Yes. A common physical exam is often used whereby the patient holds one nostril closed while trying to breathe through the other and the clinician can assess nasal breathing restriction. However, as previously mentioned congestion may be intermittent depending on allergies, environment or weather related factors.
Another tool that is easily performed and complements the physical examination is the use of a validated questionnaire called the NOSE questionnaire. Consisting of five questions that the patient will answer based on their level of nasal congestion, the questionnaire also includes a scoring severity scale. Using this questionnaire can assist in properly diagnosing nasal congestion which is critical for oral appliance compliance.
A copy of the NOSE Questionnaire (PDF) can be found in Healthcare Professionals Resources page of O2Vent.com.