Evaluation of bronchiolitis begins with a history and physical examination.

Physical findings in children with bronchiolitis may include:

• Low blood oxygen levels
• Rapid respiratory rate
• Wheezing
• Signs of severe difficulty breathing
• Rib retractions
• Nasal flaring
• Use of accessory muscles

Usually, tests are not required to make the diagnosis of bronchiolitis. Tests may be used to exclude other illnesses.

Tests that may be used to evaluate bronchiolitis include:

• Pulse oximetry
• Chest x-ray
• Arterial blood gas
• Nasal swab culture:
• This test can be used to directly identify the respiratory syncytial virus (RSV).
• Pulmonary function tests:
• Persistent symptoms may be evaluated using pulmonary function tests to evaluate the response to bronchodilator medications