Final answer:
Extreme fatigue in a 75-year-old client with congestive heart failure suggests that digitalis levels should be reviewed due to the potential of digitalis toxicity which can lead to cardiac arrhythmias and other symptoms.
Step-by-step explanation:
The question revolves around identifying a symptom that suggests a review of digitalis levels is necessary for a 75-year-old client with congestive heart failure. Digitalis is a medication used to treat conditions such as heart failure and atrial fibrillation. It is essential to monitor its levels as toxicity can occur, especially in the elderly due to renal clearance reduction, potential drug interactions, and sensitivity to the drug.
Extreme fatigue is a symptom that suggests digitalis levels should be reviewed. Digitalis toxicity can lead to an extensive range of symptoms including gastrointestinal disturbances, neurological symptoms, and cardiac arrhythmias. Extreme fatigue could indicate an underlying cardiac arrhythmia due to digitalis toxicity, especially when considered alongside the context of congestive heart failure, which could also lead to symptoms such as fluid volume overload and fatigue due to decreased erythropoietin synthesis.