Cough Reflex Test (CRT) Practice Exam 2025 - Free CRT Practice Questions and Study Guide

An abnormal elevation of the left hemidiaphragm is typically associated with left lower lobe atelectasis because when a lung segment collapses, it can cause the diaphragm on that side to move upward. This occurs due to the loss of volume and pressure in the left lower lobe that result from the atelectasis. As the affected lung lobe decreases in size, the diaphragm is not pulled down as it normally would be, leading to an observable elevation.

In contrast, other conditions such as pneumothorax or right lower lobe pneumonia generally do not result in a specific elevation of the left hemidiaphragm. A pneumothorax could cause a raised hemidiaphragm on the affected side, but it usually presents with other symptoms like sudden chest pain and difficulty breathing. Likewise, right lower lobe pneumonia would primarily affect the right side and might lead to changes in the right hemidiaphragm. Asthma exacerbations can lead to overall respiratory distress but typically do not manifest as a localized elevation of a hemidiaphragm. Thus, the direct association of left lower lobe atelectasis with left hemidiaphragm elevation makes this the correct choice.