Covid explained: A Covid-19 patient needs oxygen support when shortness of breath progresses to a more acute condition.
The ongoing second surge in Covid-19 cases has seen a huge rise in the demand for supplemental oxygen. According to the data with the National Clinical Registry, a new emerging trend during the second wave has been witnessed – Shortness of breath is the most common clinical feature among symptomatic hospitalised patients at 47.5 per cent, compared to 41.7 per cent during the first wave.
When does a Covid-19 patient need oxygen support?
A Covid-19 patient needs oxygen support when shortness of breath progresses to a more acute condition. Usually, patients with coronavirus have a respiratory tract infection, and in the most critical cases, their symptoms can include shortness of breath.
In a small proportion of such cases, this can progress to a more severe and systemic disease characterised by Acute Respiratory Distress Syndrome (ARDS).
Does a patient always show Covid symptoms when their oxygen levels drop?
No. According to the FAQs on Covid-19 from AIIMS e-ICUS, sudden deaths have been reported at presentation to the emergency department, as well as in the hospital. AIIMS has said that the reasons that have been proposed include a sudden cardiac event, preceding “silent hypoxia” that went unnoticed, or due to a thrombotic complication such as pulmonary thromboembolism.
In silent hypoxia, patients have extremely low blood oxygen levels, yet do not show signs of breathlessness. “In patients with silent hypoxia, the amount of oxygen carried in our blood, otherwise known as blood oxygen level, is lower than expected compared to the other vital signs. Silent hypoxia is not usually an early symptom to occur in Covid-19 patients. They frequently arrive at the emergency room for other reasons, such as muscle aches, fatigue, fever, and cough. Typically, when a patient begins to demonstrate silent hypoxia, they already have other Covid-19 symptoms and may be in critical condition,” the American Lung Association says.
How does coronavirus lead to shortness of breath?
Covid-19 affects the patient’s respiratory system and it leads to shortness of breath. The lungs enable the body to absorb oxygen from the air and expel carbon dioxide. When a person inhales, the tiny air sacs in the lungs — alveoli — expand to capture this oxygen, which is then transferred to blood vessels and transported through the rest of the body.
In order to fight infections, the body’s immune system releases cells that trigger inflammation that leads to the regular transfer of oxygen in the lungs. Simultaneously, fluids build up. Both these factors combined make it difficult to breathe.
How many symptomatic people now require oxygen?
Dr Balram Bhargava, DG, Indian Council of Medical Research (ICMR), said there is limited data on why more patients are requiring oxygen, and this needs to be further studied. “This (more patients requiring oxygen) could be explained by the fact that due to the sudden surge of cases there is a panic, people wanted to get admitted to hospitals, therefore oxygen requirement suddenly shot up. But there is limited data from hospital settings and more will have to be looked at. However, oxygen [remains] an important tool in the management of Covid-19 disease, particularly when oxygen saturation has fallen,” Bhargava said.
In what conditions is oxygen used in Covid-19 clinical management?
According to the clinical management protocol, a person is suffering from a moderate disease when he or she is diagnosed with pneumonia with no signs of severe disease; with the presence of clinical features of dyspnea (shortness of breath) and/or hypoxia (when the body is deprived of adequate oxygen supply at the tissue level); fever, cough, including SpO2 (oxygen saturation level) less than 94 per cent (range 90-94 per cent) in room air.
In moderate cases, oxygen therapy is the primary form of treatment: the target is to achieve 92-96% SpO2, or 88-92% in patients with chronic obstructive pulmonary disease. The devices for administering oxygen in moderate disease are nasal prongs, masks, or masks with breathing/non-rebreathing reservoir bags, depending on the requirement. The protocol also recommends awake proning (having patients lie on their stomachs) as a rescue therapy to increase oxygenation.
Severe cases are defined in three categories: severe pneumonia, acute respiratory distress syndrome, and sepsis. The clinical management protocol recommends oxygen therapy at 5 litres/min. When respiratory distress and/or hypoxemia of the patient cannot be alleviated after receiving standard oxygen therapy, the protocol recommends that high-flow nasal cannula oxygen therapy or non-invasive ventilation can be considered. “Compared to standard oxygen therapy, High Flow Nasal Cannula Oxygenation (HFNO) reduces the need for intubation. Patients with hypercapnia (exacerbation of obstructive lung disease), hemodynamic instability, multi-organ failure, or abnormal mental status should generally not receive HFNO,” the protocol says.