Pierre Robin syndrome:
Manifestations:
➧ A rare syndrome in which there is a combination of:
-Severe micrognathia
-Posterior prolapse of the tongue
Other congenital abnormalities:
-Cleft palate
-Esophageal atresia
➧ The term syndrome is now reserved for those errors of morphogenesis with the simultaneous presence of multiple anomalies caused by a single etiology.
➧ The term sequence has been introduced to include any condition that includes a series of anomalies caused by a cascade of events initiated by a single malformation.
Pierre Robin sequence:
➧ The common features of which include:
1-Mandibular hypoplasia
2-Glossoptosis (Figure 1)
3-Incomplete cleft palate (Figure 2)
Although all three are not necessarily present.
This results in:
-Respiratory obstruction in infancy
-Failure to thrive
-Occasionally cor-pulmonale
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| Figure 1: Glossoptosis |
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| Figure 2: Incomplete cleft palate |
➧ The Robin sequence may be an isolated abnormality, or it may be part of a syndrome. There may be airway and intubation problems in any of these patients.
Associated syndromes:
➧ Pierre Robin sequence has been reported as occurring in association with:
-Stickler syndrome (20%-25% of these cases)
-Campomelic dysplasia
-Trisomy 11q syndrome
-Deletion 4q syndrome
-Velocardiofacial syndrome
-Treacher-Collins syndrome.
➧ These patients frequently require anesthesia at a young age.
➧ Management of long-term airway obstruction is a matter of debate, but at present tracheostomy seems to be back in favor. The mortality from pediatric tracheostomy has declined and it increases the safety of subsequent anesthetics.
Etiology:
➧ The exact causes of the Pierre Robin sequence are unknown. Possible mechanisms include:
-Genetic causes.
-Oligohydramnios, which may limit chin growth.
-Weakness of the facial muscles (myotonia).
-Connective tissue disease.
-Genetic causes.
-Oligohydramnios, which may limit chin growth.
-Weakness of the facial muscles (myotonia).
-Connective tissue disease.
➧ The genetic causes for some of the isolated cases (Pierre Robin sequence without any associated malformations) may include mutations or deletions of parts of the DNA neighboring the SOX9 gene (located in chromosome 17 (17q24)). This gene provides instructions for making protein SOX9 that regulates the activity of other genes, especially those involved in the development of the skeleton, including the jaw during embryonic development.
Preoperative abnormalities:
1. Many present as difficult or failed intubation during resuscitation at delivery. Hypoxic brain damage may be sustained at this stage.
2. The remainder usually presents within a few hours of birth when the micrognathia and glossoptosis cause breathing and feeding difficulties, with episodes of cyanosis when the child is in the supine position. Feeding difficulties correlate with the severity of airway obstruction. Subsequently, there is a failure to thrive.
2. The remainder usually presents within a few hours of birth when the micrognathia and glossoptosis cause breathing and feeding difficulties, with episodes of cyanosis when the child is in the supine position. Feeding difficulties correlate with the severity of airway obstruction. Subsequently, there is a failure to thrive.
3. There was a high incidence of concomitant problems, which included gastroesophageal reflux, congenital heart disease, and pulmonary disease.
4. Jaw index: A new index for defining micrognathia by measurement of three facial dimensions; children with Pierre Robin have an average index of more than 3.6 times the normal value.
5. Cleft palate occurs in 60%, and eye problems in 40% of Pierre Robin patients.
6. Chronic upper airway obstruction can result in cor-pulmonale. An increased pulmonary artery pressure may produce right-to-left shunting through a patent foramen ovale or a persistent ductus arteriosus.
7. Obstructive sleep apnea may occur and managed by the use of nasal CPAP.
Airway obstruction management:
➧ A sequence of strategies is recommended in an attempt to minimize airway obstruction and allow safe feeding. The treatment required depends upon severity:
-Initially, the neonate is nursed in the prone position. If this fails, prolonged nasopharyngeal intubation may help to protect the airway.
-If respiratory distress and failure to thrive persist, and a lateral X-ray of the neck in the supine position shows upper airway obstruction, suturing of the tongue to the lower gum or lip (tongue-to-lip adhesion) may be needed. Modified nasopharyngeal tubes or splints have been described. Feeding may be undertaken via a nasogastric or a gastrostomy tube.
-Respiration and oxygen saturation are monitored, and appropriate oxygen supplementation is given. Sometimes tracheostomy may be required, although previously there has been a reluctance to resort to this.
-Benjamin and Walker (1991), classified them into three groups according to the treatment required:
1-Mild group (needing posture alone)
2-Moderate group (needing nasopharyngeal tube)
3-Severe group (needing tracheal intubation or tracheostomy).
-All deaths can occur in the latter group, from hypoxic brain damage at birth.
-As the child grows, the obstruction tends to improve, partly from the growth of the mandible and the size of the airway, and partly as a result of better neurological control of the tongue muscles.
-Problems mainly seem to resolve by the time the child is 6 months old:
-Mild cases could be nursed supine from 3 to 6 months.
In the moderate group, nasopharyngeal intubation is required for between 14 days and 14 weeks, after which they were nursed prone.
-All could sleep supine by 6 months.
Anesthetic problems:
1. Even in the un-anesthetized infant, during the first few months of life, respiratory obstruction occurs in the supine position. The main mechanism for this is thought to be glossoptosis, prolapse of the tongue backward, but it is now realized that there are multiple factors.
➧ It is believed that obstruction is related to a combination of the anatomical abnormalities of the mandible with functional impairment of the genioglossus and other pharyngeal muscles, that are concerned with the maintenance of the airway.
➧ Varying degrees of obstruction exist, ranging from none at all to obstruction when the neonate is asleep and, in the worst cases, obstruction in the awake state. In any neonate, obstruction worsens during an upper respiratory tract infection, feeding, and crying.
➧ It is suggested that the site of obstruction varies from patient to patient. From endoscopic observations, these have been classified into:
-Type 1: A true glossoptosis in which the dorsum of the tongue is as opposed to the posterior pharyngeal wall.
-Type 2: The tongue compresses the soft palate against the posterior pharyngeal wall so that all three structures meet in the upper oropharynx.
-Type 3: Medial apposition of the lateral pharyngeal walls.
-Type 4: A sphincteric constriction of the pharynx.
2. Oxygen desaturation and obstructive sleep apnea, detected by pulse oximetry and polysomnography, occur in the majority of neonates and contribute to mortality from obstruction.
3. Gastro-esophageal reflux may be present.
4. The unusual facial configuration, in particular the receding lower jaw, makes it difficult to maintain an airtight fit with an anesthetic mask.
5. Difficult or failed intubation results from a combination of micrognathia, and prolapse or inward sucking of the posteriorly attached, and often enlarged, tongue. This may be compounded by the presence of a tongue tie which, paradoxically, may prevent airway obstruction.
So, intubation problems can be underestimated because of the lack of preoperative airway obstruction. However, once the tongue tie had been corrected, subsequent intubation became easy.
So, intubation problems can be underestimated because of the lack of preoperative airway obstruction. However, once the tongue tie had been corrected, subsequent intubation became easy.
6. Pulmonary edema can occur after relief of airway obstruction following palatal repair of cleft palate.
Airway management:
➧ Monitoring by pulse oximetry, to detect airway obstruction, is crucial.
➧ Several methods have been proposed to overcome the problem of difficult intubation, some under general anesthesia, and some in awake patients. The consensus of opinion now seems to favor awake techniques.
1-Asleep technique with 'Jackson anterior commissure laryngoscope': (Figure 3)
➧ Handler and Keon (1983) described a technique for intubation for the anesthetized spontaneously breathing patient, using 'Jackson anterior commissure laryngoscope':
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| Figure 3: Jackson anterior commissure laryngoscope |
-The head is elevated above the shoulders, with flexion of the lower cervical vertebrae and extension at the atlanto-occipital joint.
-The laryngoscope is introduced into the right side of the mouth. Only the tip is directed towards the midline, the proximal end remaining laterally so that a further 30 degrees of anterior angulation can be obtained.
-The laryngoscope is introduced into the right side of the mouth. Only the tip is directed towards the midline, the proximal end remaining laterally so that a further 30 degrees of anterior angulation can be obtained.
-The narrow, closed blade prevents the tongue from falling in and obscuring the view of the larynx. When visualized, the epiglottis is elevated, and the larynx is entered.
-Intubation is then achieved by passing a lubricated tube, without its adaptor, down the laryngoscope. It is held in place with 'alligator forceps' whilst the laryngoscope is withdrawn.
-Intubation is then achieved by passing a lubricated tube, without its adaptor, down the laryngoscope. It is held in place with 'alligator forceps' whilst the laryngoscope is withdrawn.
2-Asleep technique with blind nasal intubation in the prone position:
➧ The prone position avoids the problems in the supine position, this position allows the tongue and mandible to fall forward under the effect of gravity and leave the larynx exposed.
3-Fibreoptic bronchoscopic techniques:
➧ In small infants, the 'tube over bronchoscope' technique is not always possible because of the small size of the tube, therefore a 'Seldinger technique' may be necessary:
-After the administration of atropine, ketamine IM, and topical lidocaine, a fibreoptic bronchoscope (OD 3.6 mm, L 60 cm, and suction channel 1.2 mm) is passed through one nostril.
-The tongue is held forward with 'Magill forceps', until the vocal cords are seen, but not entered, because of the risk of total obstruction.
-Under direct vision, a 'Teflon-coated guidewire' with a flexible tip is passed via the suction channel into the trachea.
-The bronchoscope is carefully removed leaving the wire in place, and an ID 3 mm nasotracheal tube is then passed over it into the trachea.
➧ Pediatric bronchoscopes of 2.5 mm diameter are now available, but their very fineness makes them less easy to handle than the 4 mm bronchoscopes).
4-Awake techniques using 'Holiger pediatric anterior commissure laryngoscope': (Figure 4)
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| Figure 4: Holiger anterior commissure laryngoscope |
5-Laryngeal mask airway (LMA) techniques:
➧ Placement of LMA following topical anesthesia in awake infants and the use of LMA to guide an introducer for subsequent intubation can be used in an emergency, and electively.
6-The use of a lighted stylet:
Read more ☛ Treacher Collins Syndrome
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