//Evaluation of the Airway http://www.expertconsultbook.com/expertconsult/b/book.do?m... Evaluation of the Airway A history and physical examination with specific reference to the airway should be performed in all children who require sedation or anesthesia. In particular, a history of a congenital syndrome or physical findings of congenital anomaly (e.g., microtia which has been associated with difficult laryngoscopy)[80] should alert the practitioner to the possibility of difficulties with management of the airway. In special situations, radiologic and laboratory studies are required to further evaluate and clarify a disorder revealed by the history and physical examination. Although many methods exist for evaluating and predicting the difficult airway in adults,[81–85] no published studies have assessed the use of any of these techniques in children.[86,][87] Routine evaluation of the airway in all children followed by correlation with any airway problems occurring during anesthetic management helps the practitioner to develop experience. This experience then may be used to identify future children who might have airway difficulties during or after anesthesia. Clinical Evaluation The medical history (both present and past) should investigate the signs and symptoms listed below; a positive history should alert the practitioner to the potential problems that are noted in parentheses (video clips are available on the website for some examples). • Presence of an upper respiratory tract infection (predisposition to coughing, laryngospasm, broncho spasm, and desaturation during anesthesia or to post-intubation subglottic edema or postoperative desaturation)[88–92] • Snoring or noisy breathing (adenoidal hypertrophy, upper airway obstruction, obstructive sleep apnea, pulmonary hypertension) • Presence and nature of cough (“croupy” cough may indicate subglottic stenosis or previous tracheoesophageal fistula repair; productive cough may indicate bronchitis or pneumonia; chronicity affects the differential diagnosis [e.g., the sudden onset of a persistent cough may indicate foreign-body aspiration]) • Past episodes of croup (post-intubation croup, subglottic stenosis) • Inspiratory stridor, usually high pitched (subglottic narrowing [see Video Clip 12-1, Coming Soon], laryngomalacia [see Video Clip 12-1, Coming Soon], macroglossia, laryngeal web [Video Clip 12-2, Coming Soon], extrathoracic foreign body or extrathoracic tracheal compression) • Hoarse voice (laryngitis, vocal cord palsy, papillomatosis [see Video Clip 12-1, Coming Soon], granuloma [see Video Clip 12-1, Coming Soon]) • Asthma and bronchodilator therapy (bronchospasm) • Repeated pneumonias (incompetent larynx with aspiration, gastroesophageal reflux, cystic fibrosis, bronchiectasis, residual tracheoesophageal fistula, pulmonary sequestration, immune suppression, congenital heart disease) • History of foreign-body aspiration (increased airway reactivity, airway obstruction, impaired neurologic function) • History of aspiration (laryngeal edema [Video Clip 12-3, Coming Soon], laryngeal cleft [Video Clip 12-4, Coming Soon]) • Previous anesthetic problems, particularly related to the airway (difficult intubation, difficulty with mask ventilation, failed or problematic extubation) • Atopy, allergy (increased airway reactivity) • History of smoking by primary caregivers (increased airway resistance)[93] • History of a congenital syndrome (many are associated with difficult airway management) The physical examination should include the following observations: • Facial expression • Presence or absence of nasal flaring • Presence or absence of mouth breathing • Color of mucous membranes • Presence or absence of retractions (suprasternal, intercostal, subcostal [see Video Clip 12-1, Coming Soon]) • Respiratory rate • Presence or absence of voice change • Mouth opening (Fig. 12-12A) • Size of mouth • Size of tongue and its relationship to other pharyngeal structures (Mallampati)[84] • Loose or missing teeth (Fig. 12-12B) • Size and configuration of palate • Size and configuration of mandible • Location of larynx in relation to the mandible (Fig. 12-12C) • Presence of stridor and if present: • Is stridor predominantly inspiratory, suggesting an upper airway (extrathoracic) lesion (epiglottitis, croup, extrathoracic foreign body)? • Is stridor both inspiratory and expiratory, suggesting an intrathoracic lesion (aspirated foreign body, vascular ring, or large esophageal foreign body)? (see Video Clip 12-1, Coming Soon) • Is the expiratory phase prolonged or stridor predominantly expiratory, suggesting lower airway disease? • Baseline oxygen saturation in room air • Microtia: • Bilateral but not unilateral microtia is associated with difficulty in visualizing the laryngeal inlet (Grade 3 or 4 Cormack and Lehane, see later).[80] Of those with bilateral microtia, 5 of 12 children (42%) had a difficult laryngeal view. However, even in the group with unilateral microtia, 2 of 81 children (2.5%) had a difficult laryngeal view compared with 0 of 93 children without microtia. Microtia may represent a mild form of hemifacial microsomia and its associated mandibular hypoplasia. The advantage of understanding this association is that ear deformity is often a more easily recognized clinical finding than mandibular hypoplasia. • Global appearance: • Are there congenital anomalies that may fit a recognizable syndrome? The finding of one anomaly mandates a search for others. If a congenital syndrome is diagnosed, specific anesthetic implications must be considered (see Appendix 12-1). 1 of 5 29/08/10 12:17 PM //Evaluation of the Airway http://www.expertconsultbook.com/expertconsult/b/book.do?m... Figure 12-12 A, How far can a child open his or her mouth? Are there any abnormalities of the mouth, tongue, palate, mandible? B, Are any teeth loose or missing? C, Is the mandible of normal configuration? How much space is there between the genu of the mandible and the thyroid cartilage? This space is an indication of the extent of the superior and posterior displacement of the larynx; there should normally be at least one finger's breadth in a newborn and three finger's breadths in an adolescent. Appendix 12-1 -- Syndromes and Disease Processes with Associated Airway Difficulties Endocrine Anesthetic Syndrome Airway Cerebral Cardiac Renal Gastrointestinal Metabolic Musculoskeletal Considerations Achondroplasia[490]* Midfacial Megacephaly ? Dwarfism, Difficult intubation [585–590] hypoplasia, hydrocephalus odontoid Difficult mask airway small nasal due to narrow hypoplasia with ? hydrocephalus passages and foramen magnum atlantoaxial mouth instability Apert syndrome[499] Maxillary Craniosynostosis, ?CHD ? Hydro- ? Esophageal Syndactyly Possible difficult hypoplasia, flat facies, nephrosis, ? atresia intubation narrow palate ? hypertelorism polycystic Associated cardiac cleft palate kidney and renal problems Arthrogryposis multiplex Associated ?VSD Thoracolumbar Difficult congenita (multiple hypoplastic scoliosis intubation congenital mandible, cleft Associated contractures)[591] palate, cardiac disease Klippel-Feil Minimal muscle syndrome, relaxant required torticollis ? Malignant hyperthermia Beckwith-Wiedemann Macroglossia: ? Mental Large heart Enlarged Omphalocele, Hypoglycemia Eventration of Difficult syndrome regresses with handicap due to kidneys hepato- up to age 4 diaphragm intubation (visceromegaly)[449–453] age; may hypoglycemia splenomegaly months Asymptomatic require partial polycythemia hypoglycemia glossectomy Omphalocele Neonatal polycythemia Cherubism (fibrous Bilateral Difficult intubation dysplasia of jaw)[506] painless due to intraoral mandibular and masses maxillary swelling may progress to airway obstruction Cornelia de Lange High arch Mental handicap ?CHD Difficult intubation syndrome[493],[494] palate, Associated cardiac micrognathia, disease spurs at anterior angle of mandible, large tongue, ? cleft 2 of 5 29/08/10 12:17 PM //Evaluation of the Airway http://www.expertconsultbook.com/expertconsult/b/book.do?m... Endocrine Anesthetic Syndrome Airway Cerebral Cardiac Renal Gastrointestinal Metabolic Musculoskeletal Considerations palate, short neck Craniofacial dysostosis of Maxillary Ocular proptosis Possible difficult Crouzon[499] hypoplasia with due to shallow intubation Eye injury inverted orbits, V-shaped craniosynostosis palate, ? large tongue Congenital Large tongue May be mentally Hypothermia, Umbilical hernia Difficult hypothyroidism handicapped hypometabolic intubation Hypothermia Decreased drug metabolism Epidermolysis bullosa[541] Pressure Need gentle lesions to mouth intubation with small and airway tube. Postoperative Possible laryngeal microstomia obstruction due to bulla formation Freeman-Sheldon Small mouth, Hypertelorism, ? Craniocarpotarsal Difficult intubation ? syndrome (whistling high palate increased dysplasia, Malignant face)[508–512] intracranial Strabismus, hyperthermia[511–512] pressure, ? kyphoscoliosis, mental hip/knee deficiency, ? contractures microcephaly Goldenhar syndrome Hypoplastic Hydrocephalus Occipitalization of Difficult intubation (oculoauriculo-vertebral zygomatic arch, atlas, cervical Cervical spine syndrome)[487],[488] mandibular vertebral defects defects hypoplasia, macrostomia, ? cleft tongue, palate, tracheo- esophageal fistula Hallermann-Streiff Malar Difficult intubation syndrome (oculo- hypoplasia, mandibulo- micrognathia, dyscephaly)[498] hypoplasia of rami and anterior displacement of tempo romandibular joint, narrow high arch