Which of the following symptoms is NOT associated with pneumothorax?

The correct answer highlights that delayed onset of symptoms is not typically associated with pneumothorax. In most cases, a pneumothorax results in rapid onset of symptoms, which can include acute respiratory distress, sudden chest pain, and potentially rapid heart rate or bradycardia depending on the severity and the patient's response.

The other options indicate symptoms that are more commonly observed in individuals experiencing a pneumothorax. Increased respiratory distress is often one of the first symptoms reported, as the presence of air in the pleural cavity can impede lung expansion. Severe cyanosis may occur if the pneumothorax is significant enough to impede oxygenation, leading to low blood oxygen levels. Bradycardia or tachycardia can occur as the body reacts to decreased oxygenation and the stress of the condition.

Thus, while symptoms may vary based on the individual and the extent of the pneumothorax, the delayed onset is generally not characteristic of this condition, making it the outlier in the list.