1. A patient with chronic obstructive pulmonary disease (COPD) presents

with dyspnea, wheezes, and productive cough. The nurse suspects that

the patient has developed a respiratory infection. Which of the

following laboratory tests would be most useful to confirm this

diagnosis?

A) Arterial blood gas (ABG) analysis

B) Chest x-ray

C) Sputum culture*

D) Pulmonary function test

Rationale: A sputum culture can identify the causative organism of a

respiratory infection and guide the appropriate antibiotic therapy. ABG

2

analysis can assess the gas exchange and acid-base balance of the

patient, but it cannot diagnose an infection. Chest x-ray can show the

presence of consolidation, atelectasis, or pleural effusion, but it cannot

differentiate between bacterial, viral, or fungal infections. Pulmonary

function test can measure the lung volumes and capacities, but it

cannot detect an infection.