A nurse is caring for a 3-year-old client who has persistent otitis media. To help identify contributing factors, the nurse should ask the parents which of the following questions?

A. The sweat chloride test is considered the most definitive diagnostic test for cystic fibrosis. In this test, sweat is collected from the skin and analyzed for chloride content. Elevated levels of chloride in the sweat are indicative of cystic fibrosis. This test is highly sensitive and specific for diagnosing the condition.

B. Stool fat content analysis can help assess pancreatic function and malabsorption, which are common manifestations of cystic fibrosis. However, it is not considered the most definitive test for diagnosing cystic fibrosis. Elevated stool fat content can be suggestive of cystic fibrosis but is not specific to the condition.

C. Sputum culture may be performed to identify respiratory pathogens and guide antibiotic therapy in individuals with cystic fibrosis, but it is not the most definitive test for diagnosing the condition. It helps identify infections and monitor lung health but does not confirm the diagnosis of cystic fibrosis.

D. Pulmonary function tests are used to assess lung function and airflow, which can be affected in individuals with cystic fibrosis. While these tests provide valuable information about lung health, they are not the most definitive test for diagnosing cystic fibrosis. They are used for monitoring disease progression and response to treatment rather than confirming the diagnosis.

C. Clubbing, characterized by bulbous enlargement of the fingertips and nail bed, is a result of chronic hypoxia in tetralogy of Fallot. In tetralogy of Fallot, there is a right-to-left shunting of blood due to the presence of a ventricular septal defect, overriding aorta, pulmonary stenosis, and right ventricular hypertrophy. This leads to reduced oxygenation of blood and chronic hypoxia, which can result in clubbing of the fingertips over time.

A This option is not the primary explanation for clubbing in tetralogy of Fallot. While decreased cardiac output may contribute to some manifestations of the condition, clubbing specifically results from chronic hypoxia rather than decreased cardiac output alone.

B Clubbing is not directly caused by a left-to-right shunting of blood. Instead, it is associated with chronic hypoxia, which can occur due to right-to-left shunting of blood in tetralogy of Fallot.

D Congestive heart failure may occur in individuals with tetralogy of Fallot but it is not the primary cause of clubbing. Clubbing in tetralogy of Fallot is primarily attributed to chronic hypoxia rather than heart failure alone.