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In areas where the medical system is tight due to the rapid spread of the new coronavirus infection, it seems that there are cases where even moderate illnesses cannot be hospitalized and are forced to undergo home medical treatment. This section summarizes therapies that assist or replace lung function in moderate disease II and later.

When the oxygen saturation of the new corona patient falls below 93% on the pulse oximeter, the body becomes slightly deficient in oxygen, and oxygen administration is applied. High-concentration oxygen is inhaled from oxygen concentrators and oxygen cylinders. Oxygen is delivered to the lungs through a tube called a cannula in the nose. Since the mouth is not covered, conversation and eating and drinking are possible. However, because there is no humidification, the inside of the nose may become dry. If the oxygen saturation is further reduced, oxygen will be administered with a face mask instead of a cannula. There is also a mask with a bag (reservoir) that stores oxygen in order to obtain a high partial pressure of inspiratory oxygen, which is said to be effective. The Venturi mask can take in the surrounding atmosphere by utilizing the negative pressure state around the jet flow that occurs when oxygen flows through the Venturi tube, and can inhale any oxygen concentration depending on the amount. Some local governments have started home oxygen therapy (HOT), which allows oxygen inhalation at the patient's home, if hospitalization is not possible even with moderate disease II, which requires oxygen inhalation.

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If normal oxygen administration (3-5 L / min) does not raise the oxygen concentration as expected, the next step is to consider wearing a ventilator, but recently, high-flow nasal cannula oxygen therapy (Nasal). High flow) is being used more and more. Nasal High Flow has been used for patients with respiratory failure before corona, but since spring last year, it has been used for corona treatment in Europe and other countries. In Japan, this treatment method was added to the "Guide for the Treatment of Coronavirus Infectious Diseases (COVID-19), Version 5.1" in May this year. It is a device that can supply high concentration oxygen at a high flow rate of 30 to 60 L / min or more from a tube thicker than the cannula. By allowing humidified oxygen from the nose to enter the lungs, the mucous membranes of the airways do not dry out, which also helps protect against inflammation. Nasal High Flow is a way to create an opportunity to recover before the ventilator is in the required stage. According to a paper reported in the journal of the American Thoracic Society last October by a French research group, a study comparing the efficacy of nasal high flow with conventional oxygen therapy in about 380 patients with new corona was found in nasal high flow. Use reduced the transition to mechanical ventilation management by approximately 20%. Unlike a ventilator, the patient's consciousness is maintained and the mouth is not covered, so it is possible to talk, eat and drink, and it is easy to maintain the quality of life. The number of medical staff is not so large, which leads to a reduction in the burden. The disadvantage is that the aerosol may be released from the patient's mouth, causing nosocomial infections. Therefore, in principle, it is recommended to carry out in a negative pressure private room. It is also useful to have the patient wear a surgical mask while the medical staff is in the room to avoid infection. This device does not work with oxygen cylinders and requires piping, so it is difficult to use it in clinics and outpatient clinics.

If the body is deficient in oxygen even with oxygen administration, a ventilator, which is defined as severe, is installed to assist the flow of air in and out of the lungs. The ventilator pumps concentrated oxygen through the patient's mouth and pressure causes the lungs to inflate. Since the tube is inserted from the mouth to the back of the throat, it seems that it is often anesthetized and unconscious while wearing it. In addition, if you pass the tube for a long time, the throat will swell and it will be difficult to remove sputum, so you may make an incision about 5 cm in the throat and pass the tube directly from there. If you make an incision, the patient will not be able to speak. In order to manage bedridden patients, tube feeding and diaper changing are also required, and multiple medical staff are required.

If the ventilator is unable to support lung function or if there is a risk of lung injury due to continued treatment, the use of extracorporeal membrane oxygenation (ECMO), which is said to be the last ticket, is considered. .. ECMO allows you to send oxygen into the blood while resting your lungs. When ECMO is attached, the patient is anesthetized in the same way as a ventilator. Blood is taken out by a pump, oxygen and carbon dioxide are exchanged with an artificial lung instead of the lung, and the blood is returned to the body to assist breathing. Use anticoagulants because ECMO is more likely to cause blood clots. It is necessary to monitor patients and equipment 24 hours a day, and 10 or more people such as doctors, nurses, and clinical engineers who are familiar with ECMO must work as a team. The duration of treatment can be several weeks or longer.

There are more options such as Nasal High Flow as a means of respiratory management for patients with new corona after moderate disease II, but if the number of infected people continues to increase, it may be difficult to secure various devices. For that reason, it is desirable to control infection.