I am sure that all of you reading this are concerned about the risk of pneumonia from the new coronavirus or SARS-CoV-2. We know that most cases of COVID-19 range from mild to moderate, but there is always the concern that should we get the virus, our case might develop into life-threatening pneumonia.
From the news on TV and the newspaper, critical cases of pneumonia require ventilators, and once a high number of critical patients is reached, that is, there is an overshoot or explosive surge in COVID-19, the number of ventilators will not be sufficient. Deaths will result from not being able to receive intensive medical care, as you may know from the situation in Hubei Province, China and Italy.
Experts say that we should "rightly fear" the SARS-CoV-2 virus, but many people may not know why ventilators are necessary when SARS-CoV-2 pneumonia becomes serious. Here I would like to explain in easy-to-understand terms why ventilators are necessary in the case of COVID-19.
Many may think that regardless of the type of illness, ventilators become necessary when the condition becomes serious, but that is not correct.
Generally speaking, there are two conditions that necessitate a ventilator. The first is a condition in which spontaneous breathing becomes difficult. The brain is the control center for spontaneous breathing, and from there, electrical signals are sent via the nervous system, which then contract the respiratory muscles and cause spontaneous breathing. This is not a very cheerful subject, but when the signal for spontaneous breathing stops, we stop breathing. When a patient is put on a ventilator temporarily before dying, this is meant to prevent a condition in which spontaneous breathing stops. Even if the brain sends a signal, spontaneous breathing will not occur unless the vital muscles contract. This is the reason that the ventilators are necessary in the case of muscle-related illness or disease.
However, in the case of COVID-19, the reason that ventilators become necessary is not because spontaneous respiration stops. The SARS-CoV-2 virus infects the cells in the alveoli, or air sacs, which take in oxygen from blood in the lungs, and the air sacs, which should be taking in air, and the area surrounding them then become filled with body fluid. In other words, it is a condition in which water is inhaled and drowning occurs. Even if an effort is made to fully use the respiratory muscles to breathe in and send air to the air sacs, air will not enter the air sacs that are filled with viscous fluid. This is the second condition that necessitates a ventilator.
Even if a little air enters the air sacs through respiratory effort, exhaling will result in filling them again with body fluid, which will prevent oxygen from entering the blood. This is where the ventilator comes in. The ventilator used in the treatment of SARS-CoV-2 pneumonia can apply what is called positive pressure respiration, which puts (positive) pressure on the air sacs, including after exhalation, and prevents them from collapsing. Respiratory effort by the patient and positive pressure from artificial respiration focus on maintaining a situation in which air sacs do not collapse as the wait begins for the inflammation to subside.
When I worked in a pediatric ward, the children who were put on ventilators used them for the two reasons above. In the first group, due to a weakening of the muscles called spinal muscular atrophy (SMA), the children were unable to breathe on their own. The second group did not, of course, have COVID-19, but due to infantile respiratory distress syndrome (IRDS) in which the lungs of premature infants do not inflate, a positive pressure ventilator was used to prevent collapse of air sacs.
On TV around March, we used to see those who expressed the view that the number of ventilators in Japan would be very insufficient. While hardly adequate, the number of ventilators nationwide for adults comes to 22,254. Of these, 13,437 are on standby (for use in COVID-19-related pneumonia), according to an emergency survey conducted by the Japanese Society of Respiratory Care Medicine and the Japan Association for Clinical Engineers in February 2020. This number includes 8,965 ventilators that are designated for use by children.
If, with the correct knowledge and accurate information, we strive with the "correct fear," to prevent infection, together we will be able to overcome the threat of COVID-19.
- Japanese Society of Respiratory Care Medicine. Jinkou kokyuuki oyobi ECMO souchi no toriatsukai daisuu-tou ni kansuru kinkyuu chousa kekka [Emergency Survey on the Number of Artificial Respiratory Instruments and ECMO Equipment].
http://square.umin.ac.jp/jrcm/pdf/info20200306.pdf (In Japanese)