LECTURE SCRIPTMANAGEMENT OF THE AIRWAY
MAJ Alan Storrow, MD, USAF
Wilford Hall Medical Center
San Antonio, Texas
Managing the compromised airway is one of the
most challenging aspects of emergency medicine. It is the first priority in
patient care; the “A” of
the ABC’s. Complete airway obstruction leads to irreversible brain
damage in 3-5 minutes and cardiac arrest in as little as 4 minutes. The physician
who understands the pathophysiologic processes that lead to airway compromise
and is skillful in airway management techniques is well prepared to intervene
successfully in this situation.
The patient who presents with acute airway obstruction is in obvious distress. If obstruction is complete, the patient cannot cough, speak or breathe; and is noted to have increased heart rate, blood pressure and paradoxical respirations with no air movement . Within minutes the patient becomes cyanotic, loses consciousness and becomes apneic. Cardiac arrest quickly follows respiratory arrest, occurring 4-10 minutes after airway obstruction.
Initial management of the airway utilizes basic maneuvers to open the airway and enhance oxygenation. Supplemental oxygen should be provided to any seriously ill or injured patient. The concentration of oxygen provided is dependent on the flow rate and type of device used. Any critically ill patient should initially receive 100% oxygen delivered by a non-rebreather mask. Pre-oxygenation of the adult patient with 100% oxygen for 2-3 minutes prior to intubation provides 4-5 L of oxygen reserve.
At the same time the patient is being provided with oxygen, basic maneuvers to open the airway are performed. Patients not suspected of having a cervical spine injury can most effectively have their airway opened by a head tilt in combination with chin lift or jaw thrust. This maneuver is usually effective in lifting the tongue off the posterior pharynx. If cervical spine injury is suspected, a chin lift or jaw thrust alone is utilized to open the airway. Patients presenting with airway obstruction due to foreign body aspiration may be treated with other techniques. Abdominal thrusts (Heimlich maneuver) are used on the conscious patient with complete upper airway obstruction or partial obstruction with poor air exchange. This technique has been credited with saving approximately 50,000 lives; it should, however, be avoided in infants, and pregnant or obese patients. Foreign body removal in the unconscious patient is best managed by direct laryngoscopy and removal with Magill forceps. Finally, use a suction device to clear blood, secretions, and particulate matter from the upper airway.
Airway adjuncts are used to provide continued airway patency once the airway has been opened or cleared. Oropharyngeal and nasopharyngeal airways both maintain airway patency by providing a passage between the tongue and posterior pharynx. The oropharyngeal airway is used only in the unconscious patient; the nasopharyngeal airway may be used in a semi-conscious or unconscious patient. While both devices are effective in maintaining airway patency, they do not provide protection from aspiration. Thus, they should only be used until a more definitive airway can be provided in patients at risk for aspiration or when endotracheal intubation is otherwise indicated.
Indications for orotracheal intubation include apnea, upper airway obstruction,
airway protection, respiratory insufficiency, controlled hyperventilation,
and administration of drugs if IV access is unobtainable. There are no
absolute contraindications to orotracheal intubation; however, caution and
technique must be exercised in patients with suspected cervical spine injury.
The patient is placed in a supine position, with the head at the level of
the intubators lower sternum. The head is in the “sniffing” position,
with the head extended on the neck and the neck slightly flexed in relation
to the trunk. A small towel placed under the occiput may facilitate this position.
With the laryngoscope in the left hand, place the blade into the right side
of the patient’s mouth, sweeping the entire tongue all the way to the
left. Lifting the
The other route for endotracheal intubation is nasotracheal intubation.
Nasotracheal intubation is technically more difficult than orotracheal intubation. An awake patient may be placed in the sitting position; otherwise, the supine position is used. The larger nostril is selected for tube placement. The nasal mucosa is constricted with phenylephrine and anesthetized with lidocaine spray. Select a cuffed tube 1 mm in size smaller than would be used for orotracheal intubation.
Lubricate the tube then insert it with the bevel toward the septum, advancing
slowly. Listen at the end of the tube; when airway sounds are at maximum gently
but swiftly advance through cords when patient inspires. Confirm tube placement
by auscultation, looking for mist in tube, and ultimately with an x-ray.
Rapid sequence induction is a technique for inducing rapid onset of sedation and paralysis for controlled orotracheal intubation. This technique allows immediate control of the airway while minimizing the risk of aspiration. It also decreases the potentially adverse physiologic responses that often accompany intubation. Rapid sequence induction is indicated in patients requiring emergent intubation who would be difficult to intubate without paralysis. It is also indicated in patients who have increased intracranial pressure or an open eye injury. Contraindications include the inability to perform orotracheal intubation due to a fixed airway obstruction or distortion of airway anatomy, or not being prepared to obtain surgical control of the airway if rapid sequence intubation is unsuccessful.
Equipment preparation, patient positioning and pre-oxygenation are all performed in the same manner as oral intubation without rapid sequence induction.
The rapid induction of sedation and paralysis begins with premedication. Non-
depolarizing paralytic agents are given in sub-paralytic doses to prevent succinylcholine
induced fasciculations which cause increased intragastric, intracranial, and
intraocular pressure. Either pancuronium or vecuronium may be used, both at
a dose of 0.01 mg/kg IV push. These medications are most effective when given
3 minutes prior to paralysis with succinylcholine. Atropine 0.01 mg/kg IV push
(minimum dose of 0.1 mg) is recommended in children to prevent the bradycardia
that can occur in response to succinylcholine. It is also recommended for adults
prior to a second dose of succinylcholine. Lidocaine 1.5 mg/kg given IV over
30-60 seconds is used to suppress the cough reflex and increased intracranial
pressure response in patients with head trauma. When indicated, these medications
may be given in rapid succession at the onset of rapid sequence induction.
Administering lidocaine and waiting for the
The next step is the induction of sedation/unconsciousness, which can be achieved with a variety of different medications. Thiopental, fentanyl, and midazolam are among the agents most commonly used. Thiopental is a barbiturate which provides rapid and brief sedation. It is the drug of choice in patients with head trauma who are hemodynamically stable. It reduces cerebral metabolism and oxygen consumption which secondarily reduces cerebral blood flow and intracranial pressure. Adverse effects include hypotension, respiratory depression, and bronchospasm in asthmatics. The dose is 3-5 mg/kg IV push. Fentanyl is a potent narcotic analgesic with rapid onset and short duration. Adverse effects include respiratory depression and potential chest wall rigidity if >10 ug/kg is given rapidly. The dose is 2-3 ug/kg IV at a rate of I-2 ug/kg/min, titrating to effect. Midazolam is a benzodiazepine which provides a rapid onset of sedation with a lesser potential for cardiorespiratory depression than other drugs in its class. Other advantages are its amnestic effect and short duration of action. Adverse effects include respiratory depression and hypotension. The dose is 0.02-0.04 mg/kg given in 1 mg boluses, not to exceed 2.5 mg over 2 minutes. Midazolam and thiopental may be combined with fentanyl to obtain effective sedation and analgesia; however, decreased doses may be needed to avoid adverse effects enhanced by using more than one of these medications. Cricoid pressure is initiated at the onset of sedation prior to inducing paralysis.
Paralysis is achieved with the depolarizing agent succinylcholine. Many of its adverse side effects can be prevented with appropriate premedication as discussed above. Succinylcholine can induce hyperkalemia in patients at risk and should be avoided in patients with pre-existing hyperkalemia or previous disease states which may make them hypersensitive to succinylcholine. These include previous burns, neuromuscular or primary muscle disease, head or spinal cord injury, or stroke. Once succinylcholine has been given, allow 45-90 seconds for relaxation and then orally intubate the patient. Cricoid pressure should be maintained until a cuffed ET tube is in place.
Indications for cricothyrotomy include failure of oral or nasal endotracheal
intubation, upper airway obstruction not relieved with other measures, and
traumatic injuries making oral or nasal intubation difficult or hazardous.
The more common complications of cricothyrotomy include bleeding, injury to adjacent structures, incorrect tube placement, infection, and subglottic stenosis.
The indications for this procedure are the same as for surgical cricothyrotomy.
Complications of percutaneous transtracheal ventilation include subcutaneous emphysema, kinking or blocking of catheter, bleeding, infection, incorrect placement and damage to surrounding structures.
It is important to remember that most pediatric cardiac arrests are due to respiratory insufficiency or failure. Successful airway management and ventilation will often result in successful cardiac resuscitation.
When managing the pediatric airway, it is important to consider anatomical differences that may influence methods or equipment used. These differences include a relatively larger head and occiput, a smaller airway, and a larger tongue to oropharynx ratio. The larynx is higher and more anterior than in the adult, and the narrowest portion of the airway in children is at the level of the cricoid ring.
The basic maneuvers of airway management in pediatric patients are similar to those in adults. The indications for supplemental oxygen and the use of airway adjuncts are the same. There are some important differences to keep in mind when opening the airway. Due to the larger head and occiput size found in infants and small children, the neck is naturally flexed with a relative alignment of the pharyngeal and tracheal axes when the child is in the supine position. Further flexion of the neck, as might occur if a pillow is placed under the head, may make visualization of the glottis more difficult. It is equally important not to hyperextend the neck of the small child or infant, as this may actually lead to airway obstruction. The patient should be placed in the “sniffing position” to open the airway; care must be taken not to hyperflex or extend as discussed. Management of airway obstruction is similar to adults except 4 back blows and 4 chest thrusts are used in an infant < 1yr old instead of abdominal thrusts.
Pediatric patients without effective respiratory effort or inadequate ventilation
The technique for pediatric orotracheal intubation is similar to that of the
Reference tables are also available to check appropriate tube and blade sizes.
1. Roberts & Hedges: Clinical Procedures in Emergency Medicine
2. Rosen & Barkin: Emergency Medicine “Concepts and Clinical Practice”,
3. Bushore, Seidel, Fleisher, Wagner: Advanced Pediatric Life Support,
4. Tintinalli, Krome, Ruiz: Emergency Medicine “A Comprehensive Study