Which of the following is a late sign of hypoxia?

• A. Anxiety
• B. Restlessness
• C. Tachycardia
• D. Cyanosis

Answer: (D)

Cyanosis appears late in hypoxia because visible blue coloring only shows up after there is substantial deoxygenated hemoglobin in the blood. Early signs, like anxiety or restlessness and a rapid heart rate, reflect the body's attempt to compensate as oxygen delivery falls. By the time cyanosis becomes evident—often around lips, mouth, or nail beds—the patient is in advanced hypoxemia and needs immediate airway support and supplemental oxygen. Remember, cyanosis can be unreliable in some patients (e.g., dark skin tones, cold conditions, or anemia), so always correlate with other signs and use pulse oximetry or other measures to assess oxygenation.