What is a key consequence of respiratory failure?

Cyanosis is a key consequence of respiratory failure because it indicates a deficiency in the oxygenation of blood. When the lungs are unable to effectively exchange gases, namely oxygen and carbon dioxide, the body may not receive enough oxygen, leading to a decrease in oxygen saturation levels in the blood. As a result, tissues may not receive adequate oxygen, causing a bluish discoloration of the skin and mucous membranes, particularly noticeable in areas with thin skin, such as the lips and fingertips. This clinical manifestation serves as a critical warning sign of respiratory distress and hypoxemia (low blood oxygen levels), necessitating immediate medical attention.

The other choices do not accurately represent the direct consequences of respiratory failure. Increased lung elasticity is not a typical response in respiratory failure; rather, lung compliance may decrease. Reactive airway disease involves airway hyperreactivity and inflammation, which are not direct results of respiratory failure. Enhanced gas exchange would imply improved function of the lungs, which contradicts the state of respiratory failure where gas exchange is impaired.