Final answer:
Paradoxical chest movement is a symptom of a spontaneous pneumothorax, also known as a collapsed lung, which can be accompanied by hypoxemia and detected via stethoscope and chest radiographs.
Step-by-step explanation:
The respiratory condition that includes paradoxical chest movement as a sign is known as a spontaneous pneumothorax, commonly referred to as a collapsed lung. This condition can occur due to subtle abnormalities in connective tissue, among other causes. A collapsed lung leads to the affected area of the chest to move inwards during inhalation, rather than outwards, which is contrary to the normal chest movement during breathing. This paradoxical movement can further lead to hypoxemia, which as in the case of Barbara mentioned, is a condition characterized by lower-than-normal levels of oxygen in the blood. Abnormal sounds such as crackling may be heard over the chest upon auscultation with a stethoscope, and chest radiographs can reveal shadows due to air where lung tissue should be.