Why many Covid patients need pulse oximeter?

Because it is cheap and helps prevent disastrous complications. Covid is an insidious disease. Many patients with catastrophically low oxygen levels in the blood, participate in conversations, use the phone, even smile. They definitely need a device to show in timely fashion that the situation is very dangerous.

"There is some heartening evidence — admittedly inconclusive — that earlier treatment makes a difference. In a small pilot study of 250 Covid-19 cases conducted by Dr. Cosentini in Italy, half were found to have mild pneumonia — but their oxygen saturation was not yet compromised. All of these patients were able to be discharged from the E.R., and they were sent home with pulse oximeters. Only 5 percent returned and were hospitalized when their oxygen saturation levels declined slightly. None of these patients required a ventilator. And none of these 250 patients died.

While there is no specific cure forCovid-19 and we have nothing that directly kills the virus, we do have treatments that help patients and prevent the need for a ventilator. These include various noninvasive methods of delivering oxygen, patient positioning maneuvers that open up parts of the lungs, and close monitoring and treatment of inflammation. There is no panacea; some patients will still have the disease worsen, and there are some patients who will still have serious injury from Covid-19 unrelated to the lungs."