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Airway Management in Pediatric Patients


Key Points

  • The first attempt at the pediatric airway should be the best attempt and includes proper preparation of equipment and positioning.

  • The pediatric airway anatomy is different in children, whose larynx is located higher in the neck with a relatively larger tongue. Children have a differently shaped epiglottis, and their vocal cords are angled.

  • The newborn rib cage is oriented parallel, and the intercostal muscles are not as effective at increasing intrathoracic volume with inspiration as are those of adults.

  • The work of breathing for each kilogram of body weight is similar in infants and adults.

  • The oxygen consumption of a full-term newborn (6 mL/kg/min) is twice that of an adult (3 mL/kg/min), which results in an increased respiratory rate.

  • An infant’s tidal volume is relatively fixed.

  • Minute alveolar ventilation in infants is more dependent on increased respiratory rate than on tidal volume.

  • Functional residual capacity (FRC) of an infant is similar to FRC of an adult when normalized to body weight because the ratio of alveolar minute ventilation to FRC is doubled (with hypoxia or apnea or under anesthesia), the infant’s FRC is diminished, and desaturation occurs more precipitously.

  • Continuous apneic oxygenation should be utilized during intubation of the neonate and small infants.

  • In infants, most airflow resistance occurs in the bronchial and small airways.

  • Resistance to airflow is inversely proportional to the radius of the lumen to the fourth power for laminar flow and to the radius of the fifth power (r 5 ) for turbulent flow.

  • There is lateral displacement of the airway in 45% of the population under 8 years of age.

  • Radiographic evaluation may be extremely helpful to diagnose a difficult airway (DA) in a child.

  • Radiographs of a child’s upper airway (AP and lateral films, fluoroscopy) may show site and cause of airway obstruction.

  • When necessary, magnetic resonance imaging (MRI) and computed tomography (CT) of pediatric patients provide more detailed information if time permits.

Introduction

One of the most challenging aspects facing anesthesiologists is maintaining the technical skills necessary for the management of the difficult airway (DA). The American Society of Anesthesiologists (ASA) guidelines define a DA as the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with any of the following: face-mask ventilation of the upper airway, layrngoscopy, ventilation using a supraglottic airway (SGA), tracheal intubation, extubation, or invasive airway. Recent reports demonstrate how important skilled airway management is to the practice of pediatric anesthesia. Data from the ASA pediatric closed claims database demonstrate a greater frequency of adverse respiratory events in the pediatric population. In the pediatric closed claims analysis, respiratory events accounted for 43% of all adverse events, most frequently related to inadequate ventilation (20%). Esophageal intubation, airway obstruction, and difficult intubation (DI) combined accounted for 14% of the remaining adverse respiratory events. In the pediatric perioperative cardiac arrest (POCA) registry, 20% of all cardiac arrests were attributed to the respiratory system. Airway obstruction and DI were responsible for 27% and 13% of these events, respectively. Incidence of difficult mask ventilation in nonobese children is 2.1%. Most of the patients who experience arrests from airway obstruction or DI have an underlying disease or syndrome. Unless otherwise indicated, throughout this chapter “patient” refers to the pediatric patient.

In addition, infants and small children display anatomic differences compared with adults. Knowledge of these differences, as well as congenital syndromes and different disease states, is required for management of the DA. Airway management in the pediatric patient may require general anesthesia (GA) before intubation attempts, which might not be a primary approach in a cooperative adult patient. Practice guidelines should be followed when managing the difficult pediatric airway in order to minimize adverse events.

Anatomy of the Pediatric Airway

The pediatric airway, particularly in infants, is different from the adult airway. Understanding these differences is important when managing the pediatric airway. The following is a brief review of the anatomy of the normal pediatric airway.

Larynx

The larynx is situated more cephalad at the third and fourth cervical vertebrae (C3–C4) level in the infant and migrates to the adult C5 level by 6 years of age. Because the infant’s larynx is more rostral (higher), the tongue is located closer to the palate and more easily opposes the palate. As a result, airway obstruction may occur during induction or emergence from anesthesia. A common misnomer is that the infant’s larynx is more anterior, when it is really more rostral or superior in the neck, compared with the adult larynx. In syndromes associated with mandibular hypoplasia, such as Pierre Robin, the larynx is actually positioned more posteriorly than normal. This results in a greater acute angulation between the laryngeal inlet and the base of the tongue. In this circumstance, direct visualization of the glottis may be difficult or impossible. Because of the cephalad position of the larynx and the large occiput, the sniffing position does not assist in visualization of the pediatric larynx. , Elevating the head only moves the larynx into a more anterior position. Infants should be positioned with the head and shoulders on a flat surface with the head in a neutral position and the neck neither flexed nor extended ( Fig. 36.1 ). A small roll can be placed under the infant’s shoulders to achieve a more neutral position ( Fig. 36.2 ).

Fig. 36.1, Infants should be positioned with the head and shoulders on a flat surface with the head in a neutral position and the neck neither flexed nor extended.

Fig. 36.2, A small roll can be placed under the infant’s shoulders to achieve a more neutral position.

Epiglottis

The infant epiglottis is long, stiff, and often described as Ω or U shaped. It projects posteriorly above the glottis at a 45-degree angle. Because the epiglottis is more obliquely angled, visualization of the vocal cords may be difficult during direct laryngoscopy. It may be necessary to lift the tip of the epiglottis with a laryngoscope blade to visualize the vocal cords. Straight laryngoscope blades are often preferred for this reason. If the patient is not paralyzed, use of a Macintosh blade is less stimulating because it is not necessary to lift the epiglottis.

Subglottis

Historically, it was thought that the cricoid cartilage was the narrowest portion of the infant’s airway, causing the larynx to be funnel shaped; however, recent studies demonstrate that the glottic opening and the subvocal cord level are the narrowest portions of the infant’s airway, and the airway is more cylindrical in shape. Tight-fitting endotracheal tubes (ETTs) that compress the mucosa at this level may cause edema and increase resistance to flow. Resistance to flow is inversely proportional to the radius of the lumen to the fourth power (r 4 ). One millimeter (1 mm) of edema can reduce the cross-sectional area of the infant trachea by 75%, versus 44% in the adult trachea.

Evaluation of the Pediatric Airway

No completed studies have evaluated the predictors of DI in children. Physical examination to predict the potential DA should be guided by the knowledge of normal anatomy and the syndromes associated with the DA.

The evaluation of the pediatric airway should begin with a history and physical examination of the head and neck. The examinations mostly involve subjective experience, and consistent evaluation criteria should improve the ability to predict the DA. Clues to a potential DA include snoring, noisy breathing, difficulty breathing with feeding or an upper respiratory tract infection, decreased neck mobility and extension, small mouth opening, and recurrent croup. Review of previous anesthesia records should be performed, if available. If a DA is encountered, documentation of events and the ability to mask ventilate are helpful for future caregivers. A prior uneventful anesthesia does not guarantee success the next time. ,

Knowledge of syndromes that may adversely affect the airway is crucial to the management of the difficult pediatric airway. The presence of one anomaly mandates a search for others. A common feature in patients with many of these syndromes is micrognathia . Micrognathia creates more difficulty with displacement of the tongue during direct laryngoscopy, thus increasing the chance that the glottis will be difficult to visualize. , The ability to intubate often changes as the child grows. Intubation often becomes easier with syndromes associated with micrognathia (e.g., Pierre Robin) as the patient ages. In mucopolysaccharide disorders or abnormalities involving the cervical spine (e.g., Klippel-Feil syndrome), intubation may become more difficult as the child ages.

Abnormalities of the ear or the presence of ear tags has been suggested as an indicator of DI. In one study, bilateral microtia was associated with an increased incidence of DI (42% vs 2% in unilateral microtia). Mandibular hypoplasia was associated with bilateral microtia 10 times more than with unilateral microtia (50% vs 5%), thus allowing bilateral microtia to be used as an indirect predictor of DI.

Physical examination must focus on the head, neck, and cervical spine. Many evaluations used to predict DA in adults have not been extrapolated to the pediatric population. Cooperation of the patient is necessary for precise evaluation. In the young or uncooperative child, appropriate evaluation is limited. Preliminary data indicate that the Mallampati classification may be an insensitive predictor of DI in the pediatric population. Pediatric anesthesiologists are at a disadvantage because they are anesthetizing patients with less objective airway information available. This underscores the need for a skilled approach to the difficult pediatric airway.

Evaluations should focus on the size and shape of the mandible, size of the mouth and tongue, absence or prominence of teeth, presence of loose teeth, and the neck length and range of motion. Berry suggests that the appropriate thyromental distance in infants is one finger breadth (1.5 cm). Lateral examinations of the head and neck may provide clues to the presence of micrognathia. Mandibular enlargement has also been identified as a risk factor for DI.

Cherubism is a childhood disease consisting of painless mandibular enlargement with or without maxillary involvement that progresses rapidly in early childhood and then regresses during puberty. In cherubism, the potential displacement space is encroached on by mandibular enlargement. Palpation of the soft tissue of the potential displacement area may reveal the problem.

Diagnostic Evaluation

Magnetic resonance imaging (MRI) and computed tomography (CT) may be extremely helpful in the evaluation of airway pathology. Flexible endoscopy may be of benefit before intubation when visualization of vocal cords is thought to be difficult or when airway pathology is suspected. In patients with unilateral hemifacial microsomia, radiographic classification of the mandibular anatomy can help predict ease of intubation.

Radiographic evaluation of patients with airway obstruction may be obtained in patients who present to the emergency room only if they are not in respiratory distress. Radiographs should be obtained in the upright position because obstruction may worsen in the supine position. In this situation, it is mandatory that a clinician skilled in airway management and capable of managing a difficult pediatric airway accompany the patient, along with the appropriate equipment.

Radiographs have high sensitivity (>86%) for the diagnosis of airway foreign body, exudative tracheitis, and innominate artery compression. For laryngomalacia and tracheomalacia, radiography has much lower sensitivity (5% and 62%, respectively). Radiologic evaluation should not take precedence over airway control in patients with a compromised airway. Other physicians, especially otolaryngologists, may be consulted and support management of a DI.

Classification of the Difficult Pediatric Airway

Difficulty with face-mask ventilation of the upper airway, laryngoscopy, ventilation using an SGA, tracheal intubation, extubation, or invasive airway is the definition of a DA according to the 2022 ASA DA management guidelines. Recognition of the DA along with the circumstances that predispose to airway problems is crucial to the safe management of the pediatric airway. Classification of the difficult pediatric airway may be made according to the anatomic location affected. Major anomalies of the head, face, mouth and tongue, nasopharynx, larynx, trachea, and neck are discussed in detail later.

Pediatric Airway Equipment

To manage a DA successfully, the appropriate equipment should be immediately available. We recommend the creation of a difficult pediatric airway cart stocked with equipment for patients ranging from premature infants to small adults. The ASA has created an infographic chart that can be used as a cognitive tool during the management of a DA. ( Fig. 36.3 ). This infographic can be placed on the DA cart. In addition, the American Academy of Pediatrics section on anesthesiology recommends the creation of a DA cart for all locations anesthetizing children. This cart should be dedicated only for use in a DA or a cannot intubate/cannot oxygenate (CICO) scenario ( Box 36.1 ). At institutions where extracorporeal membrane oxygenation (ECMO) is available, clinicians should consider this as a last resort option.

Box 36.1
Pediatric Difficult Airway Cart

Assortment of laryngoscope handles or blades

Oxyscope

Endotracheal tubes (ETTs): 2.0–7.0 mm

Oral/nasopharyngeal airways

Bite blocks

Masks

Stylets

Endotracheal tube exchangers

Laryngeal mask airways (LMAs): all sizes

Flexible intubation scope (FIS) equipment

Bronchoscopic swivel connector

Retrograde intubation kit

Percutaneous cricothyrotomy kit

Laryngoscope

McGill forceps

Albuterol adapters (for metered doses)

Intravenous (IV) catheters

Defogger

Yankauer: pediatric and adult sizes

Suction catheters

Lidocaine solution/jelly

Face Mask

When managing the DA, the ability to ventilate with a mask is more important than tracheal intubation. If at any point, face-mask ventilation becomes inadequate, call for help and proceed with the DA algorithm. When dealing with the pediatric airway, and especially the difficult pediatric airway, have a selection of masks readily available. Disposable clear-plastic masks with an inflatable rim are typically used. These masks should extend from the chin to the bridge of the nose. A leak-free seal should be obtained with minimal pressure applied to the face or mandible. Transparent masks allow visualization of secretions or vomitus during induction. These masks can be purchased in different flavors or scented before induction to make them less intimidating.

Face masks have been modified for flexible scope intubation (FSI) in a variety of ways. Frei and colleagues , described modifying a commercially available mask (Vital Signs) by drilling a hole into the lateral aspect of the mask and attaching a corrugated silicon tube. The center of the mask is fitted with a plastic ring covered by a silicon membrane. A hole 1 to 2 mm smaller than the outer diameter (OD) of the bronchoscope is punched into the membrane. This airway endoscopy mask has been used to facilitate FSI in patients ranging in age from 3 days to 12 months with spontaneous ventilation and propofol sedation. A commercially available face mask with a ventilation side port (MERA, Senko Ika Kogyo, Tokyo, Japan) was modified and used successfully to intubate nine patients ages 3 months to 11 years under inhalational anesthesia with a flexible scope and continuous manual ventilation.

Oropharyngeal Airway

Upper airway obstruction may occur during induction of anesthesia because the infant’s tongue is large in relation to the oropharynx. Appropriately sized oropharyngeal airways are necessary for air exchange. Guedel and Berman airways are the most common airways available. By holding the airway next to the child’s face, the correct size can be estimated. If the airway is too short, obstruction may be worsened. If the airway is too long, the epiglottis or uvula may be damaged. Use of a tongue depressor to insert the oropharyngeal airway is recommended to avoid impaired lymphatic drainage of the tongue.

Nasopharyngeal Airway

Nasopharyngeal airways are available in sizes 12- to 36-French and are used with caution in pediatric patients with hypertrophied adenoids. The modified nasal trumpet was first described by Beattie , followed by its use in pediatric airway management as described by Holm-Knudsen in 2005 ( Fig. 36.3 ) Fig. 36.1 .

Fig. 36.4, Modified nasal trumpet airway by Beattie is a nasal airway with an endotracheal tube connector wedged into the flared end. The patient can be ventilated through this modified nasal trumpet. The mouth, lips, and the other naris should be closed.

Fig. 36.3, Difficult airway algorithm: Pediatric patients. (1) The airway manager’s assessment and choice of techniques should be based on their previous experience; available resources, including equipment, availability, and competency of help; and the context in which airway management will occur. (2) Low- or high-flow nasal cannula, head elevated position throughout procedure. Noninvasive ventilation during preoxygenation. (3) Awake intubation techniques include flexible bronchoscope, videolaryngoscopy, direct laryngoscopy, combined techniques, and retrograde wire-aided intubation. (4) Other options include, but are not limited to, alternative awake technique, awake elective invasive airway, alternative anesthetic techniques, induction of anesthesia (if unstable or cannot be postponed) with preparations for emergency invasive airway, or postponing the case without attempting the above options. (5) Invasive airway techniques include surgical cricothyroidotomy, needle cricothyroidotomy if age-appropriate with a pressure-regulated device, large-bore cannula cricothyroidotomy, or surgical tracheostomy. Elective invasive airway techniques include the above and retrograde wire–guided intubation and percutaneous tracheostomy. Also consider rigid bronchoscopy and ECMO. (6) Includes postponing the case or postponing the intubation and returning with appropriate resources (e.g., personnel, equipment, patient preparation, awake intubation). (7) Alternative difficult intubation approaches include, but are not limited to, video-assisted laryngoscopy, alternative laryngoscope blades, combined techniques, intubating supraglottic airway (with or without flexible bronchoscopic guidance), flexible bronchoscopy, introducer, and lighted stylet. Adjuncts that may be employed during intubation attempts include tracheal tube introducers, rigid stylets, intubating stylets, or tube changers and external laryngeal manipulation. (8) Other options include, but are not limited to, proceeding with procedure utilizing face-mask or supraglottic airway ventilation. Pursuit of these options usually implies that ventilation will not be problematic. (From Apfelbaum JL, Hagberg CA, Connis RT, et al. 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology . 2022;136(1):31–81. doi: 10.1097/ALN.0000000000004002 .)

Endotracheal Tube

ETTs in a variety of sizes (2.5–7.0 mm) should be available for the pediatric patient. Laser-resistant, nasal/oral Ring-Adair-Elwyn (RAE) and wire-reinforced ETTs are available for use depending on the surgical requirement. Determination of correct ETT size is based on the patient’s age and weight. ETTs one-half size larger and smaller than the calculated size should be available ( Table 36.1 ). Traditional teaching advocates the use of uncuffed ETTs in patients younger than 8 years of age. Pediatric ETTs with low-pressure high-volume cuffs are available for use in patients with low lung compliance or those at risk for aspiration. For cuffed ETTs, a half-size smaller tube should be used because the OD of the tube is larger with the cuff.

TABLE 36.1
Formula for Endotracheal Tube Size and Depth of Insertion
Type/Insertion Formula
Uncuffed ETT (Age + 16)/4 or ETT >2 years, Age/4 + 4
Cuffed ETT Age/4 + 3.5
Length of insertion (oral) Age (years)/2 + 12 or 3 × ID (mm)
Length of insertion (nasal) 3 × ID (mm) + 2
ETT, Endotracheal tube; ID , internal diameter.

Maintenance of air leak pressure at less than 20 cm H 2 O with or without a cuff is recommended to minimize the occurrence of postintubation croup. Use of a manometer is recommended to avoid overinflation of the cuff. Koka and colleagues cite the incidence of postintubation croup as 1%. In a prospective study of more than 5000 children, however, Litman and Keon found that seven patients developed croup, defined as inspiratory stridor at least 30 minutes in duration, for an incidence of 0.1%. In that study, ETTs with air leak pressures greater than 40 cm H 2 O were replaced with the next smaller size. The presence or absence of a leak depends on the level of anesthesia and the use of muscle relaxants. Many clinicians use the degree of difficulty in passing the ETT below the vocal cords as the indicator of proper fit.

In general, there are many formulas for calculating the appropriate size of an ETT. Formulas for selecting an uncuffed ETT in children older than 2 years include (age + 16)/4 or (age/4) + 4. The use of cuffed ETTs in newborns and children under 8 years has been studied. In a group of 488 patients, patients were randomly allocated to receive a cuffed or an uncuffed ETT. The formula for the cuffed tube was (age/4) + 3. This formula was appropriate for 99% of patients. In that study, three patients in each group were treated for croup symptoms. Formulas for length of insertion of an oral ETT include length (cm) + 3 times internal diameter (mm) or length (cm) = age (years)/2 + 12. In the premature or newborn infant, the tip-to-lip distance in cm = 6 + weight (kg). Nasal-tragal length (NTL) can also be used to measure depth of insertion in neonates. A measurement is made from the center of the nasal septum to the tragus and 1 cm is added to this number ( Fig. 36.4 ). Whatever method is chosen, correct ETT position should be confirmed by auscultation of bilateral breath sounds ( Table 36.2 ). Also, leaks should be checked to a permissible pressure of 20 to 25 mm Hg.

Fig. 36.5, Nasal-tragal length (NTL) can also be used to measure depth of insertion in neonates. A measurement is made from the center of the nasal septum to the tragus, and 1 cm is added to this number.

TABLE 36.2
Suggested Endotracheal Tube Size for Infants
Age Size (mm ID)
Preterm (>1000 g) 2.5
Preterm (1000–2500 g) 3.0
Newborn to 6 months 3.0–3.5
1–2 years 4.0–4.5
>2 years (Age +16)/4 = ID
ID , Internal diameter.

Double-lumen tubes are not available for use in pediatric patients younger than 6 to 8 years. The Arndt Endobronchial Blocker (Cook Critical Care, Bloomington, IN) has been used to provide one-lung ventilation in infants. The 5.0-French blocker is available; the recommended ETT size is 4.5 mm. The Univent tube (Fuji Systems, Tokyo, Japan) is a single-lumen tube with an incorporated movable bronchial blocker inside. Pediatric sizes of the Univent tube are available: 3.5-mm internal diameter (ID) and 4.5-mm ID. The 3.5-mm Univent tube does not have a lumen for suctioning or administration of oxygen to the blocked lung. A flexible intubation scope (FIS) is needed for placement. Further detail regarding one-lung ventilation is provided in Chapter 26.

Endotracheal Tube Exchangers

ETT exchangers have multiple uses; they can be used to exchange damaged ETTs and provide a conduit for reintubation, if necessary, and should be determined on a case-by-case basis. The ASA 2022 guidelines recommend minimizing the use of airway exchange catheters for extubation purposes in pediatric patients.

Many different types of exchangers are available for use in adult patients. These tube exchangers are long, semirigid catheters that fit inside ETTs. The Frova Intubating Introducer (Cook Critical Care, Bloomington, IN) is available in a pediatric size (8-French) that allows placement of a 3.0-mm ETT. It is 33 cm in length with a hollow lumen and a blunt curved tip that is shaped like the gum elastic bougie. The blunt curved tip can be passed blindly into the trachea when visualization of the glottis is inadequate. The Frova catheter has a hollow lumen and two side ports and is packaged with removable Rapi-Fit adapters that allow ventilation and a stiffening cannula ( Fig. 36.5 ).

Fig. 36.6, Frova Intubating Introducer (Cook Critical Care, Bloomington, IN) catheter is available in a pediatric size (8-French) that allows placement of a 3-mm endotracheal tube. It is hollow with two side ports, is blunt tipped, and has a Rapi-Fit adapter.

Cook also manufactures airway exchange catheters (AECs) in four sizes. These catheters are blunt tipped and hollow, with distal side ports and a Rapi-Fit adapter. The 8-French size is 45 cm in length and can be used in 3.0-mm ETTs.

Laryngoscopes

Straight Versus Curved Blades

Laryngoscope blades in different sizes and shapes should be available before induction of anesthesia. Laryngoscope blades fall into two categories: straight and curved. Because the epiglottis is angled posteriorly, visualization of the glottis may be difficult. Straight laryngoscope blades are often recommended to lift the epiglottis in neonates and infants. The most common straight blades include the Miller, Wisconsin, Wis-Hipple, and Wis-Foregger blades. Curved blades are more suitable for older children.

Oxyscope

The Oxyscope is a fiberoptic Miller no. 1 blade with a port for insufflation of oxygen during intubation. Oxygen insufflation during laryngoscopy in spontaneously breathing, anesthetized infants has been shown to minimize the decrease in transcutaneous oxygen tension, thus making airway instrumentation safer.

Anterior Commissure Laryngoscope

The anterior commissure laryngoscope is frequently used by otolaryngologists for visualization of the glottis. It is a rigid, tubular, straight-blade laryngoscope with a distally located, recessed light source. This design permits enhanced visualization by preventing the tongue from obscuring the field of view.

Video Laryngoscopes

The angulated video-intubation laryngoscope (AVIL), invented by Dr. Marcus Weiss of Zurich, is an endoscopic intubation device. The AVIL consists of a cast-plastic Macintosh 4 laryngoscope, with the blade angulated distally, and an integrated fiberoptic endoscope (1.8 m long, OD 2.8 mm, VOLPI, Schlieren, Switzerland). The distal blade tip is angulated about 25 degrees to provide increased viewing for the fiberoptic lens. With the angulated tip, the AVIL resembles an activated McCoy blade. Flattening of the blade’s vertical flange enables the device to be used in children. The fiberoptic endoscope runs from the handle to the tip of the blade. The AVIL uses conventional laryngoscopy techniques coupled with video monitoring from the blade tip. Styletted ETTs, in a hockey stick configuration, are passed along the vertical flange of the blade under video control.

The AVIL has been used in patients ranging in age from 3 months to 17 years with manual in-line neck stabilization. In infants and small children, care should be taken with insertion of the blade; initial insertion of the blade was too deep in some patients. Several reports document the use of this device in pediatric patients with a DA. The video laryngoscope has been used successfully to intubate children with Morquio syndrome, as well as a 3-day-old neonate with Pierre Robin syndrome. ,

The GlideScope video laryngoscope (Cobalt, Verathon; Bothell, WA) has a reusable video baton and single-use laryngoscopy blades in two sizes. The laryngoscope comes with a monitor screen, and a video recording unit is also available. The GlideScope Cobalt model features a 10-mm laryngoscope blade. The blade is inserted in the midline without displacing the tongue. Two studies have been reported using the GlideScope in children with normal airways. Both studies found it suitable for intubation in pediatric patients. , In one of the studies, the time required for intubation was longer.

The Airtraq optical laryngoscope (AOL; Prodol, Vizcaya, Spain) is a single-use indirect laryngoscope for tracheal intubation. The Airtraq comes in two pediatric sizes: infant (size 0) for ETT sizes 2.5 to 3.5 and pediatric (size 1) for ETT sizes 3.5 to 5.5. Both sizes require a mouth opening of 12 to 13 mm. The rubber eyepiece may be used or a camera may be attached and used with a wireless monitor. Images from the distal tip of the blade are projected to the proximal eyepiece. The Airtraq is inserted midline, and the tip may be placed in the vallecula or used to lift the epiglottis. Once the glottis is visualized, the ETT is slowly advanced. For intubation, lubricate the ETT so that the tube advances easily. Problems with advancement of the ETT may be caused by too large diameter of the ETT, the guide channel, or incorrect angle of the ETT as it exits the channel. Two case reports documented the use of the Airtraq in pediatric patients with DAs: a 9-year-old child with Treacher Collins syndrome who weighed 23 kg and an infant with Pierre Robin syndrome who weighed 4.8 kg. , Other case reports have documented difficulty with advancement of the ETT into the trachea despite a good view of the larynx.

The McGRATH MAC blade is a small portable handheld device that combines direct laryngoscopy with enhanced video laryngoscopy and is produced by Medtronic (Boulder, CO). This battery-powered blade uses an LED light source and has a 2.5-inch (6.3-cm) LCD color display camera. The inline camera is anterior to provide direct and indirect views of the airway. It comes in sizes 1, 2, 3, and 4. The slim, disposable blades are packaged sterile for single use. This McGRATH MAC 1 blade has been used in neonates as small as 0.8 kg (see ).

The C MAC is a Karl Storz (Tuttlingen, Germany) video laryngoscope available in MAC sizes 2, 3, and 4, and in Miller sizes 0 and 1, as well as a pediatric D-BLADE, which can be used for DAs. This stainless steel laryngoscope blade is inserted into the airway as a MAC or Miller blade would be used and illuminates the oropharynx while producing an 80-degree diagonal field of view video image onto either a cable-linked monitor or a portable monitor. These images can be recorded. One study showed ease of use, glottic view, and successful intubation using the Storz Miller blade to be more favorable compared with other blades by residents and nurse anesthetists who had never used video laryngoscopy before in a simulated pediatric DA (see ).

The Coopdech video laryngoscope portable VPL-100 (Daiken Medical Co., Ltd, Osaka, Japan) is a handheld, battery-powered laryngoscope, similar to the McGRATH, except that the blades are reusable and can be autoclaved, and there is a zoom display option for the images. This single-unit video laryngoscope comes in pediatric sizes Miller 0 and 1 and MAC 2. The attached monitor has a 3.5-inch (8.9-cm) LCD display and uses a white LED light source to illuminate the oral cavity. There is little research at this point on this device in the pediatric population, but one study suggests the Coopdech video laryngoscope performed well in regard to successful intubation and time to effective ventilation.

The Pentax airway scope (AWS; Pentax-AWS, Tokyo, Japan) is a handheld, waterproof, battery-powered video laryngoscope with an attached 2.4-inch (6-cm) color LCD screen that displays an 80-degree angle view. The screen is adjustable to allow for intubation in a variety of positions. The detachable, disposable blade has a guiding groove for the ETT, and therefore no stylet is needed. The ETT can be inserted in the groove before or after laryngoscopy. There is also a channel for inserting a suction catheter. The curve of the blade allows for intubation without neck extension. The blade is inserted along the palate, without involving the patient’s tongue, inserted under the epiglottis, and then slightly elevating the epiglottis. The pediatric size will accommodate ETT with OD of 5.5 to 7.6 mm without a cuff. The neonatal size accommodates ETTs with ODs less than 5 mm. Few reports in the literature describe this video laryngoscope’s efficacy in the pediatric population. ,

Stylets

Various types of stylets are available as adjuncts to tracheal intubation, including the traditional malleable stylet, lighted stylets, and optical stylets. Stylets should be available for the DA. The stylet is inserted into the ETT until the distal end of the stylet is just short of the ETT tip. The ETT and stylet are bent into the desired shape, usually a hockey stick configuration. Complications associated with use of stylets include tracheal trauma, ETT obstruction, and shearing of the stylet. When removal of a stylet becomes difficult, the tip should be examined.

Lighted Stylets

Several different types of lighted stylets, or light wands, are currently commercially available, including the Vital Signs light wand illuminating stylet (Vital Signs, Totawa, NJ) and the Tube Stat lighted stylet (Xomed, Jacksonville, FL). Pediatric versions are available for use with ETTs as small as 2.0 to 4.0 mm. The use of the lighted stylet to guide blind tracheal intubation relies on the principle of transillumination. The presence of a well-defined glow in the neck indicates tracheal placement. Esophageal placement is indicated by the absence of a glow in the neck. Several different reports describe successful intubation of pediatric patients with the light wand. , Successful technique includes the following principles: (1) a small shoulder roll should be used to keep the head in a neutral to slightly extended position. This is extremely important in a small infant, whose neck naturally flexes when lying on a flat surface because of the large occiput; (2) the light wand should be advanced in the midline; if the light deviates to one side, the light wand should be withdrawn and repositioned; (3) the epiglottis is elevated by lifting the jaw with the nondominant hand; (4) transillumination should be assessed before advancing the light wand too far; (5) blind nasal intubation in children is often easier with the rigid stylet left in place; and (6) the wand is bent less sharply than for an oral intubation.

Benefits of light-guided tracheal intubation include use in obstructed conditions, low acquisition costs, and disposable components that eliminate the need for disinfection of equipment. As with any new technique, experience in patients with normal anatomy should be obtained before attempts in patients with a DA.

Optical Stylets

The first optical stylet, described in 1979, was a Hopkins telescope with a fiberoptic external light source (Karl Storz, Tuttlingen, Germany). The Seeing Optical Stylet (SOS) system (Clarus Medical, Minneapolis, MN) is a new, reusable, high-resolution fiberoptic endoscope with a malleable stainless-steel stylet. It combines the features of an FIS and a light wand. The Shikani SOS is portable, lightweight, and available in pediatric and adult versions. The pediatric version is compatible with ETTs 3.0 to 5.0 mm in size. The SOS can be inserted directly into an ETT, allowing intubation to be performed under direct vision. Illumination is provided by a standard green-line fiberoptic laryngoscope handle or the included SITElite halogen handle. An adjustable tube stop with an oxygen port, which goes over the shaft of the stylet, allows supplemental oxygen to be delivered. Many factors do not affect the SOS, including cervical spine injury, small mouth, large tongue, and reduced jaw mobility.

Pfitzner and colleagues described the use of the Shikani SOS on eight occasions in seven patients with DA. There were seven successful intubations; one patient, who had previous surgery and radiotherapy for a retropharyngeal rhabdomyosarcoma, could not be intubated by any method. Two patients with limited mouth opening and one patient with a C1–C2 subluxation were intubated on the first attempt. A patient with Hunter syndrome was intubated on the second attempt. A potential difficulty mentioned with the SOS is loss of the visual field, which occurs when the lens is next to a mucosal surface. Maneuvers to increase the operating space available are use of a laryngoscope to retract the base of the tongue, lifting the mandible, and pulling the tongue forward.

The Shikani Stylet is inserted into the ETT after lubrication with silicon spray. The fiberoptic cable can be connected to a video monitor. The mandible is lifted with the left hand and displaced anteriorly until the lower teeth are anterior to the upper teeth. The stylet with the loaded ETT is advanced into the trachea under direct vision. Laryngoscopy may be useful in cases of DI ( Fig. 36.6 ). The Shikani SOS (Clarus Medical, Minneapolis, MN) is a portable video stylet.

Fig. 36.7, Shikani Seeing Optical Stylet (Clarus Medical, Minneapolis, MN) is a reusable, high-resolution fiberoptic endoscope. The pediatric version is compatible with endotracheal tubes in the range of 3 to 5 mm. Supplemental oxygen can be delivered through the oxygen port. It can be used with the SITElite halogen handle (as shown) or a standard green line fiberoptic laryngoscope handle.

The Bonfils and Brambrink are semirigid intubation endoscopes (Karl Storz, Tuttlingen, Germany) that can also be used for small mouth openings in a medial or retromolar approach. They come in pediatric ODs of 2 mm and 3.5 mm with a 40-degree distal bend. There is an oxygen adaptor to allow for extended intubation time, as well as a portable LED light source. The Brambrink DCI (Karl Storz, Tuttlingen, Germany) intubation endoscope can be used with ETT sizes 2.5 to 3.5 mm. The Bonfils retromolar intubation endoscope (Karl Storz, Tuttlingen, Germany) can be used with ETT sizes 4 to 5.5 mm and uses a movable eyepiece.

Video-Optical Intubation Stylet

Another video-optical intubating stylet (Acutronic Medical Systems, Hirzel, Switzerland) consists of a flexible fiberoptic endoscope (developed by Dr. Weiss of Zurich). A sliding connector locks the video stylet onto the ETT adapter; it does not require neck extension but does require mouth opening. One report documents successful use of the video-optical intubation stylet in patients ages 6 to 16 years, with a simulated grade III laryngoscopic view; 46 of 50 patients were intubated on the first attempt; four attempts were considered failures because of prolonged intubation time (>60 seconds).

Supraglottic Airways

Laryngeal Mask Airway Family

The laryngeal mask airway (LMA North America, San Diego, CA), introduced in 1983 and approved for use in 1991 by the US Food and Drug Administration (FDA), is a standard part of the ASA DA algorithm and part of a larger class of SGAs. , Pediatric versions of the LMA Classic, as well as the disposable LMA, are available for use and are part of the pediatric DA algorithm, as described by Steward and Lerman. Application of the SGA requires minimum training and can be useful in neonatal resuscitation. The LMA Flexible is available in sizes 2 and 2.5, and the LMA ProSeal is available in a size 2.

The size of the SGA in children is determined by the patient’s weight, although a new method has been suggested. With the hand extended and palm facing up, the thumb and little finger are extended. The second, third, and fourth fingers are placed together. The fully inflated SGA is placed against the palmar side of the patient’s fingers, keeping the widest part of the SGA in line with the widest part of the three fingers. In a study of 163 children at birth to 14 years old, this method was correct in 78%. In the remaining patients, a difference of only one size was observed.

The SGA has been described as a conduit for blind intubation as well as a conduit for FSI. Awake placement of the SGA has been described in an infant with Pierre Robin syndrome. Anterograde intubation through the SGA with a guidewire was also described in an infant with micrognathia who could not be intubated with conventional methods. A soft-tipped guidewire was advanced through the SGA and the position confirmed by fluoroscopy. An ETT was inserted over the guidewire, followed by removal of the SGA. A review of the literature demonstrates different insertion techniques.

The standard technique described with the cuff deflated for adults has also been advocated for children. In addition, a rotational or reverse technique has been described. The SGA is inserted with the cuff facing the hard palate and then rotated and advanced simultaneously. An alternative technique involves inserting the SGA with the cuff partially inflated. Reports on placement of the SGA with the different techniques are conflicting. In children, one study compared two insertion techniques. The partially inflated cuff insertion technique does not increase the incidence of downfolding of the epiglottis and is an acceptable alternative to the standard technique. In another study, insertion of the partially inflated SGA required less time and was associated with a higher success rate on first attempts compared with the standard (deflated) technique. Results from a study detailing the flexible scope positioning of the SGA in children with a DA show that 29.5% of patients had a grade I (full) view of the glottis, 29.5% had a grade II (partial) view, and 41% had a grade III (epiglottis only) view. Children with a mucopolysaccharide disorder had a grade III view 54% of the time and a grade I view 14% of the time.

The ProSeal LMA is now available in pediatric sizes. This SGA has a second mask to isolate the upper esophagus with a second dorsal cuff to increase the seal against the glottis. Lopez-Gill and colleagues found that it was easily inserted, and oropharyngeal leak pressure was greater than 40 cm H 2 O ( Table 36.3 ).

TABLE 36.3
Laryngeal Mask Airway Classic Mask Size With Corresponding Cuff Volumes, Endotracheal Tube, and Flexible Bronchoscope
Mask Size Weight (kg) Maximum Cuff Volume (mL) Maximum ETT Size Maximum FIS (mm)
1 Infants up to 5 Up to 4 3.5 uncuffed 2.7
1.5 5–10 Up to 7 4.0 uncuffed 3.0
2 10–20 Up to 10 4.5 uncuffed 3.5
2.5 20–30 Up to 14 5.0 uncuffed 4.0
3 30–50 Up to 20 6.0 cuffed 5.0
4 50–70 Up to 30 6.0 cuffed 5.0
5 70–100 Up to 40 7.0 cuffed 5.0
6 >100 Up to 50 7.0 cuffed 5.0
ETT , Endotracheal tube; FIS , flexible intubation scope; LMA , laryngeal mask airway.

Air-Q Intubating Laryngeal Airway

The Air-Q intubating laryngeal airway (ILA; Cookgas, Mercury Medical, Clearwater, FL, USA) is an SGA used both for airway maintenance during routine anesthesia and as a conduit for tracheal intubation for patients with a DA. Unlike the LMA, the ILA was designed primarily to allow for the passage of conventional cuffed tracheal tubes when used for blind tracheal intubation, and it has the option for subsequent removal. The ILA also shares some structural features with the intubating laryngeal mask airway (ILMA). Compared with the LMA, the ILA allows for straightforward passage of a cuffed tracheal tube when used as a conduit for tracheal intubation because of three design differences. First, the airway tube of the ILA is wider, more rigid, and curved. Second, removal of the detachable 15-mm proximal connector increases the ID of the airway tube. Third, the ILA’s shorter length allows for easier removal after successful tracheal intubation. The Air-Q ILA is available in six sizes (1, 1.5, 2, 2.5, 3.5, and 4.5) for single use and in four sizes (2.0, 2.5, 3.5, and 4.5) for reuse. Sizing of the pediatric Air-Q ILA is similar to the LMA, in that it is weight based (size 1 for patients <5 kg; size 1.5 for patients 5–10 kg; size 2 for patients 10–20 kg).

The self-pressurized Air-Q ILA (ILA-SP) is a new first-generation SGA for children, with a self-adjusting cuff and lack of a pilot balloon. A newer version of the ILA-SP was recently introduced into our practice for routine airway maintenance in children. The ILA is currently the only supraglottic device available in pediatric patients designed to act as a conduit for tracheal intubation with cuffed tracheal tubes.

Rigid Ventilating Bronchoscope

The rigid ventilating bronchoscope is extremely useful for ventilating patients with a DA and is included in the most recent version of the ASA DA algorithm as an alternative device in the cannot intubate/cannot ventilate (CICV) situation. In any situation of potential airway collapse, the otolaryngologist and the rigid ventilating bronchoscope should be immediately available (see Chapter 29).

Induction Technique

The principles outlined in the ASA guidelines for DA management apply to the pediatric patient. Evaluation, recognition, and preparation are key elements. If a difficult airway is expected, a timeout to discuss the plan for airway management, including airway equipment and backup equipment, should be performed prior to induction. It is important to identify the primary person responsible for securing the airway, the backup or secondary person, as well as other helpers involved during this timeout, and who will be in charge of an invasive airway or ECMO, if necessary. The ASA 2022 DA guidelines infographic chart for pediatric patients can be used as a cognitive tool during management of a DA ( Fig. 36.3 ).

Preoxygenation of pediatric patients, although difficult, should be attempted if possible before any DA intervention. Studies have demonstrated that the optimal time for preoxygenation in pediatric patients is different from that in adults. Values ranging from 80 to 100 seconds have been reported for adequate preoxygenation in healthy children. , Continuous oxygenation during intubation of neonates and infants should be used to prolong the time before apneic desaturation. Continuous oxygenation during intubation can be done via nasal cannula, modified nasal trumpet connected to oxygen source, blow-by-oxygen via ETT inserted in the oropharynx, or a high-flow nasal oxygenation system. Summoning help early, using awake intubation, and preserving spontaneous ventilation during intubation attempts are also important when managing the DA. The awake or awake-sedated approach is preferred in most circumstances when managing the DA. However, in pediatric patients, the patient’s cooperation may limit the usefulness of awake intubation. One well-tolerated technique is placement of a lubricated SGA in awake infants, which provides an airway for inhalational induction.

The traditional approach to the difficult pediatric airway has been maintenance of spontaneous ventilation under inhalational anesthesia. Premedication with oral or intravenous atropine (0.01–0.02 mg/kg) is indicated for vagolytic and antimuscarinic effects. Inhalation induction may be performed with sevoflurane in 100% oxygen. Sevoflurane has been used in the management of the DA with success. , The low blood gas solubility of sevoflurane and consequent rapid induction and emergence are advantageous when managing the DA. When the ability to ventilate the patient by mask is demonstrated, a small dose of muscle relaxant or propofol may be given to facilitate intubation.

For patients who can tolerate an awake sedated intubation technique, a variety of sedating medications can be used. One must always keep in mind the risk-benefit ratio when sedating a patient with a DA. Sedatives may further compromise an airway. Sedatives should not be given to any patient in acute distress or with the potential for acute obstruction. Use of sedatives should be based on careful physical examination, anesthesiologist experience with agents involved, and overall patient condition. If no other options are available, slow titration of pharmacologic agents to effect, without loss of spontaneous ventilation, should be performed. Use of pharmacologic agents that are easily antagonized is recommended. For older children and adolescents, a combination of midazolam and fentanyl may be used. Remifentanil can also be used. Dexmedetomidine has been used successfully to perform an awake FSI in a morbidly obese patient with facial, cervical, and upper thoracic edema. In extreme circumstances, parental presence at induction may be allowed, and careful preparation of the parent must be performed before induction. As soon as the patient separates or begins to lose consciousness, a designated member of the operating room (OR) staff should immediately escort the parent out of the OR (see ).

Another important aspect for successful airway management is topicalization of the airway with local anesthesia. In pediatric patients, this may be obtained by nebulizing, spraying, or swabbing local anesthetic solution or by applying viscous gel to a gloved finger. FISs with suction ports can be used to spray local anesthesia on the vocal cords under direct vision. The maximum dose of local anesthetic allowed should be calculated before topicalization. The drug of choice is lidocaine because it has the best safety profile. Maximum doses of lidocaine are 5 mg/kg. Agents containing benzocaine (e.g., Cetacaine spray; Americaine ointment; Hurricaine ointment, gel, or spray) should be avoided in infants and young children because of the risk of methemoglobinemia.

Airway Management Techniques

Techniques for Ventilation

Obstruction of the upper airway is a common occurrence in pediatric patients undergoing an inhalation induction. Techniques for overcoming this type of obstruction include insertion of an appropriate-size oropharyngeal airway or a nasopharyngeal airway, or both. Another common mistake is occlusion of the submandibular space with incorrect placement of the anesthesiologist’s hand. Care should be taken to position the hand on the tip of the mandible and not on the submandibular space. Chin lift or jaw thrust combined with continuous positive airway pressure (CPAP) at 10 cm H 2 O has been shown to improve upper airway patency.

Additional techniques are available for mask ventilation. The two-person technique involves either one person holding the mask with both hands while an assistant compresses the reservoir bag or a second person assisting in jaw lift while the first person continues to compress the reservoir bag. Another option is using the anesthesia ventilator to provide ventilation so that one person can hold the face mask with both hands.

Techniques for Intubation

Direct Laryngoscopy

Tips for successful visualization of the larynx include proper use of external laryngeal pressure and positioning. Direct laryngoscopy involves alignment of the oral, pharyngeal, and laryngeal axes to visualize the glottis. Because the larynx is situated in a more cephalad position and the occiput is large, the sniffing position in infants does not assist in visualization of the larynx. , The infant should be positioned with the head in a neutral position with the neck neither flexed nor extended. A small shoulder or neck roll may be beneficial. Optimal external laryngeal manipulation (OELM) should also be used with a poor laryngoscopic view to improve visualization. OELM may improve the laryngoscopic view by at least one whole grade in adults. This is not cricoid pressure but rather pressing posteriorly and cephalad over the thyroid, hyoid, and cricoid cartilages. Benumof and Cooper suggest that OELM should be an instinctive and reflex response to a poor laryngoscopic view. This maneuver has also proved effective in pediatric patients. The main mechanism appears to be shortening of the incisor-to-glottis distance.

The two-anesthesiologist technique involves manipulating the larynx under direct vision by the laryngoscopist and intubation by a second anesthesiologist. This technique has been used successfully to intubate a 6-month-old infant with Pierre Robin syndrome and concomitant tongue-tie (ankyloglossia).

The retromolar or paraglossal technique has been advocated as useful in cases of DI related to a small mandible. A straight laryngoscope blade is introduced into the extreme right corner of the mouth overlying the molars, thus reducing the distance to the vocal cords. It is advanced in the space between the tongue and lateral pharyngeal wall until the epiglottis or glottis is visualized. The head is rotated to the left to improve visualization while applying external laryngeal pressure and displacing the larynx to the right. Advancement of the ETT is facilitated by retracting the corner of the mouth, to allow placement of the ETT. The styletted ETT should be shaped into the classic hockey stick configuration. An alternative approach involves placement of the ETT from the left side of the mouth. Lateral placement of the laryngoscope blade reduces the soft tissue compression because the tongue is essentially bypassed. The maxillary structures are also bypassed by the lateral blade placement, thus improving the view. Because there is a reduced space for displacement of the tongue in syndromes with micrognathia, this approach may be useful. The retromolar technique has been described as an alternative method for intubation of patients with Pierre Robin syndrome. A pediatric version of the Bonfils Retromolar Intubation Fiberscope is the Brambrink Intubation Scope (Karl Storz, Tuttlingen, Germany). It is an optical stylet that allows a retromolar approach to the DA.

In adults, the left molar approach with a Macintosh blade and OELM has been reported to improve the glottic view in cases of difficult laryngoscopy. Suspension laryngoscopy is often employed by otolaryngologists as an alternative technique for visualization of the difficult larynx. Intubation of an infant with Goldenhar syndrome was accomplished by suspension laryngoscopy. This method is similar to standard laryngoscopy by the retromolar technique.

With any direct laryngoscopy technique, limiting the number of attempts is recommended. Edema can rapidly occur and create a CICV scenario. The ASA 2022 guidelines for a DA state that attempts should be limited to 3 by the primary provider, and 1 attempt can be made by a secondary provider. In addition to providing supplemental oxygen throughout airway management, oxygenation and ventilation should be performed between each laryngoscopy attempt. After 4 attempts to secure an airway, consider waking up the patient or, if there is difficulty with ventilation, attempt to relieve any airway obstruction first and then consider waking up the patient.

Flexible Scope Intubation

Aids for FSI include face masks, oropharyngeal airways, guidewires, and the SGA. The Frei mask previously described or variations of commercially available masks have been used with success. , , The Patil-Syracuse mask (Anesthesia Associates Inc, San Marcos, CA) is available in a size 2, but it is difficult to achieve a good seal with this mask. An endoscopy mask can be made by attaching a swivel FIS adapter to a pediatric face mask in one of two ways : a commercially available swivel adapter (Instrumentation Industries, Bethel Park, PA) can be attached directly to the mask, or an adapter designed for attachment to the ETT (e.g., Portex bronchoscope adapter, Smiths Medical, Keene, NH) can be connected to the face mask with a 15-mm to 22-mm adapter.

Oropharyngeal airways may also be modified for use in pediatric FSI. A strip may be cut from the convex surface of a Guedel-style airway to produce an aid for oral flexible laryngoscopy, creating a channel. The flexible scope is placed in the channel, which helps maintain a midline position. The use of a smaller airway than predicted is suggested so that one may visualize the base of the tongue and epiglottis. Modified oropharyngeal airways are not effective as bite blocks, and one must be careful. Also, a nipple from a baby bottle has been modified to act as a conduit for FIS in an infant with an unstable cervical spine. In this case, a hole was cut obliquely into the end of the nipple. After topicalization of the airway with 2% lidocaine, FSI was performed with a 4.0-mm uncuffed ETT.

Flexible scope laryngoscopy is one of the cornerstones of DA management. Preparation for flexible laryngoscopy should include preparation of the patient (antisialogue) and checking of the FIS, light source, and suction as well as standard airway equipment. An assistant is necessary for monitoring of the patient and providing a jaw lift, which is useful because it elevates the tongue from the posterior pharynx. For older children and adolescents who will be sedated for the procedure, explanation and reassurance in a calm manner are helpful. A method of delivering oxygen is necessary as well. This can be accomplished in a variety of ways, either blowby from the anesthesia circuit or by nasal cannula. For patients who are anesthetized, an SGA or an endoscopy mask may be used to ventilate the patient while the intubation is being performed. Tips for successful oral intubation include midline placement of the FIS, advancement of the FIS only when recognizable structures are visualized, and retraction of the tongue with gauze or clamps if needed. If the view from the fiberscope is pink mucosa, the FIS is slowly pulled back until a recognizable structure is seen. If the nasal route is chosen, a topical vasoconstrictor may be used to reduce the chance of bleeding. In a series of 46 patients with DA, flexible nasal intubation was successful on the first attempt in 37 patients (80.4%) and on the second or third attempt in 7 patients (15.2%). Two failures occurred: one related to bleeding and the other to inability to introduce the scope nasally.

FSI may be performed in a variety of ways. The standard technique involves passage of the ETT over the FIS. The ultrathin flexible laryngoscope with a directable tip allows FSI to be performed with ETTs as small as 2.5 mm. Intubation of a 3-month-old infant with Pierre Robin syndrome has been successfully performed with an ultrathin fiberscope. A new 2.5-mm ultrathin FIS with a 1.2-mm suction channel has been used to intubate a newborn with a DA. This FIS has a 2.5-mm OD, 1.2-mm working suction channel, angle of deflection of 160 degrees up and 130 degrees down, and working length of 450 mm.

In scenarios where the available bronchoscope is too large for the required ETT, a staged technique may be employed. An FIS with a working channel, a cardiac catheter, and a guidewire are required. The guidewire is passed into the working channel of the fiberscope before intubation. The FIS guidewire assembly is then introduced into the mouth and positioned above the larynx. The guidewire is advanced into the trachea under direct visualization, followed by removal of the FIS. A cardiac catheter (used to stiffen the wire) is threaded over the guidewire. Finally, an ETT is advanced into the trachea over the guidewire-catheter assembly, which is then removed. A modification of this technique involves passage of the ETT over the guidewire without the reinforcing cardiac catheter. This has been used to intubate nasotracheally a 3-day-old infant with Pierre Robin syndrome.

The flexible bronchoscope may also be used as an aid for nasal intubation either under direct vision or with a guide. In these cases, an FIS is introduced into one of the nares while the ETT is advanced into the trachea through the other naris. Alternatively, if the ETT cannot be manipulated into the glottis, a guide may be placed in the opposite naris and directed into the trachea. The ETT is then removed and threaded over the guide. A urethral catheter has been used in this manner to assist in the intubation of a 2-week-old neonate with Klippel-Feil syndrome, occipital meningocele, and microretrognathia. Another variation of the staged technique involves placement of a larger ETT into the larynx under flexible scope visualization, followed by removal of the FIS, leaving the larger ETT in the larynx. A bougie is placed through the larger ETT into the trachea, and the ETT is removed. An appropriate-size ETT is then advanced over the bougie into the trachea.

FSI can be combined with a video laryngoscope to aid in intubation (combination technique). The video laryngoscope can first be inserted to help with jaw lift and/or partial visualization of the oropharynx. The flexible scope can then be used nasally or orally for intubation. Insertion of an FIS through an SGA has been successful. , , Staged intubation techniques involving an SGA, FIS, guidewires, and catheters (dilators) have been reported, including the use of SGA-assisted wire-guided flexible scope tracheal intubation. In a series of 15 cases, Heard and colleagues demonstrated that this technique was safe, successful, and easy to learn. After the FIS is placed through the SGA and the vocal cords are visualized, the guidewire is passed through the suction port of the bronchoscope and into the trachea. The SGA and FIS are carefully removed, and the ETT is advanced over the wire. A variation of this theme involves flexible scope visualization of the glottis through the SGA followed by passage of a guidewire through the suction port of an FIS into the trachea as before. The fiberscope is then removed and an airway catheter or a ureteral dilator passed over the wire into the trachea through the SGA. The SGA is then removed and an ETT advanced over the catheter into the trachea. This technique has been used successfully to manage the airway in children with mucopolysaccharidoses (MPS). The use of an SGA, an AEC, and a 2.2-mm-OD FIS has also been described. After placement of the SGA and visualization of the vocal cords, the flexible scope is removed. The FIS is placed into the lumen of a size 11 AEC, which had been cut to 25 cm. This combination was advanced through the SGA into the trachea by a connector. The SGA and FIS are removed, and an ETT is advanced over the Cook AEC.

Przybylo and colleagues reported the performance of a retrograde FSI through a tracheocutaneous fistula in a child with Nager syndrome. The ultrathin FIS was passed through the fistula in a cephalad direction past the vocal cords and exiting the nares. The ETT was then advanced over the FIS into the trachea.

Retrograde Intubation

The classic retrograde technique involves percutaneous placement of an intravenous catheter through the cricothyroid membrane into the trachea followed by placement of a guidewire. The guidewire exits the mouth or nose, and the ETT is then exchanged over the guidewire. If resistance to ETT passage occurs, counterclockwise rotation of the ETT may facilitate placement. This technique has been used for intubation of an infant with Goldenhar syndrome. A 14-French retrograde intubation set is commercially available from Cook for use with ETTs of ID 5.0 mm or greater.

A combined technique using the FIS and retrograde intubation has been used successfully in management of the difficult pediatric airway as well, as previously mentioned.

An FIS with a working channel is necessary for the combined technique. The guidewire is threaded into the suction port of an FIS that has a preloaded softened ETT on it. The FIS is passed along the guidewire until it is past the vocal cords. When the scope is past the vocal cords, the wire is withdrawn and the ETT correctly positioned. This technique allows passage without obstruction from the arytenoid cartilage or epiglottis. Oxygen insufflation can be performed through the suction port as well, even with the wire in place. Care must be taken to limit flow to avoid tracheobronchial injury from excessive gas velocity. Audenaert and colleagues used this technique in 20 patients with DA ages 1 day to 17 years and reported no major complications. Retrograde wire-guided direct laryngoscopy has also been reported for airway management in a 1-month-old infant. In that patient, attempts to pass a 2.5-mm ETT over the wire itself were unsuccessful, but tracheal intubation was achieved over the wire with direct laryngoscopy.

Emergency Access

Emergency access is divided into the emergency surgical and the emergency nonsurgical airway. Emergency surgical airway access is often difficult and requires the presence of a skilled anesthesiologist. It is the last resort in the CICV = arm of the ASA DA algorithm. Three procedures are referred to in this category: emergency tracheostomy, emergency cricothyroidotomy, and percutaneous needle cricothyroidotomy. In children younger than 6 years of age, emergency tracheostomy is usually the procedure of choice because the cricothyroid membrane is too small for cannulation. In older children, percutaneous needle cricothyroidotomy is often preferred over a surgical approach because most anesthesiologists can perform this technique rapidly. Also, there is less risk of injury to surrounding structures. Emergency cricothyroidotomy kits are available from Cook with 3.5-, 4-, and 6-mm-ID airway catheters.

The emergency nonsurgical airway access includes use of the SGA, esophageal-tracheal Combitube, and transtracheal jet ventilation (TTJV). The Combitube is available in a small-adult size and is contraindicated in patients less than 4 feet (122 cm) tall. The SGA is useful in the management of the difficult pediatric airway, as stated previously, as an SGA device or as a conduit for intubation; however, in the presence of glottic or subglottic obstruction, the SGA is ineffective, in which case TTJV is considered the technique of choice, as reported in two cases for laser endoscopic surgery. Caution with TTJV is urged because serious complications may result from its use. TTJV below a glottic or subglottic obstruction may result in barotrauma because the pathway for egress of air and oxygen is limited. Tension pneumothorax has been reported with jet ventilation through an AEC in an adult.

Other Intubation Techniques

In the past, blind digital intubation has been performed. The Bullard laryngoscope is no longer manufactured. The use of a dental mirror has also been described.

Intubating the COVID-19 Patient

Intubation of a COVID-19 patient should be performed only by experienced personnel, and training or teaching should not be performed on an infected patient. The airway equipment should be available, and the use of video laryngoscopy is recommended to minimize proximity to the infected patient. A plan should be in place for an unanticipated DA. SGA devices are acceptable alternatives to ETTs with minimal aerosolization risk, as stated by the Pediatric Difficult Intubation Collaborative (PeDI-C), a collaborative group of 35 hospitals from 6 countries including the United States and Canada. These authors suggest the use of second-generation SGA devices because they have a higher leak pressure than first-generation SGA devices. Awake FSI is not encouraged, unless it is indicated. Viral contaminant can be aerosolized during atomization. The airway equipment most familiar to the operator should be used.

Personal protective equipment (PPE) must be worn during intubation of the COVID-19 positive patient. Hand hygiene must be performed before and after donning and doffing PPE. At a minimum, an N95 respirator/mask that will fulfill the filtering efficiency criteria of the National Institute for Occupational Safety & Health (NIOSH) and eye protection must be worn. Double gloving is recommended during all airway manipulation.

During intubation and extubation, limit the number of staff in the room to reduce the risk of exposure. Prepare intubating equipment in close proximity to the patient. After intubation, place the used laryngoscope in a sealed bag and remove the outer layer of gloves. Rapid sequence intubation (RSI) is recommended to avoid positive-pressure ventilation (PPV) after adequate preoxygenation of the patient; however, this can be modified based on the patient’s clinical condition. The cuff of the ETT should be inflated before PPV. Placement of a heat and moisture exhange (HME) filter is recommended between the ETT and the circuit at all times. A plastic drape or shield over the COVID-19 patient is used ( ).

Extubation often results in greater aerosol generation as compared to intubation and should be performed with the same precautions as the intubation. Once extubated, place a mask on the patient’s face to minimize aerosolization in the immediate postextubation period. Once the patient is extubated and proper doffing occurs, hand hygiene must be performed. The patient should be recovered in the operating room or a negative pressure room until there is minimal risk for further airway manipulation.

Complications of Airway Management

Complications that result from intubation in adults can occur in the pediatric population as well. Airway injury accounted for 6% of claims in the ASA closed-claims database. Among the airway injury claims, 4% involved pediatric patients younger than 16 years. The most frequent sites of injury reported were the larynx (33%), pharynx (19%), and esophagus (18%). Injuries to the esophagus and trachea were more frequently associated with DI. Laryngeal injuries included vocal cord paralysis, granuloma, arytenoid dislocation, and hematoma. Pharyngeal injuries included lacerations, perforation, infection, sore throat, and miscellaneous injuries (foreign body, burn, hematoma, and diminished taste).

An oropharyngeal burn related to the laryngoscope lamp occurred in a term baby weighing 3.6 kg who was easily intubated at birth. The laryngoscope was switched on before intubation. Light-bulb laryngoscopes, in contrast to fiberoptic laryngoscopes, can reach temperatures that would result in burns to the oropharynx. Filaments may overlap with use, and it is common for two or more coils to touch. The resistance of the lamp decreases and the current increases, thus increasing the temperature. Koh and Coleman recommend that all light-bulb laryngoscopes be switched on for less than 1 minute; if left on, the temperature of the bulb should be manually checked before intubation. DI accounted for 62% of all esophageal injuries, with most involving esophageal perforation (90%). Esophageal perforation following DI has been reported in a neonate.

Laryngotracheal stenosis may be classified as glottic, subglottic, or tracheal. Prolonged intubation seems to be the major etiology. The mechanism responsible seems to be ischemic necrosis caused by pressure from the ETT against the glottic and subglottic mucosa. This results in an inflammatory reaction with a secondary bacterial infection and scar formation. Risk factors include too large an ETT, prolonged intubation, repeated intubation, laryngeal trauma, sepsis, and chronic inflammatory disease.

The incidence of postintubation croup varies from 0.1% to 1%. , Risk factors include age under 4 years, tight-fitting ETT, repeated intubation attempts, duration of surgery exceeding 1 hour, patient’s position other than supine, and previous history of croup. Reports are conflicting concerning the risk from a concurrent upper respiratory tract infection. Classic treatment consists of humidified air, nebulized racemic epinephrine, and dexamethasone. In pediatric trauma patients, absence of an air leak at extubation was the strongest predictor of postextubation stridor requiring treatment.

Airway Diseases and Implications

Head Anomalies

Airway Implications

Airway management in children with macrocephaly with abnormal anatomy, predicting a difficult airway, requires proper head and neck positioning and care of the associated airway anomalies that are a frequent finding in patients with mucopolysaccharidosis. If preoperative evaluation suggests presence of a DA, awake methods of tracheal intubation should be initially attempted.

In children, awake intubation may require careful use of sedatives in addition to topical anesthesia to the oropharynx, larynx, and nasopharynx (for nasotracheal intubation). A limited number of attempts at direct laryngoscopy may be made. If these are not successful, one of the various techniques of nonvisual or indirect laryngoscopy, as detailed previously, may be used to secure the airway. According to the Pediatric Difficult Intubation Registry (PeDI), more than two direct laryngoscopy attempts in children with difficult tracheal intubation are associated with high failure rate and increased severe complications. The PeDI data suggest quickly transitioning to an indirect laryngoscopy technique when direct laryngoscopy fails.

If the patient does not comply with awake tracheal intubation without the use of sedative that risks respiratory compromise, GA may be induced if mask ventilation is possible. The patient may breathe a vapor anesthetic and/or intravenous medications may be titrated until a level of anesthesia is achieved that allows tracheal intubation. The intubation may be accomplished with or without muscle relaxation. According to a recent study using the Pediatric Difficult Intubation Registry, controlled ventilation with and without the use of muscle relaxant was associated with less hypoxemia and laryngospasm complications compared to spontaneously breathing patients. Other options include flexible scope laryngoscopy in a patient breathing spontaneously through a mask or an SGA, use of a lighted stylet, use of a Bullard laryngoscope, and the retrograde technique. When mask ventilation is known to be easy, muscle relaxants may be used and have been shown to notably improve airway visualization, decrease airway trauma, and increase the chance of successful tracheal intubation.

Specific Anomalies

Head Anomalies

Airway management can be adversely affected by conditions that involve enlargement of the head. Mass lesions and macrocephaly can interfere with mask ventilation direct laryngoscopy, or both. The pathologic conditions that involve enlargement of the head and affect the airway are encephalocele, hydrocephalus, and mucopolysaccharidosis, along with other, less common conditions, such as phakomatoses, cranioskeletal dysplasias, or conjoined twins with face-to-face encroachment of the heads or proximity of the chests (thoracopagus).

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