How Tamil Nadu’s ICU Doctors Are Diagnosing COVID-19 Using Pulse Rate & Saturation
Deaths are seen mainly in severe cases of COVID-19 which require admission into Intensive Care Units (ICU). And while tests by RT-PCR kits can provide results in six hours, it often takes between 24 to 48 hours for the patient to access results due to processes when done in government hospitals. Doctors in Tamil Nadu are therefore trying to cut short the time taken for treatment to begin.
And to this end, they have found recurring patterns in the symptoms of patients with severe infection, which allows them to begin treatment as soon as the patient enters the ICU.
“Many people are coming late, they are delaying coming to hospital,” Dr P Paranthaman, Head of Medicine, Kilpauk Medical College and Hospital told The Lede. He is also in an advisory capacity with the state government’s COVID-19 expert panel.
“When they have fever, they take some medicines and they think they are better. But then breathlessness sets in and they finally come to the hospital. Their oxygen saturation is at 40% many times. This is too low and can cause death,” he said.
Normally, such low saturation of oxygen in blood would render patients unconscious. “But in COVID, despite low saturation, patients are still conscious. So they are not aware what a serious condition they are in,” explained Dr Paranthaman.
Low saturation means that cells in the body are starved of oxygen and death is often swift.
Doctors, led by Paranthaman, have identified three crucial yet simple tests for identifying severe COVID patients and treating them even before the results of the RT-PCR test for COVID comes in.
The three tests are: oxygen saturation, pulse rate and a chest X-ray or CT scan.
“In mild cases of COVID, the patient’s pulse rate is high due to anxiety. This is the normal response. Normally, if oxygen saturation is low, the compensation mechanism kicks in and the pulse rate is elevated. But in COVID this is reversed. Those who come to ICU with low saturation and breathlessness have low to normal pulse rate,” said Dr Paranthaman.
This, he says, is because the COVID virus compromises the oxygen sensing system in the body in severely affected patients.
“The oxygen sensing system in our body can identify low saturation and immediately it will increase a hormone to raise the heart rate to compensate the lack of oxygen. But there is a loss of oxygen sensing system in COVID. It is unusual. This is also what causes death. This is peculiar to severe cases. So we have found that low pulse rate is a sign of severe disease – we begin appropriate treatment immediately,” he added.
Body posture and oxygen saturation is also used to identify severe cases of COVID.
“Normally in patients with, say asthma for instance - their saturation improves when they sit up and reduces when they lie down. But in severe COVID cases, saturation improves when they lie down and reduces when they sit up. This is called Platypnea orthodeoxia and it is a characteristic of severe COVID,” he said.
So doctors check oxygen saturation levels when the patient is sitting up and also when lying down. If saturation levels vary – for instance if 90% while lying down and 80% while sitting up – it is a strong suggestion that the patient has a severe infection.
ICU doctors have also categorised treatment for patients based on their oxygen saturation levels.
“If saturation is less than 90% we use a non re-breather mask,” said Dr Paranthaman. “If it is less than 80%, we give oxygen via high flow nasal cannula. When oxygen saturation is less than 70%, we provide CPAP (Continuous Positive Airway Pressure) ventilator support,” he said.
“So with the use of pulse rate, oxygen saturation levels and a simple chest X-ray or CT, we are able to figure out which of the patients are suffering from severe COVID and we are able to decide and begin treatment immediately, without awaiting the RT-PCR test results,” said Dr Paranthaman.
The doctors said that their observations coincide with independent studies conducted in Singapore and in Italy.