Airway management.pdf

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108

Airway management is an important aspect of pediatric

emergency care. Prompt, effective airway access can mean the

difference between a good outcome and disability or death. Op-

timal management requires an understanding of the differ-

ences between children and adults with respect to airway

anatomy and physiology and response to medications to facili-

tate airway access. In most cases, the emergency physician is

called to secure a childs airway with little forewarning. This

review details a logical and practical approach to the uncom-

plicated pediatric airway. Emphasis is also placed on recogni-

tion of the difficult airway and methods to render the difficulty

less daunting. Good judgment and the appropriate skills are

the prerequisites for success.

TARGET AUDIENCE

This CME activity is intended for physicians, nurses, nurse prac-titioners, physician assistants, and paramedics who care for chil-

dren in respiratory distress or cardiopulmonary arrest. Specialists

including pediatricians, emergency physicians, pediatric emer-

gency physicians, anesthesiologists, and trauma surgeons will find

this information particularly useful.

LEARNING OBJECTIVES

After completion of this article, the reader will

1. Be able to recognize the difficult airway and make the prepara-

tions necessary for the clinical scenario.

2. Be able to discuss the role of neuromuscular blocking agents

and induction drugs in airway management.

3. Be able to describe the management of the uncomplicated air-

way using manual ventilation with a bag and mask or direct

laryngoscopy.

4. Be familiar with alternative techniques for the difficult airway,

including blind nasotracheal intubation, lighted stylet, laryngeal

mask airway, flexible fiberoptic laryngoscope, retrograde intu-bation, and needle cricothyrotomy.

INTRODUCTION

Good airway management in the pediatric emergency depart-

ment (ED) can mean the difference between an acceptable out-

come and permanent disability or death. Airway management in

the critically ill child is a challenge for several reasons: it occurs

rarely, is often unanticipated, and must be achieved with little time

to plan in children with limited respiratory reserve. Moreover, the

emergency physician must sometimes provide airway manage-

ment without the benefit of fully knowing the extent of the pa-

tients injuries or medical conditions. Antecedent conditions (eg,

full stomach, shock, elevated intracranial pressure, and cardiovas-cular disease) complicate management and may not be immedi-

ately evident. As a consequence, the emergency physician must

choose strategies that are likely to succeed with few potential

complications.

Patients in the ED who require urgent or emergent airway man-

agement usually present with little advance warning; hence, there is

limited opportunity to mobilize specialized personnel and equip-

ment before the patients arrival. This is different from the operat-

ing room where an anesthesiologist faced with a difficult airway can

usually get help from several anesthesiologists and has an array of

airway adjuncts. Elective surgical cases complicated by airway dif-

ficulty can be managed by canceling surgery until well-planned al-

ternative techniques are available. The emergency physician usually

cannot return at another time with a better strategy.Optimal outcomes with pediatric airway management require a

thorough understanding of the physiologic, pharmacodynamic, and

anatomic differences between children and adults. Additionally,

good preparation, difficult airway recognition, and familiarity with

back-up plans for airway management are essential. This review is

intended for emergency physicians and, thus, will focus on devices

and techniques easily obtained and used in the ED.

PREPARATION

The first step toward success in securing a childs airway is appre-

ciation of the unique physiologic and anatomic differences between

0749-5161/02/1802-0108 Vol. 18, No. 2

PEDIATRIC EMERGENCY CARE Printed in U.S.A.

Copyright 2002 by Lippincott Williams & Wilkins, Inc.

EDITORS NOTE: This article is the second of six that will be published in 2002 for which a total of up to 6 Category

1 CME credits can be earned. Instructions for how credits can be earned appear on the last page of the Table of Contents.

CME REVIEW ARTICLE

*Pediatric Anesthesiologist and Intensivist, Departments of PediatricAnesthesia and Critical Care, Nemours Childrens Clinic, and Professor andChief, Division of Critical Care Medicine, University of Florida, Jacksonville,Florida.

Address for reprints: Niranjan Kissoon, MBBS, Professor and Chief, Di-vision of Critical Care Medicine, University of Florida Health SciencesCenter, 820 Prudential Drive, Suite 203, Howard Building, Jacksonville,FL 32207; e-mail: [email protected]

Key Words: Airway management, intubation, emergency resuscitation,respiratory failure

Securing the childs airway in the emergencydepartmentKEVIN J. SULLIVAN, MD,* NIRANJAN KISSOON, MBBS


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adults and children. Infants and children are likely to experience

arterial oxygen desaturation more rapidly than adults for several rea-

sons (Table 1). With pulmonary disease or short periods of apnea, the

rate of desaturation can be considerably shorter (1) because of in-

creased rate of oxygen consumption and the inability of the child to

preserve functional residual capacity (FRC).

Oxygen Consumption and Metabolic Rate. On average,

adults consume a total of 2 to 3 cc/kg/min of oxygen under basal con-ditions. As a result of factors related to growth and higher basal meta-

bolic rate, infants and children may consume 2 to 3 times as much

oxygen per kilogram of body weight under basal conditions (2).

Therefore, even if physiologic oxygen stores were identical, the

child would likely experience desaturation during even short peri-

ods of apnea.

Diminished Pulmonary Reserve. The FRC, a reservoir for gas

exchange, represents a similar percentage of total lung capacity in

awake children as in adults but not in anesthetized or paralyzed chil-

dren (3, 4). The diminished outward chest recoil of the infant causes

the FRC to plummet when some of the compensatory, active mech-

anisms for FRC preservation are abolished by the administration of

neuromuscular blocking and sedative medications. The net result of

the infants higher oxygen consumption and diminished oxygen re-serves is a tendency toward more rapid arterial oxygen desaturation

that is accelerated with coexistent lung disease.

Anatomic Differences. The anatomic differences pertinent to

airway management are outlined in Table 2. The infants prominent

occiput pushes the head into a flexed position, which causes airway

obstruction when the child is placed on the back. This can be over-

come by placing a towel roll under the shoulders. Care must be

taken to avoid excessive neck extension, because this, too, can re-

sult in airway obstruction.

The relatively large tongue of the infant, along with the rela-

tively small nares, causes increased resistance to airflow from a

facemask. Care must be taken to prevent the fingers holding the

mask hand from compressing the soft tissue structures of the floor

of the mouth. This can be avoided by making sure that all of thedigits of the hand are on bones of the chin, mandible, and mask it-

self. Additionally, early use of oropharyngeal or nasopharyngeal

airways (when not contraindicated) is encouraged.

Endotracheal intubation is complicated by the presence of smaller

airway structures with the larynx located higher in the neck (C4 vs

C6), which gives it an anterior and cephalad appearance. The epiglot-

tis is longer and omega shaped, and it is positioned in a shorter neck

close to prominent adenoid and tonsillar tissue. The trachea is short

and has a greater potential for inadvertent endobronchial intubation.

Finally, the cricoid cartilage ring is the narrowest part of the airway

as opposed to the glottis in adults. Attention to these anatomic dif-

ferences can help to prevent unnecessary postextubation stridor and

subglottic stenosis.

Because pediatric patients are prone to rapid arterial oxygen de-

saturation and may be difficult to mask ventilate or intubate, it is

essential to have all airway equipment readily available and in

working order. It is also prudent to have a back-up plan and equip-

ment available for situations in which standard mask ventilation

and intubation are difficult or impossible. This is particularly rele-

vant to the ED, where the clinician may not have the luxury of a

thorough airway assessment.

Recognition of the Difficult Airway. It is critical to recognize

the difficult airway before using induction agents and neuromuscu-

lar blockade, because failure to do so can result in a life-threatening

situation in which ventilation and intubation are impossible. Choos-

ing alternative awake, asleep, or spontaneously breathing tech-

niques for airway management in children with difficult airways can

be the difference between a smooth intubation and a fatal airway

flail.

In the absence of specific anatomic markers of airway abnor-mality, facial and upper airway trauma, or inflammation, it is ex-

ceedingly unlikely to be surprised by a difficult airway. A history

of difficult airway in the patient can be identified from Medic-Alert

bracelets or from the caretakers of children with conditions known

to predispose to airway difficulty. A prior history of airway treach-

ery is a red flag to heed, particularly if the difficulties occurred in

the hands of clinicians who are experienced in the airway manage-

ment of children. Physical findings that predict airway difficulty

are summarized in Table 3 and are discussed below.

Oropharyngeal Examination. The oropharyngeal examination

is the first step in assessing the airway. The patients oral cavity is

examined with his or her mouth open and the tongue maximally

protruded. The degree of mouth opening and the size of the tongue

relative to the oral cavity are assessed. Mallampati et al. (5) classi-fied airways on the basis of the degree of visualization of the fau-

cial pillars, soft palate, and uvula. The ability to see a large part of

these structures predicts a high probability of adequate laryngeal

visualization in adults. Whether the Mallampati et al. score can suc-

cessfully predict the degree of difficulty with endotracheal intuba-

tion in small children is not known.

Macroglossia, an absolute or relative enlargement of the tongue

in relation to the oral cavity, is a prominent feature of Down and

Beckwith-Wiedemann syndromes and is associated with airway

difficulty. Infiltration or crowding of the tongue and airway struc-

tures is commonly seen in mucopolysaccharidosis, morbid obesity,

cystic hygroma, edema, and cellulitis. The presence of a high,

arched palate is also associated with airway difficulty.

Vol. 18, No. 2 SECURING THE CHILDS AIRWAY IN THE ED 109

TABLE 1Respiratory physiologic differences between children and adults

Increased respiratory rateIncreased chest wall complianceDecreased lung elastic recoil (lower lung compliance)Diminished functional residual capacityIncreased rate of oxygen consumption

TABLE 2Anatomic differences between pediatric and adult airways

More prominent occiputTongue occupies relatively larger proportion of oral cavitySmall nasal passagesHypertrophied lymphoid tissueShort tracheaLong epiglottis

Larynx appears more anterior and cephalad

TABLE 3Findings that predict the presence of a difficult airway

Limited mouth openingCervical spine immobility (immobilization, trauma, degenerative

processes)Small mouthProminent central incisorsShort mandibleShort neckLarge tongue (relative or absolute)Obese patientsLaryngeal edema (infection, inhalation thermal injury)Mandibular, midface, and facial trauma


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Neck Extension. Neck extension is often necessary during

laryngoscopy to create a direct, straight line of vision from the

mouth to the glottic structures. Successful laryngoscopy can be per-

formed without neck extension, as is often necessary in the setting

of known or suspected cervical spine trauma. However, inability to

extend the neck as a result of trauma or congenital cervical spine

abnormalities (eg, trisomy 21, Goldenhar and Klippel-Feil syn-

dromes), juvenile rheumatoid arthritis, or prior cervical spine fixa-tion is a predictor of difficult intubation and ventilation.

Mandible Length. The mandible length refers to the distance

from the thyroid cartilage to the chin and is normally greater than

1.5 cm in infants (6). Patients who have a short mandible present

greater difficulty in lining up the pharyngeal, laryngotracheal, and

oral axes. These patients are said to have an anterior larynx because

the line of vision during laryngoscopy falls posterior to the airway

structures. Children with short mandibles must also compress more

tongue and oral structures into a small space, which often results in

difficulty with mask ventilation. Micrognathia is a salient feature of

Treacher-Collins and Pierre Robin syndromes.

The degree of airway abnormality, prior history of airway mis-

adventure(s), and the ability of the patient to physiologically toler-

ate the proposed airway procedure are factors that must be consid-ered when deciding on an airway strategy. It is imperative to

carefully consider these factors before attempting to control the air-

way in the spontaneously breathing child. When presented with the

profoundly compromised or apneic child, these criteria are useful

to predict airway compromise and allow for ancillary personnel

and techniques while the clinician initiates simultaneous airway

support.

Monitoring. Monitoring of the electrocardiogram, pulse ox-

imeter, and noninvasive blood pressure is important for several rea-

sons. This allows the clinician to assess the patients response to in-

duction drugs, ventilation, brief periods of apnea, and the detection

of unsuspected problems such as ongoing internal bleeding, peri-

cardial tamponade, tension pneumothorax, and increased intracra-

nial pressure.It is also essential to monitor of end-tidal carbon dioxide

(ETCO2). Detection of ETCO2 after endotracheal intubation is a

very sensitive and specific method to confirm endotracheal place-

ment of the tube. Despite proper tube placement, there may be lit-

tle or no carbon dioxide detected with the markedly diminished

pulmonary blood flow seen during cardiac arrest and profound hy-

povolemia (7). It is also possible to have a few weak signals of car-

bon dioxide if the endotracheal tube is in the esophagus and an

ETCO2 signal if the endotracheal tube is in the pharynx, above the

vocal cords (8, 9). Despite these pitfalls, ETCO2 detection and vi-

sualization of the endotracheal tube as it passes through the glottis

is the most reliable way to prevent inadvertent esophageal intuba-

tion. Additionally, the trend in ETCO2 is a guide to assessing the

response of the patient to cardiopulmonary resuscitation, fluid ther-

apy, inotropic agents, and the adequacy of ventilation (10, 11). It

can also rapidly detect inadvertent extubation during transport and

endotracheal tube repositioning.

Equipment for Airway Management. The equipment avail-

able for emergency airway management is listed in Table 4. Self-

inflating resuscitation bags are the simplest and most commonly

used items in the ED. They require a high liter flow of oxygen and

an inspiratory manifold and reservoir to maximize inspired oxygen

concentration (1214). Self-inflating resuscitation bags offer the ad-

vantage of allowing ventilation of the patient with room air if the

oxygen source becomes exhausted or disconnected. However, spon-

taneous ventilation through the inspiratory valve may be difficult.

Rebreathing of carbon dioxide is not possible, irrespective of the

rate of fresh gas flow into the apparatus as a result of the presence of

unidirectional exhalation valves. Positive end-expiratory pressure

(PEEP) can be administered through manipulation of built-in popoff

valves or through the addition of extraneous PEEP valves.

The use of Mapleson D ventilation bags allows for easy sponta-

neous ventilation and allows the clinician to easily adjust levels of

PEEP without the addition of extraneous valves. Unlike self-filling

bags, Mapleson circuits require a continuous oxygen supply to

function, because they cannot entrain room air. It is also necessaryto ensure a fresh gas flow at least 2 to 3 times the minute ventila-

tion for spontaneous ventilation and 1 to 2 times the minute venti-

lation for controlled ventilation to prevent rebreathing of carbon

dioxide (15).

As a general rule, the airway cart should contain at least one al-

ternative for the difficult airway. The rescue device should allow

for the restoration of ventilation and oxygenation in the event that

endotracheal intubation is not possible and mask ventilation is mar-

ginal or not possible. This category includes nonsurgical and surgi-

cal approaches as outlined in Table 4.

Medications. Medications are used to attenuate deleterious re-

flex autonomic responses to airway manipulation and to render the

patient unconscious and amnesic. Neuromuscular blockade is pro-

vided to optimize laryngeal visualization and to prevent coughing.

Emergency clinicians should be intimately familiar with the com-

monly used medications, side effects, routes of elimination, and

pharmacokinetic profiles. The Broselow-Luten tape (Armstrong

Medical Industries, Lincolnshire, IL) allows for accurate dosing for

patients if their weight is not known or if the clinician cannot im-

mediately recall the dose (16).

Premedication. Premedication may be conveniently grouped

into 4 categories and remembered by the acronym LOAD (17).

Lidocaine is most commonly used as an intravenous medication

for the purpose of suppressing reflex autonomic and airway re-

sponses to laryngoscopy and endotracheal intubation. Lidocaine at-

tenuates increases in intracranial pressure during laryngoscopy in

110 PEDIATRIC EMERGENCY CARE April 2002

TABLE 4Suggested airway cart equipment for the emergency department

Laryngoscope blades of all sizes and styles and Magill forcepsEndotracheal tubes of all sizes, cuffed and uncuffedCO2 detector (adult and pediatric)Facemasks (neonate to adult)All sizes of naso- and oropharyngeal airwaysSuction equipment and catheters

Self-inflating resuscitation bagsEndotracheal tube guides

Semi-rigid intubating stylet (some hollow variants facilitate jetventilation)

Light wandFlexible fiberoptic intubation equipmentEmergency nonsurgical ventilation

Transtracheal jet ventilationLaryngeal mask airwayTracheoesophageal combitube

Emergency surgical airway accessCricothyrotomy equipment

Needle (14-gauge catheter over needle, 3.0 ID endotracheal tubeadapter)

Seldinger kits available for children younger than 910 years

The expertise and experience of the ED clinician should dictate the con-

tents of the airway cart.Adapted from Practice guidelines for management of the difficult airway:a report by the American Society of Anesthesiologists Task Force on theManagement of the Difficult Airway. Anesthesiology 1993; 78:597602.


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children with intracranial hypertension. It is given as an intra-

venous bolus of 1 to 2 mg/kg 2 to 3 minutes before laryngoscopy,

and it has direct anesthetic properties on the central nervous system

(17). Lidocaine can also be nebulized or sprayed onto airway struc-

tures or into the trachea to diminish the patients response to laryn-

goscopy and intubation. Concentrations of 1%, 2%, and 4% can be

given in volumes calculated to keep the total dose below the toxic

limit of 5 mg/kg.Opioids and benzodiazepines do not reliably produce uncon-

sciousness unless they are administered in large quantities. In such

doses, they often also produce apnea. As such, these medications

are best used as adjunct therapies for amnesia and analgesia with

other induction drugs. Additionally, these medications may be used

for conscious sedation in the spontaneously breathing patient who

is to be kept awake and responsive during endotracheal intubation.

Opioids produce sedation and blunt the response to noxious airway

stimuli, whereas benzodiazepines induce sedation and amnesia.

After adequate topical anesthesia of the airways, short-acting med-

ications such as midazolam in 0.05 to 0.1 mg/kg increments and

fentanyl in 1 to 2 g/kg increments can be given to render the pa-

tient less anxious and more comfortable.

Synergistic respiratory depression results from concomitant ad-ministration of opioids and benzodiazepines; however, with careful

titration of these medications, it is possible to avoid respiratory de-

pression. Should respiratory depression or excessive somnolence

occur, these are the only medications for which reliable and rapid

antagonists exist and allow reversal if spontaneous ventilation is

threatened. Slow titration of these agents will allow the clinician to

avoid excessive respiratory depression and the chest wall rigidity

that has been described with the rapid administration of large quan-

tities of fentanyl to children (18). Owing to differences in drug pro-

tein binding, central nervous system perfusion and permeability,

and receptor affinity, the risk for respiratory depression and apnea

is greater in neonates (1921).

Anticholinergic medications including glycopyrrolate, scopol-

amine, and atropine have several applications in the managementof the difficult pediatric airway. They cause tachycardia and drying

of oral secretions, and scopolamine also causes amnesia. Neonates

have a tendency to respond to laryngoscopy or hypoxemia with a

dramatic slowing of the heart rate as a result of parasympathetic

nervous system activation. Because stroke volume cannot be aug-

mented appreciably in neonates, cardiac output is dependent on

heart rates that are neither excessively fast nor slow (22). Neonates

are, therefore, good candidates for premedication with anticholin-

ergic medications, especially when succinylcholine is used. Many

investigators recommend premedication with atropine for all chil-

dren younger than 10 years (17). Atropine sulfate in an intravenous

dose of 0.02 mg/kg with a minimum dose of 0.1 mg can be given

to prevent bradycardia during airway management. Atropine sul-

fate can also be given intramuscularly in a dose of 0.04 mg/kg. The

site of intramuscular injection affects the rate of response to at-

ropine, with lingual injection producing faster response than del-

toid or vastus lateralis injection (23). Anticholinergic medications,

such as glycopyrrolate (0.01 mg/kg), are given to dry oropharyn-

geal secretions to optimize visualization during fiberoptic tech-

niques of airway management. This is optimally given 30 minutes

before airway management is attempted and, therefore, may be of

limited use in emergency airway management. Scopolamine is also

a potent antisialagogue and has the added benefit of producing se-

dation and amnesia.

Defasciculating doses of nondepolarizing neuromuscular block-

ers (NMBs) are administered to patients for two reasons. Before

widespread availability of rapidly acting, nondepolarizing NMBs,

this priming dose of neuromuscular blocker would allow for

much more rapid onset of paralysis if the patient received one tenth

of the usual intubating dose (ie, pancuronium) 3 to 5 minutes be-

fore administration of the customary intubating dose (24). This is a

less common concern today with the availability of medications

such as mivacurium, rocuronium, and rapacuronium.

The second reason to administer a fraction of the usual dose of anondepolarizing NMB is to attenuate the fasciculations commonly

seen with the administration of succinylcholine. Although the

mechanism is not clear, elevations in intracranial and intraocular

pressure occur contemporaneously with fasciculations and may be

attenuated by prior administration of a defasciculating dose of non-

depolarizing NMBs (17, 25). Some patients may experience

diplopia, muscle weakness, and a sense of difficulty breathing re-

sulted from the weakness induced by this dose. It is therefore pru-

dent to try to render the patient amnesic to preintubation events and

to be prepared to quickly secure the airway should these symptoms

become problematic.

Other medications useful for airway management include a topi-

cal vasoconstrictor to minimize the risk of epistaxis during nasal ap-

proaches. Naloxone, 12 g/kg intravenously repeated as needed torestore adequate respiratory drive without excessively reversing se-

dation, and flumazenil (0.0050.01 mg/kg) are useful for reversing

excessive respiratory depression caused by benzodiazepines and opi-

oids when used in awake attempts at airway management during

spontaneous ventilation (26). Repeated doses may be needed to treat

recurrent respiratory depression, because the half-lives of these an-

tagonists are generally shorter than the drugs they are designed to

antagonize.

NEUROMUSCULAR BLOCKERS. The purpose of NMBs is to

provide complete muscle relaxation to facilitate endotracheal in-

tubation. These drugs differ in their onset times, duration of ac-

tion, side effects, and routes of metabolism. Succinylcholine, mi-

vacurium, and rocuronium provide alternatives for all situations

in the ED.DEPOLARIZING NEUROMUSCULAR BLOCKADE. Succinylcholine is

a depolarizing NMB that produces reliable intubating conditions in

the shortest amount of time. In children, an intravenous dose of 2

mg/kg (45 mg/kg intramuscularly) produces intubating conditions

within 30 to 45 seconds (46 min after intramuscular injection) (24).

In older children, the onset of paralysis is heralded by skeletal mus-

cle fasciculation, which is usually not seen in infants. The principal

benefit of neuromuscular blockade is that most patients will recover

from it in approximately 5 to 7 minutes. Thus, neuromuscular block-

ade is ideal for rapid sequence intubation (RSI) and for use in the dif-

ficult airway.

In emergencies where succinylcholine is believed to be the best

drug for airway management, there should little reservation about

using it. However, there are relative contraindications to its use,

which are outlined in Table 5. The tendency to elevate serum

potassium levels is of little clinical relevance in most patients.

However, patients with burns, denervating nerve injuries (eg,

stroke, spinal cord injury), crush injury, intra-abdominal abscess,

and myopathy are at risk for marked elevations in serum potas-

sium that can result in cardiac arrest (2729). Hyperkalemia does

not seem to be problematic in patients with cerebral palsy or

myelomeningocele (30, 31). For acquired risk factors (eg, burns,

denervating injuries), it is recommended that succinylcholine be

avoided for the period between 1 and 2 days to 6 months to 2

years after the injury (32).

There is also concern that succinylcholine administration will ex-



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acerbate intracranial hypertension or elevate intraocular pressure in

patients with an open eye injury. Elevations in intraocular and in-

tracranial pressure occur contemporaneously with the skeletal mus-

cle fasciculations that follow succinylcholine administration, but themechanism of pressure elevation is not known. It is also unclear

whether small children (younger than 6 to 8 years) possess adequate

muscle mass to produce substantial fasciculations, and substantial

fasciculations are not commonly seen in infants (24). Despite this,

many clinicians believe that administration of a defasciculating dose

of a nondepolarizing NMB (10% of the usual intubating dose) may

help to attenuate these deleterious effects (17, 25). It is reasonable

to administer this nondepolarizing NMB dose 1 to 3 minutes before

succinylcholine administration if intracranial hypertension or in-

traocular pressure is of concern.

Succinylcholine may also cause arrhythmias in children, particu-

larly bradyarrhythmias, after intravenous injection. Succinylcholine

structurally resembles two acetylcholine molecules bonded together,

and it has a tendency to act as a muscarinic surge at the parasympa-thetic receptors on the heart. Children are particularly prone to the

vagal effects of succinylcholine, and this drug should probably al-

ways be preceded by intravenous atropine in children in the ED (33).

Atropine premedication may be less critical when succinylcholine is

administered intramuscularly (34).

NONDEPOLARIZING NEUROMUSCULAR BLOCKADE. Mivacurium

is a nondepolarizing NMB that represents a reasonable compro-

mise between succinylcholine and other NMBs. Mivacurium in

an intravenous dose of 0.3 mg/kg provides muscle relaxation (al-

beit sometimes weak relaxation) in 60 to 90 seconds and provides

clinical relaxation for 8 to 15 minutes in the absence of pharma-

cologic antagonism. Recovery to 25% of baseline twitch height is

evident in 6 minutes in infants and in 10 minutes in children (35,

36). Like succinylcholine, mivacurium is dependent on plasma

cholinesterase for elimination, but, unlike succinylcholine, it can

be antagonized with neostigmine. Rapid administration causes

histamine release. The intensity of neuromuscular blockade with

this drug has been somewhat variable and less complete than suc-

cinylcholine.

Rocuronium is a nondepolarizing NMB that produces strong

muscle relaxation in 30 to 45 seconds to just over 1 minute when

administered in a dose of 0.6 to 1.2 mg/kg intravenously (higher

doses for RSI conditions). Rocuronium is similar to succinyl-

choline in its ability to produce favorable RSI conditions (37);

likewise, it is of rapid onset, but its duration of effect tends to be

about 30 to 45 minutes. The return of the first twitch in the train of

four returns in approximately 17 minutes and can be pharmacolog-

ically antagonized with neostigmine if necessary (37). Like suc-

cinylcholine, rocuronium can be administered intramuscularly in

the absence of intravenous access (38). In high doses, it sometimes

causes tachycardia. Rocuronium is best used for RSI when there is

a reason to avoid succinylcholine, and the airway is not anticipated

to be difficult. Rocuronium is metabolized and excreted by the liver

and can be antagonized by neostigmine.SEDATIVE AND INDUCTION DRUGS. Sedative and induction drugs

produce unconsciousness and amnesia and facilitate endotracheal

intubation. A detailed discussion of the pharmacodynamics and

pharmacokinetics of the induction agents is beyond the scope of

this report, but the salient features are reviewed briefly. Sodium

thiopental (STP) reliably produces unconsciousness, amnesia, and

apnea in induction doses of 4 to 7 mg/kg intravenously (40).

Lower doses are required in neonates because of decreased protein

binding (41). The clinical effects of STP dissipate rapidly because

of redistribution from the central nervous system to fat and mus-

cle, which explains why a medication with an elimination half-life

of 3 to 10 hours in children is clinically effective for only 20 min-

utes (42). After repeated doses of STP are administered, saturation

of muscle and fat sites occurs and redistribution no longer takesplace.

Induction doses of STP lower intracranial pressure more than

mean arterial pressure (43). Thus, cerebral perfusion pressure is pre-

served or improved, whereas the medication decreases the cerebral

rate of oxygen consumption (43). STP is also a potent antiepileptic

drug even in small doses, but it is of short duration because of redis-

tribution. STP is a direct myocardial depressant, causing tachycardia

by a central vagolytic mechanism, venous capacitance vessel pool-

ing of blood, and reduced cardiac output (43). Patients with car-

diomyopathy, profound hypovolemia, and insufficient baroreceptor

reflexes can experience profound hypotension from customary in-

duction doses of STP. Therefore, if STP is to be used in these cir-

cumstances, smaller doses should be titrated cautiously.

Ketamine can be considered to be the opposite of STP with re-spect to its hemodynamic profile. Its usual intravenous dose of 1 to

2 mg/kg increments produces dissociative analgesia and amnesia.

Intramuscular administration is unpredictable, but an intramuscular

dose of 4 to 6 mg/kg is usually sufficient. Ketamine increases heart

rate, blood pressure, and cardiac output through its stimulation of

central sympathetic nervous system outflow (26). It is a direct myo-

cardial depressant (44) and must be used with caution in patients

with depleted catecholamine reserves (severe end-stage shock) in

whom deleterious hemodynamic effects may be observed. As op-

posed to all of the other induction drugs, respiratory drive is rela-

tively preserved with ketamine (26), although intact laryngeal re-

flexes cannot be presumed to be present. Patients ventilate

spontaneously, which makes this an attractive sedative for proce-

dures in unintubated patients in whom it is preferable to maintain

spontaneous ventilation. However, preservation of spontaneous

ventilation cannot be assured in neonates receiving ketamine or in

older children who are premedicated with large doses of opioid

medications. Ketamine is a potent bronchodilator and may be the

drug of choice for intubation of the severe asthmatic. As a potent

sialogogue, however, concomitant administration of an anticholin-

ergic medication should be considered to prevent copious airway

and salivary secretions. In contrast to STP, the central nervous sys-

tem effects of ketamine include increased cerebral metabolic rate,

intracranial pressure, and cerebral blood flow (43). As such, it is a

poor choice for the patient with increased intracranial pressure.

Emergence delirium is less common in children than adults. How-


TABLE 5Selected potential deleterious effects

associated with the use of succinylcholine

HyperkalemiaMyopathyHistory of malignant hyperthermiaDenervating injury or disease process ( 23 d, lasting for 36 mo or

longer)

Recent burns (more than 24 h and less than 6 mo since injuryriskbelieved to decrease with healing)

Crush injuriesAbdominal abscesses

ArrythmiasIncreased intracranial pressureIncreased intraocular pressureMyalgiasIncreased intragastric pressure


6/14

ever, premedication with a benzodiazepine is an effective way to

attenuate this side effect.

Etomidate incorporates the best of STP and ketamine. Etomidate,

in an induction dose of 0.3 to 0.4 mg/kg intravenously, preserves car-

diovascular stability (45, 46), producing minimal changes in blood

pressure, cardiac output, or systemic vascular resistance. It results in

less respiratory depression than barbiturates, and it decreases cere-

bral metabolic rate of oxygen, intracranial pressure, cerebral bloodflow, and maintains cerebral perfusion pressure (43). Etomidate may

potentiate seizure foci in patients with seizure disorders (47, 48). Pre-

vious investigators have demonstrated increased mortality among

patients receiving prolonged infusions of etomidate for sedation (49).

Etomidate transiently inhibits the enzymes responsible for the syn-

thesis of adrenal steroids (49), and both induction doses and long-

term infusions may cause reversible adrenal insufficiency (50, 51).

However, this is not likely to be of clinical significance during use in

the ED. Etomidate is a good choice for induction of anesthesia in pa-

tients who are critically ill with unknown circulatory or central ner-

vous system disease.

Benzodiazepines, including midazolam, diazepam, and loraze-

pam, are commonly used in the ED to provide sedation and amne-

sia during airway management. Benzodiazepines are attractive be-cause of their antiepileptic properties and the relative hemodynamic

stability that they provide. One should be cautious, however, when

they are used with opioids or other sedative hypnotic medications,

because this may produce synergistic respiratory depression.

BASIC AIRWAY MANAGEMENT

Schematic approaches to the pediatric airway are outlined in Fig-

ure 1. For practical purposes, the pediatric airway in the ED can be

classified into three categories: the uncomplicated airway, the ob-

viously difficult airway, and the difficult airway that is not antici-

pated.

Any approach to securing the childs airway must be simple and

likely to be successful on first attempt. Individual practitioner pref-erence, familiarity, and confidence should dictate the options avail-

able in a given ED. Although it is necessary to be familiar with all

of the approaches, it is critical to be particularly adept at a few.

Figure 1A depicts a global approach to the pediatric airway and

emphasizes the importance of recognition of the difficult airway

(defined as an airway predicted to be difficult to mask ventilate and

intubate) before administering sedating or paralyzing drugs. Figure

1B outlines the approach to the straightforward pediatric airway

and advocates rapid sequence induction or modified rapid sequence

induction for most pediatric patients with uncomplicated airways.

It also provides escape arms for lost airways (unable to mask ven-

tilate or intubate) and the unrecognized difficult airway (able to

mask, unable to intubate).

The difficult airway algorithm (Fig. 1C) provides some recom-

mendations for an approach to the airway that is known to be diffi-

cult. It emphasizes the importance of maintaining spontaneous ven-

tilation if the patient is fairly stable. The patient can remain

conscious and breathing spontaneously, or sedatives can be titrated

to help manage the less cooperative patient. The sedatives used

should be easily reversible if drug-induced respiratory compromise

occurs.

The lost airway algorithm (Fig. 1D) provides some recommenda-

tions for airway management if bag-mask ventilation or intubation is

not possible, and spontaneous ventilation is inadequate or absent.

This algorithm recognizes the difficulty in pediatric transtracheal

techniques and offers the clinician the opportunity to decide whether

airflow obstruction during mask ventilation can be bypassed by in-

troducing a laryngeal mask airway (LMA) or Combitube (Kendall,

Mansfield, MA) (for larger children). If this is unsuccessful or un-

available, the next step is to proceed immediately to invasive airway

management. For the profoundly hypoxemic patient who is in ex-

tremis, the clinician should proceed directly to needle cricothyrot-

omy in children, because this is the technique that is most likely to be

rapidly successful.The final algorithm, the crash airway algorithm (Fig. 1E), pro-

vides some recommendations for airway management in the patient

who is critically ill or unstable. It acknowledges that it may not be

necessary to provide pharmacologic assistance for the patient who

is already moribund and unlikely to react to or recall the airway in-

tervention. We advocate immediate initiation of bag-mask ventila-

tion before the first attempt at endotracheal intubation. This may

restore some physiologic stability and prevent or forestall cardio-

vascular collapse. Likewise, for the patient with intracranial hyper-

tension, mask ventilation is the most effective in rapidly lowering

intracranial pressure and improving cerebral blood flow. We sug-

gest using STP or etomidate plus lidocaine and a muscle relaxant if

the patient is moribund and intracranial hypertension is present. For

other patients, laryngoscopy and intubation can be performed with-out pharmacologic assistance.

It should be emphasized that algorithms are helpful; however,

clinical judgment, experience, and expertise should guide the indi-

vidual approach. Maintaining spontaneous ventilation (if it is phys-

iologically adequate) in the difficult airway scenario is critical. Fi-

nally, it is important to recognize when airway interventions are

ineffective. At this point, failure to proceed to another translaryn-

geal or transtracheal form of support may result in an adverse pa-

tient outcome.

The single most valuable asset available to the clinician is profi-

ciency at bag-mask ventilation. This is the technique that will buy

time and preserve life while other airway equipment, personnel, and

techniques can be mobilized. Poor technique results in hypoventila-

tion, gastric insufflation with air, and subsequent aspiration of gas-tric contents. Good technique involves preserving good maskface

seal, inflating the chest with the minimal required pressure, main-

taining the optimal patency of the upper airway through manipula-

tion of the mandible and cervical spine (when not contraindicated),

and insertion of oropharyngeal or nasopharyngeal airways (when

not contraindicated) to maintain patency of the upper airway. Good

mask technique, positioning, and gentle cricoid pressure are re-

quired to help minimize the risks of gastric aspiration. Cricoid pres-

sure must be applied gently (depress the trachea 12 cm) in infants,

because the pliable trachea can be completely occluded by the Sell-

ick maneuver if performed with too much pressure.

In most children, placement of the endotracheal tube under direct

visualization with the RSI technique is all that is needed. All at-

tempts at direct laryngoscopy should be gentle and brief. Failure to

do so will result in further airway bleeding and edema and may ex-

acerbate intracranial hypertension. Indeed, the most common sce-

nario leading to severe injury in lost airway scenarios is progressive

airway compromise as a result of repeated iatrogenic trauma and

failure to abandon a technique that has proven to be ineffective.

The Uncomplicated Pediatric Airway. Patients in the ED

can generally be assumed to have a full stomach. Rapid sequence

induction is an airway strategy that is designed to minimize the risk

of aspiration of gastric contents. In this scenario, the patient is pre-

oxygenated by breathing spontaneously, and induction drugs and

paralytics are injected in rapid sequence. The patient is allowed to

become apneic without ventilating with positive pressure. As soon



7/14


A

B

FIG. 1. A, Global algorithm for pediatric airway management in the emergency department.B, Management of the straightforward pediatric airway. (continued)


8/14


FIG. 1. (Continued) C, Difficult airway algorithm. Options for endotracheal tube placement while the patient is breathing spontaneously include, but are notlimited to, awake direct laryngoscopy, blind nasal (children 10 y), fiberoptic methods (Bullard, flexible bronchoscope), intubating laryngeal mask airway, lightwand, retrograde techniques.D, Lost airway algorithm. (continued)

C

D


9/14


as the patient is paralyzed and sedated, the clinician performs direct

laryngoscopy and places the endotracheal tube under direct visual-

ization while an assistant provides gentle cricoid pressure (Sellickmaneuver). This technique provides optimal conditions for endo-

tracheal intubation and minimizes the risk of gastric aspiration. It

should be the technique most commonly used in the ED.

Rapid sequence induction may require modification when ap-

plied to younger children, especially infants and those with severe

lung pathology, because they are likely to desaturate quickly. In this

setting, a modified rapid sequence induction is selected. After pre-

oxygenation, a sedative and paralytic medication is given intra-

venously as cricoid pressure is gently applied. The airway is gently

ventilated with positive pressure until laryngoscopy and endotra-

cheal intubation. This prevents, or minimizes, the arterial oxygen

desaturation associated with brief periods of apnea in the sick infant.

The Obviously Difficult Airway. The child with a history or

physical findings suggestive of a difficult airway presents the clin-ician with the opportunity to avoid the pitfalls associated with a sit-

uation in which intubation and ventilation are impossible. Patients

with obviously difficult airways include those with syndromes as-

sociated with abnormal airway anatomy and those with abnormal

airways resulting from trauma or airway inflammation (eg, epiglot-

titis, caustic ingestion, or thermal injury). The approach to airway

management is dictated by the urgency of the patients condition

and the perceived difficulty the airway presents.

If it is likely that bag-valve-mask ventilation will be successful,

drugs that will abolish respiratory drive or paralyze the respiratory

muscles should not be given. In such instances, it is preferable to

secure the airway with the patient breathing spontaneously. Op-

tions for accomplishing this include generous topical airway anes-

thesia followed by awake laryngoscopy, fiberoptic bronchoscopy,

blind nasotracheal intubation, light wand intubation, and retrogradetechniques. The choice of technique will depend on the preference

and confidence level of the practitioner, age and degree of cooper-

ation of the child, and the specific clinical circumstances. It may

also be appropriate to involve other health care professionals

skilled in airway access to assist if time permits.

For patients who are likely to be easy to bag-mask ventilate, but dif-

ficult to intubate endotracheally, other approaches are possible. In this

situation, the risk of gastric aspiration during airway manipulations

must be weighed against the increased cooperation gained by admin-

istering sedatives and/or paralytic agents. In agitated and uncoopera-

tive patients, the risk benefit ratio may favor sedation and/or paraly-

sis. The favorable conditions gained may more than offset the risk of

aspiration. In addition to the techniques described previously, the

spontaneously breathing patient can also be taken to the operatingroom and intubated while spontaneously inhaling volatile anesthetics.

In the ED there will be patients with difficult airways and limited

physiological reserve who are in need of immediate airway access.

Approaches in such a setting include the quick confirmation that

one can neither mask ventilate nor endotracheally intubate the

patient. If neither can be done, it is appropriate to place a tempo-

rizing airway (eg, LMA, Combitube) or proceed directly to an in-

vasive airway technique.

Options for invasive airway management in children in the ED in-

clude needle cricothyrotomy and/or placement of a larger cricothy-

roid tube via the Seldinger technique. Needle cricothyroidotomy is

the easiest and safest technique for temporary ventilatory support in

E

FIG. 1. (Continued) E, Crash airway algorithm. Adapted from Walls RW. The emergency airway algorithms. In: Manual of emergency airway management.Philadelphia: Lippincott Williams & Wilkins, 2000;1626.


10/14

the ED and should be considered the technique of choice. The tech-

nique for gas exchange is dictated by patient age. Bag ventilation or

transtracheal jet ventilation (TTJV) with the pressure regulator set to

a low pounds per square inch (PSI) can be used to temporarily restore

oxygenation while a more definitive airway is pursued (52). How-

ever, TTJV should be used only by those who are skilled and com-

fortable with the technique.

Despite all of the opinions and reviews written on this subject,few clinicians actually have experience applying technique in chil-

dren. The cricothyroid membrane is small and may be difficult to

palpate in infants and smaller children. In such instances, it is ap-

propriate to place an intravenous catheter through the trachea in the

region of the cricothyroid membrane. Oxygenation and life-

sustaining levels of ventilation can be sustained for an hour or more

in dogs with nearly complete upper airway obstruction. Gas ex-

change was provided by low-flow oxygen in spontaneously breath-

ing animals and by positive pressure ventilation with a self-filling

bag in paralyzed animals (53).

Needle cricothyrotomy in children is a temporary measure and

is used to preserve oxygenation until a definitive airway can be ob-

tained. Although oxygenation may be preserved at life-sustaining

levels with this technique, ventilation is often marginally adequatefor a finite time period, and careful attention must be paid to the

rise and fall of the chest and oxygenation. Complete, or high-grade

proximal airway obstruction, can result in inadequate exhalation

and air trapping, leading to barotrauma and pneumothoraces.

Complications from errant placement of the needle and catheter

include pneumothorax, subcutaneous emphysema resulting in the

loss of favorable conditions for subsequent attempts at correct

catheter placement, mediastinal emphysema, esophageal injury,

and bleeding. In addition, ventilation with a self-filling resuscita-

tion bag may be difficult because of the high resistance imposed

by the small intravenous catheter in the airway. It may be neces-

sary to disable the pop-off valve on the self-filling bag to optimize

ventilation. Finally, TTJV requires the use of specialized equip-

ment and may cause injury if used improperly (54). Careful mon-itoring of the rise and fall of the chest, oxygen saturations, and

carbon dioxide tensions on blood gases is mandatory. Tracheos-

tomy (with surgical consultation in ED or operating room) or

translaryngeal endotracheal intubation from above can then be at-

tempted after oxygenation is ensured by needle cricothyrotomy.

Commercial kits are available for needle cricothyrotomy with sub-

sequent passage of a guidewire into the trachea, passage of serial

dilators, and placement of a cricothyrotomy tube. The wider bore

cricothyrotomy tube is much more able to facilitate ventilation

than the needle catheter; however, such kits exist only for children

older than 10 years.

The Unanticipated Difficult Airway. Despite attempts to

screen for and predict airway difficulties, the difficult airway may

be first recognized during the laryngoscopy phase of RSI. The next

step is to immediately determine whether the patient can be venti-

lated with bag and mask. If the patient can be ventilated, the tech-

niques available include optimizing the position and allowing the

most skilled individual present to repeat laryngoscopy. If the pa-

tient cannot be intubated, alternative techniques of airway manage-

ment include fiberoptic intubation, Bullard laryngoscopy, light

wand, retrograde techniques, and placement of LMA with blind or

fiberoptic placement of an endotracheal tube through the LMA.

Other options are needle cricothyrotomy with bag or transtracheal

jet ventilation or the placement of a cricothyrotomy tube via the

Seldinger technique (patient age and size permitting).

If the patient cannot be ventilated, urgent action is needed to es-

tablish ventilation. In rapid succession, this includes calling for

help, placement of oral and nasal airways (when not contraindi-

cated), and two-hand mask grip with optimization of sniffing posi-

tion and forward mandible displacement (observing c-spine precau-

tions when indicated) while an assistant squeezes the resuscitation

bag. If air cannot be moved effectively, the clinician must quickly

decide whether the airway obstruction can be remedied with LMA

placement or tracheoesophageal Combitube placement (if the pa-tient is an appropriate candidate for this device). Generally speak-

ing, pathology at the level of the supraglottis or below may not be

bypassed with these modalities, and it may be more prudent to pro-

ceed immediately to needle cricothyrotomy. Alternatively, older

children can be managed with placement of a cricothyrotomy tube

via Seldinger technique. For speed and simplicity, needle cricothy-

rotomy is probably the procedure that is most familiar to ED physi-

cians.

Review of Specific Techniques. Needle cricothyrotomy is

performed when anatomic injury prevents the movement of gas

from the upper airway into the trachea and the trachea cannot be in-

tubated via the translaryngeal route. A 14-gauge catheter over a

needle is introduced into the trachea in the region of the cricothy-

roid membrane. A syringe is attached to the needle and aspiratedfor free flow of air indicating entry into the trachea. With the

catheter firmly held in the trachea, the catheter is directly attached

to the endotracheal tube adapter from a 3.0 endotracheal tube. A re-

suscitation bag can then be attached to the catheter adapter assem-

bly, and oxygen can be insufflated into the lungs. Alternatively, the

barrel of a 3-cc syringe can be placed in the hub of the catheter, and

an endotracheal tube adapter from a 7.0 endotracheal tube can com-

plete the assembly for resuscitation bag attachment. An alternative

method for insufflating gas into the trachea is to connect a high-

pressure wall source (50 PSI) to the catheter via a hand-operated jet

injector with a pressure regulator gauge apparatus to prevent baro-

trauma. For children younger than 5 years, needle cricothyrotomy

with bag ventilation is the technique of choice (55). For children

between the ages of 5 and 10 years, options include needle cri-cothyrotomy with bag ventilation or TTJV with the pressure regu-

lator set to a low PSI that is sufficient to inflate the chest. For chil-

dren older than 10 years, the patients size may allow the clinician

to place a larger bore cricothyroid tube from commercially avail-

able kits, such as TTJV catheters or Seldinger cricothyroid sets

(Cook Critical Care, Bloomington, IN) (52).

The LMA is a recent addition to the difficult airway algorithm

presented by the American Society of Anesthesiologists (55) and

has recently been suggested for pediatric advanced life support by

the American Heart Association (56). The LMA consists of a wide

bore tube with a standard 15-mm adapter at the proximal end for at-

tachment to a breathing circuit or resuscitation bag. The distal end

is an elliptical mask that is inflated through a pilot balloon and con-

forms to the shape of the larynx. It provides a low-pressure seal for

mask ventilation at the level of the larynx (Fig. 2).

The advantage of the LMA is that it can effectively bypass the

supraglottic structures and can free the clinicians hands for further

airway endeavors. It also serves as an effective conduit for placement

of a fiberoptic bronchoscope into the trachea, because the LMA

opening is at the entrance of the glottis. LMAs come in varying sizes

and can be used in the smallest of pediatric patients (Table 6). LMAs

designed to facilitate fiberoptic intubation through the LMA are now

available with a modified laryngeal aperture with a movable flange

designed to lift the epiglottis from the path of the bronchoscope.

The LMA provides no more airway protection than a simple face-

mask. Patients may aspirate gastric contents, and the low-pressure



11/14

seal may make ventilation difficult in patients who require elevatedinflating pressures because of obesity or intrinsic lung disease.

Placement of the LMA requires more sedation or anesthesia than

placement of an oral or nasal airway, and practice is required to be

proficient at proper placement and use of this instrument. Inability

to ventilate through the LMA is either a result of downfolding of the

epiglottis over the glottis during LMA placement or obstruction be-

low the level of the glottis.

The tracheoesophageal Combitube can be very helpful in allowing

ventilation and oxygenation to be preserved when mask ventilation

is difficult. The Combitube is a cylindrical device with two separate

lumens and two separate 15-mm airway adapters at the proximal end.

One of the lumens (white) serves as an endotracheal tube if the de-

vice should end up in the trachea as it is passed blindly through the

mouth. There other lumen (blue) has a sealed distal end and proximal

fenestrations to allow air to be delivered to the region of the glottis

by bag mask. A proximal balloon is inflated in the hypopharynx to

provide an adequate airway seal to permit ventilation. With the de-

vice placed blindly into the espohagus it serves the function of an

LMA, and the endotracheal tube lumen (white) can be used to facil-

itate passage of a nasogastric tube to evacuate the stomach (Fig. 3).

The Combitube has the disadvantage of being available in only one

size and is, therefore, helpful only in adolescents (patients older than15 years and5 ft tall) and has the potential to cause esophageal in-

jury in patients with esophageal pathology.

Although patients sometimes cannot be ventilated by mask or


TABLE 6Suggested sizes for laryngeal mask airways in children

Mask size Patient size Weight (kg) Cuff volume (mL)

1 Infant 6.5 2 to 42 Child 6.520 102.5 Child 2030 153 Small adult 30 20

4 Normal and large adult 30Reprinted with permission from Morgan GE Jr, Mikhail MS. Airway

management. In: Clinical anesthesiology, ed 2. Stamford, CT: Appletonand Lange, 1996; 5072.

FIG. 3. Tracheoesophageal Combitube placed in esophagus or tracheacan provide emergency ventilation.A, The tracheoesophageal Combitubehas two lumens and two cuffs. B, If placed in the esophagus, ventilationthrough the blind tube will force gas out the side perforations and into thelarynx. C, If placed in the trachea, ventilation through the patent clear tubewill direct gas into the trachea. Reprinted with permission from Morgan GEJr, Mikhail MS. Airway management. In: Clinical anesthesiology, ed 2.Stamford, CT: Appleton-Lange, 1996;59.

A

B

FIG. 2. A, Laryngeal mask airways (LMA) of different sizes. B,Schematic drawing of proper placement of LMA: side view of LMA (A),insertion of LMA with head in sniffing position while pressing devicealong hard palate (B), advancement of LMA against posterior pharynx un-til seated (C), correctly seated LMA (D). Reprinted with permission fromMorgan GE Jr, Mikhail MS. Airway management. In: Clinical anesthesiol-ogy, ed 2. Stamford, CT: Appleton-Lange, 1996; 56.


12/14

LMA, it is more likely that the patient can be ventilated to some de-

gree but cannot be intubated by the translaryngeal route under di-

rect visualization. This is common in patients with cervical spine

trauma, cervical spine fusion, limited mouth opening, and other

anatomic reasons contributing to the clinicians inability to align

the oral, pharyngeal, and laryngeal axes. In this situation, transla-

ryngeal tracheal intubation is possible via the blindor indirect vi-

sualization techniques.Indirect visualization techniques allow the clinician to see the

larynx indirectly using flexible fiberoptic bronchoscopy or a

Bullard laryngoscope. The Bullard laryngoscope is available in

adult and pediatric sizes (Fig. 4) and consists essentially of a

fiberoptic apparatus mounted on a handheld, L-shaped frame. It is

inserted into the oropharynx and allows the airway structures to

be directly visualized while the preloaded endotracheal tube is

passed off a wire stylet through the glottis under indirect visual-

ization. This can be done when the patient is awake (with topical

anesthesia) or asleep with either spontaneous or positive pressure

mask ventilation (asleep and paralyzed). Flexible fiberoptic intu-

bation entails the use of a variety of sizes (outer diameter and

length) of fiberoptic bronchoscopes over which an endotracheal

tube has been loaded. The bronchoscope can be introduced intothe airway via the oral or nasal routes and, likewise, can be done

when the patient is awake, asleep and breathing spontaneously, or

asleep and paralyzed. This can be accomplished via intermittent

attempts between mask ventilation with periods of apnea or it can

be performed through specialized facemasks that allow for con-

tinuous ventilation while flexible fiberoptic bronchoscopy is per-

formed.

Blindtechniques are methods in which the endotracheal tube is

placed into the trachea without direct or indirect visualization.

These techniques essentially include blind nasal techniques as well

as light wand intubations. Blind nasal intubation is easier in a spon-

taneously breathing patient. This technique involves the introduc-

tion of an endotracheal tube into the nasopharynx of the patient and

the advancement of the tube as the breath sounds in the endotra-cheal tube become louder. Commercially available endotracheal

tubes that incorporate a guiding ring and cable in the wall of the en-

dotracheal tube make it easy to direct the tube in an anterior direc-

tion for easier insertion. This technique is not advisable in patients

with potential basilar skull fracture. Techniques to facilitate seda-

tion with spontaneous ventilation include light benzodiazepine-

opioid sedation with topical airway anesthesia, inhalation anesthe-

sia, or ketamine-benzodiazepine methods. Blind nasal intubation is

not likely to be successful in small children because of the anterior

location of the glottis and the small laryngeal aperture that is ob-

scured by the epiglottis. This technique is not recommended for

routine use in children younger than 10 years (55).Light wand techniques involve passing an endotracheal tube

from an illuminated intubating stylet into the trachea without direct

or indirect visualization. The light wand has a very bright light on

its tip that is blindly passed through the glottic aperture. Placement

is attempted when a very bright light is visible through the skin

overlying the thyroid and cricoid cartilage. The main pitfall of this

technique is that, even with esophageal placement of the stylet, a

very bright light can sometimes still be seen through the anterior

neck. It is important to practice this technique to be able to reliably

distinguish between correct and incorrect stylet positions so as to

pass the endotracheal tube without displacing the stylet. This tech-

nique works better in anesthetized patients.

The final methods for translaryngeal intubation are collectively

referred to as retrograde techniques. This term encompasses a widevariety of permutations of maneuvers but in its distilled form refers

to the placement of a guidewire into the airway via the cricothyroid

membrane or trachea. The wire is passed proximally through the

laryngeal aperture and retrieved from the oropharynx. The wire is

passed through the Murphy eye of the endotracheal tube, and the

endotracheal tube is advanced into the trachea over the guidewire.

Alternatively, the guidewire can be passed through the working port

of a bronchoscope over which an endotracheal tube has already been

loaded. The bronchoscope and endotracheal tube combination is ad-

vanced over the guidewire and placed in the trachea under indirect

visualization. These techniques work best with generous topical air-

way anesthesia or after the induction of anesthesia.

CONCLUSIONS

Proper airway management requires practice and judgment in

addition to an appreciation of the anatomic, pharmacologic, and

physiologic differences that separate infants and children from

adults. It is prudent to become proficient at techniques for airway

management beyond simple direct laryngoscopy and endotracheal

intubation, even though most cases will require nothing more. The

clinician should strive to be familiar with many techniques, but

should become very adept at only a few.

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FIG. 4. Bullard laryngoscope. The Bullard laryngoscope is a metalframe with fiberoptic components that is inserted into the airway and allowsthe operator to insert the endotracheal tube under indirect visualization. Un-like a conventional laryngoscope, it is not necessary to align the oral, pha-ryngeal, and tracheal axes.


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