Which client should the nurse follow up with immediately?

The scenario most warranting immediate follow-up is a client with atrial fibrillation who is reporting black stools. This finding is significant because black stools, or melena, typically indicate the presence of digested blood in the gastrointestinal tract, which can be a sign of a serious underlying condition such as a gastrointestinal bleed. In a client with atrial fibrillation, there may be an increased risk of bleeding due to anticoagulation therapy, which is commonly used to prevent thromboembolic events associated with this arrhythmia. Therefore, the presence of black stools suggests a need for immediate evaluation and intervention to address what could be a life-threatening situation.

In contrast, while the other clients present concerning situations, they may not require the same level of urgency. The client with COPD and respiratory acidosis requires careful monitoring and management, but immediate intervention is usually directed toward maintaining respiratory function. The diabetic client refusing to eat after insulin does pose the risk of hypoglycemia; however, the immediate risk is typically manageable through timely glucose monitoring and administration of carbohydrates. The client with acute pancreatitis reporting epigastric pain also requires attention, but symptoms can vary and may not immediately signify a critical or life-threatening condition compared to a potential gastrointestinal bleed.