Airway problems in children--can the orthodontist help?

The adequacy of the nasopharyngeal airway has been found to be related to craniofacial development. Obstruction of the airway by adenoid tissue, nasal septal deviation or abnormal morphology of the area is associated with characteristic changes in craniofacial morphology such as long anterior face height, facial retrognathism, and a steep inclination of mandibular plane often with a high vaulted palate and crossbite. Some studies have shown the changes to be reversible after adenoidectomy which improves nasal airway patency and a control mechanism for facial growth has been proposed to account for the relationships between airway adequacy, craniofacial morphology and craniocervical postural relationships. It is therefore important to be able to measure nasal respiratory resistance so that the effect of operative procedures in the area such as rapid maxillary expansion (RME) can be determined. Nasal respiratory resistance (NRR) is a measure of airway adequacy. It can be recorded by rhinomanometry, a non-invasive technique which measures resistance to airflow by simultaneous recording of flow and pressure drop over the nose. Recent technical advances based on microcomputer technology have made recording easier, but most studies have used threshold values for pressure or flow to calculate nasal respiratory resistance. At the Rhinomanometric Meeting in Berlin in 1987 proposals were made concerning the accurate determination of the laminar and turbulent flow coefficients using a mathematical model known as the Rohrer equation. The equipment is now available to enable such recordings to be made and is providing valuable and accurate data which form the basis for the improved understanding of the effect of rapid maxillary expansion on nasal airway adequacy.