A 6-year-old child with Pierre Robin Syndrome (PRS) presents for bilateral inguinal hernia repair. As a newborn, he underwent tongue-lip adhesion surgery for upper airway obstruction and feeding difficulties. The patient’s anesthetic record reads, “Anterior larynx. Grade 4 Cormak/Lehane (C-L) direct laryngoscopic view despite laryngeal pressure, with an inability to intubate the trachea. Subsequently, a nasal flexible bronchoscopic intubation was successfully performed.” It is noted the patient has been free of any problems since then, and no other surgery has been performed.

What Is Pierre Robin Syndrome?

Named after the French physician who described its symptomatology and management, Pierre Robin Syndrome (or Sequence; PRS) is a congenital disorder characterized by a triad of craniofacial anomalies: mandibular hypoplasia, cleft secondary palate, and glossoptosis (rostral displacement of the tongue).¹ Due to this combination of features, PRS is commonly viewed as a classic anticipated difficult airway scenario for pediatric anesthesia practitioners. In half of PRS cases, the positioning of the tongue during development precludes fusion of the maxillary arches, resulting in an often wide, U-shaped cleft palate; this, combined with backward displacement of the tongue, causes airway obstruction, respiratory difficulties, sleep apnea, difficulty swallowing, chronic hypoxemia, pulmonary hypertension, and failure to thrive. Accurate pre-procedural diagnosis is important to ensure that the physical features are not part of another multiple malformation disorder, such as Treacher Collins syndrome, Stickler syndrome, or Velocardiofacial syndrome, since the airway plan will be affected by the presence of associated abnormalities (e.g., congenital heart disease). Recently, a genetic link was found for PRS, increasing the potential for diagnostic accuracy in families and individuals.

Management of breathing and feeding difficulties in infants with PRS has reduced the mortality rate to less than 5%. Enteral feeding or prone positioning during nursing can achieve satisfactory nutrition for growth,² and respiratory difficulty can, in many cases, be managed without operative intervention.³ After birth, the mandible grows normally, and surgery to correct the cleft palate results in improved airway anatomy and swallowing ability. Tracheotomy is rarely indicated to treat respiratory problems. Occasionally, mandibular distraction surgery is used to lengthen the mandible, which brings the tongue forward and improves breathing and feeding. With effective treatment, most PRS individuals undergo normal childhood growth and development and experience a healthy, normal adult life.

The implications of the manifestations of PRS are obvious for an anesthesiologist attempting to secure the airway: the trachea is not intubated easily, and bag-mask-ventilation (BMV) is usually difficult. Compounding these problems is that PRS individuals often require surgery, presenting the anesthesiologist with the unique situation of repeated administrations of general anesthesia on a patient with a notoriously difficult airway.

What Are Other Congenital or Acquired Abnormalities Associated with Airway Difficulty?

Several congenital syndromes feature head, neck, and cervical spine anomalies which may complicate the pediatric airway, as summarized in Table 48–1.^4,5 Some abnormalities can also be acquired, for example, temporomandibular joint dysfunction following trauma (e.g., forceps delivery) or inflammation or microstomia from burns and caustic lesions. The following points summarize some issues that the anesthesiologist may encounter when attempting BMV or intubation in patients with these specific malformations. Otherwise, basic strategies for failed BMV and tracheal intubation will be discussed in other sections of this chapter. Marraro⁶ provides a good resource on congenital and acquired malformations that may contribute to difficult pediatric airway.

• 
  

  Children with craniofacial synostosis have high arched palates and small nasal passages, which leads them to breathe primarily through the mouth. Oral airway occlusion occurs with mouth closure. Obstructive apnea can occur from high resistance to air flow via the small nares. Preservation of spontaneous ventilation is critical.

  
  
• 
  

  In patients with hemifacial hypoplasia or other distortions in facial features, BMV will be challenging. Use of an extraglottic device (EGD) may be beneficial.

  
  
• 
  

  Conditions in which there is limited anterior mandibular space relative to the size of the tongue (e.g., PRS, Treacher Collins syndrome) will make direct laryngoscopy and tracheal intubation difficult. Use of an EGD as a conduit for flexible bronchoscopic-guided intubation may be necessary.

  
  
• 
  

  Tongue hyperplasia and/or mandibular/maxillary hypoplasia can increase the chance of airway obstruction since mass ratio of tongue to space will be limited. Curved blades may allow direct laryngoscopy in patients with large tongues (macroglossia), although in some patients with mandibular hypoplasia, direct laryngoscopy may be nearly impossible. BMV can be difficult to maintain in patients with macroglossia. Oral and/or nasopharyngeal airways may be useful to maintain airway patency. The use of an EGD or tracheal intubation may be required.

  
  
• 
  

  Patients with severe hemifacial microsomia (Goldenhar’s Syndrome) may be difficult to ventilate using a face mask, and laryngoscopy may be challenging, especially if mouth opening is restricted due to contractures following previous surgery. Ventilation with an EGD and nasal flexible bronchoscopic intubation are options.

  
  
• 
  

  Microstomia (reduced mouth opening) makes laryngoscopy and endotracheal intubation difficult. Various devices may be available for ventilation (e.g., nasopharyngeal airways) and intubation.

  
  
• 
  

  Visualization of the larynx can be challenging when movement of the cervical spine or temporomandibular joint is limited. Patients who have had previous reconstructive surgery may be difficult to intubate due to contractures that limit neck movement. Options include intubation using a nasal flexible bronchoscope or lightwand or intubation devices which minimize cervical movement (e.g., flexible bronchoscope or video-laryngoscopes).

  
  
• 
  

  Glossopexy (tongue sutured to lip) may be needed in patients with glossoptosis, in which the tongue is displaced rostrally to lie at the roof of the mouth.

  
  
• 
  

  Hurler’s syndrome (congenital mucopolysaccharidosis) is associated with tongue enlargement, soft tissue thickening, and blockage of nasal passages. Frequently, these patients also have a history of snoring. Primary goals are to preserve spontaneous breathing and minimize airway obstruction. An intubating EGD is an option for use during flexible bronchoscopic intubation. Unfortunately, progressive airway obstruction can lead to severe respiratory distress, which can be untreatable.

In clinical practice, use of an EGD may be an effective alternative to tracheal intubation for maintaining airway patency, but they are not without risks. Patients who may be susceptible to airway obstruction must receive adequate anesthesia to avoid laryngospasm, which would greatly worsen the scenario. Tracheal intubation options are discussed later in the chapter.

How Do You Perform Airway Assessment on This Patient?

Thorough documentation of patient history is essential in this case due to the diagnosis of a syndrome associated with difficult airway. Even though the patient is out of the high-risk age range for airway complications, the anesthesia practitioner must take into account previous procedures in which establishment of an airway was attempted. At the same time, the anesthesia practitioner must take into account age-related changes in airway structures since the last airway management. Additionally, current symptoms, if any, should be recognized and documented. These may include difficulty in breathing in different body positions, upper airway resistance syndrome, and obstructive sleep apnea.

Height, weight, and hematocrit should be recorded. Typical systematic tools for airway assessment in adults (see sections “Difficult BMV: MOANS,” “Difficult DL Intubation: LEMON,” “Difficult VL Intubation: CRANE,” “Difficult Use of an EGD: RODS,” and “Difficult Cricothyrotomy: SHORT” in Chapter 1) may not necessarily be applicable in children.⁷ Instead, neck extension and flexibility, mouth opening, and—particularly for PRS patients—accommodation of the tongue in the submandibular space upon direct laryngoscopy, are key factors to predicting difficulty of intubation. Regardless of whether these measurements prove normal, one should always be prepared for a difficult ventilation and intubation and have the appropriate equipment available and ready to use. In general, physical examination includes evaluation of:

• 
  

  size and shape of head

  
  
• 
  

  gross facial features

  
  
• 
  

  symmetry and size of mandible

  
  
• 
  

  tongue size

  
  
• 
  

  prominence of upper incisors

  
  
• 
  

  range of motion in the jaw, head, and neck

Note that protruding teeth, limited mouth opening, and micrognathia are signs of difficult direct laryngoscopy.⁸

It is important to point out that a substantial number of PRS patients present after the neonatal period with issues not related to respiratory failure, including sleep and swallowing problems. A presentation of respiratory failure is predictive of a more severe airway obstruction type and may require a tracheotomy.⁹

Do You Have Any Other Medical Concerns for This Child?

In isolation, PRS is not associated with major cardiac or other comorbidities. These patients have usually received general anesthesia early in their life, and PRS infants may suffer from such difficulties as recurrent aspiration and pulmonary hypertension.

What Are the General Principles and Processes for Approaching the Pediatric Difficult Airway?

Comprehensive planning is critical for managing a pediatric patient with a difficult airway. Although the anesthetic plan will be guided primarily by the patient’s physical examination and history, surgical procedure and anesthesia practitioner’s experience and familiarity with the available resources will also influence planning. Since pediatric patients can often desaturate quickly in challenging situations, each patient must be evaluated carefully in order to anticipate potential difficulties and plan for unforeseen issues. The anesthesia practitioner should have sufficient experience with the normal airway before attempting to deal with a difficult one; additional expertise will often be solicited upon suspicion of a difficult airway.

Equipment should be prepared to deal with both difficult ventilation and intubation. In addition, the patient should be prepared so as to best facilitate anesthetic procedures (i.e., careful use of props such as shoulder rolls/bolster and a pillow to maintain some cervical flexion and atlanto-occipital extension). More importantly, the induction technique will need to be tailored to the specific needs of the patient. The anesthetic plan should be discussed thoroughly with the patient (and their parents) and the entire surgical team and should be well documented. The benefits of the planned surgery should always be weighed against the potential risks of the anesthetic management.¹⁰ Table 48–2 lists some key points that should be considered prior to intubating the trachea of a child with a difficult airway.

Induction Technique

The primary objectives for induction in a difficult airway situation include maintaining spontaneous ventilation and achieving a plane of anesthesia that will enable airway instrumentation. It is essential to allow sufficient time for visualization of the structures and performance of intubation. A few key considerations are as follows:

• 
  

  Induction should be smooth and gradual, with the ability to safely abort if alternative plans fail.

  
  
• 
  

  Sedative agents are known to cause loss of airway muscle tone and increase airway resistance. In some cases, a limited sedative regime, such as oral midazolam 0.3 to 0.5 mg·kg⁻¹, will be needed as premedication in preparation for smooth induction.

  
  
• 
  

  Atropine (oral 30–40 μg·kg⁻¹ or intramuscular [IM] 20 μg·kg⁻¹) or glycopyrrolate can be used to dry secretions and support heart rate during induction. However, these agents are typically given once IV assess is secured.

  
  
• 
  

  Since most experts believe that maintenance of spontaneous ventilation is a top priority, inhalation induction remains the most popular approach. It is important to point out that inhalation approach still carries a risk of apnea, laryngospasm, and loss of airway.¹¹ Furthermore, this technique can be challenging if the face mask does not have a tight seal. The most commonly used induction agent is sevoflurane, which is short-acting and allows for spontaneous ventilation and easy reversal of anesthetic effects.¹² Regardless, an IV line should be in place prior to airway instrumentation, regardless of induction route. This will be necessary to administer medication to manage the plane of anesthesia.

  
  
• 
  

  An IV propofol–remifentanil infusion can often preserve spontaneous ventilation (90% or more of patients will breathe spontaneously with remifentanil 0.05 μg·kg⁻¹·min⁻¹), possesses an ultrashort half-life, and is easily titrated.¹³ Ketamine 1 to 2 mg·kg⁻¹, titrated carefully, may also be used. Similar to the inhalation technique, IV technique still carries a risk of apnea and loss of airway. In clinical practice, sevoflurane induction will often commence first, and intravenous (IV) propofol/remifentanil infusion may be then added to deepen the plane of anesthesia and/ or be used during airway management.

What Are the Clinical Strategies for Failed BMV?

In general, mask position and seal should be evaluated if BMV has failed on first attempt. In most cases, repositioning of the mask or fingers, a change of mask size or type, and/or ensuring the circuit is continuous will be adequate to address the problem, although additional steps, including chin-lift, jaw thrust, or CPAP, may be needed:

• 
  

  Mask-ventilation technique should be such that the patient’s airway does not become obstructed (e.g., covering the nose can be stressful for infants).

  
  
• 
  

  If the airway becomes obstructed, the patient can be moved to a lateral or prone position with application of a jaw thrust and/or an oral airway can be inserted to facilitate airway patency.

  
  
• 
  

  A chin lift reverses posterior, gravity-induced displacement of the epiglottis and widens the pharyngeal cavity. One hand is used to lift the inferior border of the mental protuberance to bring the teeth together without protruding the mandible. The thumb and index finger form a C-shape to hold the mask, while the ring finger performs the lift. Large adenoids and tonsils may limit the efficacy of this maneuver in opening the airway.¹⁴

  
  
• 
  

  A jaw thrust can force the mouth open and requires two hands to pull the mandibular angles upward and anterior. This technique is recommended when the chin lift is not successful¹⁵ and can also be used to confirm an adequate depth of anesthesia for EGD insertion.

  
  
• 
  

  Continuous positive airway pressure (CPAP) (e.g., 10 cm H₂O) increases airway volume and area. High airway pressures should be avoided since they will increase the work of breathing, decrease respiratory compliance, and impair venous return to the heart.

  
  
• 
  

  If adequate gas exchange cannot be maintained despite the above maneuvers, an oral or nasal airway should be inserted to hold the tongue forward and relieve obstruction by the lips, teeth, and nose. However, an oral airway that is too large may cause obstruction by forcing the epiglottis down over the glottis or may obstruct venous or lymphatic drainage, leading to swelling. On the other hand, if the oral airway is too small, it may cause obstruction by pushing the tongue backward. A poorly positioned airway can also induce pressure necrosis of the tongue. Distance between the mouth and the angle of the mandible can be used to determine roughly the appropriate size of airway.¹⁶

  
  
• 
  

  If oral airway insertion fails, the use of an EGD (e.g., i-gel, LMA) is a good option.

What Are the Clinical Strategies for Difficult Intubation?

In children with an anticipated difficult airway, conventional direct laryngoscopy or an alternative management strategy should be considered in advance. If the surgery does not require endotracheal intubation, an EGD may be attempted; if this fails, laryngoscopy may be attempted, with a straight blade. Mallampati classification and use of anatomic measurements to predict poor viewing during direct laryngoscopy has been shown to be inaccurate in children.⁵ Intubation of an awake patient (e.g., flexible bronchoscopic intubation) is preferable, although anesthesia will often need to be induced in pediatric population as many children are vigorous and uncooperative. Minimizing attempts at direct laryngoscopy is important to mitigate upper airway trauma.⁴ In some cases, retrograde intubation or cricothyrotomy may be necessary. In extreme cases, a tracheotomy will be needed; a considerable number of patients with craniofacial anomalies require tracheotomy.¹⁷ Figure 48–1 provides an algorithm that can be followed to guide intubation of a patient with a known difficult airway.

For patients with an unexpected difficulty, the following steps are suggested^4,10,11:

1. 
   

   Call for help

   
   
2. 
   

   Maintain ventilation—if ventilation is inadequate, refer to the above strategies.

   
   
3. 
   

   Reattempt intubation with direct laryngoscopy—optimize patient position (“sniffing position” with cervical spine flexion, atlanto-occipital extension, and chin above sternum). If inadequate, consider using a different blade (e.g., McCoy levering or video-laryngoscope [e.g., GlideScope^®]); technique (paraglossal¹⁸ or retromolar/right molar¹⁹ approaches may help in infants with their large tongue-to-space ratio and involves advancing the blade from the lateral pharyngeal wall); a stylet; or backward, upward, rightward pressure (BURP).

   
   
4. 
   

   Place EGD. Depending on the situation, proceeding with general anesthesia using an EGD. May be suitable only if adequate oxygenation and ventilation can be maintained and does not affect the proposed surgical procedure. Otherwise, flexible bronchoscopic intubation through an EGD should be considered.

   
   
5. 
   

   Attempt no more than four attempts at intubation (with no more than two direct laryngoscopy attempts) in order to minimize morbidity.

   
   
6. 
   

   If failed intubation is encountered, wake the patient up if possible. Otherwise, a surgical airway or needle cricothyrotomy (in emergency) may be the fastest option in the “can’t ventilate, can’t oxygenate” situation.

Preparation of airway equipment for cases in which difficulty is anticipated includes:

• 
  

  Various face masks, nasal, and oropharyngeal airways.

  
  
• 
  

  Two laryngoscopes with straight blades of varying lengths and widths (McCoy levering may be suitable).

  
  
• 
  

  Multiple endotracheal tubes (ETTs) with lubricated intubating stylets preloaded and prepared.

  
  
• 
  

  EGDs (preferably devices manufactured for tracheal intubation) for airway rescue and for a conduit for tracheal intubation (e.g., Fastrach-LMA [intubating], air-Q, etc.).

  
  
• 
  

  Other appropriate intubating devices (lightwand [Trachlight], pediatric Bullard laryngoscope, GlideScope^®, infant flexible bronchoscope). All devices should be loaded, tested, and lubricated (where appropriate).

  
  
• 
  

  Surgical tracheotomy tray and uncuffed percutaneous cricothyrotomy set. Most importantly, personnel experienced with this emergency procedure, such as an ENT surgeon, must be immediately available or, preferably, already present in the room.

Although a detailed description of all airway tools is beyond the scope of this chapter, most devices have been covered and discussed in other chapters. Briefly, use of alternative laryngoscope blades or modified laryngoscopes (e.g., McCoy, Bullard) may improve difficult airway intubation success. EGDs have been used successfully in children as a conduit for endoscopic intubation and should be available in all cases of pediatric airway management, particularly when anticipating a difficulty. Flexible or rigid bronchoscopes may be used for intubation. A transillumination technique using a lightwand (e.g., Trachlight) may be used when direct laryngoscopy or flexible bronchoscopy has failed. This light-guided intubation technique has proven to be simple and effective following appropriate experience and training. In short, when the tip of the lightwand is placed inside the glottis, a bright glow can be seen in the anterior soft tissue of the neck. If the lightwand is placed in the esophagus, however, no illumination is observed. Practical tips when using a videolaryngoscope can be found in (Table 48–3).