One can also determine
the Glasgow Coma Scale (GCS). It is generally accepted that a
GCS < 8 requires definite airway intervention to prevent aspiration
pneumonitis, to insure adequate oxygen delivery and to avoid hypercarbia.
If a patient is responding only to painful stimuli or is unresponsive/unconscious,
the GCS is or has a high likelihood of being less than 8.
ASSESS: Adequacy of Gas Exchange
- Physical Examination
Airway patency does not insure adequate
What is the nature of the injury? Maxillofacial
trauma/airway burns have the potential for airway compromise.
Is there obvious airway or chest trauma (sucking chest wounds,
flail segments) or cyanosis?
Is there tachypnea, use of accessory
muscles of respiration or evidence of tracheal shift?
Stridor indicates upper airway compromise.
Hyperresonance to percussion/lack of air entry suggests pneumothorax
while dullness to percussion/lack of air entry suggests hemothorax.
(Note that this is often difficult to determine in the setting
of a noisy resuscitation room) Bowel sounds in the chest may
be indicative of a ruptured diaphragm.
Place a hand over the mouth and feel
for air exchange. If necessary, insert a finger and sweep to
clear the mouth of any foreign bodies (especially dislodged
teeth) and to evaluate for evidence of maxillofacial trauma.
ASSESS: Adequacy of Gas Exchange
Pulse oximetry gives immediate feedback
although it is necessary to be aware of its pitfalls (motion,
peripheral vasoconstriction, carboxy/methaemoglobinemia). The
only parameter measured by oximetry is haemoglobin saturation.
Arterial blood gases provide a more
complete picture of the patient although there is a defined
waiting period (institution dependent). Results provide feedback
on oxygenation, ventilation and tissue perfusion.
Can surgical intervention such as tube thoracostomy resolve
the problem? If not, basic to advanced airway measures must
Securing the Airway
If a decision is made to secure the airway with an endotracheal
tube, several questions arise.
1) How quickly
must the airway be secured?
Airway intervention can be classified
as being immediate, emergent or urgent.(2)
If apnea is evident on the primary survey,
immediate endotracheal intubation is warranted.
However, simple mechanical means of
opening the airway and providing ventilation should not be overlooked
in the rush to intubate. As previously noted, inspect the mouth
for foreign bodies. Blood and secretions should be suctioned.
Breathing should be assisted with bag- mask ventilation as preparations
are made to intubate. Consideration of possible spinal cord
injuries or direct traumatic tracheal injuries should not prevent
attempts at lifesaving translaryngeal intubation.
Patients who are hypoventilating, have
significant head injury, or are cyanotic require emergency intervention
to establish a patent airway and effective ventilation. Occasionally,
opening the airway and providing bag-valve-mask ventilation
sufficiently improves oxygen- ation to allow use of a more elective
method of tracheal intubation. Otherwise, these patients should
be treated as above.
N.B. In both immediate and emergent
intubations, do not hesitate to proceed to a surgical airway
if initial attempts are unsuccessful.
Patients with burns, maxillofacial injury
and cervical hematomas will likely require a secure airway to
prevent upper airway obstruction. Patients with chest wall and
pulmonary injuries are usually initially well compensated but
may eventually require mechanical ventilation. With these patients,
there is often time for a history, appropriate physical exam
and cervical radiographs such that a planned approach to the
airway may be undertaken.
2) Which route
of intubation is to be employed? (oral vs. nasal)
Prior to the most recent revision of
the ATLS course, a very simplistic approach to the airway was
taken (see fig. 1). Blind nasotracheal intubation was heavily
relied upon although most anaesthetists are more comfortable
with direct orotracheal intubation.
Blind nasotracheal intubation requires
a spontaneously breathing unconscious or cooperative conscious
patient. There is an unacceptable failure rate (35%) and it
requires 3.7 vs. 1.3 oral attempts. Nasal intubations are contraindicated
in the patient with basal skull or mid-face fracture. The procedure
can precipitate epistaxis which may interfere with subsequent
alternative attempts at intubation if unsuccessful. There is
a high incidence of sinusitis if a tube is left in place greater
than 72 hours.
Current teaching recognizes the integral
role of the anaesthesia provider. The most important determinant
of whether to proceed with orotracheal or nasotracheal intubation
is the experience of the physician. Both techniques are safe
and effective if performed properly.(3)
3) What is
the status of the cervical spine?
N.B. Assume the cervical spine to be
unstable until proven otherwise.
Up to 50% of patients sustaining cervical
spine trauma develop neurologic abnormalities ranging from nerve
root compression and weakness to quadri- plegia, and in many
instances, death. As many as 10% of patient with cervical spinal
cord injury are initially neurologically intact, but develop
deficits during the course of emergency care.(4)
The radiographic dictum "one view is
no view" is nowhere more apt than in the roentgenographic evaluation
of acute spinal injury. (i.e. a single cross table lateral is
not enough). In the lateral view, one must be able to demonstrate
all 7 cervical vertebrae and preferably including T1 as approximately
30% of injuries occur at the C7-T1 level.
The AP view is assessed for vertical
alignment of the spinous and articular process and abnormalities
in joint and disc spaces.
The open mouth view is used to assess
the integrity of the atlanto-occipital and atlanto-axial joints
as well as the odontoid process.
Oblique views may be used to detail
more clearly the intervertebral foramen and the vertebral arches.
Most authors feel that a technically
adequate, normal three view series can be used to clear the
C-spine when there is appropriate correlation with the clinical
Pleuridirectional and CT scanning are
used to rule out injury when the plain radiographs are suspicious
or equivocal or when there is clinical evidence of a cord injury
despite negative radiographs.
The lateral cervical spine has a sensitivity
of about 85%. This increases to 92% in a three view series and
up to 100% when selective CT scanning is employed.(5)
Anaesthetists should be skilled at basic
interpretation of the C-spine films. Secondary spinal injury
is often a result of misinterpretation of films.
When reading a C-spine film, concentrate
- soft tissue
- vertebral alignment
1) Abnormal soft tissue can provide
significant information with regards to the localization of
C-spine trauma. A prevertebral hematoma is usually associated
with a fracture and should draw attention to a hyperextension
injury. Normally, the distance between the posterior pharyngeal
air column and the anterior inferior aspect of C2 is less than
7 mm. and the distance from C6 should be 22 mm. in adults (not
valid when Nasogastric/Orotracheal tubes are in place).
2) Normally, the cervical spine has
a lordotic curve. Some contend that the loss of lordosis is
suggestive of muscle spasm and C-spine injury although this
is not totally reliable. Spinal muscles do not play a significant
role in neck stability. Instead, it is mainly dependent on the
ligamentous and bony complex.
Four lines can be drawn to assess alignment:
- anterior margin of the vertebral
- posterior margin of the vertebral
- spinolaminar line
- spinous processes
Disruption of any one of these smooth
lines are suggestive of injury.
Biomechanical studies by White and coworkers6
have shown that instability of the cervical spine exists if
1) all the anterior or posterior elements are destroyed, 2)
there is greater than 3 1/2 mm horizontal displacement of one
vertebral body onto another, or 3) there is greater than 11
degrees of kyphotic hyperangulation. Additional helpful findings
include widening of the intervertebral disk space, prevertebral
hematoma and displacement of the apophyseal joints.
4) How do airway
management techniques affect C spine movement?
Basic Airway Maneuvers
In a study where all ligaments in a
cadaveric model were transected between C5-6 leaving only the
muscles intact, various airway management techniques were applied
with and without collars used to splint the unstable spine.
A chin lift / jaw thrust produced significant (>5mm.) increase
in disc space despite the presence of either a hard / soft collar.
Likewise, oral endotracheal intubation (curved or straight blade)
produced a 3-4 mm increase in disc space. In contrast, oral
/ nasal airway insertion was responsible for 2 mm posterior
subluxation (i.e minimal change).(7)
Advanced Airway Maneuvers
In another study, a group of healthy,
anaesthetized and paralyzed volunteers scheduled for elective
surgery were investigated for cervical spine movement during
intubation. Significant movement was noted during routine intubation
regardless of blade choice (Macintosh vs. Miller). The presence
of a Philadelphia collar was inconsequential. However, there
was a significant decrease in cervical spine movement (not complete
elimination) during orotracheal intubation when the patient
was placed on a short spine board and an assistant applied "in
Cricoid pressure is considered the standard
of care in the trauma patient. Sellick's maneuver increases
the convexity of the cervical spine, stretches the esophagus
taut, and thus improves its fixation by the posterior aspect
of the cricoid cartilage.
A potential concern exists regarding
the application of cricoid pressure against a potentially unstable
C-spine, especially at the C5-7 level. Some authors state that
instability at this level is a contraindication to cricoid pressure.
However, this appears to be more of a theoretical than practical
concern. In many situations, the status of the C-spine is not
clearly defined when airway management is initiated. As well,
information from large volume trauma centers where cricoid pressure
is routinely applied does not reveal an increased incidence
of secondary neurologic injury.
Contraindications to the application
of cricoid pressure are:
- Suspected airway injury (especially
injuries at the cricotracheal junction).
- Foreign body at the level of the
cricoid (either within the esophagus or the trachea).
- Active vomiting.
- Awake intubation or lightly sedated
5) If the spine
is unstable, should the airway be secured with the patient awake
The optimal mode of intubation is controversial.
As part of the early efforts aimed at reducing secondary neurologic
injury, a hypothesis was generated that the airway of patients
with unstable cervical spines could not be safely managed by
oral intubation. Although never proven, it was assumed that
movement associated with oral intubation and "in line immobilization"
would lead to secondary neurologic injury.(9) Suderman
et al(10) showed no difference in new neurologic deficits
in a study comparing awake vs. anaesthetized oral/nasal intubations
in a ten year review of 150 patients. Rosen (11) has
labeled this unsubstantiated hypothesis as a "therapeutic legend
of emergency medicine". There are numerous studies showing that
induction of anaesthesia and oral intubation in neck-injured
patients results in outcomes similar to those patients undergoing
Optimum care does not necessarily mean
the same care. Different centres may choose different approaches
as long as the essential elements are preserved.(9)
6) Which drugs
are most appropriate in the trauma setting?
Securing the airway can be performed
with or without pharmacologic assistance.
Patients with maxillofacial trauma,
evidence of airway obstruction / injury or other objective evidence
which may suggest a difficult laryngeal visualization should
have their airway secured while awake. Consider the use of local
anaesthetic topicalization with / without the addition of sedative
medication (e.g. fentanyl / midazolam).
For the patient with anticipated normal
anatomy, a rapid sequence intubation is an appropriate choice.
If possible, the patient is preoxygenated for 3-5 minutes or
asked to take several vital capacity breaths.
considering the use of succinylcholine)
- Larger doses of succinylcholine are
required and onset may be delayed.
- Duration of action may be increased
and retard the return to spontaneous breathing if ventilation
/ intubation is unsuccessful.
- A pre-curarization dose may lead
to aspiration of gastric/pharyngeal contents.
- dTC attenuates the increase in intragastric
and ?intracranial pressure.
In hemodynamically stable trauma patients,
rapid sequence induction is likely to produce an exaggerated
hemodynamic response that may be associated with:
- Increased myocardial oxygen consumption
(detrimental to the patient with ischemic heart disease)
- Elevation of intracranial pressure
(detrimental to the patient with head injury)
- Elevation of intraocular pressure
(detrimental to the patient with open eye injury)
The use of titrated doses of narcotics,
short acting ß-blockers (e.g. esmolol) and lidocaine,
whether alone or in combin- ation can be beneficial in attenuating
the response to laryngoscopy/intubation.
A large variety of intravenous induction
agents are available for the rapid sequence induction of anaesthesia.
With the possible exception of ketamine, these drugs are all
cardiovascular depressants and should be administered in reduced
(25-50% of normal) doses. In severely hemodynamically compromised
patients, these agents should be omitted entirely. The most
common drug given at trauma centres throughout the world for
the purpose of intubation is sodium thiopental. Although not
available in Canada, etomidate has gained popularity because
of its supposed hemodynamic stability in euvolemic patients
at usual induction doses.
It is the opinion of this author that
succinylcholine is still the drug of choice for intubation of
the trauma patient. At the time of writing, none of the non-
depolarizers can match succinylcholine in either its speed of
onset or offset.
- Does cause an increase in intragastric
pressure but also causes a simultaneous increase in lower
- tone which will prevent aspiration.
- Probably does not cause an elevation
in intracranial pressure.(12)
- May cause an increase in intraocular
pressure although this can be attenuated by a non-depolarizing
- Does cause an increase in K+ although
this is not an issue in the patient with new onset paralysis
from trauma who requires airway intervention in the resuscitation
room. It is a potential problem in the patient with massive
- Rarely causes cardiac dysrhythmias
in adult patients and pre-treatment with atropine will attenuate
Contraindications to succinylcholine
- the patient with malignant hyperthermia
- ongoing neuromuscular pathology
- underlying hyperkalemia regardless
Nondepolarizing Muscle Relaxants:
The use of these drugs avoids the potential
complications from succinylcholine. However, large doses of
these agents are required to produce an acceptable onset time.
This greatly increases the duration of action of the drug.
The drug of choice at the present time
is vecuronium which is given in a dose of 0.15-.0.25 mg/kg.
It has no cardiovascular effects. Although mivacurium has a
short duration of action, it has a long onset time. Increasing
the induction dose would speed onset at the expense of unacceptable
histamine release and hypotension. Rocuronium will probably
become the NDMR of choice once available in Canada as it has
an even shorter onset time than vecuronium.
What do you do when the airway cannot
be secured with traditional techniques?
The following is a list of alternative
techniques to secure the airway:
Gum Rubber Bougie
this device is placed in the trachea, one can sense the "bumps"
of the tracheal rings in contrast to the smooth sensation of
the esophagus. The endotracheal tube is then fed over the bougie.
good technique for the patient with potential C-spine injury
as the neck is maintained in the neutral position. However,
most of the commercially available stylets require low light
levels and concomitant resuscitation may be slowed. Newer models
claim superior brightness such that dimming the room lights
may no longer be required.
This technique requires considerable
expertise as well as a cooperative patient. It is best to use
the largest scope possible as airway bleeding and/or secretions
may limit success.
Tip: attach oxygen source to suction
port so as to both oxygenate the patient and clear secretions.
Retrograde or Translaryngeal
is probably the route of choice in the setting of maxillofacial
trauma. Various techniques have been described.(13,14)
The common denominator is the passage of a needle / wire system
through the cricothyroid membrane up into the oropharynx with
subsequent antegrade threading of an endotracheal tube over
the wire into the trachea.
anaesthesia providers should be familiar with this skill. Equipment
to perform this procedure should be immediately available. Personnel
should be readily available to proceed to a formal cricothyroidotomy
laryngeal mask is used for the "cannot intubate, cannot ventilate"
scenario. It is relatively easy to insert although a learning
curve does exist. It can be placed blindly or with the aid of
a laryngoscope. Remem- ber that the airway is not secure with
a laryngeal mask. It is a stop-gap measure only.
Combitube is a field airway device which is inserted blindly
into the esophagus and allows for indirect ventilation via a
double lumen design. It is the opinion of the author that this
is the tube of choice for the "cannot intubate, cannot ventilate"
scenario. No learning curve exists and it is superior to the
laryngeal mask for airway protection.
S. Efficacy of Cervical Spine Immobilization Methods. J. Trauma;
C. Textbook of Trauma Anesthesia and Critical Care. Mosby Year
Trauma Life Support Course for Physicians. The American College
of Surgeons; 1993
WA. Fractures and dislocations of the cervical spine: An end
result study. J. Bone Surg 1957;39-A:341-76
S.E. et al. Clearing the Cervical Spine: Initial Radiologic
Evaluation. J.Trauma 27:9 1055-1060
AA. et al. Biomechanical analysis of clinical stability in the
cervical spine. Clin Orthop 1975;109:85-96
C. et al. Experimental Cervical Spine Injury Model: Evaluation
of Airway Management and Splinting Techniques. Ann Emerg Med
TG et al. Cervical Spine Movement During Orotracheal Intubation.
Ann Emerg Med 15:4 417-20
ET. Tracheal intubation in the cervical spine-injured patient-Editorial.
Can J Anaesth 1992; 39:2 105-9
V, Crosby ET, Lui A. Elective oral tracheal intubation in cervical
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P, Wolfe RE. Therapeutic legends of emergency medicine. J Emerg
Med 1989;7: 387-9
WD, et al; Succinylcholine Does Not Change Intracranial Pressure,
Cerebral Blood Flow Velocity, or The Electroencephalogram in
Patients with Neurologic Injury. Anesth Analg 1994;78:469-73
P, Riou B. Retrograde technique for tracheal intubation in trauma
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HK. et al. Tranlaryngeal guided intubation for difficult intubation.
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