病人接受靜脈注射萬古黴素（vancomycin）時，臉部、頸部及上胸部出現潮紅，且伴隨低血壓。護理師最優先應採取哪項措施？

核心概念：萬古黴素（Vancomycin）輸注相關的紅人症候群（Red Man Syndrome, RMS）的處理。 為何正確答案對： B. 病人出現臉部、頸部、上胸部潮紅，並伴隨低血壓，這是典型的紅人症候群表現。此反應是由於萬古黴素輸注速度過快，引起組織胺（Histamine）釋放。處理原則是立即減緩輸注速度（Slow the rate of the vancomycin infusion），以減少組織胺的釋放。若症狀輕微，減速後通常可繼續輸注。若症狀嚴重或伴隨其他過敏徵象，則需考慮停止。 為何其他選項錯： D. 給予抗組織胺（Administer an antihistamine immediately）是 RMS 的輔助處理，但首要步驟是減緩或暫停輸注，以阻止組織胺釋放。 C. 停止輸注（Stop the infusion）雖然是處理嚴重 RMS 的選項，但對於初期症狀，減緩輸注速度是更為恰當的第一步，不一定需要立即完全停止。 A. 加速 IV 流速（Increase the IV fluid rate）會加劇組織胺釋放，使症狀惡化，是錯誤的。

Core concept: management of vancomycin infusion–related Red Man Syndrome (RMS). Why the correct answer is right: B. The client exhibits flushing of the face, neck, and upper chest accompanied by hypotension—classic findings of Red Man Syndrome. This reaction is caused by histamine release due to rapid vancomycin infusion. The principle of management is to slow the rate of the vancomycin infusion immediately to reduce histamine release. If symptoms are mild, the infusion may often be continued at a slower rate; if symptoms are severe or accompanied by other allergic signs, stopping the infusion should be considered. Why the other options are wrong: A. Administering an antihistamine immediately is an adjunctive treatment for RMS, but the first step is to slow or pause the infusion to halt histamine release. C. Stopping the infusion is an option for severe RMS, but for early symptoms, slowing the infusion rate is a more appropriate first step and does not necessarily require complete cessation. D. Increasing the IV flow rate would worsen histamine release and exacerbate symptoms, and is therefore incorrect.