrate only
static responses and signal only muscle
length.
• Motor neurons cause muscle spindles to
shorten, which prevents the unloading
effect of muscle contraction.
25. Golgi tendon organs
• Located in the tendons of muscles and are
arranged in series.
• They are supplied by group Ib afferent
fibers and are excited both by stretch and
by contraction of the muscle (very
sensitive to changes in muscle tension)
26. Extrafusal
skeletal
muscle fiber
Spinal
cord
Intrafusal
muscle
spindle fiber
Afferent input from sensory endings of muscle spindle fiber
Alpha motor neuron output to regular skeletal-muscle fiber
Stretch reflex pathway
γ motor-neuron output to contractile end portions of spindle fiber
Descending pathways coactivating α and γ motor neurons
Figure 8.26 (1)
Page 287
27. Relaxed muscle; spindle Contracted muscle in Contracted muscle in
fiber sensitive to stretch hypothetical situation of normal situation of
of muscle no spindle coactivation; spindle coactivation;
slackened spindle fiber contracted spindle fiber
not sensitive to stretch sensitive to stretch of
of muscle muscle
28. • Nuclear bag fibers • Nuclear chain fibers
• Ia fibers • Ia fibers
• Show a dynamic • Show a Static
response: response
– Discharge most rapidly – Discharge at an
while the muscle is increased rate
being stretched & less throughout the period
rapidly during when a muscle is
sustained contraction stretched
• Signal the amount of
displacement
Primary endings Signal Velocity and
amount of change in muscle length
30. The stretch reflex includes
• a monosynaptic excitatory pathway from
group Ia (and II) muscle spindle afferent
fibers to a motor neurons that supply the
same and synergistic muscles and
• a disynaptic inhibitory pathway to
antagonistic motor neurons.
31. Myotatic stretch reflex
• The simplest reflex
• Monosynaptic
• Physiological significance:
– Resting muscle tone and thus A key reflex in
maintenance of posture
32. The tonic stretch reflex
• Physiological significance: Resting muscle
tone
– Judged by the resistance that a joint offers to
bending
– Receptors: Ia & II from muscle spindle
– Triggered by the static responses of group Ia
and II afferents.
– Any slight extension or flexion (during
standing) will elicit a tonic stretch reflex in
muscles required to oppose the movement,
thus helping an individual to stand upright.
33. Phasic stretch reflex
• Physiological significance:
• Receptors: Ia from muscle spindle
• Triggered by the dynamic responses of
group Ia fibers
• Enhancement of voluntary muscle
contraction by co-activation of gamma and
alpha motor neurons
34. Myotatic stretch reflex
• Clinical significance in diagnosis of
diseases
– tendon jerks
– muscle tone
36. Extensor muscle of knee Muscle
(quadriceps femoris) spindle
Patellar
tendon
Alpha motor
neuron
Figure 8.27
Page 288
37. Inverse stretch reflex
• Disynaptic (inhibitory interneuron+ α-mn )
• Inhibition of α-mn of same muscle
• Receptor: Golgi tendon organ (in series with
muscle fibers)
• Stimulus: increase in muscle tension by
– excessive stretch
– excessive active muscle contraction
• Result: relaxation (sudden stop in contraction)
• Safety:
– regulates muscle tension
– protects the tendon from tearing
38.
39. Withdrawal reflex
• Polysynaptic
• Protective
• Painful stimulation of skin, subcutaneous
tissue or muscle
• Stimulation of flexorscontraction
• Reciprocal innervation
• Simultaneous inhibition of antagonists
relaxation
40. = Inhibitory interneuron Components of a
Figure 5.33 = Excitatory interneuron
= Synapse
reflex arc
Receptor
= Inhibits
Page 178 = Stimulates Afferent pathway
Integrating center
Efferent pathway
Effector organs
Thermal
pain receptor
in finger
Ascending pathway
to brain
Afferent
Pathway
Stimulus
Biceps Efferent pathway
(flexor) Integrating center
contracts Triceps (spinal cord)
(extensor)
Hand relaxes
withdrawn
Effector
organs
Response
41. Crossed extensor reflex
• Supporting reflex, serves to maintain
posture
• Polysynaptic
• Irradiation of stimulation
• Reciprocal innervation
• Flexion and withdrawal of the painfully
stimulated limb
• + extension of the other limb
43. Upper motor
Dorsal root neuron of
ganglion cell Interneuron in corticospinal tract
the spinal cord
S Y α-motor neuron in
the spinal cord
Effector
W
U
X V
Receptor
Z
T
47. The Motor system 1
• Cortex
• The Corticospinal tract
• Alpha motor neuron
• Muscles
48. Motor Control
Motor Cortex
UMN
Corticospinal
Alpha motor tract (UMN)
neuron
axon, LMN Alpha motor
neuron,
LMN
Muscle
49. Four Hierarchical Components that
Control Movements
• Motor systems consist of separate neural
circuits that are linked.
• Ultimately, whether directly or indirectly
distributed, all motor processing is focused
on a single target ‘the motor neuron’
constituting the ‘final common pathway’ of
motor system.
50. Four Hierarchical Components that
Control Movements
Spinal cord
Brainstem
Subcortical (basal nuclei, thalamus,
cerebellum)
Cortical –(primary motor cortex, premotor
and supplementary motor areas)
51. Motor system 2
• Cortex
• corticospinal tract
• Alpha motor neuron
• Muscles
• Two control circuits that influence
the activity of corticospinal tract
– Cerebellum
– Basal Ganglia
53. Motor system 3
• Cortex
• corticospinal tract
• Alpha motor neuron
• Muscles
• + two control circuits influence the corticospinal tract
• Cerebellum and BG
• The Indirect brainstem motor control
centers and pathways which tonically
activate the Lower Motor Neurons
especially those that innervate the Axial
and Antigravity muscles
55. Upper Motor Neuron
• The corticospinal tract has its main influence on
LMN that innervate the muscles of the distal
extremities, i.e., the hand and the foot
• The corticospinal tract has collaterals that
modulate the control of indirect brainstem motor
centers, so that we are not as a statue opposing
gravity and can move at will and have the right
amount of supporting tone
• When there is lesion of UMN, clinical findings
are a combination of both direct + indirect effects
56. Premotor and
supplementary motor Figur
areas
Cortical e
level 8.24
Sensory
areas of Primary motor cortex Page
cortex 285
Subcortical
level
Basal
nuclei Thalamus Cerebellum
Brain stem Brain stem
level
nuclei
Spinal cord
level Afferent Motor
neuron
terminals neurons
Muscle
fibers
Periphery
Movement
57. “To move things is all that mankind can do…
for such the sole executant is muscle,
whether in whispering a syllable or in felling
a forest”.. Charles Sherrington
• The spinal cord contains certain motor
programs for the generation of
coordinated movements and that these
programs are accessed, executed, and
modified by descending commands from
the brain.
58. Types of Movements
• Involuntary motor acts
– Reflex: the most automatic behaviors (such
as reflexes-organized at spinal cord level)
• Voluntary motor acts
– The maintenance of position (posture)
– Goal directed movements- skilled voluntary
movements- organized at higher centers
59. Somatic musculature in relation to
the joint they act on
• Axial muscles:
– For movements of the trunk
• Proximal muscles (or girdle muscles)
– For movements of the shoulder, elbow, pelvis
and knee
• Distal muscles
– That move the hands, feet, and digits (fingers
and toes)
60. Important aspects of hierarchical
organization:
• Somatotopic maps – preserved in
interconnections at different levels
• each hierarchical level receives
information from periphery so that sensory
input can modify the action of descending
commands
• The higher levels have capacity to control
the information that reaches them,
allowing or suppressing the transmission
of afferent volleys through sensory relays.
61. Important aspects of hierarchical
organization:
• The various motor control levels are also
organized in parallel: so that each level
can act independently on the final
common pathway.
• This allows commands from higher levels
either to modify or to supersede lower
order reflex behavior.
65. UMNL is a combination of
Loss of regulation
of indirect
brainstem motor
control centers
Loss of direct
CST control
of LM
neurons
66. Upper Motor Neuron Lesion
• Loss of distal extremity strength Loss of
• Loss of distal extremity dexterity direct
• Babinski sign effect
• Increased tone
Loss of
• Hyperreflexia
indirect
• Clasp-knife phenomenon effect
67. UMNL on opposite side of clinical findings if
lesion is above the decussation
68. UMNL on same side of clinical findings if
lesion in the spinal cord after decussation
69.
70.
71.
72.
73. Figure 9: The brain of a
recovered stroke patient relies
on a compensatory neural
pathway (dark blue) as
substitution for the damaged
neuralpathway (blue dashed).
The cerebello-thalamo -cortical
pathway (green) is “teaching” the
supplementary motor area its
new function, which is indicated
by abnormal activity in the
cerebellum and thalamus.
(Freely adapted from Azari &
Seitz, 2000)
74.
75.
76. Airway Management
in the Emergency Department
and ICU
Mehdi Khosravi, MD Pulmonary/CCM Fellow
Giuditta Angelini, MD Assistant Professor
Jonathan T. Ketzler, MD Associate Professor
Douglas B. Coursin, MD Professor
Departments of Anesthesiology & Medicine
University of Wisconsin, Madison
77. Global Assessment
Assess underlying need for airway control
• Duration of intubation
- Nasal intubation less advantageous for potentially prolonged ventilator
requirements
• Permanent support
- Underlying advanced intrinsic lung or neuromuscular disease
• Temporary support
• Anesthesia
• Presence of reversible intrinsic lung or neuromuscular disease
• Protection of the airway due to depressed mental status
• Presence of reversible upper airway pathology
• Patient care needs (e.g., transport, CT scan, etc.)
• Significant comorbidities
Aspiration potential or increased respiratory secretions
Hemodynamic issues such as cardiac disease or sepsis
Renal or liver failure
78. Global Assessment
Pathophysiology of the respiratory failure
• Hypoxic respiratory failure
- In case of hypoxic respiratory failure, different noninvasive oxygen delivery
devices can be used.
- The severity of hypoxia and presence or absence of underlying disease (such
as COPD) will dictate the device of choice.
• Hypercapnic respiratory failure
- The noninvasive device of choice for hypercapnic respiratory failure is BIPAP.
Assessment of above mentioned patient characteristics in
conjunction with the mechanism of respiratory distress
leads the clinician to proper choice and duration of
invasive or noninvasive options for airway management.
Code status should be clarified prior to proceeding.
79. Global Assessment
Oxygenation
• Respiratory rate and use of accessory muscles
- Is the patient in respiratory distress?
• Amount of supplemental oxygen
- What is the patient’s oxygen demand?
• Pulse oximeter or arterial blood gas
- Is the patient physiologically capable of providing appropriate supply?
Airway
• Anatomy
- Will this patient be difficult to intubate?
• Patency
- Is there a reversible anatomical cause of respiratory failure as opposed to
intrinsic lung dysfunction?
• Airway device in place
- Is there a nasopharyngeal airway or combitube in place?
80. Oxygen Delivery Devices
(In order of degree of support)
Nasal Cannula
• 4% increase in FiO2 for each 1 L of flow (e.g., 4 L flow = 37% or 6 L flow
= 45%)
Face tent
• At most delivers 40% at 10-15 L flow
Ventimask
• Small amount of rebreathing
• 8 L flow = 40%, 15 L flow = 60%
Nonrebreather mask
• Attached reservoir bag allows 100% oxygen to enter mask with
inlet/outlet ports to allow exhalation to escape - does not guarantee
100% delivery.
81. Oxygen Delivery Devices
Noninvasive Positive Pressure
CPAP is a continuous positive pressure
• Indicated in hypoxic respiratory failure and obstructive sleep apnea
BiPAP allows for an inspiratory and expiratory pressure to support and improve
spontaneous ventilation
• Mainly indicated in hypercapnic respiratory failure and obstructive sleep apnea
If use of noninvasive modes of ventilation does not result in improved ventilation
or oxygenation in two to three hours, intubation should be considered
These devices can be used if following conditions are met:
• Patient is cooperative with appropriate level of consciousness
• Patient does not have increased respiratory secretions or aspiration potential
• Concurrent enteral feeding is contraindicated.
Facilitates early extubation, especially in COPD patients
Some devices allow respiratory rate to be set.
Up to 10 L of oxygen can be delivered into the mask for 100% oxygen delivery.
Nasal or oral (full face) mask can be used; less aspiration potential with nasal.
82. Degree of Respiratory Distress
Respiratory pattern
• Accessory muscle use is an indication of distress.
• Rate > 30 can indicate need for more support by noninvasive positive
pressure or intubation
Need for artificial airway
• Tongue and epiglottis fall back against posterior pharyngeal wall
• Nasopharyngeal airway better tolerated
Pulse oximetry
• O2 saturation less than 92% on 60 - 100% oxygen can suggest the need
for intubation based on whether there is anything immediately reversible
which could improve ventilation.
Arterial blood gas
• pH < 7.3 can indicate need for more support by noninvasive positive
pressure or intubation.
83. Temporizing Measures
Naloxone for narcotic overdose
• 40 mcg every minute up to 200 mcg with:
- 45 minutes to one hour duration of action
• 0.4 - 2 mg of naloxone is indicated in patients with respiratory arrest and
history suggestive of narcotic overdose
- There is a potential for pulmonary edema, so large dose is reserved
for known overdose and respiratory arrest
• Caution in patients with history of narcotic dependence
• Naloxone drip can be titrated starting at half the bolus dose used to
obtain an effect
- Manufacturer recommended 2 mg in 500 ml of normal saline or D5
gives 0.004 mg/ml concentration
84. Temporizing Measures (cont'd)
Flumazenil for benzodiazepine overdose
• 0.2 mg every minute up to 1 mg
• Caution in patients with history of benzodiazepine or alcohol dependence
• Caution in patients with history of seizure disorder as it will decrease the
seizure threshold
Artificial airway for upper airway obstruction in patients
with oversedation
• May be necessary in patients with sleep apnea despite judicious sedation
100% oxygen and maintenance of spontaneous
ventilation in patients with pneumothorax
• Washout of nitrogen may decrease size of pneumothorax
• Positive pressure may cause conversion to tension pneumothorax
86. Indications for Intubation
Depressed mental status
• Head trauma patients with GCS 8 or less is an indication for intubation
- Associated with increased intracranial pressure
- Associated with need for operative intervention
- Avoid hypoxemia and hypercarbia which can increase morbidity and
mortality
• Drug overdose patients may require 24 - 48 hours airway control.
Upper airway edema
• Inhalation injuries
• Ludwig’s angina
• Epiglottitis
87. Underlying Lung Disease
Chronic obstructive lung disease
• Application of controlled ventilation may interfere with complete
exhalation, overdistend alveoli, and impair right heart and pulmonary
venous return.
Pulmonary embolus
• Pulmonary artery and right ventricle already have high pressure and
dependent on preload
• Application of controlled ventilation may deteriorate oxygenation and
systemic pressure.
Restrictive lung disease
• May require less than 6 cc/kg Vt to prevent elevated intrapulmonary
pressure
• Application of positive pressure may result in barotrauma in addition to
impaired preload.
88. Airway Anatomy Suggesting Difficult
Intubation
Length of upper incisors and overriding maxillary teeth
Interincisor (between front teeth) distance < 3 cm (two finger tips)
Thyromental distance < 7 cm
• tip of mandible to hyoid bone (three finger breaths)
Neck extension < 35 degrees
Sternomental distance < 12.5 cm
• With the head fully extended and mouth closed
Narrow palate (less than three finger breaths)
Mallampati score class III or IV
Stiff joint syndrome Prayer Sign
• About one third of diabetics characterized by short stature, joint rigidity, and tight waxy skin
• Positive prayer sign with an inability to oppose fingers
No sign is foolproof to indicate intubation difficulty
Erden V, et al. Brit J Anesth. 2003;91:159-160.
89. Mallampati Score
Class I: Uvula/tonsillar pillars visible
Class II: Tip of uvula/pillars hidden by tongue
Class III: Only soft palate visible
Class IV: Only hard palate visible
Den Herder, et al. Laryngoscope. 2005;115(4):735-739.
90. Comorbidities
Potential for aspiration requires rapid sequence intubation with
cricoid pressure
• Clear liquids < 4 hours
• Particulate or solids < 8 hours
• Acute injury with sympathetic stimulation and diabetics may have
prolonged gastric emptying time.
Potential for hypotension
• Cardiac dysfunction, hypovolemia, and sepsis
• May need to consider awake intubation with topical anesthesia
(aerosolized lidocaine) as sedation may precipitate hemodynamic
compromise and even arrest.
Organ failure
• Renal and hepatic failure will limit medication used.
• Potential for preexisting pulmonary edema and airway bleeding from
manipulation
91. Induction Agents
Sodium Thiopental
• 3 - 5 mg/kg IV
• Profound hypotension in patients with hypovolemia, histamine release,
arteritis
• Dose should be decreased in both renal and hepatic failure.
Etomidate
• 0.1 - 0.3 mg/kg IV
• Lower dose range for elderly and hypovolemic patients
• Hemodynamic stability, myoclonus
• Caution should be exercised as even one dose causes adrenal
suppression due to similar steroid hormone structure.
• Unlikely to have prolonged effect in organ failure
92. Induction Agents (cont'd)
Propofol
• 2 - 3 mg/kg IV
• Hypotension, especially in patients with systolic heart dysfunction,
bradycardia, and even heart block
• Unlikely to have prolonged effect in organ failure
Ketamine
• 1 - 4 mg/kg IV, 5 - 10 mg/kg IM
• Stimulates sympathetic nervous system
• Requires atropine due to stimulated salivation and midazolam for
potential of dysphoria
• Avoid in patients with loss of autoregulation and closed head injury
93. Neuromuscular Blockers
Succinylcholine
• 1 - 2 mg/kg IV, 4 mg/kg IM
• Avoid in patients with malignant hyperthermia, > 24 hours out from burn or
trauma injury, upper motor neuron injury, and preexisting hyperkalemia
Rocuronium
• 0.6 - 1.2 mg/kg, highest dose required for rapid sequence
• Hemodynamically stable, 10% renal elimination
Vecuronium
• 0.1 mg/kg
• Hemodynamically stable, 10% renal elimination
Cisatricurium
• 0.2 mg/kg
• Mild histamine release, Hoffman degradation, not prolonged in renal or
hepatic failure
94. Rapid Sequence Intubation
Preoxygenate for three to five minutes prior to induction
• Wash out nitrogen to avoid premature desaturation during intubation.
Crycoid pressure should be applied from prior to induction
until confirmation of appropriate placement.
Succinylcholine 1 - 2 mg/kg IV will achieve intubation
conditions in 30 seconds; Rocuronium 1.2 mg/kg IV will
achieve intubation conditions in 45 seconds.
• Other muscle relaxants do not produce intubation conditions in less than
60 seconds.
Avoid mask ventilation after induction.
• Potentially can inflate stomach
• Use only if necessary to ensure appropriate oxygenation during
prolonged intubation.
96. Cricoid Pressure
Cricoid is circumferential
cartilage
Pressure obstructs
esophagus to prevent
escape of gastric
contents
Maintains airway patency
Koziol C, et al. AORN. 2000;72(6):1018-1030.
97. Sniffing Position
Align oral, pharyngeal, and laryngeal axes to
bring epiglottis and vocal cords into view.
Hirsch N, et al. Anesthesiology. 2000;93(5):1366.
98. Mask Ventilation
Mask ventilation crucial,
especially in patients who are
difficult to intubate
Sniffing position with tight
mask fit optimal
May require two hands
Mask ventilation crucial,
especially in patients who are
difficult to intubate
Sniffing position with tight
mask fit optimal
May require two hands
99. Laryngoscope Blades and Endotracheal
Tubes
Mac blade: End of blade should be placed in front of epiglottis in valecula
ETT for Fastrach LMA
Pediatric uncuffed ETT
ETT for blind nasal
Standard ETT
Miller blade: End of blade should be under epiglottis
100. Graded Views on Intubation
Grade 1: Full glottis visible
Grade 2: Only posterior commissure
Grade 3: Only epiglottis
Grade 4: No glottis structures are visible
Yarnamoto K, et al. Anesthesiology. 1997;86(2):316.
101. Confirmation of Placement
Direct visualization
Humidity fogging the endotracheal tube
End tidal CO2 which is maintained after > 5 breaths
• Low cardiac output results in decreased delivery of CO2
Refill in 5 seconds of self-inflating bulb at the end of the
endotracheal tube
Symmetrical chest wall movement
Bilateral breath sounds
Maintenance of oxygenation by pulse oximetry
Absence of epigastric auscultation during ventilation
102. Additional Considerations
Always have additional personnel and an experienced
provider as backup available for potential failed
intubation
Always have suction available
Never give a muscle relaxant if difficult mask ventilation
is demonstrated or expected
Awake intubation should be considered in the following:
• If patient is so hemodynamically unstable that induction drugs cannot be
tolerated (topicalize airway)
• If patient has a history or an exam which suggests difficult mask
ventilation and/or direct laryngoscopy
104. Alternative Methods
Blind nasal intubation
• Bleeding may cause problems with subsequent attempts.
• Contraindicated in patients with facial trauma due to cribiform plate disruption or
CSF leak
• Avoid in immune suppressed (i.e., bone marrow transplant)
Eschmann stylet
Fiber optic bronchoscopic intubation
• Awake vs. asleep
Laryngeal mask airway
• Allows ventilation while bridging to more definitive airway
Light wand
Retrograde intubation
• Through cricothyrotomy
Surgical tracheostomy
Combitube
105. Eschman Stylet
Use especially if Grade III
view achieved
Direct laryngoscopy is
performed
Place Eschman where
trachea is anticipated
May feel tracheal rings
against stiffness of stylet
Thread 7.0 or 7.5 ETT
over stylet with the
laryngoscope still in place
106. Fiberoptic Scope
Essentially what is used to do a
bronchoscopy
Can be used to thread an
endotracheal tube into the
trachea either while the patient
is asleep or on an awake
patient with a topicalized airway
Via laryngeal mask airway in
place due to inability to intubate
with DL:
• Aintree (airway exchange catheter) can
be threaded over the FOB to be placed
into trachea upon visualization
• Wire-guided airway exchange catheter
can also be used with one more step
108. LMA Placement
Guide the LMA along the
palate
Eventual position should
be underneath the
epiglottis, in front of the
tracheal opening, with the
tip in the esophagus
FOB placement through
LMA positions in front of
trachea
Martin S, et al. J Trauma Injury, Infection Crit Care.
1999;47(2):352-357.
109. The FastrachTM Laryngeal
Mask Airway
Reinforced LMA allows for
passage of ETT without
visualization of trachea.
10% failure rate in
experienced hands
20% failure rate in
inexperienced
110. The Light Wand
Transillumination of trachea
with light at distal end
Trachea not visualized
directly
Should not be used with
tumors, trauma, or foreign
bodies of upper airway
Minimal complication
except for mucosal bleed
10% failure rate on first
attempt in experienced
hands
111. Retrograde Intubation
Puncture of the
cricothyroid membrane
with retrograde passage of
a wire to the trachea
Endotracheal tube guided
endoscopically over the
wire through the trachea
Catheter through the
cricothyroid can be used
for jet ventilation if
necessary.
Wesler N, et al. Acta Anaes Scan. 2004;48(4):412-416.
112. Combitube
Emergency airway used mostly by
paramedics and emergency
physicians for failed endotracheal
intubation
Ventilation confirmed through blind
blue tube
• Combitube is in the esophagus and salem
sump can be placed through white tube
Ventilation confirmed through white
(clear) tube with patent distal end
• Combitube is in the trachea and salem sump
should be placed outside of combitube into
esophagus
• Fiber optic exchange can be accomplished
through combitube
113. Combitube (cont'd)
Should be changed to endotracheal tube (ETT) or
tracheostomy to prevent progressive airway edema
If in esophagus, take down pharyngeal cuff and attempt direct
laryngoscopy (DL) or fiber optic bronchoscope (FOB)
placement around combitube
Failed exchange attempt can be solved with operative
tracheostomy
Placement of combitube can produce significant airway
trauma
• Removal prior to DL or FOB should be done with caution after thorough airway
evaluation
• Cricoid pressure should be maintained and emergency tracheostomy equipment
available
114. Tracheostomy
Surgical airway through
the cervical trachea
Emergent procedure
carries risk of bleeding
due to proximity of
innominate artery
Can be difficult and time
consuming in emergent
situations
Sharpe M, et al. Laryngoscope. 2003;113(3):530-536.
115. Case Scenario #1
The patient is 70 kg with a 20-year history of diabetes.
On exam, the patient has intercisor distance of 4 cm,
thyromental distance is 8 cm, neck extension is 45
degrees, and mallampati score is 1.
Your staff wants to use thiopental and pancuronium.
Do you have any further questions for this patient or
would you proceed with your staff?
116. Case Scenario #1 - Answer
A diabetic for 20 years needs assessment for stiff joint
syndrome.
You should have the patient demonstrate the prayer sign.
If the patient is unable to oppose their fingers, you should
not give pancuronium.
You may want to proceed with an LMA and FOB at your
disposal.
If the patient has a history of gastroparesis, you may want
to consider an awake FOB.
117. Case Scenario #2
43-year-old patient with HIV, likely PCP pneumonia who
had been prophylaxed with dapsone
RR is 38, oxygen saturation is 90% on 100% NRB mask
The patient is on his way to get a CT scan.
Is it appropriate to proceed without intubation?
118. Case Scenario #2 - Answer
Dapsone will produce some degree of
methemoglobinemia.
Therefore, some degree of desaturation may not be
overcome.
The patient is in significant respiratory distress and will
be confined in an area without easy access.
Intubation should be considered as an extra measure of
safety, especially as this patient is likely to get worse.
119. Case Scenario #3
40-year-old, 182-kg man has a history of sleep apnea
and systolic ejection fraction of 25%. He has a Strep
pneumonia in his left lower lobe and progressive
respiratory insufficiency.
He extends his neck to 50 degrees and has a mallampati
score of 2.
Would you proceed with an awake FOB?
120. Case Scenario #3 - Answer
The patient’s airway anatomy is not suggestive of
difficulty.
However, with supine position, subcutaneous tissue may
impair your ability to visualize or ventilate.
Use of gravity, including a shoulder roll, extreme sniffing
position, and reverse trendelenburg may be helpful with
asleep DL.
Prudent to have some accessory equipment, including
an LMA and FOB, for back up
121. References
1. Caplan RA, et al. Practice guidelines for management of the
difficult airway. Anesthesiology. 1993;78:597-602.
2. Langeron O, et al. Predictors of difficult mask ventilation.
Anesthesiology. 2000;92:1229-36.
3. Frerk CM, et al. Predicting difficult intubation. Anaesthesia.
1991;46:1005-08.
4. Tse JC, et al. Predicting difficult endotracheal intubation in
surgical patients scheduled for general anesthesia.
Anesthesia & Analgesia. 1995;81:254-8.
5. Benumof JL, et al. LMA and the ASA difficult airway
algorithm. Anesthesiology. 1996;84:686-99.
6. Reynolds S, Heffner J. Airway management of the critically
ill patient. Chest. 2005;127:1397-1412.
