Manual of Emergency Airway Management, 3rd Edition

20.Approach to the Pediatric Airway

Robert C. Luten

John D McAllister

The Clinical Challenge

Airway management in the pediatric patient presents many potential challenges, including age-related drug dosing and equipment sizing, anatomical variation that continuously evolves as development proceeds from infancy to adolescence, and the performance anxiety that invariably accompanies the resuscitation of a critically ill child. Clinical competence in managing the airway of a critically ill or injured child requires an appreciation of age- and size-related factors, and a degree of familiarity and comfort with the fundamental approach to pediatric airway emergencies.

The principles of airway management in children and adults are the same. Medications used to facilitate intubation, the need for alternative airway management techniques, and many other aspects of airway management are generally the same in the child and adult. There are, however, a few important differences that must be considered in emergency airway management situations. These differences are most exaggerated in the first 2 years of life, after which the pediatric airway gradually evolves into the adult airway.

This discussion focuses on the main differences between adults and children and their significance in airway management.

Approach to the Pediatric Patient

General Issues

A recent review of the pediatric resuscitation process attempted to define elements of the mental (cognitive) burden of providers when dealing with the unique aspects of critically ill children compared with adults. Age- and size-related variables unique to children introduce the need for more complex, nonautomatic, or knowledge-based mental activities, such as calculating drug doses and selecting equipment. The concentration required to undertake these activities may subtract from other important mental activity such as assessment, evaluation, prioritization, and synthesis of information, referred to in the resuscitative process as critical thinking activity. The cumulative effect of these factors leads to inevitable time delays and a corresponding increase in the potential for decision-making errors in the pediatric resuscitative process. This is in sharp contrast to adult resuscitation, where drug doses, equipment sizing, and physiological parameters are usually familiar to the provider, leading to more automatic-type decisions that free the adult provider's attention for critical thinking. In children, the decision-making process is prolonged due to the cognitive burden of age-related anatomical and physiological variation, and the calculation of drug doses. Drug dosing determinations are subject to error, particularly as doses are weight related, and the ultimate dose selected tends to vary significantly by age. The use of resuscitation aids in pediatric resuscitation significantly reduces the cognitive load (and error) related to drug dosing calculations and equipment selection by relegating these activities to a lower order of mental function (referred to as “automatic” or “rule based”). The result is reduced error, attenuation of psychological stress, and an increase in critical thinking time. Table 20-1 is a length-based, color-coded equipment reference chart (Broselow-Luten–based “resuscitation guide”) for pediatric airway management that eliminates error-prone strategies based on age and weight. Both equipment and drug dosing information are included in the Broselow-Luten system and can be accessed by a single length measurement or patient weight.

Specific Issues

Anatomical and Functional Issues

The approach to the child with airway obstruction (the most common form of a difficult pediatric airway) incorporates several unique features of the pediatric anatomy.

TABLE 20-1 Equipment Selection

Pinka Red Purple Yellow White Blue Orange Green sLength (cm)-based pediatric equipment chart Weight (kg) 6–7 8–9 10–11 12–14 15–18 19–23 23–31 31–41 Length (cm) 60.75–67.75 67.75–75.25 75.25–85 85–98.25 98.25–110.75 110.75–122.5 122.5–137.5 137.5–155 Endotracheal tube size (mm) 3.5 3.5 4.0 4.5 5.0 5.5 6.0 cuff 6.5 cuff Lip-tip length (mm) 10–10.5 10.5–11 11–12 12.5–13.5 14–15 15.5–16.5 17–18 18.5–19.5 Laryngoscope Size + blade 1 Straight 1 Straight 1 Straight 2 Straight 2 Straight 2 Straight or curved 2 Straight or curved 3 Straight or curved Suction catheter 8F 8F 8F 8–10F 10F 10F 10F 12F Stylet 6F 6F 6F 6F 6F 14F 14F 14F Oral airway 50 mm 50 mm 60 mm 60 mm 60 mm 70 mm 80 mm 80 mm Nasopharyngeal airway 14F 14F 18F 20F 22F 24F 26F 30F Bag/valve device Infant Infant Child Child Child Child Child/adult Adult Oxygen mask Newborn Newborn Pediatric Pediatric Pediatric Pediatric Adult Adult Vascular access 22–24/23–25 22–24/23–25 20–22/23–25 18–22/21–23 18–22/21–23 18–20/21–23 18–20/21–22 16–20/18–21 Catheter/butterfly Intraosseous Intraosseous Intraosseous Intraosseous Intraosseous Intraosseous Nasogastric tube 5–8F 5–8F 8–10F 10F 10–12F 12–14F 14–18F 18F Urinary catheter 5–8F 5–8F 8–10F 10F 10–12F 10–12F 12F 12F Chest tube 10–12F 10–12F 16–20F 20–24F 20–24F 24–32F 24–32F 32–40F Blood pressure cuff Newborn/infant Newborn/infant Infant/Child Child Child Child Child/adult Adult Laryngeal mask airway (LMA)b 1.5 1.5 2 2 2 2–2.5 2.5 3 Directions for use: (a) measure patient length with centimeter tape or with a Broselow tape; (b) using measured length in centimeters or Broselow tape measurement, access appropriate equipment column; (c) column for endotracheal tubes, oral and nasopharyngeal airways, and LMAs, always select one size smaller and one size larger than recommended size. aFor infants smaller than the pink zone, but not preterm, use the same equipment as the pink zone. bBased on manufacturer's weight-based guidelines: Mask size Patient size 1 ≤5 kg 1.5 5–10 kg 2 10–20 kg 2.5 20–30 kg 3 >30 kg Permission to reproduce with modification from Luten RC, Wears RL, Broselow J, et al. Managing the unique size related issues of pediatric resuscitation: reducing cognitive load with resuscitation aids. Ann Emerg Med 1992;21:900–904.

a. Children obstruct more readily than adults. The pediatric airway, as opposed to the adult airway, is especially susceptible to airway obstruction due to swelling. See Table 22-2 in Chapter 22, which outlines the effect of 1-mm edema on airway resistance in the infant (4-mm airway diameter) versus the adult (8-mm airway diameter). Nebulized racemic epinephrine causes local vasoconstriction and can reduce mucosal swelling and edema to some extent. For diseases such as croup, where the anatomical site of swelling occurs at the level of the cricoid ring, the narrowest part of the pediatric airway, racemic epinephrine can have dramatic results. Disorders located in areas with greater airway calibre, such as the supraglottic swelling of epiglottitis or the retropharyngeal swelling of an abscess, rarely see results as dramatic. In these latter examples, especially in epiglottitis, efforts to force a nebulized medication on a child may agitate the child, leading to increased airflow velocity and dynamic upper airway obstruction.

b. Noxious interventions can lead to dynamic airway obstruction and precipitate respiratory arrest. The work of breathing in the crying child increases 32-fold, elevating the threat of dynamic airway obstruction and hence the principle of maintaining children in a quiet, comfortable environment during evaluation and management for potential airway obstruction; another reason to “leave them alone” (Fig. 20-1A–C).

c. Bag-mask ventilation (BMV) may be of particular value in the child who has arrested from upper airway obstruction. Note in Figure 20-1C that efforts by the patient to alleviate the obstruction may actually exacerbate it because increased inspiratory effort creates a more negative extrathoracic pressure, leading to collapsing of the malleable extrathoracic trachea. The application of positive pressure via BMV causes the opposite effect by stenting the airway open and relieving the dynamic component of obstruction (Fig. 20-1C and D). This mechanism explains the recommendation to try BMV as a temporizing measure, even if the patient arrests from obstruction. Case reports of successful resuscitation in patients that arrest from epiglottitis by BMV have borne this out.

d. Apart from differences related to size, there are certain anatomical peculiarities of the pediatric airway. The glottic opening is situated at the level of the first cervical vertebra (C-1) in infancy. This level transitions to the level of C-3 to C-4 by age 7 and to the level of C-5 to C-6 in the adult. Thus, the glottic opening tends to be higher and more anterior in children as opposed to adults. The size of the tongue with respect to the oral cavity is larger in children, particularly infants. These two factors lead to the recommendation that a straight laryngoscope blade be used in children younger than 3 years to elevate this distensible anatomy and enhance visualization of the glottic aperture (Table 20-2).

Blind nasotracheal intubation is difficult and relatively contraindicated in children younger than 10 years for at least two reasons: children have large tonsils and adenoids that may bleed significantly when traumatized, and the angle between the epiglottis and the laryngeal opening is also more acute than that in the adult.

Children possess a small cricothyroid membrane. In children younger than 3 to 4 years of age, it is virtually nonexistent. For this reason, needle cricothyrotomy may be difficult, and surgical cricothyrotomy is virtually impossible and contraindicated in infants and small children as old as 10 years.

Although younger children possess a relatively high, anterior airway with the attendant difficulties in visualization of the glottic aperture, this anatomical pattern is fortunately rather consistent from one child to another, so this difficulty can be anticipated. Adults may have difficult airways related to body habitus, arthritis, or chronic disease, modified by variations in individual underlying anatomy, and so are less consistent from one individual to another.

In summary, children younger than 2 years have higher anterior airways. In children older than 8 years, the airway tends to be similar to the adult, whereas years 2 to 8 represent a transition period. Figure 20-2 demonstrates anatomical differences particular to children.

Figure 20-1 • Intra- and Extrathoracic Trachea and the Dynamic Changes that Occur in the Presence of Upper Airway Obstruction. A: Normal anatomy. B: The changes that occur with normal inspiration; that is, dynamic collapsing of the upper airway associated with the negative pressure of inspiration on the extrathoracic trachea. C: Exaggeration of the collapse secondary to superimposed obstruction at the subglottic area. D: Positive pressure ventilation (PPV) stents the collapse/obstruction versus the patient's own inspiratory efforts, which increase the obstruction. Source: Adapted from Cote CJ, Ryan JF, Todres ID, et al., eds. A practice of anesthesia for infants and children, 2nd ed. Philadelphia: WB Saunders; 1993, with permission.

TABLE 20-2 Anatomical Differences Between Adults and Children

Anatomy Clinical significance Large intraoral tongue occupying relatively large portion of oral cavity Straight blade preferred over curved to push distensible anatomy out of the way to visualize the larynx High tracheal opening: C-1 in infancy vs. C-3 to C-4 at age 7, C-4 to C-5 in the adult High anterior airway position of the glottic opening compared with that in adults Large occiput that may cause flexion of the airway, large tounge that easily collapses against the posterior pharynx Sniffing position is preferred. The larger occiput actually elevates the head into the sniffing position in most infants and children. A towel may be required under shoulders to elevate torso relative to head in small infants Cricoid ring is the narrowest portion of the trachea as compared with the vocal cords in the adult Uncuffed tubes provide adequate seal because they fit snugly at the level of the cricoid ring Correct tube size essential because variable expansion cuffed tubes not used Consistent anatomical variations with age with fewer abnormal variations related to body habitus, arthritis, chronic disease Younger than 2 years, high anterior; 2 to 8 years, transition; older than 8 years, small adult Large tonsils and adenoids may bleed; more acute angle between epiglottis and laryngeal opening results in nasotracheal intubation attempt failures. Blind nasotracheal intubation not indicated in children; nasotracheal intubation failure Small cricothyroid membrane Needle cricothyrotomy difficult, trachea is the landmark, surgical cricothyrotomy impossible in infants and small children

Physiological Issues

Although there are many physiological differences between children and adults, the one of most importance with respect to emergency airway management (Box 20-1) is that children have a basal oxygen consumption that is approximately twice that of adults. Coupling that factor with the decrease in functional residual capacity (FRC) to body weight ratio seen in children compared to adults means that children desaturate much more rapidly than adults given an equivalent duration of preoxygenation. The clinician must anticipate and communicate this possibility to the staff and be prepared to provide supplemental oxygen by BMV if the patient's oxygen saturation drops below 90%.

Figure 20-2 • The anatomical differences particular to children are (a) higher, more anterior position of the glottic opening (note the relationship of the vocal cords to the chin/neck junction); (b) relatively larger tongue in the infant, which lies between the mouth and glottic opening; (c) relatively larger and more floppy epiglottis in the child; (d) the cricoid ring is the narrowest portion of the pediatric airway versus the vocal cords in the adult; (e) position and size of the cricothyroid membrane in the infant; (f) sharper, more difficult angle for blind nasotracheal intubation; and (g) larger relative size of the occiput in the infant.

Drug Dosage and Selection

Drug dosage determinations are most appropriately and safely done using resuscitation aids such as the Broselow-Luten system previously described.

The dose of succinylcholine (SCh) in children is different from that in adults. SCh is rapidly metabolized by plasma esterases and distributed to extracellular water. Children have a larger volume of extracellular fluid water relative to adults: at birth 45%; at age 2 months, approximately 30%; at age 6 years, 20%; and at adulthood, 16% to 18%. The recommended dose of SCh, therefore, is higher on a per kilo basis in children than adults (2 mg/kg vs. 1–1.5 mg/kg).

BOX 20-1 Physiological Differences

Physiological difference	Significance
Basal O2 consumption is twice adult values (>6 mL/kg/minute). Proportionally smaller functional residual capacity as compared with adults.	Shortened period of protection from hypoxia for equivalent preoxygenation time as compared with adults. Infants and small children often require bag-mask ventilation while maintaining cricoid pressure to avoid hypoxia.

In 1993, the U.S. Food and Drug Administration (FDA), in conjunction with pharmaceutical companies, revised the package labeling for SCh in the wake of reports of hyperkalemic cardiac arrest following the administration of SCh in patients with previously undiagnosed neuromuscular disease. Initially, it stated that SCh was contraindicated for elective anesthesia in pediatric patients because of this concern, although the wording was subsequently altered to embrace a risk–benefit analysis when deciding to use SCh in children. However, both the initial advisory warning and the revised warning continue to recommend SCh for emergency or full-stomach intubation in children. Pediatric drug doses are provided in Table 20-3.

Equipment Selection

Table 20-1 references length-based recommendations for emergency equipment in pediatric patients. Appropriately sized equipment can be chosen with a centimeter length measurement or with a Broselow tape.

A word of caution with respect to the storage of airway management equipment for children: Despite best efforts (e.g., equipment lists or periodic checks), it is not uncommon for newborn equipment to be mixed in with or placed in proximity to the smallest pediatric equipment—“the pink zone.” This practice may lead to newborn equipment being used in older children for whom it may not function properly or may, in fact, be dangerous. Examples include the #0 laryngoscope blade, which is too short to allow visualization of the airway; the 250-cc newborn BMV, which provides inadequate ventilation volumes; and various other equipment, such as oral airways that can cause airway obstruction if too small, or a curved laryngoscope blade that may not reach and pick up the relatively large epiglottis, or effectively remove the large tongue from the laryngoscopic view of the airway. See Table 20-4.

TABLE 20-3 Drugs—Pediatric Considerations

Drug Dosage Pediatric-specific comments Premedications Lidocaine 1.5 mg/kg IV Head injury, asthma, older than 10 years Fentanyl 1–3 mg/kg IV In head injury, older than 10 years Induction agents Midazolam 0.3 mg/kg IV Use 0.1 mg/kg if hypotensive Thiopental 3–5 mg/kg IV Lower dose to 1 mg/kg or delete if perfusion poor perfusion poor Etomidate 0.3 mg/kg IV Ketamine 1–2 mg/kg IV, 4 mg/kg IM Propofol 2–3 mg/kg IV Paralytics Succinylcholine 2 mg/kg IV Have atropine drawn up and ready Pan/vecuronium 0.2 mg/kg IV May increase to 0.3 mg/kg of vecuronium for RSI. (0.1 mg/kg for maintenance of paralysis) Rocuronium 1.0 mg/kg IV (for rapid sequence intubation (RSI))

TABLE 20-4 Dangerous Equipment

Equipment Problem #0 or #00 laryngoscope endotracheal tube (ET) blades Valuable time can be lost trying to visual-ize the glottic opening if mistaken for a #1 blade. Curved #1 laryngoscope ET blades Straight blades are preferred because · The epiglottis is picked up directly, not indirectly, by compressing the hyoepi-glottic ligament in the vallecula. · The tongue and mandibular anatomy are more easily elevated from the field of vision. 250-cc bag-mask ventilation Cannot generate adequate tidal volumes. Cuffed ET tubes <5.0 mm If leak pressures are not monitored, ischemia of the tracheal mucosa may develop with the potential for scarring and stenosis. Oral airways <50 mm Unless appropriate size oral airways are used, they may act to increase, rather than relieve, obstruction. Any otherequipment too small Sizing is critical to function! Note. Only appropriate size is functional. It is a frequent occurrence for very small sizes to be placed in the pediatric area without attention to appropriateness of size. The results can be devastating.

a. Endotracheal tubes

The correct ETT size for the patient can be determined by a length measurement and by referring to the equipment selection chart. The formula

(16 + age in years)/4

is also a reasonably accurate method of determining the correct tube size. However, the formula cannot be used in children younger than 1 year and is only useful if an accurate age is known, which cannot always be determined in an emergency. Uncuffed endotracheal tubes (ETTs) are recommended in the younger pediatric age groups, and cuffed tubes are used for size 5.5 mm and up (Fig. 20-3).

When intubating a young child, there is a tendency to insert the ETT too far, usually into the right mainstem bronchus. Insertion of the ETT to a predetermined, appropriate distance will avoid this. Various formulas have been proffered as aids to determine the correct insertion distance (e.g., internal diameter [ID] of the tube times 3). For example, a 3.5-mm ID tube ought to be inserted 3.5 × 3 = 10.5 cm at the lip. Alternatively, a length-based chart can be used.

b. Tube securing devices

An all too frequent complication following intubation is inadvertent extubation. ETTs must be secured at the mouth, and since head and neck movement translates in ETT movement, a cervical collar is employed (Fig. 20-4). In the infant, small movements are capable of dislocating the ETT into the esophagus, emphasizing the importance of head and neck immobilization. The ETT at the mouth is traditionally secured by taping the tube to the cheek. Alternatively, various commercial devices are available.

Figure 20-3 • Airway Shape. Note the position of the narrowest portion of the pediatric airway, which is at the cricoid ring, creating a funnel shape, versus a straight pipe as seen in the adult, where the vocal cords form the narrowest portion. This is the rationale for using the uncuffed tube in the child; it fits snugly, unlike the cuffed tube used in the adult, which is inflated once the tube passes the cords to produce a snug fit. Source: Modified with permission from Cote CJ, Todres ID. The pediatric airway. In: Cote CJ, Ryan JF, Todres ID, et al., eds. A practice of anesthesia for infants and children, 2nd ed. Philadelphia: WB Saunders; 1993.

c. Oxygen masks

The simple rebreather mask used for most patients provides a maximum of 35% to 60% oxygen and requires a flow rate of 6 to 10 L/minute. A nonrebreather mask can provide approximately 70% oxygen in children if a flow rate of 10 to 12 L/minute is used. For emergency airway management, and particularly for preoxygenation for rapid sequence intubation (RSI), the pediatric nonrebreather mask is preferable. Adult nonrebreather masks can be used for older children but are too large to be used for infants and small children. Properly configured bag-mask systems (i.e., those that have a one-way exhalation valve [e.g., “duck bill”] and small dead space) are capable of delivering oxygen concentrations >90%, if correctly used. The spontaneously breathing patient opens the duck-billed valve on inspiration, and on expiration, the expired CO₂ is vented into the atmosphere. Adult type units tend not to be used in infants and small children where the capacity to generate sufficient negative inspiratory pressure to open the duck bill valve may be lacking, leading some to prefer pediatric nonrebreather masks.

d. Oral airways

Oral airways should only be used in children who are unconscious. In the conscious or semiconscious child, these airways can incite vomiting. Oral airways can be selected based on the Broselow tape measurement or can be approximated by selecting an oral airway that fits the distance from the angle of the mouth to the tragus of the ear.

e. Nasopharyngeal airways

Nasopharyngeal airways are helpful in the obtunded but responsive child. The correctly sized nasopharyngeal airway is the largest one that comfortably fits in the naris but does not produce blanching of the nasal skin. The correct length is from the tip of the nose to the tragus of the ear, and usually corresponds to the nasopharyngeal airway with the correct diameter. Care must be taken to suction these airways regularly to avoid blockage.

Figure 20-4 • Securing Tube Placement. Unsecured tube sliding in/down (A). Unsecured tube sliding out/up (B). Tube secured to prevent in/out, up/down movement (C). Secured tube moving down and in as head flexes (D). Secured tube moving up/out as head extends (E). Neck movement prevented by cervical collar, thus preventing tube movement in the trachea (F).

f. BMV may lead to insufflation of the stomach, hindering full diaphragmatic excursion and preventing effective ventilation. A nasogastric (NG) tube should be placed soon after intubation to decompress the stomach in any patient who has undergone BMV and requires ongoing mechanical ventilation post intubation. Often in such patients, the abdomen is distended or tense, making the problem obvious, but other times it is difficult to identify the difference between this and the normally protuberant abdomen of the young child. If there is any difficulty in ventilation, particularly related to apparently high resistance, an NG tube should be placed. Length-based systems identify the appropriate NG tube size.

g. Bag-mask ventilation equipment

For emergency airway management, the self-inflating bag is preferred over the anesthesia ventilation bag. The BMV should have an oxygen reservoir so that at 10 to 15 L of oxygen flow, one can provide a F_iO₂of 90% to 95%. The smallest bag that should be used is 450 mL. Neonatal bags that are smaller (250 mL) do not provide effective tidal volume even for small infants. Many of the BMV devices have a pop-off valve. The pop-off valve is usually set at approximately 35 to 45 cm of water pressure (CWP) and is used to prevent barotrauma. Emergency airway management often requires higher peak airway pressures, so the bag should be configured without a pop-off valve or with a pop-off valve that can be defeated. Practically, it is a good practice to store the BMV device with the pop-off valve defeated so that initial attempts to ventilate the patient can achieve sufficient peak airway pressure to achieve ventilation. Chapter 21 discusses this issue in more detail and offers suggestions to prevent its occurrence.

h. End-tidal CO₂ detectors

Colorimetric end-tidal carbon dioxide (ETCO₂) detectors are as useful in children as in adults. A pediatric size exists for children weighing <15 kg. The adult model should be used for children weighing >15 kg. The resistance to airflow created by the pediatric-size device may make ventilation of the older child, where the larger size is more appropriate, more difficult.

i. Airway alternatives (Table 20-5)

Orotracheal intubation is the procedure of choice for emergency airway management of the pediatric patient, including those patients with potential cervical spine injury where RSI with inline manual stabilization is preferred. Nasotracheal intubation is relatively contraindicated in children for the reasons previously discussed.

Cricothyrotomy is the preferred emergency surgical airway in adults. The cricothyroid space emerges as one ages and is really only accessible after the age of 10 years. “Needle cricothyrotomy” in children younger than 8 to 10 years is the term used when one accesses the airway in a percutaneous manner in young children even though it is recognized that the point of entry into the airway is often the trachea as opposed to the cricothyroid space.

The only other device that has been demonstrated to be of use in failed airway management in young children is the laryngeal mask airway, which is supplied in sizes small enough for young infants and newborns, and, as a temporizing measure, might be useful when intubation cannot be done or fails. The Combitube is easy to insert, but currently there are no models for pediatric patients less than 48 inches tall. These and other adjuncts are discussed in Chapter 21.

Initiation of Mechanical Ventilation

In pediatrics, two modes of ventilation are used for emergency ventilation. For newborns and small infants, pressure-limited ventilators are traditionally used. For larger infants and older children, volume-limited ventilators are used, as in adults. One can arbitrarily set 10 kg as the weight below which pressure-limited ventilators should be used, although volume-limited ventilators have been used effectively in smaller children. Generally speaking, the younger the child, the more rapid is the ventilatory rate. The initial ventilatory rate in infants is typically set between 20 and 25 per minute. Inspiratory/expiratory ratios are set at 1:2. The typical peak inspiratory pressure at initiation of ventilation is between 15 and 20 CWP. These initial settings in a pressure-controlled ventilation mode will usually give a tidal volume of 8 to 12 mL/kg. These initial settings are adjusted according to subsequent clinical evaluation and chest rise. Positive end-expiratory pressure should also be set at 3 to 5 cm of water and F_iO₂ at 1.0. Once initial settings have been established, it is critical that the patient be quickly re-evaluated and adjustments made, particularly as pulmonary compliance, airways resistance, and leak volumes change with time, precluding adequate ventilation with the initial settings of pressure-controlled ventilation. Clinical evaluation of ventilatory adequacy is more important than formulae or guidelines for ensuring adequate ventilation. Once adjustments are made and the patient appears clinically to be ventilated and oxygenating, blood gas determinations, or continuous pulse oximetry and ETCO₂ monitoring, should be used for confirmation and to guide additional adjustments (Table 20-6 and Box 20-2).

TABLE 20-5 Alternatives for Airway Support

Alternatives for Airway Support Bag-mask ventilation May be the most reliable temporizing measure in children. Equipment selection, adjuncts, and good technique are essential. Orotracheal intubation (usually with rapid sequence intubation) Still the procedure of choice for emergent airway in potential cervical spine injury and most other circumstances. Needle cricothyrotomy Recommended as last resort in infants and children, but data lacking. Laryngeal mask Possible alternative but requires further evaluation. Blind nasotracheal intubation Not indicated for children younger than 10 years.

RSI Techniques for Children

The procedure of RSI in children is essentially the same procedure as in adults with a few important differences outlined as follows:

TABLE 20-6 Initiation of Mechanical Ventilation

I. Initial settings Ventilator type Pressure limited Volume limited Respiratory rate 20–25/minute 12–20/min, by age Positive end-expiratory pressure 3–5 cm H2O 3–5 cm H2O FiO2 1.0 (100%) 1.0 (100%) Inspiratory time ≥0.6 seconds ≥0.6 seconds Inspiratory/expiratory ratio 1:2 1:2 Pressure/volume settings For pressure ventilation, start with peak inspiratory pressure (PIP) of 15–20 cm H2O. Assess chest rise and adjust to higher pressures as needed. For volume ventilation, start with tidal volumes of 8–12 mL/kg. Start at lower volumes and increase to a PIP of 20–30 cm H2O. These are initial setting guidelines only. Assess chest rise and adjust accordingly. II. Evaluate clinically and make adjustments Most patients will be ventilated with volume-cycled ventilators. Poor chest rise, poor color, and decreased breath sounds require higher tidal volume. Check for pneumo, blocked tube. Ensure that tube size and position are optimal and leaks are not present. For patients ventilated with pressure-cycled ventilators, these findings may indicate the need to increase the peak inspiratory pressure. III. Laboratory information Arterial blood gas should be performed approximately 10–15 minutes after settings are stabilized. Additional samples may be necessary after each venstilator adjustment, unless ventilatory status is monitored by ETCO2 and SpO2.

BOX 20-2 Emergency Pediatric Airway Management—Practical Considerations

Anatomical

· Anticipate high anterior glottic opening.

· Do not hyperextend the neck.

· Uncuffed tubes are used in children younger than 8 years.

· Use straight blades in young children.

Physiological

· Anticipate possible desaturation.

Drug dosage and equipment selection

· Use length-based system. Do not use memory or do calculations.

· Nasogastric tube is an important airway adjunct in infants.

· Stock pediatric nonrebreather masks.

Airway alternatives for failed or difficult airway

· Surgical cricothyrotomy—contraindicated until age 10 years.

· Blind nasotracheal intubation—contraindicated until age 10 years.

· Combitube—only if >4 feet tall.

· Needle cricothyrotomy—acceptable.

A. Preparation

· Use resuscitation aids that address age- and size-related issues in drug dosing and equipment selection (e.g., Broselow-Luten tape).

B. Preoxygenation

· Be meticulous. Children desaturate more rapidly than adults.

C. Pretreatment

· None. Atropine is optional but may be drawn up and kept at bedside used principally in infants less than one year of age.

D. Paralysis with induction

· Induction agent selection as for adult: dose by length or weight.

· SCh 2 mg/kg IV or rocuronium 1 mg/kg.

E. Protection and positioning

· Apply Sellick's maneuver.

F. Placement with proof

· Anticipate desaturation; bag ventilate if oxygen saturation (S_pO₂) is less than 90%.

· Confirm tube placement with ETCO₂ as for adult.

G. Postintubation management

Mechanical ventilation in the child can be accomplished using either pressure-controlled or volume-controlled techniques. Regardless of the technique used, one should ensure that the chest rise is adequate. The Broselow-Luten length-based system gives guidelines for approximate starting tidal volumes and ventilator rates. In almost all cases, children who are intubated and mechanically ventilated should be paralyzed and sedated in the emergency department to prevent deleterious rises in intracranial or intrathoracic pressures.

Evidence

1. When is “a kid a kid” from the standpoint of airway management? The term “kids are different” is a long-used term to bring attention to the unique differences between children and adults. From an airway management perspective, those differences are most pronounced in the first year of life, after which there is a gradual transition, both anatomically and physiologically, to adulthood. Although arbitrary, for simplicity's sake, and because many children requiring airway management cannot be weighed, we define “children” as patients who fit on the Broselow tape. Those that do not are considered adults for dosing, equipment selection, and other recommendations. Children who are larger than the last zone on the tape are usually at least 80 lb (36 kg), at least 5 feet tall (>150 cm or >60 inch), and at least 10 years old.

2. What are the particular barriers to successful airway management in children? Pediatric emergency airway management is often fraught with a lack of familiarity and complicated by a degree of complexity that for the average emergency airway manager may translate into errors and time delay. This mental burden (or “cognitive load”) can be reduced by the use of resuscitation aids. Time is saved and error reduced.

Time delay and error are associated with the management of children in emergency situations (1). Pediatric emergencies are complicated by the fact that children vary in size, creating logistical difficulties, especially with respect to drug dosing and equipment selection. A recent review analyzed the effect of these variables on the mental burden in the resuscitative process and demonstrated how resuscitation aids can help mitigate their effect (2). Simulated emergency patient encounters have confirmed that the Broselow-Luten color-coded emergency system reduces time delay and errors by eliminating the cognitive burden associated with these situations (3).

Other factors also contribute to an increased cognitive load in managing children. To the extent that the process can be simplified (e.g., limiting the number of recommended medications, reducing the complexity and number of decisions required), time is freed up for critical thinking that can then be dedicated to the priorities of airway management. RSI in children is a good example. The management of children in extremis can be stressful. RSI should be kept simple and uncomplicated to reduce stress.

3. Should I use a nondepolarizing relaxant to defasciculate prior to using SCh in children? Defasciculation has been recommended in past editions of this text to attenuate the rise in intracranial pressure (ICP) seen in patients with intracranial pathology. As discussed in Chapter 17, this recommendation has been dropped for this edition of the text. Rapid and atraumatic tracheal intubation is the primary goal for all head-injured trauma patients. Minimizing the complexity of RSI by eliminating the defasciculation step contributes positively to this intent. Our view is that the SCh-induced increase in ICP in this setting is not relevant, and that even if there is a modest increase in ICP with SCh, the consequences of poor airway and ventilatory management outweigh any potential benefit. The deleterious effects of hypoxia, hypercarbia, noxious stimulation associated with laryngoscopy, delay in securing airway, and aspiration are much more significant. Defasciculation therapy is therefore not recommended in the emergency setting, and the ICP concerns are not a significant contraindication to SCh.

4. Should atropine be used as a premedication for RSI in children? The evidence does not support this. However, it is an issue that is difficult to definitively resolve based on current literature. Traditionally, atropine has been used to prevent the bradycardia associated with a single dose of SCh in children, a rare, but serious event. A few recent studies failed to show a difference in response to SCh with or without atropine in children (4,5), with similar numbers in the atropine- and non–atropine-treated groups developing transient, self-limited decreases in heart rate. The absence of evidence of benefit, however, should not be construed as “proof” when dealing with uncommon events, although this evidence is of note. Atropine also has significant, but rare side effects (6). Thus, we are currently not recommending its routine use in this situation.

There is a theoretical benefit for giving atropine when manipulating the airway of infants younger than 1 year due to their disproportionate predominance in vagal tone, coupled with a relatively greater dependency on heart rate for cardiac output (7). However, most bradycardic episodes are due to hypoxia or are a transient, vagally mediated reflex response that resolves spontaneously. It is better to treat the hypoxia or the reflex if it occurs.

In summary, in an effort to keep the process of RSI in children as simple as possible, we are not recommending the routine use of atropine. In special circumstances, such as with infants younger than 1 year (3, 4, and 5 kg, and pink or red zones on the Braselow-Luten tape and airway card), atropine should be considered an option.

5. Should opioids be used as pretreatment medications in children? There is excellent evidence that premedication with synthetic opioids prior to direct laryngoscopy and tracheal intubation attenuates the increase in ICP, intraocular pressure (IOP), mean arterial pressure, myocardial oxygen consumption, and pulmonary artery pressure caused by this noxious stimulus. The attenuation of the reflex sympathetic response to laryngoscopy and intubation conferred by pretreatment with an opioid is dose dependent and generally requires 3 to 5 minutes for peak effect (fentanyl). During this time, the side effects of a narcotic can be significant (respiratory depression, cough, decreased locus of control, hypotension, stiff chest). RSI in an emergency is usually a life-threatening cardiorespiratory event that already has created a stress-induced increase in catechols. For this reason, and because the dosing and administration of small doses of opioids in children is fraught with the potential for overdose, we do not routinely recommend use of opioids in children and place more emphasis on induction of general anesthesia and rapid onset of muscle relaxation to create ideal intubating conditions.

6. Should lidocaine be used as a pretreatment medication in children? Lidocaine has been recommended for children with presumed elevation of ICP (usually due to head trauma) to prevent further rises in ICP related to laryngoscopy and intubation (8). Most of the data for this recommendation, however, is extrapolated from adult studies and nontraumatic elevated ICP situations.

There are no data to support or refute the use of lidocaine in children to prevent or mitigate the reflex bronchospasm related to airway manipulation. Studies related to the use of lidocaine in children to blunt the sympathetic response to intubation are inconsistent (9,10).

We therefore do not recommend the use of lidocaine pretreatment for children younger than 10 years undergoing RSI.

7. Succinylcholine versus rocuronium as a paralytic in children—which is the preferred agent? In the 1990s, the FDA warned against the use of SCh in children following case reports of hyperkalemic cardiac arrest following the administration of SCh to patients with undiagnosed neuromuscular disease. The pediatric anesthesia community at that time challenged the FDA decision on the basis of the risk versus benefit in patients requiring emergency intubation, leading to a modification of their position to a “caution.” There is no body of evidence that specifically addresses the relative risks and benefits of SCh versus rocuronium in children to guide recommendations. Both are used, and preferences are personal.

Currently, SCh remains the agent of choice for emergency full-stomach intubations (11,12). Although rocuronium is preferred in pediatrics by some practitioners, for simplicity's sake, we recommend SCh as first-line treatment for adults and children.

8. Are uncuffed ETTs now recommended in pediatric emergency airway management? The issue of whether cuffed ETTs are safe or required in children younger than 8 to 10 years has been debated for some time because of the anatomical and functional seal afforded by the subglottic area. Two studies have addressed this issue (13,14). Deakers et al. (13) studied 282 patients intubated either in the operating room, emergency department, or intensive care unit. In their observational prospective, nonrandomized study, they found no difference in postextubation stridor, the need for reintubation, or long-term upper airway symptomatology. Khine et al. (14) compared the incidence of postextubation croup, inadequate ventilation, anaesthetic gases in the environment, and the requirement for a second laryngoscopy due to the tube being too large. In this study, which looked at children younger than 8 years only, the authors found no difference in croup, more attempts at intubation with uncuffed tubes, less gas flow required with cuffed tubes, or less gas leakage into the environment.

Even though it may seem that the use of cuffed tubes in younger children does not result in any postextubation sequelae, it must be made clear that these studies monitored cuff inflation pressures, a practice that is uncommonly performed in emergency intubations. For this reason, it seems reasonable to recommend the use of uncuffed ETTs to avoid excessive tracheal mucosal pressure with the potential sequelae of scarring and stenosis. However, for some patients in whom high mean airway pressures are expected, such as those with acute respiratory diseases and asthma, the placement of a cuffed tube with the cuff initially deflated, and inflated if necessary, may be appropriate. The most recent Pediatric Advanced Life Support standards (15) recommend cuffed tubes, but with the qualifier only if leak pressures are monitored.

9. Why do children desaturate more quickly than adults with comparable degrees of preoxygenation? The infant uses 6 mL of oxygen per kilogram per minute as compared with the adult who uses 3 mL per kilogram per minute. The FRC reduction in an apneic child is far greater than in the apneic adult. This is due to the differences in the elastic forces of the chest wall and the lung. In children, the chest wall is more compliant, and the lung elastic recoil is less than in adults. An analysis of these forces reveals that if they are brought into equilibrium as in the apneic patient, a value of FRC around 10% of TLC is predicted instead of the observed value of slightly less than 40%. These same factors also reduce the FRC in the spontaneously breathing patient, albeit to a lesser degree. FRC is further reduced with the induction of anesthesia and by the supine position. The clinical implication of the decreased effective FRC combined with increased oxygen consumption is that the preoxygenated, paralyzed infant has a disproportionately smaller store of intrapulmonary oxygen to draw on as compared to the adult. Pulmonary pathology in critically ill patients may further reduce the ability to preoxygenate. It is therefore critical that these factors be considered when preoxygenating and intervening in pediatric patients. BMV with cricoid pressure may be required to maintain oxygen saturation above 90% during RSI, especially if multiple attempts are required or the child has a disorder that compromises the ability to preoxygenate (16,17).

References

1. Oakley P. Inaccuracy and delay in decision making in pediatric resuscitation, and a proposed reference chart to reduce error. Br Med J 1988;297:817–819.

2. Luten R, Wears R, Broselow J, et al. Managing the unique size related issues of pediatric resuscitation: reducing cognitive load with resuscitation aids. Acad Emerg Med 2002;9: 840–847.

3. Shah AN, Frush KS. Reduction in error severity associated with use of a pediatric medication dosing system: a crossover trial. Presented at the AAP 2001 National Conference and Exhibition, Section on Critical Care, October, 2001.

4. McAuliffe G, Bisonnette B, Boutin C. Should the routine use of atropine before succinylcholine in children be reconsidered? Can J Anaesth 1995;42:724–729.

5. Fleming B, McCollough M, Henderson SO. Myth: atropine should be administered before succinylcholine for neonatal and pediatric intubation. Can J Emerg Med 2005;7(2):114–117.

6. Tsou CH, Chiang CE, Kao T, et al. Atropine-triggered idiopathic ventricular tachycardia in an asymptomatic pediatric patient. Can J Anaesth 2004;51(8):856–857.

7. Rothrock SG, Pagane J. Pediatric rapid sequence intubation incidence of reflex bradycardia and effects of pretreatment with atropine. Pediatr Emerg Care 2005;21(9):637–638.

8. Zaritsky AL, Nadkarni VM, Hickey RW, et al. PALS Provider Manual. Dallas, TX: American Heart Association; 2002.

9. Splinter WM. Intravenous lidocaine does not attenuate the haemodynamic response of children to laryngoscopy and tracheal intubation. Can J Anaesth 1990;37(Pt 1):440–443.

10. Tanaka K. Effects of intravenous injections of lidocaine on hemodynamics and catecholamine levels during endotracheal intubation in infants and children. Aichi Gakuin Daigaku Shigakkai Shi 1989;27:345–358.

11. Robinson AL, Jerwood DC, Stokes MA. Routine suxamethonium in children: a regional survey of current usage. Anaesthesia 1996;51:874–878.

12. Weir PS. Anaesthesia for appendicectomy in childhood: a survey of practice in Northern Ireland. Ulster Med J 1997;66:34–37.

13. Deakers TW, Reynolds G, Stretton M, et al. Cuffed endotracheal tubes in pediatric intensive care. J Pediatr 1994;125:57–62.

14. Khine HH, Corddry DH, Kettrick RG, et al. Comparison of cuffed and uncuffed endotracheal tubes in young children during general anesthesia. Anesthesiology 1997;86:627–631.

15. American Heart Association. Pediatric Advanced Life Support. Circulation 2005;112:IV-167–IV-187.

16. Angostoni E, Mead J. Statics of the respiratory system. In: Fenn WO, Rahn H, eds. Handbook of Physiology. Washington, DC: American Physiologic Society; 1964.

17. Lumb A. Elastic forces and lung volumes. In: Nunn's Applied Respiratory Physiology, 5th ed. Oxford, England: Butterworth-Heineman; 2000:51–53.