What vital sign should be measured before starting a blood transfusion?

Prior to initiating a blood transfusion, it is crucial to assess the patient's vital signs to establish a baseline and monitor any changes that may occur as a result of the transfusion. Vital signs typically include blood pressure, pulse rate, and respiratory rate. This comprehensive assessment helps identify any immediate adverse reactions to the transfusion.

Monitoring vital signs before, during, and after the transfusion is critical, not just to observe for potential transfusion reactions but also to ensure patient safety and effectiveness of the transfusion. By establishing a baseline, healthcare providers can compare these initial readings against any subsequent changes, indicating possible complications. Thus, the correct choice involves measuring a complete set of vital signs, ensuring thorough preparation for the procedure.