[Verified Answer]: Before early 1950’s, there were reports…

Before early 1950’s, there were reports that patients under anesthesia died of hypoxia when technicians misconnected oxygen pipelines with lines from nitrous oxide tanks. When this happened, anesthesiologists turned on oxygen valve but delivered nitrous oxide gas to the patient, instead of intended oxygen gas. Which of the following interventions would you rank as the most effective to prevent patient harms from accidental misconnections?