一位病患被診斷為低血鉀，護理師應優先評估下列何項發現？
A client is diagnosed with hypokalemia. Which assessment finding should the nurse prioritize?
- AIrregular heart rhythm✓ 正解心律不整
- BBilateral muscle weakness雙側肌肉無力
- CDecreased bowel sounds腸蠕動音減低
- DPresence of U waves on ECG心電圖出現 U 波
低血鉀（hypokalemia）會影響心肌細胞的靜止膜電位，導致心臟傳導異常及心肌興奮性改變。根據 NCLEX 的安全優先原則（Safety and Priority），心血管系統的穩定性直接關係到病人的生命存活，心律不整（arrhythmia）是低血鉀最致命的併發症，因此應優先評估心律。其他選項如肌力減弱、腸蠕動減慢或 ECG 上的 U 波變化雖然也是低血鉀的典型表現，但心律不整代表心臟電氣活動已出現不穩定，可能迅速惡化為致命性心律不整（如室性心搏過速），故列為首要監測項目。
Hypokalemia affects the resting membrane potential of cardiac muscle cells, leading to abnormal cardiac conduction and altered myocardial excitability. According to the NCLEX safety and priority principles, the stability of the cardiovascular system is directly related to the client's survival. Cardiac arrhythmias are the most lethal complication of hypokalemia, so cardiac rhythm should be assessed first. Although the other options, such as muscle weakness, decreased bowel sounds, and U waves on the ECG, are also typical manifestations of hypokalemia, arrhythmias indicate that the cardiac electrical activity has become unstable and can rapidly progress to lethal dysrhythmias (such as ventricular tachycardia), making them the priority monitoring target.