## **Core Concept**
Propranolol is a non-selective beta-blocker that inhibits both β1 and β2 adrenergic receptors. In patients with Chronic Obstructive Pulmonary Disease (COPD), the use of propranolol can exacerbate respiratory symptoms due to its effect on airway smooth muscle. COPD patients often have compromised lung function, and β2 receptor blockade can lead to bronchoconstriction.

## **Why the Correct Answer is Right**
The correct answer, **bronchospasm**, is a direct consequence of β2 adrenergic receptor blockade by propranolol. In healthy individuals, β2 receptors in the lungs cause bronchodilation when stimulated. However, in COPD patients, who already have narrowed airways, blockade of these receptors by propranolol can induce significant bronchospasm, worsening respiratory symptoms and potentially leading to severe respiratory distress.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While propranolol can cause bradycardia due to its effect on β1 receptors in the heart, this is not the most predictive and dangerous side effect in the context of COPD.
- **Option B:** Propranolol can affect cardiac output, but the most concerning side effect in COPD patients is related to respiratory function rather than cardiac function.
- **Option C:** Masking symptoms of hypoglycemia is a concern with beta-blockers, but it is not directly related to the acute respiratory effects seen in COPD.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while beta-blockers are crucial in managing cardiovascular diseases, their use in COPD patients requires caution. **Selective β1 blockers** are preferred in patients with COPD or asthma when beta-blockade is necessary, as they are less likely to induce bronchospasm.

## **Correct Answer:** . bronchospasm