Which finding indicates the effectiveness of digoxin administration in a client with heart failure?

The effectiveness of digoxin administration in a client with heart failure is indicated by a decrease in cardiac workload. Digoxin works by enhancing the force of heart contractions, thereby improving cardiac output. When the heart is able to pump more effectively, it reduces the energy needed to maintain circulation, subsequently decreasing the overall workload. This is particularly important in heart failure, where the heart is compromised and struggles to maintain adequate blood flow.

Improving the heart's efficiency means less strain on the heart, which is a key goal in managing heart failure. The other options, while they might be clinically relevant, do not directly reflect the primary measures of effectiveness regarding digoxin's action on the heart's performance in heart failure management. For example, an increased heart rate could indicate worsening heart function or a side effect of digoxin toxicity. Similarly, decreased blood pressure could suggest poor perfusion or inadequate cardiac output. Improved respiratory rate may indicate better oxygenation, but it does not specifically assess the effectiveness of digoxin in modifying the heart's workload. Thus, decreased cardiac workload truly encapsulates the therapeutic aim when administering digoxin in this context.