Airway management of the severely retrognathic child: use of the laryngeal mask airway. (Original Article).

Abstract

Successful airway management of an infant or child with moderate to severe retrognathia first requires recognition of a potential problem. If the child cannot be intubated in a standard fashion, the use of a laryngeal mask airway (LMA) should be considered. We describe two cases wherein a toddler and an infant with severe retrognathia failed multiple attempts at traditional intubation. Both had an anterior larynx and hypoplasia of the mandible. In both cases, a subsequent LMA was successfully placed. The severely retrognathic newborn or child presents to the physician a unique challenge in airway management. Techniques to manage this difficult pediatric airway are different from those used in the adult. Otolaryngologists should be aware of this intubation technique and include it in their armamentarium of airway-management strategies. The LMA is not recommended as the technique of choice for securing a difficult airway, but it is an effective alternative when indicated, and it might be life-saving.

Introduction

The severely retrognathic infant or child presents a unique challenge to the otolaryngologist. Techniques for managing this difficult airway in children are different from those used in adults. For the severely retrognathic infant or child, airway management frequently involves blind intubation or tracheostomy under local anesthesia. When these procedures cannot be carried out, the laryngeal mask airway (LMA) is an effective alternative. (1)

In this article, we describe two cases in which the LMA was used to blindly intubate the larynx after standard intubation techniques had failed. Our purpose is to review for otolaryngologists the various techniques used to establish the airway in the severely retrognathic child and to make them more aware of LMA and its application.

Case reports

Patient 1. A 26-month-old boy with Treacher Collins syndrome (mandibulofacial dysostosis) had a history of obstructive sleep apnea characterized by loud snoring and dysphasia. He was a mouth breather with moderately severe retrognathia. An oral cavity examination revealed the presence of a high-arched palate and a large tongue, and his tonsils and soft palate could not be visualized. Based on the patient's history of apnea and physical examination findings documenting the obstruction, he was selected to undergo tonsillectomy and adenoidectomy.

Because the patient's limited mouth opening (1.5 cm) and his retrognathia were of concern, he underwent inhalation anesthesia with no paralytic agents. Multiple attempts were made to intubate the larynx via standard techniques, including rigid bronchoscopy. Eventually, a No. 2. LMA was inserted, and the patient was easily ventilated. A 4.5 endotracheal tube (ETT) was connected to a 4.0 ETT and blindly inserted through the LMA. The LMA and the 4.5 ETT were then removed, leaving the patient intubated with the 4.0 ETT (figure 1). The trachea was visualized through a flexible fiberoptic nasopharyn-goscope placed through the 4.0 ETT. In all, the intubation process required 1 hour and 30 minutes. The patient's tonsillar base could not be visualized because of his micrognathia and displaced tongue, so a uvulectomy was performed.

Because of concern about postoperative swelling, the patient was placed in the intensive care unit following extubation. There he developed respiratory distress with [CO.sub.2] retention. He was administered racemic epinephrine, intravenous steroids, and heliox and fitted with bilateral nasal trumpets. After 24 hours, the respiratory distress resolved, and the boy was transferred to the floor without any further problems.

Six weeks later, a sleep study revealed that the patient still had obstructive apnea. His apnea/hypopnea index was 4.5. His lowest oxygen saturation reading was 79%, and his longest apneic event lasted 75 seconds. Clinically, he was still snoring and waking up gasping for breath.

Approximately 6 months after his initial surgery, he was taken to the operating room for a tonsillectomy to relieve his obstructive sleep apnea. He underwent inhalation induction of nitrous oxide and oxygen, with no paralytic agents. Again, several unsuccessful attempts were made to visualize the larynx via standard techniques. Using the same LMA technique with the interconnected ETTs, the patient was intubated in 30 minutes. The tonsillectomy was performed without difficulty. He was taken to the intensive care unit still intubated, and he was extubated the next morning without difficulty. The results of his second sleep study were worse than the first, but he ultimately obtained excellent relief with bilevel positive airway pressure.

Patient 2. A 6-day-old, full-term girl who had received minimal prenatal care was apneic at delivery (figure 2). She was unable to be intubated at birth because of severe hypoplasia and immobility of the mandible. After responding to masked ventilation and oxygen, her Apgar scores were 5 and 8. Her retrognathic mandible had caused a posterior prolapse of the tongue base, which subsequently caused intermittent airway obstruction. The infant had multiple craniofacial and preaxial skeletal anomalies and was diagnosed with Nager's syndrome. Initially, she was stable on room air. However, her recurrent obstructive airway problems continued and culminated in the need for a tracheostomy to secure the airway.

An inability to open the infant's mouth precluded the use of standard techniques to establish the airway. Because her mouth opening was only 0.5 cm,

a No. 1 LMA was lubricated and inserted through the oral cavity with a moderate amount of pressure. The infant then began spontaneously ventilating through the LMA, and her oxygen saturation level immediately increased from 80 to 98% on 100% oxygen. A 3.0 ETT connected to a 2.5 ETT was inserted into the LMA. The LMA was left in place over the ETT because the initial attempt to remove it resulted in extubation. A tracheostomy was then performed in the usual fashion. In this case, it took only 29 minutes to establish the airway.

Discussion

Management of the retrognathic child is challenging. The otolaryngologist and anesthesiologist team should plan the preoperative, operative, and postoperative airway management of these patients.

Various congenital syndromes with micrognathia, macroglossia, and short neck make the viewing of the larynx with a rigid scope nearly impossible. (2) Anesthesiologists are usually able to intubate the difficult adult airway with a flexible endoscope. However, many institutions do not have pediatric flexible fiberoptic scopes. (3) Moreover, neonates and children are generally not cooperative enough to undergo an awake intubation.

The LMA became commercially available in the United Kingdom in 1988. (4) In the United States, the federal Food and Drug Administration approved its use in 1991. LMA has been used primarily in adults. (5,6) Since it became available, estimates of its use worldwide range from 10 million to 20 million cases. (6) The American Society of Anesthesiologists includes the use of the LMA in its algorithm for the management of the difficult airway. (5)

The LMA is reusable and must be sterilized between each use. It is available in six sizes, based on the weight of the patient. Lubrication is applied to the posterior aspect of the mask prior to insertion. Special care should be taken to avoid lubricating the interior surface of the LMA because this can cause a laryngeal spasm. (5) The LMA is placed into the hypopharynx of the anesthetized patient until resistance is met. (4) At this point, the tip of the LMA should align the base of the hypopharynx with the sides of the pyriform sinus, and the upper portion of the mask should push the base of the tongue forward. (7)

The anterior surface of the LMA is a grate made of two bands that traverse across the cuff aperture. This design helps prevent the impaction of the epiglottis. (8) Ideally, the epiglottis and the esophagus are outside the mask, and only the laryngeal opening is inside; however, such positioning occurs only 50% of the time. (5) In the other 50% of cases, the epiglottis becomes folded down; the lateral aryepiglottic folds might fold inward, as well. (5,9) However, even with such a partial obstruction, ventilating the pediatric patient with the LMA is not difficult.

The use of the LMA in otolaryngologic anesthesia is gaining acceptance. In some institutions, the LMA is being used in pediatric otolaryngology during tympanostomy tube placement, cleft lip repair, tonsillectomy, and adenoidectomy. (2,8) Rothschild and Kavee reported its use during four separate procedures on patients with mild subglottic stenosis. (6)

The LMA is also used in the pediatric population at several institutions for fiberoptic bronchoscopy and bronchoalveolar lavage under general anesthesia. (9-11) Because the internal diameter of the LMA is larger than the equivalent ETT for a particular patient, the LMA can accommodate fiberoptic bronchoscopy without significantly obstructing the airway around the bronchoscope. The LMA can distort the pediatric supraglottic anatomy, so prior to the administration of general anesthesia, it is recommended that a flexible nasopharyngoscopy be performed on an awake child to fully view the supraglottic area. (9) Even with the smallest LMA, laryngospasm and bronchospasm have been reported in as many as 30% of patients. (11) Infants appear to have a higher risk of laryngospasm and bronchospasm than adults, which is thought to be the result of an inadequate depth of anesthesia. (11) Once the level of anesthesia is increased and positive pressure ventilation is administered, the spasms resolve. (11)

LMA has been used in patients with various pediatric syndromes, including craniodiaphyseal dysplasia, the mucopolysaccharidoses, Freeman-Sheldon syndrome, Hurler's syndrome, and Cockayne's syndrome. (12-16) In such cases, a weight-appropriate LMA is inserted after an adequate depth of anesthesia, without any paralytic agents, has been achieved. (A child should not be paralyzed until after the airway is secured.) A fiberoptic bronchoscope is then passed through the appropriate-sized ETT and down through the vocal folds. (12) In several of these cases, an elastic bougie or a guidewire was passed through a bronchoscope. (3,12,14) Next, an ETT was "railroaded," or pushed, over the bougie or guidewire, and then the bougie or guidewire was removed. Placing a small amount of lubricant over the sides of the interconnected ETT will facilitate its passage through the LMA.

When possible, it is recommended that confirmation that the ETT has been placed correctly should be obtained by fiberoscopy. (1,3) Proper placement can also be assessed by auscultation, capnography, and ventilations from the self-inflating anesthesia bag. (1,13)

Patients who have craniofacial syndromes that involve the midface and mandible are predisposed to airway obstruction. Treacher Collins syndrome and Nager's syndrome are two such anomalies. Treacher Collins syndrome is characterized by antimongoloid-slanting palpebral fissures and mandibular hypoplasia. (17) Nager's syndrome is very similar, but it is also characterized by preaxial skeletal defects. Nager's syndrome is also much more rare, as only 22 cases have been reported in the literature. (17) The micrognathic mandible associated with these two syndromes causes a posterior prolapse of the tongue base, which results in airway obstruction.

Antenatal sonography can be used to assess fetal anatomy, including facial structures (figure 3). The fetal profile frequently affords the viewer a clear image of the fetal chin. The mandible can be imaged and measured in the axial plane, and normative measurements have been reported. (18) It can be difficult to make a definitive diagnosis of micrognathia on the basis of an in utero evaluation because a variable degree of phenotypic expression might be present; there is also the potential for in utero development of anomalies, including Pierre Robin syndrome. (19)

Postnatal management of the fetus suspected of having micrognathia requires that personnel who are facile in managing the neonatal airway be present during the infant's delivery. If the micrognathia in our patient 2 had been detected at the prenatal screening ultrasound, maternal fetal circulation or uroplacental circulation would have been used to establish the airway at birth. (20) A tracheostomy would have been performed on the newborn while she was maintained on the placental circulation.

The two patients described in this article were treated successfully because the otolaryngologist and anesthesiologist recognized a potential problem during the preoperative evaluation. Because these patients were much too young to undergo an awake intubation with a fiberoptic endoscope, inhalation anesthesia without paralysis was administered. In both cases, the same anesthesiologist administered the anesthesia. As our proficiency at managing these difficult airways increased, the time required to establish the airway significantly decreased.

Several cases have been described in the anesthesiology and critical care literature in which the larynx was blindly intubated with an LMA. (1,13,14) To our knowledge, this article is the first such report to appear in the otolaryngology literature.

References

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(2.) Hinton AE, O'Connell JM, van Besouw JP, Wyatt ME. Neonatal and paediatric fibre-optic laryngoscopy and bronchoscopy using the laryngeal mask airway. J Laryngol Otol 1997;111:349-53.

(3.) Hasan MA, Black AE. A new technique for fibreoptic intubation in children. Anaesthesia 1994;49:1031-3.

(4.) Badr A, Tobias JD, Rasmussen GE, et al. Bronchoscopic airway evaluation facilitated by the laryngeal mask airway in pediatric patients. Pediatr Pulmonol 1996;21:57-61.

(5.) Griner RL II. AANA Journal course: Update for nurse anesthetists--the laryngeal mask airway: Attributes and inadequacies. AANA J 1996;64:485-96.

(6.) Rothschild MA, Kavee EH. The modified laryngeal mask airway: Four head and neck procedures in two children with mild subglottic stenosis. Int J Pediatr Otorhinolaryngol 1997;41:163-73.

(7.) Pennant JA, White PF. The laryngeal mask airway. Its uses in anesthesiology. Anesthesiology 1993;79:144-63.

(8.) Ruby RR, Webster AC, Morley-Forster PK, Dain S. Laryngeal mask airway in paediatric otolaryngologic surgery. J Otolaryngol 1995;24:288-91.

(9.) Tunkel DE, Fisher QA. Pediatric flexible fiberoptic bronchoscopy through the laryngeal mask airway. Arch Otolaryngol Head Neck Surg 1996;122:1364-7.

(10.) Baraka A, Choueiry P, Medawwar A. The laryngeal mask airway for fibreoptic bronchoscopy in children. Paediatr Anaesth 1995;5:197-8.

(11.) Bandla HP, Smith DE, Kiernan MP. Laryngeal mask airway facilitated fibreoptic bronchoscopy in infants. Can J Anaesth 1997;44:1242-7.

(12.) Appleby JN, Bingham RM. Craniodiaphyseal dysplasia: Another cause of difficult intubation. Paediatr Anaesth 1996;6:225-9.

(13.) Barnes SD. Emergent intubation of the difficult pediatric airway using the laryngeal mask airway. Am J Crit Care 1996;5:376-8.

(14.) Wooldridge WJ, Dearlove OR, Khan AA. Anaesthesia for Cockayne syndrome. Three case reports. Anaesthesia 1996;51:478-81.

(15.) Walker RW, Allen DL, Rothera MR. A fibreoptic intubation technique for children with mucopolysaccharidoses using the laryngeal mask airway. Paediatr Anaesth 1997;7:421-6.

(16.) Munro HM, Butler PJ, Washington EJ. Freeman-Sheldon (whistling face) syndrome. Anaesthetic and airway management. Paediatr Anaesth 1997;7:345-8.

(17.) Jones KL, ed. Smith's Recognizable Pattern of Human Malformation. 4th ed. Toronto: W.B. Saunders, 1988:210-6.

(18.) Watson WJ, Katz VL. Sonographic measurement of the fetal mandible: Standards for normal pregnancy. Am J Perinatol 1993;10:226-8.

(19.) Pilu G, Romero R, Reece EA, et al. The prenatal diagnosis of Robin anomalad. Am J Obstet Gynecol 1986;154:630-2.

(20.) Stocks RM, Egerman RS, Woodson GE, et al. Airway management of neonates with antenatally detected head and neck anomalies. Arch Otolaryngol Head Neck Surg 1997;123:641-5.

From the Department of Otolaryngology--Head and Neck Surgery, LeBonheur Children's Medical Center (Dr. Stocks, Dr. Thompson, and Dr. Peery), and the Department of Obstetrics and Gynecology (Dr. Egerman), University of Tennessee, Memphis.

Reprint requests: Rose Mary S. Stocks, MD, PharmD, 777 Washington, P-110, Memphis, TN 38105. Phone: [phone]; fax: [phone]; e-mail: [e-mail]

Originally presented at a meeting of the Pacific Coast Otolaryngologic- Ophthalmological Society; Victoria, British Columbia; June 22, 1999.