Charles Nargozian

The airway in patients with craniofacial abnormalities

Airway management for patients with craniofacial disorders poses many challenges. The anaesthesiologist must be familiar with the normal bony and soft‐tissue anatomy in the airway and how anatomy is altered by various congenital disorders. Specific areas to assess include the oral cavity, anterior mandibular space, maxilla, temporomandibular joint and vertebral column. Congenital conditions that may alter normal anatomy and therefore anaesthetic management include cleft lip and palate with or without Pierre Robin syndrome, craniofacial dysostosis, mandibulofacial dysostosis/Treacher Collins syndrome, hemifacial microsomia, Klippel‐Feil syndrome, Beckwith‐Wiedemann syndrome, trisomy 21/Downs syndrome, Freeman–Sheldon/whistling face syndrome/craniocarpotarsal dysplasia, fibrodysplasia ossificans progressiva, mucopolysaccharidosis and vascular malformations.

Hemifacial microsomia: anatomical prediction of difficult intubation

Hemifacial microsomia (HFM) is associated with a difficult airway. We hypothesized that a difficult intubation would be predicted by radiographic evaluation of the severity of mandibular hypoplasia. A retrospective review of anaesthetic and surgical records of 102 children with HFM from 1986 to 1996 was conducted for radiographic classification of mandibular hypoplasia and degree of difficulty with intubation. Intubation was classified as Grade A—easy, Grade B—difficult, or Grade C—very difficult. The mandibular anatomy was categorized as Type I—‘mini‐mandible’, Type II—abnormal condylar size and shape, or Type III—absent ramus, condyle, and temporomandibular joint. In the 82 patients with HFM, 70% were classified as Grade A, 21% had Grade B and 9% had Grade C airways. No patients with Type I mandible had Grade C airway, while 25% of the patients with Type III mandible had Grade C airway. The correlation of the degree of airway difficulty with mandibular type was significant (P=0.001). In 20 patients with bilateral mandibular hypoplasia, 30% had Grade A, 35% had Grade B, and 35% had Grade C airways. We conclude that radiographic classification of mandibular deformity is a useful adjunct for preoperative prediction of airway difficulty in the management of children with unilateral HFM.

Utility of airway exchange catheters in pediatric patients with a known difficult airway.

Objective: To evaluate the utility of the Cook airway exchange catheter (CAEC) for extubation/reintubation in pediatric patients with a known difficult airway. Design: Prospective, nonrandomized. Setting: Pediatric intensive care unit; single academic institution. Patients: Twenty intubated children ≤18 yrs of age with a known difficult airway requiring extubation. Interventions: The CAEC was inserted into the trachea before extubation in children with a known difficult airway who were at risk for a difficult reintubation. The CAEC provided a means of a “guided” reintubation while maintaining the ability to provide supplemental oxygenation directly into the trachea. Measurements and Main Results: The respiratory rate, oxygen saturation, and amount of oxygen administered were measured immediately before extubation and at 5-, 15-, 30-, and 60-min intervals thereafter. In addition, the child’s ability to tolerate the CAEC was noted and rated (0 = tolerable without difficulty, 1 = tolerable with difficulty, 2 = intolerable). No sedatives were administered in the presence of the CAEC. The duration of the CAEC placement was dependent on the satisfaction of the child’s airway patency as determined by the unlikely need for reintubation. Five of the 20 (25%) children who had been extubated were reintubated in the intensive care unit with the assistance of the CAEC. Three of the five (60%) children were reintubated for upper airway obstruction. The ability to provide supplemental oxygen through the CAEC into the trachea during reintubation diminished the potential for hypoxia and maintained the ability to reintubate the trachea using the CAEC as a guidewire to pass an endotracheal tube. Conclusions: In children with a known difficult airway who are at risk for a difficult reintubation, the CAEC is a useful tool for a trial of extubation in the intensive care unit.

Simulation and airway-management training

Purpose of review Simulators can be used to teach simple technical skills or used in more realistic settings to teach or assess various cognitive/affective skills. Although simulators have become widespread, their use and efficacy in these various areas have not been delineated and are still being explored. This review will discuss the present state of using medical simulation for airway-management training. Recent findings Airway management includes both specialized technical skills and higher-order cognitive skills and behaviors. Since no one simulator is capable of covering all the functions necessary to teach these varied skills, medical specialists will need to train on a couple of different simulators. Now widely accepted in medical education, simulator training is being mandated in certain situations at some institutions because of a belief that it alters the physician. In this article its efficacy in teaching the specific psychomotor skills of bronchoscopy were validated but its use in teaching higher cognitive skills remained inconclusive. Summary Simulators are here to stay. Presently their usage in teaching psychomotor skills has scientific validity in specific tasks but their efficacy for teaching higher-order cognitive skills is still evolving. Future studies will continue to delineate the usage in different areas by studying the outcome in skills training and retention.

Teaching consultants airway management skills

Airway management skills are integral to the practice of anaesthesiology and also to the practice of emergency medicine and allied health professions such as respiratory care, emergency medical technology, and emergency and critical care nursing. The basic information to be taught is the same but the level of detail will vary depending on the audience. The learning process usually involves progression from didactic lessons to skills training on inanimate models to supervised clinical practice. Modalities that may be used for skills training include cadavers, recently dead patients, videotapes, mannequins, simulators and virtual reality trainers. To maintain knowledge and skills, review and possible retraining should be conducted on an approximately annual basis.

Epidural anesthesia in patients with palliated cyanotic congenital heart disease

ATIENTS WITH palliated cyanotic congenital heart P disease (CHD) are surviving in greater numbers, and present for noncardiac surgical procedures that demand an understanding of progressive cyanotic CHD and the physiologic implications of varied anesthetic techniques. As these patients grow into young adulthood, they are desirous of discussing their anesthetic options, and may express a strong preference to retain consciousness and avoid a general anesthetic. Carefully administered regional anesthesia has a place in the options offered to such patients, and, therefore, two cases are presented to illustrate experience with these patients and epidural anesthesia.

Anesthetic concerns of external maxillary distraction osteogenesis.

BackgroundExternal maxillary distractions present additional anesthetic concerns to the existing complexity of the patient with craniofacial disorder. The distraction hardware is rigidly fixed to the cranium and projects in the frontofacial midline, thus limiting oronasal airway access. MethodsA review of 16 patients (10 male, 6 female) having external maxillary distraction was done. Patients with patent tracheostomies were excluded. In all cases, the same type of external distraction device was used (R.E.D., K.L.S. Martin, Jacksonville, FL, USA). Perioperative records were reviewed for medical history; operative diagnosis, presence of airway disease, tracheostomy, laryngoscopy grade, use of fiberoptic bronchoscope, procedure, operative time, use of intraoperative steroid, day of postoperative extubation, and need for reintubation were documented. ResultsThe study group was subdivided into two diagnostic categories: those with syndromic craniosynostosis (n = 9) and those with cleft lip/palate (CLP) (n = 7). Patients in the craniosynostotic group had grade 1 laryngoscopy views, with the exception of a single patient with Crouzon syndrome who had a grade 3 view. This was the only patient who required fiberoptic intubation. One patient with Apert syndrome required reintubation (48 hours after surgery); successful extubation was done 96 hours later. In the cleft lip/palate group, all patients had grade 1 laryngoscopic views, except one with a grade 3 view; no patient required fiberoptic intubation. Six of the seven patients were extubated immediately after surgery, with one patient extubated the next day. No patient experienced failure of extubation. ConclusionsExternal maxillary distraction minimally affects anesthetic management provided certain safeguards are observed. The vertical bar can be left attached to the cranial portion of the distractor, or it can be removed for extubation or reintubation. Removal of the vertical bar allows unobstructed direct laryngoscopy. This emphasizes the importance for the emergent availability of the appropriate screwdrivers and wire cutters to remove the vertical bar and trained personnel to perform the removal.

THE DIFFICULT AIRWAY IN THE PEDIATRIC PATIENT WITH CRANIOFACIAL ANOMALY

Airway management in patients with craniofacial disorders poses many challenges to the anesthesiologist. To develop an anesthetic plan one needs the knowledge of how existing anatomy will affect ventilation by face mask and tracheal intubation. Often, difficulty in one does not translate into difficulty in the other. Another complicating factor that needs to be considered in the pediatric patient is growth. Airway anatomy changes as the child grows, and this may influence the airway in a positive, negative, or neutral manner. Although it would be tempting to list the various syndromes alphabetically with their concomitant problems, a more useful approach is to discuss how the anatomic considerations influence airway management. From these, one can take the salient features of a given syndrome and see which factors will cause problems. Structurally, the airway consists of soft tissue and bony elements. When considering the potential for distortions in anatomy, the effects of both of these elements may be interdependent or independent of each other. In the case of the upper airway, the oral cavity can be viewed as a box bounded by the bony structures of the maxilla and the mandible, which is filled to some extent by the soft tissue of the tongue. The ratio of the volume of the oral cavity to the tongue can give an indication of whether upper airway obstruction is likely or not. Maxillary or mandibular abnormalities may reduce the volume of the oral cavity, while the tongue, when affected by the disease process, is often enlarged. As the ratio of soft tissue to volume increases, the probability of airway obstruction increases. An allied idea is that of the anterior mandibular space. This is the space within the confines of the mandible into which the soft tissue of the tongue can be displaced during laryngoscopy. Anomalies that make this space small relative to the size of the tongue will make tracheal intubation by direct laryngoscopy more difficult. Mandibular hypoplasia, as seen in Pierre Robin sequence, is such a disorder and exemplifies the idea of the anterior larynx. It is a situation in which the larynx is positioned cephalad under the base of the tongue. Because there is no space into which to displace the tongue, the spatial anatomy does not change during direct laryngoscopy and the larynx remains anterior to the laryngoscope blade and difficult to visualize. Maxillary hypoplasia can cause a similar change in the mass-to-volume ratio of the upper airway, again making airway obstruction more likely. Patients who have maxillary hypoplasia, e.g., Apert syndrome, often have some degree of nasal obstruction or choanal stenosis. The result is that these patients remain primarily mouth breathers. Should their mouth close, they obstruct. Fortunately, in these patients, the mandible usually is of normal size so that tracheal intubation is not difficult. Another important component of the upper airway is the function of the temporomandibular joints (TMJ). These represent the hinges, or the points at which the box of the upper airway swings open. It is important to remember that the jaw not only hinges open but also translocates forward. Abnormalities in which the jaw opens but does not slide forward may give the false impression that visualizing the trachea will be easy. Translocation is easily tested by asking the patient to jut his jaw forward. Problems that do not allow the TMJ to fully open seem to be more common. It is important then to assess if the rigidity is fixed or one that may be overcome once the patient is anesthetized. Fusion of the TMJ, whether congenital or secondary to trauma, will not change with anesthesia; however, if trismus is secondary to pain or inflammation, then movement may be accomplished once the patient is asleep, allowing access to the oral cavity. The last bony structure to consider is the vertebral column. Function of the atlanto-occipital section of the vertebral column and the ability to flex and extend are the two factors that affect the ability of the anesthesiologist to align the axes of the trachea and the oral cavity with the line of vision to the glottis. The largest degree of flexion-extension occurs at the lower cervical region, with the atlanto-occipital area also playing a major part. Fusions, hemivertebrae, and arthritic changes may decrease mobility to the extent that tracheal intubation is difficult or impossible. Other congenital or acquired disease processes that cause instability of the vertebral column may put the spinal cord in danger of impingement. In these circumstances, motion of the neck must be avoided and alternate methods of tracheal intubation sought. After the fixed structural bony abnormalities are taken into consideration, the soft-tissue aspects need to be examined. Soft-tissue problems usually fall into two categories, causing either limitation in movement or distortion by mass effect. Soft-tissue limitation of motion usually affects mouth opening. This can be seen with various syndromes or rare disease states. Freeman–Sheldon syndrome is one such case in which there is a fixed microstomia that does not widen with muscular relaxation. Other rare disorders that cause similar limitations include fibrofacial myositis officans and dermatomyositis. Mass effects from soft tissue can fall into various categories. Problems may be congenital in origin, the result of surgical interventions, or due to disease states that develop later in life. Macroglossia may present as a congenital disorder in several syndromes. As previously discussed, a large tongue fills the oral cavity, making visualization of the larynx difficult. This occurs in Beckwith–Wiedemann syndrome, Down syndrome, and Sturge–Weber syndrome, and various syndromes associated with dwarfism. Other problems that cause mass effect include soft-tissue tumors and some forms of arteriovenous and lymphatic malformations. Sometimes these disease states can cause secondary problems by erosion or mechanical obstruction of airway structures.