Physical Therapy Assistant Practice Exam

Which laboratory test is most appropriate to confirm suspected hypercapnia in a patient?

1. Pulmonary function tests

2. Arterial blood gas analysis

3. Chest X-ray

4. Sputum culture

The correct answer is: Arterial blood gas analysis

To confirm suspected hypercapnia, arterial blood gas analysis is the most appropriate laboratory test. Hypercapnia refers to an elevated level of carbon dioxide (CO2) in the blood, which can occur in various respiratory conditions. Arterial blood gas analysis provides precise measurements of oxygen (O2), carbon dioxide (CO2), pH, and bicarbonate levels, allowing healthcare providers to assess the respiratory function and metabolic status of the patient. By evaluating the levels of CO2 in the arterial blood, this test can effectively indicate whether a patient is experiencing hypercapnia and to what extent. Other tests, while useful in different contexts, do not directly measure CO2 levels. For example, pulmonary function tests assess lung capacity and airflow, but they do not provide information about blood gas levels. A chest X-ray can reveal structural issues in the lungs but cannot measure gas exchange or CO2 levels. Lastly, sputum culture is used to identify infections or pathogens in the respiratory tract and does not relate to the measurement of carbon dioxide in the blood. Thus, arterial blood gas analysis stands out as the definitive test for confirming hypercapnia in a clinical setting.