下列何者為缺氧（Hypoxia）的早期徵兆？

大腦對缺氧極為敏感。早期缺氧徵兆包括：躁動不安（Restlessness）、意識改變或定向力混亂（Confusion）。發紺（Cyanosis）通常是極為晚期的表現；心跳過慢（Bradycardia）與低血壓通常在缺氧代償失敗後才會出現，屬於後期徵象。

Restlessness or confusion is an early sign of hypoxia because the brain is highly sensitive to decreased oxygen levels, leading to immediate behavioral and cognitive changes. Late signs such as cyanosis, bradycardia, and hypotension typically occur only after compensatory mechanisms have failed.

美台對生命徵象監測的解讀邏輯一致，皆強調對「早期行為改變」的敏感度。