Any patient using this degree of effort to breathe may collapse at any time and must be considered for respiratory support. Certain features in the patient history can be very useful in the differential diagnosis. A history of heavy alcohol or tobacco consumption is suspicious for squamous cell carcinoma. Use of ACE inhibitors or a family history of airway problems suggest angioedema. In these cases, the patient should be asked if any minor episodes of swelling preceded the presenting complaint.
Infectious etiology is suggested by a history of throat pain or fever.
Previous dental pain or poor dentition are typically seen in those with Ludwig's angina. Previous surgery or tracheotomy are clues to possible subglottic stenosis. These symptoms can develop slowly over many years. Questions should also be asked about any previous history of laryngeal trauma. If the voice has changed, the time course of the change should be noted.