Manual of Emergency Airway Management, 3rd Edition

21.Pediatric Airway Techniques

Robert C. Luten

Steven A Godwin

Technique

For the most part, the airway devices and techniques used in older children and adolescents are no different than those used in adults. The same cannot be said of small children (younger than 3 years) and infants (younger than 1 year), mostly related to two factors: the airway anatomy in these age groups is substantially different from the adult form, and some of the commonly used rescue devices are not available in pediatric sizes (e.g., Combitube). We limit our discussion to those rescue devices that are available for the pediatric population and that have evidence of successful use in children.

Mastering these techniques is straightforward and necessary if one is to manage the emergent pediatric airway. The following discussion describes the appropriate use of the various airway modalities in pediatrics, with emphasis on age appropriateness.

Techniques Used in All Children

Bag-mask Ventilation and Endotracheal Intubation

Refer to Chapter 5 for a detailed description of bag-mask ventilation (BMV) and endotracheal intubation. As in adults, oral and nasopharyngeal airways are important adjuncts to BMV, especially in small children where the tongue is relatively large in relation to the volume of the oral cavity. Recommendations and the rationale for the use of specific equipment (curved or straight blades, cuffed vs. uncuffed tubes) are described in Chapter 20. Use of size-appropriate equipment for pediatric airway management is critical to success, even in the most experienced hands. Proper BMV technique is particularly important in pediatric patients because the indication for intervention is most often primarily related to a respiratory disorder, and the child is likely to be hypoxic. In addition, pediatric patients are subject to more rapid oxyhemoglobin desaturation (see Chapter 20), meaning that BMV with cricoid pressure (Sellick's maneuver) applied is frequently required during the preoxygenation and paralysis phases of rapid sequence intubation (RSI). Pediatric BMV requires smaller tidal volumes, higher rates, and size-specific equipment. The pediatric airway is particularly amenable to positive pressure ventilation, even in the presence of upper airway obstruction (see Chapter 20).

1. Tips for successful BMV and endotracheal intubation in infants and children

Although BMV in the pediatric population fails infrequently, it must be done correctly: the mask seal must be adequate, the airway open, and the rate and volume of ventilation appropriate to the patient's age. Two errors of technique tend to occur. First, there is a tendency in the excitement of the situation to press the mask portion of the unit downward in an attempt to obtain a tight seal, resulting in neck flexion and upper airway obstruction. Second, there is a tendency to bag at an excessive rate.

a. Positioning

Children have a relatively large occiput compared with adults. In the supine position, the occiput of the unsupported, relaxed patient may produce flexion of the head and neck and resultant airway obstruction. Proper positioning of the patient therefore is key to prevent obstruction and provide optimal alignment of the axes of the airway (see Chapter 20). Optimal alignment of the laryngeal, pharyngeal, and oral axes in adults usually requires elevation of the occiput to flex the neck on the torso and extend the head at the atlanto-occipital joint. Because of the larger relative size of the occiput in small children, elevation of the occiput is usually unnecessary, and extension of the head may actually cause obstruction. Slight anterior displacement of the atlanto-occipital junction is all that is needed (i.e., pulling up on the chin to create the sniffing position). In small infants, elevation of the shoulders with a towel may be needed to counteract the effect of the large occiput that causes the head to flex forward on the chest. As a general rule, once correctly positioned, the external auditory canal should lie just anterior to the shoulders. Whether this position requires support beneath the occiput (older child/adult), the shoulders (small infant), or no support (small child) (Fig. 21-1A) can be determined using this rule of thumb. These are guidelines only, and each individual patient is different. A quick trial to find the optimal position may be of use. Figure 21-1B demonstrates the most common position for intubating the small child, the so-called sniffing position, and how this is achieved in this size child.

b. BMV

Always place an oral airway in the unconscious child before ventilating with a bag and mask because the pediatric tongue is large relative to the size of the oropharynx and is more prone to obstruct the upper airway. The positioning described in the previous paragraph is usually obtained while applying the one-handed, C-grip technique. The thumb and forefinger place and support the mask from the bridge of the nose to the cleft of the chin, avoiding the eyes. The bony prominences of the chin are lifted up by the rest of the fingers, placing the head in mild extension to form the sniffing position. Care is taken to avoid pressure on the airway anteriorly to prevent collapsing and obstructing the pliable trachea.

Further elevation of the jaw with one or two hands in a jaw thrust–like maneuver can only enhance airway patency. The cadence for bagging can be facilitated by the mnemonic “squeeze, release, release,” which will allow adequate time for exhalation during the cycle. If ventilation is not immediately obtained with these maneuvers, positioning should be reassessed and a nasopharyngeal airway be placed to supplement the oropharyngeal airway.

c. Endotracheal intubation

Even with optimal positioning, external manipulation of the airway (e.g., BURP maneuver, see Chapter 5) may increase visualization of the glottis. This may be especially helpful in small children who have anterior airways, and trauma patients who cannot be optimally aligned.

d. BMV and cricoid pressure

Studies in children have shown that cricoid pressure not only prevents passive regurgitation, but also prevents gastric insufflation, even with ventilation pressures greater than 40 cm H₂O. This is especially important in infants, in whom gastric distention may compromise ventilation and increase the risk of aspiration.

e. Pop-off (also know as positive pressure relief) valves: the good and the bad

A pop-off valve is designed to prevent the delivery of excessive pressure to the lower airway in an attempt to limit the risk of barotrauma. These valves are incorporated in the infant and pediatric resuscitation bags of most manufacturers. At a preset level, an escape valve opens, limiting the peak pressure that can be delivered, usually 35 to 45 cm of water pressure (CWP), depending on the manufacturer. The bag-mask units tend to be packaged by the manufacturer with the valve ready to function, thereby limiting the risk of barotrauma with initial ventilation attempts. However, in the face of upper airway obstruction, increased airway resistance, or decreased pulmonary compliance, higher pressures may be required. In situations such as these, the operator should disable the valve. With some devices, this must be done manually, although some manufacturers provide a built-in feature that disables the positive pressure relief valve.

In addition to the pop-off valve, many manufacturers incorporate manometer ports into the bag so that one can monitor peak airway pressures as they perform BMV. A leak at the site of the manometer port may interfere with one's ability to achieve airway pressures sufficient to effect adequate gas exchange.

Even though trouble shooting inadequate BMV starts with evaluating the adequacy of mask seal and assessing airway patency, the performance of a “leak test” immediately before beginning BMV will detect the status of the pop-off valve, and also tests for a leak at the manometer site. The leak test is performed by removing the mask from the BVM, occluding the mask port with the palm of one hand, and squeezing the bag with the other hand. If the bag remains tight, no escape of gas, or “leak,” has occurred. If the bag does not remain tight, gas is escaping from the system, most commonly from the pop-off valve or the manometer port, although other causes for the leak may be present. The pressure leakage from an open manometer port occurs immediately on compressing the bag as opposed to the open pop-off valve, which vents once a pressure of 35 to 40 CWP is exceeded. The amount of volume lost will vary, depending on the size of the leak. This test is also useful for screening adult bags for malfunctions and leaks. After a negative test (i.e., the bag remains tight with squeezing), the port occluding palm hand should be released, and the bag squeezed to confirm that gas escapes properly from the outlet valve.

Laryngeal Mask Airway

The laryngeal mask airway (LMA) is a safe and effective airway management device for children undergoing general anesthesia and is considered a rescue option in the event of a failed airway in children and infants. Placement of the LMA in children requires some training but is a relatively easily learned skill, particularly if the correct size of mask is chosen. The LMA has also been used successfully in difficult pediatric airways and should be considered as an alternative device for emergency airway management in these patients. As in the adult, difficult pediatric intubations have also been facilitated by the use of the LMA in combination with such devices as the bronchoscope.

The LMA has a few important associated complications, which are especially prevalent in smaller infants, including partial airway obstruction by the epiglottis, loss of adequate seal with patient movement, and air leakage with positive pressure ventilation. To avoid obstruction by the epiglottis in these younger children and infants, some authors have suggested a rotational placement technique where the mask is inserted through the oral cavity “upside-down” and then rotated 180 degrees as it is advanced into the hypopharynx. The LMA is contraindicated in the pediatric patient or adult with intact protective airway reflexes, and therefore, is not suitable for awake airway management unless the patient is adequately sedated and the airway is topically anesthetized. It is also contraindicated if foreign body aspiration is present or suspected because it may aggravate an already desperate situation and is likely to fail to provide adequate ventilation and oxygenation because the obstruction is distal to the device. The LMA comes in multiple sizes to accommodate children from neonate to adolescent. (See also Chapter 10.)

Needle Cricothyrotomy

Although virtually every textbook chapter, article, or lecture on pediatric airway management refers to the technique of needle cricothyrotomy as the recommended last-resort rescue procedure, there is little literature to support its use and safety. Few of the “experts” who write about needle cricothyrotomy have significant experience performing the procedure on live humans. Newer devices, such as the LMA and others, may further reduce the infrequent need for needle cricothyrotomy, but nevertheless, any clinician who manages pediatric emergencies as part of his or her practice must be familiar with the procedure and its indications, and have the appropriate equipment readily accessible in the emergency department.

Needle cricothyrotomy is indicated as a life-saving, last-resort procedure in children younger than 8 to 10 years who present or progress to the “can't intubate, can't ventilate” scenario and whose obstruction is proximal to glottic opening. The classic indication is epiglottitis where BMV and intubation are judged to have failed (although true failure of BMV is rare in epiglottitis, and failure is more often caused by a failure of technique than by a truly insurmountable obstruction). Other indications include facial trauma, angioedema, and other conditions that preclude access to the glottic opening from above. Needle cricothyrotomy is rarely helpful in patients who have aspirated a foreign body that cannot be visualized by direct laryngoscopy because these foreign bodies are usually in the lower airway. It would also be of questionable value in the patient with croup because the obstruction is subglottic. In these patients, the obstruction is more likely to be bypassed by an endotracheal tube (ETT) introduced orally into the trachea with a stylet, than blindly by needle cricothyrotomy.

Various commercially available needles are also available for percutaneous needle cricothyrotomy as well (Table 21-1). The simplest equipment, appropriate for use in infants, consists of the following:

· 14-gauge over-the-needle catheter

· 3.0-mm ETT adapter

· 3-mL or 5-mL syringe

It is a good practice to preassemble the kit, place it in a clear bag, seal the bag, and tape it in an accessible place in the resuscitation area.

1. Procedure

Place the child in the supine position with the head extended over a towel under the shoulder. This forces the trachea anteriorly such that it is easily palpable and can be stabilized with two fingers of one hand. The key to success is strict immobilization of the trachea throughout the procedure. The following statement appears in many textbooks describing this procedure: “Carefully palpate the cricothyroid membrane.” In reality, it is difficult to do this in an infant and is not essential. Indeed, in smaller children, it may be impossible to precisely locate the cricothyroid membrane, so the proximal trachea is often accessed. The priority is an airway and provision of oxygen. Complications from inserting the catheter elsewhere into the trachea besides the cricothyroid membrane are addressed later. Consider the trachea as one would a large vein, and cannulate it with the catheter-over-needle device directed caudad at a 30-degree angle. Aspirate air to ensure tracheal entry, and then slide the catheter gently off the needle, removing the needle. Attach the 3.0-mm ETT adapter to the catheter and commence bag ventilation. The provider will note exaggerated resistance to bagging. This is normal and is related to the small diameter of the catheter and the turbulence created by ventilating through it. It is not generally the result of a misplaced catheter or poor lung compliance secondary to pneumothorax. It is helpful to practice BMV through a catheter to experience the feel of the significantly increased resistance. The required pressures are well above the limits of the pop-off valve; therefore, it must be disabled in order to permit gas flow through the catheter. Jet ventilation has also been advocated, although extreme caution must be exercised to prevent barotrauma. Jet ventilation should be considered only by those familiar with its use and in children older than 5 to 6 years. However, even in this age group, if adequate oxygen saturation can be maintained with the bag technique described previously, this is preferable to jet ventilation. If jet ventilation is used, the ventilator must have a pressure control valve system. Start with low pressure (20 PSI), and titrate to adequate chest rise and fall and oxygen saturation, using exceedingly brief bursts of ventilation while observing chest rise, followed by sufficient exhalation time again judged by watching the chest fall. Percutaneous needle ventilation techniques are contraindicated in patients with complete upper airway obstruction.

Techniques Used in Adolescents and Adults

Blind Nasotracheal Intubation

Nasotracheal intubation in children is uniformly discouraged and is frequently considered contraindicated. This recommendation is based on the fact that the sharp angle of the nasopharynx and pharyngotracheal axis in children precludes a reasonable likelihood of success with this technique when performed blindly. A second reason is that children are at increased risk for hemorrhage because of the preponderance of highly vascular and delicate adenoidal tissue. The direct visualization technique is, however, commonly used in small infants and children for chronic ventilator management in the intensive care unit setting. Using direct visualization with a laryngoscope once the ETT has passed into the oro- and hypopharynx, tracheal placement is aided with Magill forceps. However, this technique is not helpful in emergency airway management. In general, the technique of blind nasotracheal intubation, which is essentially the same as that described for adults in Chapter 9, has few, if any, primary indications in pediatric emergency airway management, and in any case, is not recommended for patients younger than 10 years.

Combitube

The Combitube represents an excellent, easily learned rescue airway device that is available only for patients of height greater than 48 inches, so is of limited application in pediatric emergency airway management. The use of the Combitube is identical to that described in Chapter 10.

Surgical Cricothyrotomy

The cricothyroid membrane in small infants and children is minimally developed (Fig. 21-2). Identification of the key landmarks is at best extremely difficult, even in the noncrisis situation. The low likelihood of success, combined with the high anticipated complication rate from attempts to perform this procedure in an emergency, make it contraindicated in small children and infants. Surgical or cricothyrotome-based cricothyrotomy should not be attempted in children younger than 10 years, except in extraordinary circumstances. In children younger than 10 years, needle cricothyrotomy with BMV is recommended. As with adults, adolescents may have easily identifiable and accessible anatomy, and therefore, cricothyrotomy may be a reasonable rescue technique in this age group. Cricothyrotomy using a commercially available kit (Pedi-trake) has not been shown to be successful or even safe. Box 21-1 summarizes recommendations for invasive airway procedures in children.

BOX 21-1 Summary Recommendations for Invasive Airway Procedures in Children

5 years old

Needle cricothyrotomy and bag ventilation

5–10 years old

Consider needle cricothyrotomy and bag ventilation^a

Percutaneous Seldinger technique and bag ventilation

(Transtracheal jet ventilation [TTJV] regulated to low PSI is discouraged unless done by experienced operator)

>10 years

Operator preference

Needle cricothyrotomy with TTJV or Surgical cricothyrotomy

Evidence

1. Does a needle cricothyrotomy with BMV in children provide sufficient oxygenation and ventilation to avoid hypoxia and hypercarbia? The evidence surrounding pediatric needle cricothyrotomies is based on an animal study by Cote et al. (1) using a 30-kg dog model. Cote was able to demonstrate that dogs representative in size of a 9- to 10-year-old child could be oxygenated through a 12-gauge catheter and 3.0 ETT adapter with a bag for at least 1 hour (the study duration). Rises in PaCO₂ levels were noted, but were not believed to be significant because children normally tolerate mild degrees of hypercarbia well (1).

One adult retrospective study reported that 48 patients were successfully oxygenated and ventilated using transtracheal ventilation through a 13-gauge intratracheal catheter for up to 360 minutes. Transtracheal jet ventilation (TTJV) was used primarily in 47 of these patients, although 6 patients did receive conventional bagging measures until TTJV circuits could be initiated. During manual transtracheal ventilation, each patient demonstrated increases in PaCO₂ on blood gases but maintained PaO₂ values greater than 100 mm Hg (2).

2. The LMA should be considered as both a rescue device and an alternative airway in the management of difficult emergency pediatric airways. Most of the literature regarding the use of LMAs in children has been compiled from the anesthesia experience in the operating room. Therefore, little information is available for the use of the LMA in the acute emergency setting. However, an observational study by Lopez-Gil et al. has demonstrated that the skill for placement of the LMA could be rapidly learned by anesthesia residents with a low complication rate (3,4). Published case reports have demonstrated success of the LMA in the pediatric patient with difficult airways, including isolated severe retrognathia, Dandy-Walker syndrome, and Pierre Robin syndrome (5,6).

At least one prospective study reports a higher incidence of airway obstruction, higher ventilatory pressures, larger inspiratory leaks, and more complications in smaller children (those weighing <10 kg) with LMA use than in the older child. These authors recommend that the risk–benefit should be carefully weighed in younger children before using the LMA with paralysis and positive pressure ventilation. Importantly, the success rate for placement of the LMA in this study that was performed in elective cases undergoing prolonged ventilation was high at 98% (7). Although airway managers should be aware of these potential complications, this study is not generalizable to the emergency setting and should not deter providers from implementing this as a rescue device in infants or young children with failed airways, or as a planned approach to an infant or young child with an identified difficult airway. In the failed airway situation, the LMA may be a lifesaving bridge, providing effective oxygenation and ventilation until a definitive airway can be secured.

References

1. Cote CJ, Eavey RD, Todres ID, et al. Cricothyroid membrane puncture: oxygenation and ventilation in a dog model using an intravenous catheter. Crit Care Med 1988;16:615–619.

2. Ravussin P, Freeman J. A new transtracheal catheter for ventilation and resuscitation. Can Aneaesth Soc J 1985;32:60–64.

3. Lopez-Gil, Brimacombe J, Alvarez M. Safety and efficacy of the laryngeal mask airway: a prospective survey of 1,400 children. Anaesthesia 1996;51:969–972.

4. Lopez-Gil, Brimacombe J, Cebrian J, et al. Laryneal mask airway in pediatric practice: a prospective study of skill acquisition by anesthesia residents. Anesthesiology 1996;84:807–811.

5. Selim M, Mowafi H, Al-Ghamdi A, et al. Intubation via LMA in pediatric patients with difficult airways. Can J Anaesth 1999;46:891–893.

6. Stocks RM, Egerman R, Thompson JW, et al. Airway management of the severely retro-gnathic child: use of the laryngeal mask airway. Ear Nose Throat J 2002;81:223–226.

7. Park C, Bahk JH, Ahn WS, et al. The laryngeal mask airway in infants and children. Can J Anaesth 2001;48:413–417.