Since I'm just a student I think it's best if I defer to the textbook: "If your service has a pulse oximeter, you should have a protocol describing when to use

Since I'm just a student I think it's best if I defer to the textbook: "If your service has a pulse oximeter, you should have a protocol describing when to use it. Generally this will include all patients complaining of respiratory problems or otherwise at risk for hypoxia. When used properly, the device can help you to assess the effectiveness of artificial respirations, oxygen therapy, and bronchodilator (inhaler) therapy."