Passage
Obstructive respiratory illnesses are characterized by an increased difficulty exhaling much of the air in the lungs. Asthma and chronic obstructive pulmonary disease (COPD) are two of the most common obstructive respiratory illnesses. Asthma is due to allergen hypersensitivity and can be identified by temporary airway inflammation, which causes the bronchioles to narrow. The decreased airway diameter increases the resistance to airflow. Subsequently, air becomes "trapped" in the lungs, restricting the amount of air that can be moved in each breath.COPD refers to a spectrum of disorders and can be a result of emphysema, the irreversible destruction of pulmonary tissue. The breakdown of elastic proteins in the lungs results in a loss of pulmonary resiliency and chronic lung hyperinflation. Because the walls between individual alveoli are broken down, the alveolar sacs that remain are larger.Lung diseases can be diagnosed and monitored using spirometry. A spirometer measures the flow rate and volume of inhaled and exhaled air. In one pulmonary test, a patient is asked to exhale forcibly and completely into a spirometer after maximum inhalation. This test is done to measure the patient's forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) , the total amount of air exhaled in a single breath.
Figure 1 Forced expiratory spirogram of a healthy individual
Adapted from T. Barreiro, "An Approach to Interpreting Spirometry." American Family Physician. ©2004 AAFP.
-Which of the following FEV1 spirograms would be expected in a patient with asthma?

Question

Passage
Obstructive respiratory illnesses are characterized by an increased difficulty exhaling much of the air in the lungs. Asthma and chronic obstructive pulmonary disease (COPD) are two of the most common obstructive respiratory illnesses. Asthma is due to allergen hypersensitivity and can be identified by temporary airway inflammation, which causes the bronchioles to narrow. The decreased airway diameter increases the resistance to airflow. Subsequently, air becomes "trapped" in the lungs, restricting the amount of air that can be moved in each breath.COPD refers to a spectrum of disorders and can be a result of emphysema, the irreversible destruction of pulmonary tissue. The breakdown of elastic proteins in the lungs results in a loss of pulmonary resiliency and chronic lung hyperinflation. Because the walls between individual alveoli are broken down, the alveolar sacs that remain are larger.Lung diseases can be diagnosed and monitored using spirometry. A spirometer measures the flow rate and volume of inhaled and exhaled air. In one pulmonary test, a patient is asked to exhale forcibly and completely into a spirometer after maximum inhalation. This test is done to measure the patient's forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) , the total amount of air exhaled in a single breath.

Figure 1 Forced expiratory spirogram of a healthy individual
Adapted from T. Barreiro, "An Approach to Interpreting Spirometry." American Family Physician. ©2004 AAFP.
-Which of the following FEV1 spirograms would be expected in a patient with asthma?

Quizplus · Accepted Answer

11ecba2d_0f79_119f_a3bf_9b1de0d928db_MD0008_00 The spirogram of the healthy individual shown in Figure 1 provides the baseline values for FEV1 and FVC. According to the passage, the FEV1 measurement is the volume of air forcibly exhaled in the first second. Because asthma is characterized by a decreased airway diameter and an increased resistance to flow, the volumetric rate of forcibly exhaled air would decrease. Therefore, FEV1 would decrease, and the volume exhaled at 1 second on the patient's spirometry tracing should be lower (Choices C and D). Forced vital capacity (FVC) is defined in the passage as the total volume of air exhaled in a single breath. The passage states that less air can be exhaled in asthma due to air trapping in the lungs. Therefore, FVC would decrease, and the volume exhaled at the end of the patient's spirometry tracing should also be lower (Choice B). Educational objective: The narrowing of respiratory airways in asthma increases resistance to airflow, which would decrease the volumetric rate of forcibly exhaled air (FEV1 decreases). The narrow airways also trap air in the lungs, decreasing the total volume of air that can be exhaled (FVC decreases).

Passage Obstructive Respiratory Illnesses Are Characterized by an Increased Difficulty Exhaling