During the early days of the ongoing second wave of the covid-19 pandemic, a shortfall of ventilators for those who required high degrees of respiratory support in hospitals created major panic and distress not just among patients and their famlies but also the medical community. In such situations, can Non-Invasive Ventilation (NIV) therapy, used mainly in the monitoring and treatment of Chronic Obstructive Pulmonary Disease (COPD) and sleep apnea, be used to provide both oxygenation and ventilation support without intubating the patient? There are also claims that NIVs are a better option compared to High Flow Nasal Cannula (HFNC) as HFNCs consume more oxygen than NIVs.
In an interview with Mint, Dr. Sibasish Dey, head of medical affairs (Asia and Latin America) at ResMed, a global company dealing with connected sleep and respiratory care devices, talks about situations in which NIVs can be useful, and whether they can be used in a home-care scenario as well.
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Under ordinary circumstances, what is the use-case for NIV machines, and can they be mobilised to help a Covid-19 patient?
A Non-Invasive Ventilator (NIV) delivers oxygen (ventilation support) with the help of a tightly fitted face mask, eliminating the need to insert tubes or sedate the patient. The mask over the patient’s nose and mouth supports the patient’s breathing by providing a predetermined level of pressurised air to the lungs. NIVs work by creating positive airway pressure, causing air to be forced into the lungs (down the pressure gradient), lessening the respiratory effort by the body. Under ordinary circumstances, patients suffering from Chronic Obstructive Pulmonary Disease (COPD) with type II respiratory failure can use NIV therapy for varying duration in the day to help improve the symptoms. Patients with conditions that cause muscle weakness and motor neurone diseases may require constant NIV as per the stage of the disease. Some of the other conditions that NIVs can help with are Obesity Hypoventilation Syndrome, neuromuscular diseases and chest wall disorders.
For Covid-19, the World Health Organisation (WHO) as well as the Ministry of Health and Family Welfare (MoHFW) guidelines have advocated using NIV or Bi-level therapy for covid-19 patients. A well-fitted non-vented mask with an exhalation port for NIV device minimises the widespread dispersion of exhaled air and is associated with a low risk of airborne transmission.
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Is the Continuous Positive Airway Pressure (CPAP) machine, commonly used by those suffering from sleep apnea, similar to an NIV? Can patients who own CPAP machines use it if they face a critical situation related to covid-19 and are unable to access hospitalisation?
NIV (also known as Bi-level) and CPAP are recommended in covid-19 management. In overwhelming circumstances, which has happened in the last several weeks, in absence of a proper Bi-level device, the CPAP mode has also been used as a last resort to facilitate ventilation in patients. It has also been seen that NIVs are more manageable than an Invasive Mechanical Ventilator (IMV). Studies associated with the treatment of covid-19 have also shown that optimised initiation of NIV leads to fewer intubations, lower nosocomial infections, and hence lower mortality.
Ideally, these machines should be used with constant monitoring by healthcare professionals. However, in dire circumstances, when hospitalization is not possible or caregivers want to set up ‘ICU at home' services, which are offered by various corporate hospitals, only then can they seek the option to buy an NIV device under the guidance of a trained doctor/pulmonologist as there are multiple variants of NIVs that differ according to functions and settings. A few other things to remember while using an NIV at home are: A pulmonary technician/nursing staff is essential while setting up the device and guiding the patient to use it and to monitor the patient. In the case of covid-19, the basic vitals (such as oxygen saturation, tidal volume, minute ventilation, body temperature and pulse rate etc) require regular monitoring by a healthcare professional. Do not set up the NIV device on your own, and also remember that the patient must be counselled beforehand and allowed the opportunity to practice breathing with the ventilator. Either the technician can hold the mask in place or assist the patient to have it in place. Regular cleaning of mask and tube is a must to avoid any infections.
What are the advantages of NIV over HFNC?
HFNC is used to deliver a high flow of oxygen to the patient. It is simpler to use and apply than non-invasive ventilation (NIV) and appears to be a good alternative treatment for hypoxemic acute respiratory failure (ARF). HFNC delivers a high fraction of inspired oxygen (FiO2), generates a low level of positive pressure, and provides a washout of dead space in the upper airways, improving mechanical pulmonary properties and unloading inspiratory muscles during ARF. However, in the last few weeks, when there has a been a deluge of infections and constrained oxygen supply, using an HFNC becomes tricky from oxygen consumption point of view. An HFNC uses 20- 60 litres of oxygen per minute compared to NIV that may use about 15 litres/min. In a critical situation of oxygen dearth that we are currently in, NIVs may be recommended to cut down on the consumption of oxygen. Most state governments have advised their hospitals to use NIVs where required instead of HFNC, given the advantages it has in the current situation.