October 14, 2020 1:08:02 pm
Dr Amit Mandal, a critical care specialist, in conversation with Parul, answered some common and vital questions about oxygen levels in Covid-19, the need to monitor oxygen saturation levels, silent depletion of levels of oxygen, its symptoms, and how masking, maintaining social distance and hand hygiene are the best ways to prevent the infection
What is Covid-19 pneumonia?
Pneumonia is an infection of the lung and can be caused by many organisms – bacteria, fungus and virus. Pneumonia caused by SARS-CoV-2 virus infection is called Covid pneumonia. What is the normal blood-oxygen level in our body?
Normal blood-oxygen level is about 75 to 100 mm Hg. This can be found from a blood test called Arterial Blood Gas test (invasive test from an arterial blood sample). Saturation of more than 95 per cent is considered normal, any saturation below this is considered abnormal. This can be observed with the help of a pulse oximeter, with the help of a finger probe.
Why do many Covid-19 patients have alarmingly low oxygen levels?
All patients do not have low oxygen levels. Only patients with significant lung involvement along with other abnormal blood parameters—seriously ill or critically ill patients may have alarmingly low oxygen levels.
How essential is it to closely monitor oxygen saturation in the early stages of Covid?
All patients with Covid-19 infection do not require hospitalisation, only individuals who start developing low oxygen saturations are the ones who require hospitalisation. Hence, the individuals with high risk factors, age above 65, men, those with diabetes, hypertension, cardiac diseases, smokers, those who have had organ transplant, should be monitored with pulse oximeters at home to avoid any delay in seeking admission.
Can silent depletion of oxygen levels in asymptomatic patients cause serious medical issues?
This infection is known to cause low oxygen levels but without any development of symptoms. This can be dangerous as crucial time can be lost before admission. Delayed admission has been one of the causes of poor outcomes.
Many asymptomatic patients don’t complain of any shortness of breath or difficulty in breathing. Is this what the term happy hypoxia imply?
Yes. In any other disease, a patient would develop symptoms as soon as the oxygen levels go below the normal levels. The coronavirus infection can cause patients to be hypoxic (low level of oxygen) yet not develop symptoms – this is called Happy Hypoxia. Symptoms are like alarm levels in the body to enable individuals to seek medical attention.
Do low oxygen levels necessarily mean a person has Covid-19?
No. There are numerous medical conditions which can cause low oxygen levels and Covid is just one of them.
What symptoms does one needs to look out for in case of depleting oxygen levels?
Covid-19 may cause hypoxia without the patient having any symptoms. Hence, if we wait for symptoms to develop, we may be late in offering medical care to the patient. One can only monitor such patients at high risk and identify the patients developing low oxygen with the help of a pulse oximeter. We advise our patients to keep note of their pulse oximeter 2-3 times daily with a 6 minute walk test (6 MWT). If the saturation is < 94 per cent or there is a significant (> 4 per cent) drop in saturation before and after walking– then they are supposed to seek admission at the closest facility.
There are reports of shortage of oxygen and also how people book cylinders to use at home in case a patient develops respiratory problems. Doctors advise against administering oxygen at home, as they say they need to assess if they need support through a cylinder or ventilator.
One of the reasons being debated is the presentation of some of our patients late for medical therapy. When a patient develops hypoxia, there are other organ dysfunctions also which need to be monitored and cared for along with supplemental oxygen support. Hence, by offering only supplemental oxygen support – we may not be treating the patient appropriately. Such individuals need to be admitted for observation, monitoring and started on appropriate medications too. It is thus not advisable to administer oxygen at home, devoid of any other treatment. We advise supplemental oxygen only after patient have received treatment at a hospital and are recovering from the illness.
What is the importance of a pulse oximeter? Would you advise patients to keep one at home? What are your suggestions as a doctor for the use of this device?
A pulse oximeter helps to identify the patients at risk in home isolation for an early admission and appropriate therapy. Yes it is advisable to have one at home and monitor the saturation (SpO2) two-three times daily with a 6 MWT.
Does it help in to seek medical attention if patients monitor their oxygen levels with an oximeter?
Yes – only when the readings are correctly observed and followed and they suggest hypoxia.
Also, is an oximeter vital for home quarantine patients? How accurate are the readings?
Yes, in patients with high risk factors. Young individuals with mild disease need not be monitored with a pulse oximeter. Finger probe pulse oximeters available for home use are not very accurate but serve their purpose as an indicator for seeking urgent medical attention and possible hospitalisation.
Do you have any other suggestions as a doctor?
Covid-19 has taught us that there is nothing perfect in this world in spite of the advancements humankind has made. We are still waiting for more evidence on what is the best prophylaxis to prevent this infection, the best modality of treating it, the best way to monitor these patients, etc. We can only try and do our best with the existing knowledge from the experience that we have got from across the globe and put it into practice in an ethical and scientifically balanced manner. Masking, maintaining social distance and hand hygiene are the best ways to prevent the infection.
We should avoid shunning or shaming individuals or families who have got infected – rather we should reach out to them (in a safe manner) and help them stay safe and cared for. As a significant number of them would be isolated and cannot go out for the daily essential items. We should try and do our best to keep the elders and seniors with comorbidities, diabetes, hypertension, cardiac disease, etc safe and protected.
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