Final answer:
The priority assessment finding for a client one hour post-op following a thoracentesis is respiratory distress.
Step-by-step explanation:
The priority assessment finding for a client who is one hour post-op following a thoracentesis would be respiratory distress. This is because thoracentesis involves removing fluid or air from the chest cavity, and respiratory distress could indicate complications related to the procedure, such as pneumothorax or hemothorax.
Severe pain at the insertion site, a small amount of blood-tinged drainage at the insertion site, and a slightly elevated temperature are important assessments, but they are not as immediately concerning as respiratory distress.