Physicists have created external artificial lungs for newborns. Connection to a ventilator - indications and implementation. Estimated advantages and disadvantages of Artificial blood
The fact that blowing air into the lungs can revive a person has been known since ancient times, but auxiliary devices for this began to be produced only in the Middle Ages. In 1530, Paracelsus first used a mouth duct with leather bellows designed to fan a fire in a fireplace. Thirteen years later, Vesaleus published his work “On the Structure of the Human Body,” in which he substantiated the benefits of ventilation of the lungs through a tube inserted into the trachea. And in 2013, researchers at Case Western Reserve University created a prototype artificial lung. The device uses purified atmospheric air and does not require concentrated oxygen. The structure of the device resembles a human lung with silicone capillaries and alveoli and operates on a mechanical pump. Biopolymer tubes imitate the branching of bronchi into bronchioles. In the future, it is planned to improve the device with reference to myocardial contractions. Mobile device with a high probability can replace a transport ventilator.
The dimensions of the artificial lung are up to 15x15x10 centimeters; they want to bring its dimensions as close as possible to the human organ. Huge area of gas diffusion membrane gives a 3-5 fold increase in the efficiency of oxygen exchange.
The device is currently being tested on pigs, but tests have already shown its effectiveness in treating respiratory failure. The introduction of an artificial lung will help eliminate the need for more massive transport ventilators that operate with explosive oxygen cylinders.
An artificial lung makes it possible to activate a patient otherwise confined to a bedside intensive care unit or a transport ventilator. And with activation, the chance of recovery and psychological state increase.
Patients waiting for a donor lung transplant usually have to spend a long time in the hospital on an artificial oxygenation machine, using which you can only lie in a bed and watch the machine breathe for you.
The project of an artificial lung, capable of prosthetic respiratory failure, gives these patients a chance for a speedy recovery.
The portable artificial lung kit includes the lung itself and a blood pump. Autonomous operation valid for up to three months. The small size of the device allows it to replace the transport ventilator of emergency medical services.
The operation of the lung is based on a portable pump that enriches the blood with air gases.
Some people (especially newborns) do not require long-term supply of highly concentrated oxygen due to its oxidizing properties.
Another non-standard analogue of mechanical ventilation used for severe spinal cord injury is transcutaneous electrical stimulation of the phrenic nerves (“phrenicus stimulation”). A transpleural lung massage according to V.P. Smolnikov has been developed - creating a state of pulsating pneumothorax in the pleural cavities.
Severe breathing disorders require emergency assistance in the form of forced ventilation lungs. Whether the failure of the lungs themselves or the respiratory muscles is an absolute necessity to connect complex equipment to saturate the blood with oxygen. Various models artificial lung ventilation devices - an integral equipment of intensive care or resuscitation services, necessary to maintain the life of patients who have developed acute respiratory disorders.
In emergency situations, such equipment is, of course, important and necessary. However, as a means of regular and long-term therapy, it, unfortunately, is not without its drawbacks. For example:
- the need for constant hospital stay;
- permanent risk of inflammatory complications caused by the use of a pump to supply air to the lungs;
- restrictions in the quality of life and independence (immobility, inability to eat normally, speech difficulties, etc.).
It allows you to eliminate all these difficulties while simultaneously improving the process of blood saturation with oxygen. innovation system artificial lung iLA, the resuscitation, therapeutic and rehabilitation use of which is offered today by clinics in Germany.
Coping with breathing disorder without risk
The iLA system is a fundamentally different development. Its action is extrapulmonary and completely non-invasive. Breathing disorders can be overcome without forced ventilation. The blood oxygen saturation scheme is characterized by the following promising innovations:
- lack of an air pump;
- absence of invasive (“implanted”) devices in the lungs and airways.
Patients who receive the iLA artificial lung are not tied to stationary device and hospital bed, they can move normally, communicate with other people, eat and drink independently.
The most important advantage: there is no need to put a patient into an artificial coma with artificial respiration support. The use of standard mechanical ventilation devices in many cases requires a comatose “switching off” of the patient. For what? To relieve the physiological effects of respiratory depression of the lungs. Unfortunately, it is a fact: ventilators depress the lungs. The pump supplies air inside under pressure. The rhythm of air supply reproduces the rhythm of breaths. But during natural inhalation, the lungs expand, as a result of which the pressure in them decreases. And at the artificial entrance ( forced submission air), the pressure, on the contrary, increases. This is the oppressive factor: the lungs are in a stressful mode, which causes an inflammatory reaction, which in especially severe cases can be transmitted to other organs - for example, the liver or kidneys.
This is why two factors are of paramount and equal importance in the use of pump respiratory support devices: urgency and caution.
The iLA system, while expanding the range of benefits in artificial respiratory support, eliminates the associated dangers.
How does a blood oxygen saturation machine work?
The name “artificial lung” has a special meaning in this case, since the iLA system operates completely autonomously and is not a functional addition to the patient’s own lungs. In fact, this is the world's first artificial lung in the true sense of the word (not a pulmonary pump). It is not the lungs that are ventilated, but the blood itself. Applied membrane system saturating the blood with oxygen and removing carbon dioxide. By the way, in German clinics the system is called a membrane ventilator (iLA Membranventilator). Blood is supplied to the system naturally, by the force of compression of the heart muscle (and not by a membrane pump, as in a heart-lung machine). Gas exchange occurs in the membrane layers of the apparatus in approximately the same way as in the alveoli of the lungs. The system really works as a “third lung”, relieving the patient’s diseased respiratory organs.
The membrane exchange apparatus (the “artificial lung” itself) is compact, measuring 14 by 14 centimeters. The patient carries the device with him. Blood enters it through a catheter port - a special connection to the femoral artery. To connect the device, no surgery is required: the port is inserted into the artery much like a syringe needle. The connection is made in the groin area; the special design of the port does not limit mobility and does not cause any inconvenience to the patient at all.
The system can be used without interruption for quite a long period of time, up to one month.
Indications for use of iLA
In principle, these are any breathing disorders, especially chronic ones. The benefits of an artificial lung are most evident in the following cases:
- chronic obstructive pulmonary disease;
- acute respiratory distress syndrome;
- respiratory injuries;
- the so-called Weaning phase: weaning off the ventilator;
- patient support before lung transplantation.
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, but 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
For artificial ventilation and maintenance normal functioning lungs there are indications:
- 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 cells with sufficient oxygen. Artificial lungs are placed in cases of 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:
- 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.
- 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 apparatus is used in intensive care and belongs to mechanical method 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:
- Auto– the patient’s breathing is completely suppressed pharmacological drugs. The patient breathes fully using compression.
- Auxiliary– the person’s breathing is maintained, and gas is supplied when attempting to inhale.
- 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.
- 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.
- 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 artificial ventilation device and during its operation, problems may arise:
- 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.
- 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.
- 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.
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 simulating the work of a real organ.
It must be said that the human lung is 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 is difficult to restore, so this moment The only way to replace damaged parts of an 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 efficiently carries oxygen and carbon dioxide and oxygenating hemoglobin in the blood. "This is one of the first steps toward recreating the entire 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 lung function offline in a miniature microchip-based device. 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 landed on synthetic membrane on one side are epithelial cells from the alveoli of the human lung, and on the other are cells of the pulmonary vessels. 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 during breathing significantly enhances the absorption of nanoparticles.
