Chemical industry, let us breathe more smoothly

Recently, words such as "silent hypoxia" and "white lung" have appeared in the
public eye.
For the new coronavirus infection, regardless of age, blood oxygen concentration is a key indicator
to judge whether a patient is severely ill.
In judging blood oxygen concentration, oximeter is an important equipment, and in the process of treating critically ill patients, the role of ventilators and oxygen generators is also crucial
.
The purpose of this article is to introduce readers to equipment such as oximeters, ventilators, and oxygen concentrators, and how the chemical industry can help people produce and use these devices
.

Oxygen: The most familiar chemical

Oxygen is probably the chemical that humans are most exposed to and familiar with, and we are exposed to oxygen
all the time.

In industry, especially in the chemical industry, oxygen is used very widely
.
About 25% of the oxygen produced in industry is used in the chemical industry
.
Among them, ethylene reacts with oxygen to produce ethylene oxide, known as ethylene direct oxidation method, which is a classic reaction
in which oxygen participates.
Ethylene oxide is the raw material of ethylene glycol, which is an important raw material
for products such as polyester and antifreeze.
About 55% of oxygen is used in the steel industry, while the remaining 20% is used in medical, welding and water treatment
.

The respiratory and circulatory system is the body's key system
for absorbing and transporting oxygen.
Blood oxygen content has become a key indicator
of whether human cells can get enough oxygen to ensure the normal operation of the human body.
The normal arterial oxygen saturation of the human body is 96% ~ 99%, if it is lower than 90%, it is considered hypoxemia, and less than 80% may damage the brain, heart and other organ functions
.

For the new coronavirus infection, blood oxygen saturation is a key indicator
to judge whether a patient is severely ill.
According to the ninth version of China's new crown diagnosis and treatment plan, in the resting state, it means that the blood oxygen saturation ≤ 93%, that is, it is severe
.

Oximeter: A large collection of semiconductor chemicals

Recently, many of us have known about or used oximeters
.
Whether in the hospital or at home, oximeters are a key instrument
for understanding a patient's blood oxygen status.

In principle, an oximeter is an instrument
that measures blood oxygen by pulse.
Because the fingers, toes, earlobes and other parts of the human body are transparent and filled with microvessels, the light-emitting diodes (LEDs) and light sensors in the oximeter can send and receive pulsed signals through these tissues, and the blood oxygen saturation can be read after calculation
.
This non-invasive method of measuring peripheral oxygen saturation, or oxygen saturation, is more likely to have a 2%
error than arterial oxygen saturation readings.
However, the correlation between the two is high, making this oximeter the first choice
for clinical applications of oximetry.

Structurally, an oximeter requires a microprocessor and memory, two digital-to-analog converters that control LEDs, a device that filters and amplifies the signal received by the optical sensor, and an analog-to-digital converter
that digitizes the received signal to a microprocessor.
LEDs and light sensors are placed in small probes that are in contact with the patient's fingertips or earlobes, and oximeters typically include small liquid crystal displays
.
Therefore, don't look at the oximeter is small, but like computers and mobile phones, it is also a large collection of
semiconductor chemicals.
For example, the basic materials of LEDs commonly used in oximeters are classic semiconductor gallium compounds, such as gallium nitride, indium gallium nitride, gallium arsenide, etc
.

Experts pointed out that when blood oxygen saturation decreases, many patients do not have serious self-perceived symptoms
.
Because elderly patients are slow to respond to hypoxia, or even do not feel chest tightness, dyspnea, etc.
, this phenomenon can be called "silent hypoxia"
.
If the hypoxia is not corrected in a short period of time, the condition can easily progress to critical illness
.
In addition, even healthy young people are still at risk
of severe disease after contracting the new coronavirus.
Recently, the Beijing Municipal Health Commission and the Beijing Municipal Medical Security Bureau issued a notice to organize the distribution of blood oxygen clips to high-risk groups such as the elderly, and clarify the concise monitoring and early warning standards
.
Using an oximeter, the tendency of the disease to progression to severe disease can be detected at an early stage, allowing for early intervention
.

Ventilators, oxygen generators: materials and chemicals are closely related

If you unfortunately become a seriously ill patient with the new crown, the blood oxygen saturation has been reduced, and oxygen therapy
is required at this time.
Oxygen therapy is very flexible, and oxygen concentrators are not only standard equipment in hospitals, but can also be moved
to the home.

The principle of oxygen generator is closely
related to chemical industry.
In industry, high-purity oxygen is obtained through air separation devices, and the general method is to separate
oxygen from other components such as nitrogen in the air through high pressure and low temperature.

The earliest household oxygen generator was invented by the chemical company United Carbide in the United States
.
The main working principle of oxygen generators is divided into two categories, one is called pressure swing adsorption, and the other is called membrane gas separation
.
Among them, oxygen concentrators using pressure swing adsorption technology are widely used in oxygen supply
in healthcare applications.
The oxygen generator uses molecular sieve to adsorb gas, and rapidly adsorb nitrogen under high pressure to zeolite minerals to purify oxygen
.
The classic oxygen generator uses a twin-bed molecular sieve, and there are currently multi-bed molecular sieve products, which have a larger oxygen output and faster
speed.

If symptoms continue to worsen and respiratory failure occurs, a ventilator must be present
.
Ventilators have a longer
history than oxygen concentrators.
In the history of the development of ventilators, it has witnessed the beginning
of the application of a variety of polymer materials in the medical field.
For example, polymethyl methacrylate has become the preferred material for ventilator masks since the 60s of the 20th century, and the materials for endotracheal intubation are silicone, polyvinyl chloride, etc
.
In addition, non-invasive home ventilators can also be used to improve
the breathing of patients with mild new crown disease.