Artificial lungs that are small enough to be carried in a backpack have already been successfully tested on animals. Such devices can make the lives of those people whose own lungs, for whatever reason, do not function properly, much more comfortable. Until now, very cumbersome equipment was used for these purposes, but a new device being developed by scientists in this moment, can change that once and for all.

A person whose lungs are unable to perform their primary function is usually attached to machines that pump their blood through a gas exchanger, enriching it with oxygen and removing carbon dioxide from it. Of course, during this process the person is forced to lie on a bed or couch. And the longer they lie down, the weaker their muscles become, making recovery unlikely. It is precisely in order to make patients mobile that compact artificial lungs were developed. The problem became especially pressing in 2009, when there was an outbreak of swine flu, as a result of which many patients suffered from lung failure.

Artificial lungs can not only help patients recover from some lung infections, but also allow patients to wait for suitable donor lungs for transplantation. As you know, the queue can sometimes last for many years. The situation is complicated by the fact that people with failing lungs, as a rule, also have a greatly weakened heart, which must pump blood through.

“The creation of artificial lungs is much more difficult task than designing an artificial heart. The heart simply pumps blood, while the lungs are a complex network of alvioles, within which the process of gas exchange occurs. “Today, there is no technology that can even come close to the efficiency of real lungs,” says William Federspiel, an employee at the University of Pittsburgh.

William Federspiel's team has developed an artificial lung that includes a pump (to support the heart) and a gas exchanger, but the device is so compact that it can easily fit into a small bag or backpack. The device is connected to tubes connected to the human circulatory system, effectively enriching the blood with oxygen and removing excess carbon dioxide from it. This month, successful tests of the device were completed on four experimental sheep, during which the animals’ blood was saturated with oxygen for different periods of time. Thus, scientists gradually increased the continuous operation time of the device to five days.

An alternative model of artificial lungs is being developed by researchers at Carnegie Mellon University in Pittsburgh. This device is intended primarily for those patients whose heart is healthy enough to independently pump blood through an external artificial organ. The device is connected in the same way to tubes directly connected to the person’s heart, after which it is attached to his body with belts. While both devices require an oxygen source, in other words, an additional portable cylinder. On the other hand, scientists are currently trying to solve this problem, and they are quite successful.

Right now, researchers are testing a prototype artificial lung that no longer requires an oxygen tank. According to the official statement, the new generation of the device will be even more compact, and oxygen will be released from the surrounding air. The prototype is currently being tested on laboratory rats and is showing truly impressive results. The secret of the new artificial lung model is the use of ultrathin (only 20 micrometers) tubes made of polymer membranes, which significantly increase the gas exchange surface.

Content

If breathing is impaired, the patient is given artificial ventilation or mechanical ventilation. It is used for life support when the patient cannot breathe on his own or when he is lying on the operating table under anesthesia that causes a lack of oxygen. There are several types of mechanical ventilation - from simple manual to hardware. Almost anyone can handle the first one, while the second one requires an understanding of the design and rules for using medical equipment.

What is artificial ventilation

In medicine, mechanical ventilation is understood as the artificial injection of air into the lungs in order to ensure gas exchange between environment and alveoli. Artificial ventilation can be used as a resuscitation measure when a person has serious problems with spontaneous breathing, or as a means of protecting against a lack of oxygen. The latter condition occurs during anesthesia or spontaneous diseases.

The forms of artificial ventilation are hardware and direct. The first uses a gas mixture for breathing, which is pumped into the lungs by a device through an endotracheal tube. Direct involves rhythmic compression and expansion of the lungs to ensure passive inhalation and exhalation without the use of a device. If an "electric lung" is used, the muscles are stimulated by an impulse.

Indications for mechanical ventilation

There are indications for artificial ventilation and maintaining normal lung function:

• sudden cessation of blood circulation;
• mechanical asphyxia of breathing;
• chest and brain injuries;
• acute poisoning;
• a sharp decline blood pressure;
• cardiogenic shock;
• asthmatic attack.

After operation

The endotracheal tube of the artificial ventilation device is inserted into the patient’s lungs in the operating room or after delivery from it to the intensive care unit or the ward for monitoring the patient’s condition after anesthesia. The goals and objectives of the need for mechanical ventilation after surgery are:

• elimination of coughing up sputum and secretions from the lungs, which reduces the incidence of infectious complications;
• reducing the need for support of the cardiovascular system, reducing the risk of lower deep venous thrombosis;
• creating conditions for tube feeding to reduce the incidence of gastrointestinal upset and return normal peristalsis;
• reduction of the negative effect on skeletal muscles after prolonged action of anesthetics;
• rapid normalization of mental functions, normalization of sleep and wakefulness.

For pneumonia

If a patient develops severe pneumonia, this quickly leads to the development of acute respiratory failure. Indications for the use of artificial ventilation for this disease are:

• disorders of consciousness and psyche;
• reduction in blood pressure to a critical level;
• intermittent breathing more than 40 times per minute.

Artificial ventilation is performed in the early stages of the disease to increase efficiency and reduce the risk of death. Mechanical ventilation lasts 10-14 days; tracheostomy is performed 3-4 hours after insertion of the tube. If the pneumonia is massive, it is performed with positive end expiratory pressure (PEEP) to improve lung distribution and reduce venous shunting. Along with mechanical ventilation, intensive antibiotic therapy is carried out.

For stroke

Connecting a ventilator in the treatment of stroke is considered a rehabilitation measure for the patient and is prescribed when indicated:

• internal bleeding;
• lung damage;
• pathology in the field of respiratory function;
• coma.

During an ischemic or hemorrhagic attack, difficulty breathing is observed, which is restored by a ventilator in order to normalize lost brain functions and provide cell support sufficient quantity oxygen. They put artificial lungs for a stroke for up to two weeks. During this time, the acute period of the disease changes, and brain swelling decreases. You need to get rid of mechanical ventilation as early as possible.

Types of ventilation

Modern methods of artificial ventilation are divided into two conditional groups. Simple ones are used in emergency cases, and hardware ones are used in a hospital setting. The first ones can be used when a person does not have spontaneous breathing, he has an acute development of respiratory rhythm disturbances or a pathological regime. TO simple techniques include:

1. Mouth to mouth or mouth to nose– the victim’s head is tilted back to the maximum level, the entrance to the larynx is opened, and the root of the tongue is displaced. The person conducting the procedure stands on the side, squeezes the wings of the patient’s nose with his hand, tilting his head back, and holds his mouth with the other hand. Taking a deep breath, the rescuer presses his lips tightly to the patient’s mouth or nose and exhales sharply and vigorously. The patient should exhale due to the elasticity of the lungs and sternum. At the same time, a cardiac massage is performed.
2. Using an S-duct or Reuben bag. Before use, the patient's airways must be cleared, and then the mask must be pressed tightly.

Ventilation modes in intensive care

The artificial respiration device is used in intensive care and refers to the mechanical method of ventilation. It consists of a respirator and an endotracheal tube or tracheostomy cannula. For adults and children, different devices are used, differing in the size of the inserted device and the adjustable breathing frequency. Hardware ventilation is carried out in high-frequency mode (more than 60 cycles per minute) in order to reduce tidal volume, reduce pressure in the lungs, adapt the patient to the respirator and facilitate blood flow to the heart.

Methods

High-frequency artificial ventilation is divided into three methods used by modern doctors:

• volumetric– characterized by a respiratory rate of 80-100 per minute;
• oscillatory– 600-3600 per minute with vibration of continuous or intermittent flow;
• jet– 100-300 per minute, is the most popular, in which oxygen or a mixture of gases under pressure is injected into the respiratory tract using a needle or thin catheter; other options are an endotracheal tube, tracheostomy, catheter through the nose or skin.

In addition to the considered methods, which differ in breathing frequency, ventilation modes are distinguished according to the type of device used:

1. Auto– the patient’s breathing is completely suppressed by pharmacological drugs. The patient breathes fully using compression.
2. Auxiliary– the person’s breathing is maintained, and gas is supplied when attempting to inhale.
3. Periodic forced– used when transferring from mechanical ventilation to spontaneous breathing. A gradual decrease in the frequency of artificial breaths forces the patient to breathe on his own.
4. With PEEP– with it, intrapulmonary pressure remains positive relative to atmospheric pressure. This allows for better distribution of air in the lungs and eliminates swelling.
5. Electrical stimulation of the diaphragm– is carried out through external needle electrodes, which irritate the nerves on the diaphragm and cause it to contract rhythmically.

Ventilator

In the intensive care unit or post-operative ward, a ventilator is used. This medical equipment necessary to supply a gas mixture of oxygen and dry air to the lungs. A forced mode is used to saturate cells and blood with oxygen and remove carbon dioxide from the body. How many types of ventilators are there:

• by type of equipment used– endotracheal tube, mask;
• according to the operating algorithm used– manual, mechanical, with neurocontrolled ventilation;
• according to the age– for children, adults, newborns;
• by drive– pneumomechanical, electronic, manual;
• by appointment– general, special;
• according to the applied area– intensive care unit, resuscitation department, postoperative department, anesthesiology, newborns.

Technique for artificial ventilation

Doctors use ventilators to perform artificial ventilation. After examining the patient, the doctor determines the frequency and depth of breaths and selects the gas mixture. Gases for continuous breathing are supplied through a hose connected to an endotracheal tube; the device regulates and controls the composition of the mixture. If a mask is used that covers the nose and mouth, the device is equipped with an alarm system that notifies of a violation of the breathing process. For long-term ventilation, the endotracheal tube is inserted into the hole through the anterior wall of the trachea.

Problems during artificial ventilation

After installing the ventilator and during its operation, problems may arise:

1. The presence of a patient's struggle with the ventilator. To correct it, hypoxia is eliminated, the position of the inserted endotracheal tube and the equipment itself are checked.
2. Desynchronization with a respirator. Leads to a drop in tidal volume and inadequate ventilation. The causes are considered to be coughing, holding your breath, lung pathologies, spasms in the bronchi, and an incorrectly installed device.
3. High pressure in the respiratory tract. The causes are: violation of the integrity of the tube, bronchospasms, pulmonary edema, hypoxia.

Weaning from mechanical ventilation

The use of mechanical ventilation may be accompanied by injuries due to high blood pressure, pneumonia, decreased heart function and other complications. Therefore, it is important to stop mechanical ventilation as quickly as possible, taking into account the clinical situation. The indication for weaning is a positive dynamics of recovery with the following indicators:

• restoration of breathing with a frequency of less than 35 per minute;
• minute ventilation decreased to 10 ml/kg or less;
• the patient does not have elevated temperature or infections, apnea;
• blood counts are stable.

Before weaning from the respirator, check the remains of the muscle blockade and reduce the dose of sedatives to a minimum. The following modes of weaning from artificial ventilation are distinguished.

Mohammadhossein Dabaghi ​​et.al. \Biomicrofluidics 2018

A team of scientists from Canada and Germany has created external artificial lungs for newborns born with problems respiratory system. The new external lungs are a system of microchannels consisting of double-sided porous membranes that enrich the blood flowing through them with oxygen. Blood flows through such channels on its own, which is a huge plus and helps avoid many problems associated with external pumps, according to an article in Biomicrofluidics.

Respiratory distress syndrome (RDS) occurs in approximately 60 percent of newborns at 28 weeks' gestation, and in 15-20 percent at 32-36 weeks. However, because the lungs are one of the organs that develop late in pregnancy, premature infants with RDS need additional external help to oxygenate the blood until their own lungs can fully perform their functions on their own. At the same time, there are cases when mechanical ventilation is not enough, and doctors are forced to enrich the blood with oxygen directly. In such cases, it is necessary to drive the baby’s blood through special membrane systems in which the blood is saturated with oxygen.

But, unlike adults, newborn children usually have a blood volume of no more than 400–500 milliliters, which means that to avoid excessive dilution of the blood and a decrease in hematocrit, it is dangerous to use more than 30–40 milliliters of blood for oxygenation outside the body. This fact limits the time that a unit of blood can spend outside the body, that is, the oxygenation process must occur quite quickly. In addition, to avoid pressure changes that occur when using a perfusion pump and can damage blood cells, it is ideal to move blood through membrane system must be provided by the heart. And, although this is not critical, it would be good if the membranes could enrich the blood with oxygen using ordinary air, and not a specially prepared mixture of gases or pure oxygen.

Scientists tried to satisfy all these requirements using the concept of an artificial placenta. It involves the exchange of gases between the blood and an external source, without mixing the baby's blood with other liquids (only by adding a saline solution to maintain the amount of fluid circulating in the blood vessels). At the same time, since the volume of blood outside the body should not exceed 30 milliliters, it is necessary to create a structure in which, at a fixed volume, the area of ​​contact of blood with the gas exchange membrane is maximum. The easiest way to do this is to fill a parallelepiped with very small height with blood, but such a structure will be very unstable. It was the fact that the structure must be thin, but at the same time durable, and also made of porous materials, that imposed the main restrictions on the creation of artificial lungs.

For effective gas exchange, scientists placed two square (43x43 millimeters) porous polydimethylsiloxane membranes parallel to each other, placing between them a network of square columns with a side of a millimeter, forming many straight channels perpendicular to each other through which blood flows. In addition to mechanically retaining the membranes, these columns also contributed to the mixing of the blood, making it more homogeneous in composition throughout the system. Also, for sufficient stability of the structure, absence of deformation during operation and reduction of the influence of defects, one of the membranes must be thick enough to ensure the strength of the structure, but at the same time thin enough so that gas exchange can occur through it. To reduce the thickness of the polydimethylsiloxane layer without losing mechanical properties, the researchers inserted a network of reinforced steel strips into it.

The human lungs are a paired organ located in the chest. Their main function is breathing. The right lung has a larger volume compared to the left. This is due to the fact that the human heart, being in the middle of the chest, has a displacement in left side. Lung volume is on average about 3 liters, and among professional athletes more than 8. The size of one woman's lung roughly corresponds to a three-liter jar flattened on one side, with a mass 350 g. For men, these parameters are 10-15% more.

Formation and development

Lung formation begins at 16-18 days embryonic development from the inner part of the embryonic lobe - entoblast. From this moment until approximately the second trimester of pregnancy, the bronchial tree develops. Alveolar formation and development begins already from the middle of the second trimester. By the time of birth, the structure of a baby’s lungs is completely identical to that of an adult. It should only be noted that before the first breath there is no air in the lungs of a newborn. And the sensations during the first breath for a baby are akin to the sensations of an adult who tries to inhale water.

The increase in the number of alveoli continues until 20-22 years. This happens especially strongly in the first one and a half to two years of life. And after 50 years, the process of involution begins, caused by age-related changes. The capacity of the lungs and their size decreases. After 70 years, the diffusion of oxygen in the alveoli worsens.

Structure

The left lung consists of two lobes - upper and lower. The right one, in addition to the above, also has a middle lobe. Each of them is divided into segments, and those, in turn, into labulas. The lung skeleton consists of tree-like branching bronchi. Each bronchus enters the body of the lung along with an artery and vein. But since these veins and arteries are from the pulmonary circulation, then blood saturated with carbon dioxide flows through the arteries, and blood enriched with oxygen flows through the veins. The bronchi end in bronchioles in the labulae, forming one and a half dozen alveoli in each. Gas exchange occurs in them.

The total surface area of ​​the alveoli on which the process of gas exchange occurs is not constant and changes with each phase of inhalation and exhalation. On exhalation it is 35-40 sq.m., and on inhalation it is 100-115 sq.m.

Prevention

The main method of preventing most diseases is to quit smoking and follow safety rules when working in hazardous industries. Surprisingly, but Quitting smoking reduces the risk of lung cancer by 93%. Regular physical exercise, frequent stays fresh air And healthy eating give almost anyone a chance to avoid many dangerous diseases. After all, many of them are not treated, and only a lung transplant can save them.

Transplantation

The world's first lung transplant operation was performed in 1948 by our doctor, Demikhov. Since then, the number of such operations in the world has exceeded 50 thousand. The complexity of this operation is even somewhat more complicated than a heart transplant. The fact is that the lungs, in addition to the main function of breathing, also have an additional function - the production of immunoglobulin. And his task is to destroy everything alien. And for transplanted lungs, such a foreign body may turn out to be the entire recipient’s body. Therefore, after transplantation, the patient is required to take immunosuppressive drugs for life. The difficulty of preserving donor lungs is another complicating factor. Separated from the body, they “live” for no more than 4 hours. You can transplant either one or two lungs. The operating team consists of 35-40 highly qualified doctors. Almost 75% of transplants occur with just three diseases:
COPD
Cystic fibrosis
Hamman-Rich syndrome

The cost of such an operation in the West is about 100 thousand euros. Patient survival is at 60%. In Russia, such operations are performed free of charge, and only every third recipient survives. And if more than 3,000 transplantations are performed annually all over the world, then in Russia there are only 15-20. A fairly strong decline in prices for donor organs in Europe and the United States was observed during the active phase of the war in Yugoslavia. Many analysts attribute this to Hashim Thaci's business of selling live Serbs for organs. Which, by the way, was confirmed by Carla Del Ponte.

Artificial lungs - panacea or science fiction?

In 1952, the world's first operation using ECMO was performed in England. ECMO is not a device or a device, but a whole complex for saturating the patient’s blood with oxygen outside his body and removing carbon dioxide from it. This is extremely difficult process can, in principle, serve as a kind of artificial lung. Only the patient found himself bedridden and often unconscious. But with the use of ECMO, almost 80% of patients survive in sepsis, and more than 65% of patients with serious lung injury. The ECMO complexes themselves are very expensive, and for example in Germany there are only 5 of them, and the cost of the procedure is about 17 thousand dollars.

In 2002, Japan announced it was testing a device similar to ECMO, only the size of two packs of cigarettes. The matter did not go further than testing. After 8 years, American scientists from the Yale Institute created an almost complete artificial lung. It was made half of synthetic materials, and half from living cells of lung tissue. The device was tested on a rat, and it produced a specific immunoglobulin in response to the introduction of pathological bacteria.

And literally a year later, in 2011, already in Canada, scientists designed and tested a device that was fundamentally different from the above. An artificial lung that completely imitated a human one. Silicone vessels up to 10 microns thick, a gas-permeable surface area similar to a human organ. Most importantly, this device, unlike others, did not require pure oxygen and was able to enrich the blood with oxygen from the air. And it doesn’t need third-party energy sources to work. It can be implanted into chest. Human trials are planned for 2020.

But for now these are all just developments and experimental samples. And this year, scientists at the University of Pittsburgh announced the PAAL device. This is the same ECMO complex, only the size of a soccer ball. To enrich the blood, he needs pure oxygen, and it can only be used on an outpatient basis, but the patient remains mobile. And today, this is the most best alternative human lungs.

American scientists from Yale University, led by Laura Niklason, made a breakthrough: they managed to create an artificial lung and transplant it into rats. A lung was also created separately, working autonomously and imitating the work of a real organ.

It must be said that the human lung is a complex mechanism. The surface area of ​​one lung in an adult is about 70 square meters, assembled to ensure efficient transfer of oxygen and carbon dioxide between the blood and the air. But lung tissue difficult to restore, so at the moment the only way to replace damaged areas of the organ is a transplant. This procedure is very risky due to the high percentage of rejections. According to statistics, ten years after transplantation only 10-20% of patients remain alive.

Laura Niklason comments: “We were able to develop and manufacture a lung suitable for transplantation into rats that effectively transports oxygen and carbon dioxide and oxygenates hemoglobin in the blood. This is one of the first steps towards recreating whole lung in larger animals and ultimately in humans."

Scientists removed cellular components from the lungs of an adult rat, leaving behind the branching structures of the pulmonary tract and blood vessels that served as a framework for the new lungs. And they were helped to grow lung cells by a new bioreactor that imitates the process of lung development in an embryo. As a result, the grown cells were transplanted onto the prepared scaffold. These cells filled the extracellular matrix - a tissue structure that provides mechanical support and transport of substances. Transplanted into rats for 45 to 120 minutes, these artificial lungs absorbed oxygen and expelled carbon dioxide just like real ones.

But researchers from Harvard University managed to simulate the operation of the lung in autonomous mode in a miniature device based on a microchip. They note that this lung's ability to absorb nanoparticles in the air and mimic the inflammatory response to pathogenic microbes represents proof-of-principle that organs on microchips could replace laboratory animals in the future.

Actually, scientists have created a device for the wall of the alveoli, a pulmonary vesicle through which gas exchange with capillaries occurs. To do this, they planted epithelial cells from the alveoli of the human lung on a synthetic membrane on one side, and cells of the pulmonary vessels on the other. Air is supplied to the lung cells in the device, a liquid simulating blood is supplied to the “vessels,” and periodic stretching and compression conveys the breathing process.

In order to test the reaction of the new lungs to the influence, scientists forced him to “inhale” Escherichia coli bacteria along with air, which fell on the “lung” side. And at the same time, from the side of the “vessels,” the researchers released white blood cells into the liquid stream. Lung cells detected the presence of bacteria and launched an immune response: white blood cells crossed the membrane to the other side and destroyed foreign organisms.

In addition, scientists added nanoparticles, including typical air pollutants, to the air “inhaled” by the device. Some types of these particles entered the lung cells and caused inflammation, and many freely passed into the “bloodstream.” At the same time, the researchers found that mechanical pressure when breathing, it significantly enhances the absorption of nanoparticles.