46.3.1 How Do You Assess the Airway of This Patient?
Robin sequence poses the classic small chin conundrum: difficult BMV and difficult direct laryngoscopy (DL).4,5 The lack of a well-developed mentum creates significant problems with mask fit (no seal below the lower lip), making BMV difficult or impossible. The glossoptosis places the tongue posteriorly and superiorly into apposition with the roof of the mouth. If Mallampati scores could be performed on these infants, they would score a IV! With loss of consciousness, airway obstruction often becomes complete, and its correction by an oropharyngeal airway is difficult unless a perfect fit is achieved. These patients are usually at their best in the prone position, because gravity helps keep the tongue off the roof of the mouth. They may develop varying degrees of obstruction when placed supine.
On the positive side, extraglottic devices, such as the laryngeal mask airway (LMA), have been reported to be effective in providing ventilation and oxygenation.6,7,8 An appropriately sized oropharyngeal airway (OPA), nasopharyngeal airway (NPA), or laryngeal mask airway (LMA), can often be placed easily and will usually maintain the airway. The LMA may well prove to be the airway of choice for some surgical procedures in Robin sequence, particularly minor procedures not involving or near the airway.
Glossoptosis and mandibular hypoplasia combine to make direct laryngoscopy very difficult. The glottic opening is angled away from the oral axis more than the usual 90 degrees, and the virtual absence of a submental space means that the laryngoscope blade cannot displace the tongue into this area. Fortunately, the cleft palate in Robin sequence is not accompanied by a cleft lip, and therefore does not interfere with laryngoscopy. In extreme cases, the mandibular hypoplasia is so severe that the tongue completely obstructs direct visualization of the larynx, despite optimal direct laryngoscopic technique, delivering a true Cormack/Lehane (C/L) Grade 4 view of the larynx.
Until recently, many alternate intubation devices were not available in pediatric sizes. However, there is now growing experience with newer alternate pediatric intubation techniques. The author and his colleagues have successfully intubated infants with Robin sequence using the infant Airtraq optical laryngoscope™, Trachlight™, STORZ video laryngoscope™, GlideScope®, and Bonfils intubation fiberscope™. Others have reported successful use of the Bullard™ laryngoscope, Shikani optical stylet™,9 and flexible bronchoscopic intubation, with or without the use of an LMA guide.10
Subglottic anatomy is normal but these patients are usually too young to have an identifiable crycothyroid membrane: this precludes surgical or percutaneous cricothyrotomy. However, open or percutaneous tracheotomy is possible and increased familiarity, and experience, with percutaneous tracheal access may bring this approach within the skill set of most pediatric anesthesia practitioners. Tracheal catheter jet ventilation using the Enk™ adaptor is still considered a feasible emergency pediatric option, although experience is extremely limited. Surgical backup and even full double setup is advisable for severe cases.
How do we recognize such a severe case? Risk factors include hyomental distance less than 1 cm (ie, severe mandibular hypoplasia), inability to maintain airway when awake and supine (severe glossoptosis), oxygen dependence, history of significant pulmonary disease, and prior episodes of failed airway in competent hands.
46.3.2 Do You Have Any Medical Concerns for This Patient?
Isolated Robin sequence is not associated with major cardiac or other malformations. However, these patients usually require anesthetics during their first year of life—a time when their anatomic challenges are complicated by the normal physiologic limitations of infancy, such as reduced effectiveness of denitrogenation increasing the risk and speed of onset of desaturation. In addition, some of these infants have problems with recurrent aspiration and pulmonary hypertension further reducing cardiopulmonary reserve. In Robin sequence infants airway obstruction is followed almost immediately by desaturation and bradycardia. Planning steps A, B, and C is vital as there is precious little time to think once the airway is lost.