Vital signs, at your fingertips

Until recently, most of us had never heard of a pulse oximeter. It is a simple device that can detect a drop in blood oxygen level well before a person starts getting out of breath. You clip the gadget on your finger (nail side up), press an “on” button and, within seconds, it lights up with numbers indicating your blood oxygen and your heart rate or pulse. If you are healthy, you should get a blood oxygen reading of 95 to 98. You should check with your doctor if it falls below 92.

The device, which looks like a mini stapler, surged in popularity as word spread that people with the coronavirus frequently arrive at hospitals with abnormally low oxygen levels.