Final answer:
When aspirating fluid, it is important to measure its volume and pH and flush the tube with water.
Step-by-step explanation:
When aspirating fluid, it is important to measure its volume and pH. Measuring the volume will give you an idea of how much fluid was obtained, while measuring the pH will provide information about the acidity or alkalinity of the fluid. After measuring the fluid, it is necessary to flush the tube with water to ensure that no residue remains. This prevents contamination and ensures accurate measurements in future aspirations.