A pulse oximeter provides a quick read on the saturation of oxygen in your blood. Some doctors believe it is a helpful device to have at home during the coronavirus pandemic. Others aren't so sure. Each week we answer some of your pressing questions about the coronavirus and how to stay safe. Email us your questions at goatsandsoda@npr.org with the subject line: "Weekly Coronavirus Questions." This week, we're considering questions about pulse oximeters.   As the coronavirus continues to spread, a small medical device called a pulse oximeter has started to fly off the shelves. In fact, demand has spiked to such...