Which of the following actions is appropriate when measuring a patient's vital signs?

The action of documenting the readings immediately after taking them is crucial in the process of measuring a patient’s vital signs. This practice ensures that the data is recorded clearly and accurately while it is fresh in the technician's mind, reducing the chances of error that might occur if the readings are postponed or forgotten. Immediate documentation also contributes to maintaining accurate medical records, which are vital for ongoing patient care and treatment plans.

When considering the other options, asking the patient to sit up quickly after taking their blood pressure could lead to inaccuracies or discomfort for the patient, as rapid changes in position can affect blood pressure readings. Using an automated device without confirming its accuracy risks relying on potentially faulty equipment, which could lead to misinterpretations of the patient's health. Lastly, telling the patient they are normal regardless of the numbers undermines the role of the technician in providing truthful and comprehensive information; it is essential to communicate findings honestly so appropriate actions can be taken based on the patient’s actual condition.