Here are the answers to your questions: 22. According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria, a patient with an FEV$_{1}$ of 40% predicted would be classified as having: The correct option is: Severe COPD (GOLD 3) Explanation: The GOLD criteria for classifying COPD severity based on post-bronchodilator FEV$_{1}$ are: GOLD 1 (Mild): FEV$_{1} \ge 80\%$ predicted GOLD 2 (Moderate): $50\% \le$ FEV$_{1} < 80\%$ predicted GOLD 3 (Severe): $30\% \le$ FEV$_{1} < 50\%$ predicted GOLD 4 (Very Severe): FEV$_{1} < 30\%$ predicted A patient with an FEV$_{1}$ of 40% predicted falls within the $30\% \le$ FEV$_{1} < 50\%$ range, classifying it as Severe COPD (GOLD 3). 23. What is the primary difference between a restrictive and obstructive lung disease as observed in spirometry? The correct option is: Obstructive lung disease reduces FEV$_{1}$/FVC ratio Explanation: Obstructive lung diseases (like COPD and asthma) are characterized by difficulty exhaling air due to airway obstruction. This leads to a disproportionate reduction in the forced expiratory volume in one second (FEV$_{1}$) compared to the forced vital capacity (FVC), resulting in a reduced FEV$_{1}$/FVC ratio (typically $< 0.70$). Restrictive lung diseases (like pulmonary fibrosis) are characterized by reduced lung volumes due to stiffness of the lungs or chest wall. Both FEV$_{1}$ and FVC are reduced, but the FEV$_{1}$/FVC ratio often remains normal or even increased. The other options are incorrect: restrictive lung disease decreases total lung capacity and residual volume, and obstructive lung disease does not necessarily lead to increased lung compliance in all cases (though it can in emphysema). 24. Which of the following is a key distinguishing factor between asthma and COPD in terms of pathophysiology? The options for this question are not visible in the image. Please provide the options for a complete answer. 3 done, 2 left today. You're making progress.