Modern ventilators - types, description and characteristics. Chursin V.V. Artificial lung ventilation (educational manual) On a lung ventilator
Lecture # 6
Subject " Cardiopulmonary resuscitation »
1) The concept of resuscitation.
2) Tasks of resuscitation.
3) Technique for artificial lung ventilation.
4) Technique of external heart massage.
Lecture.
Resuscitation- This is a complex of therapeutic measures aimed at restoring cardiac activity, respiration and vital activity of an organism in a terminal state.
In a terminal state, regardless of its cause, pathological changes occur in the body, affecting almost all organs and systems (brain, heart, respiratory system, metabolism, etc.) and occurring in tissues at different times. Given that organs and tissues continue to live for some time even after a complete stop of the heart and breathing, with timely resuscitation, it is possible to achieve the effect of reviving the patient.
Resuscitation tasks:
ensuring free patency of the respiratory tract;
carrying out IVL;
restoration of blood circulation.
Signs of life:
the presence of a heartbeat - determined by listening to heart tones over the area of \u200b\u200bthe heart;
the presence of a pulse on the arteries: radial, carotid, femoral.
the presence of breathing: is determined by the movement of the chest, anterior abdominal wall, bringing a piece of cotton wool, a thread, a mirror to the nose and mouth (it will fog up) by the movement of the air flow.
the presence of a reaction of pupils to light (narrowing of the pupil to a beam of light is a positive reaction. During the day, close the eye with the palm of your hand => when abducting => pupil change).
Stages of cardiopulmonary resuscitation:
1. Ensure airway patency:
Free the oral cavity and pharynx from foreign matter (blood, mucus, vomit, dentures, chewing gum) with a hand wrapped in a napkin, handkerchief, after turning the head of the rescued to one side.
After that, perform the triple Safar technique:
1) Tilt your head as far as possible to straighten the airways;
2) Push the lower jaw forward to prevent tongue retraction;
3) Slightly open your mouth.
Using the “mouth-to-mouth” method (“mouth to mouth”), the rescuer pinches the patient’s nose, takes a deep breath, presses his lips to the patient’s mouth through a napkin or clean handkerchief and exhales air with effort. In this case, it is necessary to monitor whether the chest rises when the patient inhales. It is more convenient to check the ventilation using the Safar S-shaped air duct, because it prevents the retraction of the tongue.
IVL method "mouth to nose" ("mouth to nose"), the rescuer closes the patient's mouth, pushing the lower jaw forward, covers the patient's nose with his lips and blows air into it.
In young children, air is blown into the mouth and nose at the same time. carefully, so as not to break the lung tissue.
3. Indirect cardiac massage:
do simultaneously with IVL. The patient should lie on a hard surface (floor, board).
The rescuer puts his hand on the lower part of the sternum, the second on top of it and jerkily presses on the sternum with the whole weight of his body with a frequency of 60 times in 1 minute.
If the rescuer is alone, after two blows of air, 10-12 pressures on the sternum should be done.
If two help => one does mechanical ventilation, the second heart massage. After every 4-6 pressures on the sternum, take one breath. Resuscitation is carried out until the restoration of breathing and heartbeat. When signs of biological death appear, resuscitation stops.
Technique for artificial lung ventilation.
Artificial ventilation of the lungs according to the "mouth to mouth" or "mouth to nose" method. For artificial ventilation of the lungs, it is necessary to lay the patient on his back, unfasten the clothing that restricts the chest and ensure free airway patency. The contents present in the oral cavity or pharynx must be quickly removed with a finger, a napkin, a handkerchief, or with any suction (you can use a rubber syringe, after cutting off its thin tip). To free the airways, the head of the victim should be pulled back. It must be remembered that excessive abduction of the head can lead to narrowing of the airways. For a more complete opening of the airways, it is necessary to push the lower jaw forward. If one of the types of air outlets is available, it should be inserted into the pharynx to prevent tongue retraction. In the absence of an air outlet during artificial respiration, you should keep your head in the allotted position, moving the lower jaw forward with your hand.
To carry out breathing in the mouth-to-mouth method, the victim's head is held in a certain position. The resuscitator, taking a deep breath and tightly pressing his mouth to the patient's mouth, blows exhaled air into his lungs. In this case, with the hand located at the forehead of the victim, it is necessary to pinch the nose. Exhalation is carried out passively, due to the elastic forces of the chest. The number of breaths per minute should be at least 16-20. Insufflation should be carried out quickly and abruptly (less abruptly in children) so that the duration of inspiration is 2 times less than the exhalation time.
It is necessary to ensure that the inhaled air does not lead to excessive distension of the stomach. In this case, there is a danger of getting food masses from the stomach into the bronchi. Of course, mouth-to-mouth breathing creates significant hygienic inconveniences. Direct contact with the patient's mouth can be avoided by blowing air through a gauze napkin, handkerchief or any other loose tissue.
When using the mouth-to-nose breathing method, air is blown through the nose. In this case, the victim's mouth should be closed with a hand, which simultaneously shifts the lower jaw forward to prevent tongue retraction.
Artificial ventilation of the lungs with manual respirators.
It is necessary to ensure the patency of the respiratory tract. A mask is tightly applied to the nose and mouth of the patient. Squeezing the bag, inhale, exhale through the valve of the bag, while the duration of the exhalation is 2 times longer than the duration of the inhalation.
In no case should you start artificial respiration without freeing the airways (mouth and pharynx) from foreign bodies or food masses.
Technique of external heart massage.
The meaning of external heart massage is the rhythmic compression of the heart between the sternum and spine. In this case, blood is expelled from the left ventricle into the aorta and enters, in particular, into the brain, and from the right ventricle into the lungs, where it is saturated with oxygen. After the pressure on the sternum stops, the chambers of the heart are filled with blood again. When providing external massage, the patient is laid on his back on a solid foundation (floor, earth). Do not massage on a mattress or soft surface. The resuscitator stands on the side of the patient and with the palmar surfaces of the hands superimposed on one another, presses on the sternum with such force as to bend it towards the spine by 4-5 cm. The frequency of compressions is 50-70 times per minute. Hands should lie on the lower third of the sternum, i.e. 2 transverse fingers above the xiphoid process. In children, heart massage should be performed with only one hand, and in infants, with the tips of two fingers with a frequency of 100-120 pressures per minute. The point of application of the fingers in children under 1 year old is at the lower end of the sternum. If resuscitation is carried out by one person, then every 15 pressures on the sternum, he must stop the massage and take 2 strong quick breaths using the “mouth-to-mouth”, “mouth-to-nose” method or with a special manual respirator. With the participation of two people in resuscitation, one injection into the lungs should be made after every 5 compressions on the sternum.
Control questions for consolidation:
What are the main tasks of resuscitation?
Describe the sequence of provision of artificial lung ventilation
Explain what resuscitation is.
Educational literature for students of medical schools V. M. Buyanov;
Additional;
Electronic resources.
Artificial ventilation of the lungs is used not only in case of sudden cessation of blood circulation, but also in other terminal conditions, when the activity of the heart is preserved, but the function of external respiration is sharply impaired (mechanical asphyxia, extensive trauma to the chest, brain, acute poisoning, severe arterial hypotension, areactive cardiogenic shock). , status asthmaticus and other conditions in which metabolic and gaseous acidosis progresses).
Before proceeding with the restoration of breathing, it is advisable to make sure that the airway is free. To do this, open the patient's mouth (remove removable dentures) and use fingers, a curved clamp and gauze to remove food debris and other visible foreign objects.
If possible, the contents are aspirated using an electric suction through a wide lumen of a tube inserted directly into the oral cavity, and then through a nasal catheter. In cases of regurgitation and aspiration of gastric contents, it is necessary to thoroughly clean the oral cavity, since even a minimal reflux into the bronchial tree causes severe post-resuscitation complications (Mendelssohn's syndrome).
Patients with acute myocardial infarction should limit themselves to food, since overeating, especially on the first day of the disease, is often the direct cause of sudden circulatory arrest. Carrying out resuscitation in these cases is accompanied by regurgitation and aspiration of gastric contents. To prevent this formidable complication, it is necessary to give the patient a slightly elevated position by raising the head end of the bed, or to create a Trendelenburg position. In the first case, the risk of reflux of the contents of the stomach into the trachea decreases, although during mechanical ventilation a certain part of the inhaled air enters the stomach, it becomes stretched, and regurgitation occurs sooner or later with indirect heart massage. In the Trendelenburg position, it is possible to evacuate the outflowing contents of the stomach with the help of an electric suction, followed by the introduction of a probe into the stomach. To carry out these manipulations requires a certain amount of time and appropriate skills. Therefore, first you need to slightly raise the head end, and then insert the probe to remove the contents of the stomach.
The applied method of strong pressure on the epigastric region of the patient to prevent hyperdistension of the stomach can cause the evacuation of air and stomach contents, followed by its immediate aspiration.
IVL is usually started in the position of the patient on his back with his head thrown back. This contributes to the complete opening of the upper respiratory tract, as the root of the tongue moves away from the back of the pharynx. In the absence of a ventilator at the scene, mouth-to-mouth or mouth-to-nose breathing should be started immediately. The choice of IVL technique is mainly determined by muscle relaxation and patency of the corresponding section of the upper respiratory tract. With sufficient muscle relaxation and a free (passable for air) oral cavity, it is better to carry out mouth-to-mouth breathing. To do this, the resuscitator, throwing back the patient's head, with one hand pushes the lower jaw forward, and tightly closes the victim's nose with the index and thumb of the other hand. After a deep breath, the resuscitator, tightly pressing his mouth to the half-open mouth of the patient, makes a forced exhalation (within 1 s). In this case, the patient's chest rises freely and easily, and after opening the mouth and nose, a passive exhalation is carried out with a typical sound of exhaled air.
In some cases, it is necessary to carry out mechanical ventilation in the presence of signs of spasm of the masticatory muscles (in the first seconds after a sudden stop of blood circulation). It is inappropriate to spend time on the introduction of a mouth expander, as this is not always possible. Ventilation should begin mouth to nose. As with mouth-to-mouth breathing, the patient's head is thrown back and, having previously clasped the region of the patient's lower nasal passages with his lips, make a deep exhalation.
At this time, the victim's mouth is covered with the thumb or forefinger of the resuscitator's hand supporting the chin. Passive exhalation is carried out mainly through the patient's mouth. Usually, when breathing mouth to mouth or mouth to nose, a gauze or handkerchief is used. They, as a rule, interfere with the conduct of mechanical ventilation, as they quickly get wet, stray and prevent the passage of air into the upper respiratory tract of the patient.
In the clinic, various air tubes and masks are widely used for mechanical ventilation. It is most physiological to use for this purpose an S-shaped tube, which is inserted into the oral cavity above the tongue before entering the larynx. The patient's head is thrown back, the S-shaped tube is inserted 8-12 cm into the pharynx with a bend and fixed in this position with a special cup-shaped flange. The latter, located in the middle of the tube, tightly presses the patient's lips to it and provides adequate ventilation of the lungs. The resuscitator is located behind the head of the patient, with the little fingers and ring fingers of both hands pushes the lower jaw forward, with the index fingers firmly presses the flange of the S-shaped tube, and closes the patient's nose with the thumbs. The doctor makes a deep exhalation into the mouthpiece of the tube, after which an excursion of the patient's chest is noted. If, when breathing into the patient, there is a feeling of resistance or only the epigastric region rises, it is necessary to tighten the tube somewhat, since the epiglottis may have wedged over the entrance to the larynx or the distal end of the tube is located above the entrance to the esophagus.
In this case, with continued ventilation, the possibility of regurgitation of the contents of the stomach is not ruled out.
It is easier and more reliable in emergency situations to use a conventional anesthetic-breathing mask, when the exhaled air of the resuscitator is blown through its fitting. The mask is hermetically fixed to the face of the victim, also throwing back the head, pushing the lower jaw, as well as when breathing through the S-shaped tube. This method resembles a mouth-to-nose ventilator, since with a tight fixation of the anesthetic-breathing mask, the victim's mouth is usually closed. With a certain skill, the mask can be positioned so that the oral cavity opens slightly: for this, the patient's lower jaw is pushed forward. For better ventilation of the lungs with the help of an anesthetic-respiratory mask, you can first enter the oropharyngeal air duct; then breathing is carried out through the mouth and nose of the victim.
It must be remembered that with all methods of expiratory ventilation based on blowing into the injured air of the resuscitator, the oxygen concentration in the exhaled air should be at least 17-18 vol%. If resuscitation is carried out by one person, then with an increase in his physical activity, the oxygen concentration in the exhaled air drops below 16% by volume and, of course, the oxygenation of the patient's blood decreases sharply. In addition, although when saving the life of a patient, hygienic precautions during mechanical ventilation according to the mouth-to-mouth or mouth-to-nose method fade into the background, they cannot be neglected, especially if resuscitation of infectious patients is carried out. For this purpose, in any department of a medical institution, there must be devices for manual ventilation. Such devices allow ventilation through an anesthetic-breathing mask (as well as through an endotracheal tube) with ambient air or oxygen from a centralized oxygen system or from a portable oxygen cylinder to the suction valve of a reservoir tank. By regulating the supply of oxygen, it is possible to achieve from 30 to 100% of its concentration in the inhaled air. The use of devices for manual ventilation makes it possible to securely fix the anesthetic-breathing mask to the patient's face, since active inhalation into the patient and his passive exhalation are carried out through a non-reversible breathing valve. The use of such breathing apparatus for resuscitation requires certain skills. The patient's head is thrown back, the lower jaw is pushed forward with the little finger and held by the chin with the ring and middle fingers, the mask is fixed with one hand, holding it by the fitting with the thumb and forefinger; with the other hand, the resuscitator compresses the breathing bellows. It is best to choose a position behind the head of the patient.
In a number of cases, especially in the elderly, in the absence of teeth and atrophied alveolar processes of the jaws, it is not possible to achieve tight sealing of the anesthetic-breathing mask with the face of the victim. In such a situation, it is advisable to use an oropharyngeal air duct or to carry out mechanical ventilation after sealing the mask only with the patient's nose with a tightly closed oral cavity. Naturally, in the latter case, a smaller anesthetic-respiratory mask is selected, and its sealed rim (obturator) is half filled with air. All this does not exclude errors in the implementation of mechanical ventilation and requires preliminary training of medical personnel on special dummies for cardiopulmonary resuscitation. So, with their help, you can work out the basic resuscitation measures and, most importantly, learn to determine the patency of the airways with sufficient chest excursion, and evaluate the amount of inhaled air. For adult victims, the required tidal volume is between 500 and 1000 ml. With excessive air blowing, a lung rupture is possible, most often in cases of emphysema, air entering the stomach, followed by regurgitation and aspiration of the stomach contents. True, in modern devices for manual ventilation there is a safety valve that dumps excess air into the atmosphere. However, this is also possible with insufficient ventilation of the lungs due to impaired airway patency. To avoid this, constant monitoring of the chest excursion or auscultation of respiratory sounds is necessary (mandatory on both sides).
In emergency situations, when the patient's life depends on a few minutes, it is natural to strive to provide assistance as quickly and efficiently as possible. This sometimes entails abrupt and unjustified movements. So, too vigorous tilting of the patient's head can lead to impaired cerebral circulation, especially in patients with inflammatory diseases of the brain, traumatic brain injury. Excessive air blowing, as mentioned above, can result in lung rupture and pneumothorax, and forced ventilation in the presence of foreign bodies in the oral cavity can contribute to their dislocation into the bronchial tree. In such cases, even if it is possible to restore cardiac activity and respiration, the patient may die from complications associated with resuscitation (lung rupture, hemo- and pneumothorax, aspiration of gastric contents, aspiration pneumonia, Mendelssohn's syndrome).
Most adequately, mechanical ventilation can be performed after endotracheal intubation. At the same time, there are indications and contraindications for this manipulation with a sudden cessation of blood circulation. It is generally accepted that in the early stages of cardiopulmonary resuscitation, one should not spend time on this procedure: breathing stops during intubation, and if it is technically difficult to perform (a short neck in the victim, stiffness in the cervical spine), then due to aggravation of hypoxia death may occur. However, if for a number of reasons, in particular due to the presence of foreign bodies and vomit in the airways, it is impossible to perform mechanical ventilation, endotracheal intubation becomes essential. At the same time, with the help of a laryngoscope, visual control and careful evacuation of vomit and other foreign bodies from the oral cavity are carried out. In addition, the introduction of an endotracheal tube into the trachea makes it possible to establish adequate mechanical ventilation, followed by aspiration through the tube of the contents of the bronchial tree and appropriate pathogenetic treatment. It is advisable to introduce an endotracheal tube in cases where resuscitation lasts more than 20-30 minutes or when cardiac activity is restored, but breathing is sharply impaired or inadequate. Simultaneously with endotracheal intubation, a gastric tube is inserted into the stomach cavity. For this purpose, under the control of a laryngoscope, an endotracheal tube is first introduced into the esophagus, and a thin gastric tube is inserted through it into the stomach; then the endotracheal tube is removed, and the proximal end of the gastric tube is brought out through the nasal passage using a nasal catheter.
Endotracheal intubation is best done after pre-ventilation with a manual breathing apparatus with 100% oxygen. For intubation, it is necessary to tilt the patient's head so that the pharynx and trachea form a straight line, the so-called "classic Jackson position". It is more convenient to put the patient in the "improved Jackson position", in which the head is thrown back, but raised above the level of the bed by 8-10 cm. Having opened the patient's mouth with the index and thumb of the right hand, with the left hand, gradually pushing the tongue slightly to the left and up from the blade with the tool, a laryngoscope is inserted into the oral cavity. It is best to use a curved laryngoscope blade (Macintosh type) with its end between the anterior pharyngeal wall and the base of the epiglottis. Raising the epiglottis by pressing the end of the blade on the anterior wall of the pharynx at the site of the glosso-epiglossal fold, the glottis is made visible. Sometimes this requires some pressure from the outside on the anterior wall of the larynx. With the right hand, under visual control, an endotracheal tube is passed into the trachea through the glottis. In resuscitation, it is advisable to use an endotracheal tube with an inflatable cuff to prevent leakage of stomach contents from the oral cavity into the trachea. Do not insert the endotracheal tube beyond the glottis beyond the end of the inflatable cuff.
With the correct location of the tube in the trachea, both halves of the chest rise evenly during breathing, inhalation and exhalation do not cause a feeling of resistance: during auscultation, breathing is uniform on both sides of the lungs. If the endotracheal tube is mistakenly inserted into the esophagus, then with each breath the epigastric region rises, there are no respiratory noises during auscultation of the lungs, and exhalation is difficult or absent.
Often, an endotracheal tube is passed into the right bronchus, obturating it, then breathing is not heard on the left, and the opposite variant of the development of such a complication is not excluded. Sometimes, if the cuff is overinflated, it can cover the opening of the endotracheal tube.
At this time, with each breath, an additional amount of air enters the lungs, and exhalation is sharply difficult. Therefore, when inflating the cuff, it is necessary to focus on the control balloon, which is connected to the obturation cuff.
As already mentioned, in some cases it is technically difficult to carry out endotracheal intubation. This is especially difficult if the patient has a short, thick neck and limited mobility in the cervical spine, since only part of the glottis is visible with direct laryngoscopy. In such cases, it is necessary to insert a metal conductor (with an olive at its distal end) into the endotracheal tube and give the tube a steeper bend, allowing it to be inserted into the trachea.
To avoid perforation of the trachea with a metal conductor, the endotracheal tube with the conductor is inserted a short distance (2-3 cm) beyond the glottis and the conductor is immediately removed, and the tube is passed into the patient's trachea with gentle translational movements.
Endotracheal intubation can also be performed blindly, while the index and middle fingers of the left hand are inserted deep along the root of the tongue, the epiglottis is pushed forward with the middle finger, and the inlet to the esophagus is determined with the index finger. An endotracheal tube is passed into the trachea between the index and middle fingers.
It should be noted that endotracheal intubation can be performed under conditions of good muscle relaxation, which occurs 20-30 seconds after cardiac arrest. With trismus (spasm) of masticatory muscles, when it is difficult to open the jaws and put the laryngoscope blade between the teeth, it is possible to carry out the usual tracheal intubation after the preliminary administration of muscle relaxants, which is not entirely desirable (prolonged shutdown of breathing against the background of hypoxia, difficult recovery of consciousness, further oppression of cardiac activity) , or try to insert an endotracheal tube into the fuck through the nose. A smooth tube without a cuff with a pronounced bend, lubricated with sterile petroleum jelly, is inserted through the nasal passage towards the trachea under visual control with direct laryngoscopy using guiding intubation forceps or forceps.
If direct laryngoscopy is not possible, an attempt should be made to introduce an endotracheal tube into the trachea through the nose, using as a control the appearance of breath sounds in the lungs when air is blown into them.
Thus, in cardiopulmonary resuscitation, all methods of mechanical ventilation can be successfully applied. Naturally, expiratory ventilation methods such as mouth-to-mouth or mouth-to-nose breathing should only be used when manual ventilators are not available at the scene.
Each doctor should familiarize himself with the technique of endotracheal intubation, since in some cases only the introduction of an endotracheal tube into the trachea can provide adequate ventilation and prevent severe complications associated with regurgitation and aspiration of stomach contents.
For prolonged mechanical ventilation, volumetric respirators of the RO-2, RO-5, RO-6 type are used. As a rule, ventilation is carried out through an endotracheal tube. The ventilation mode is selected depending on the indicators of the partial tension of carbon dioxide, oxygen in arterial blood; IVL is carried out in the mode of moderate hyperventilation. To synchronize the operation of the respirator with the patient's spontaneous breathing, morphine hydrochloride (1 ml of a 1% solution), seduxen (1-2 ml of a 0.5% solution), sodium oxybutyrate (10-20 ml of a 20% solution) are used. True, it is not always possible to achieve the desired effect. Before introducing muscle relaxants, you should make sure that the airway is patent. And only with a sharp excitation of the patient (not associated with hypoxia due to errors in mechanical ventilation), when narcotic drugs do not lead to the shutdown of spontaneous breathing, short-term muscle relaxants can be used (ditilin 1-2 mg / kg of body weight). Tubocurarine and other non-depolarizing muscle relaxants are dangerous to use due to the possibility of further lowering blood pressure.
Prof. A.I. Gritsyuk
"In what cases is artificial ventilation of the lungs, methods of mechanical ventilation" section
Human life and health are the greatest values on Earth. No amount of wealth or material possessions will help bring back the loss of a loved one. There are many emergency situations and health conditions that directly threaten human life (accidents, emergencies, sudden respiratory or cardiac arrest).
In such cases, timely resuscitation is of great importance. Before the arrival of the ambulance, they are often forced to provide eyewitnesses at the scene. Any delay is fatal.
One of the main components of resuscitation is artificial ventilation of the lungs - maintaining life in the human body by blowing air.
The main indications and methods of IVL
Artificial ventilation of the lungs is carried out according to vital indications. Resuscitation should be started only if there are a combination of signs indicating clinical death. If at least 1 sign of life is present, mechanical ventilation is prohibited.
Signs of clinical death can be considered:
- lack of breathing (easy to determine with a mirror);
- lack of consciousness (the person does not respond to the voice);
- absence of a pulse on the carotid artery (place 3 fingers on the left and right sides of the neck at the level of the Adam's apple);
- the pupil does not react to light (determined by a directed beam of light).
Methods of artificial lung ventilation are emergency and their use involves the achievement of the main goal - the return of a person to life, which is possible only with:
- restoration of heartbeat and breathing;
- improvement of oxygen metabolism;
- preventing brain cell death.
Artificial ventilation of the lungs is most often necessary for:
So what is mechanical ventilation?
The natural gas exchange of the lungs is a change of inspirations (phases of high volume) and exhalations (phases of low volume), artificial - the restoration of this ability of the human body through outside help.
The technique of artificial lung ventilation involves resuscitation in a strictly defined sequence, which must not be violated. There are several IVL techniques, each of which has its own procedure (Table 1).
Table 1 - Methods of artificial lung ventilation
| Name of technique | Action algorithm |
|---|---|
| mouth to mouth |
|
| mouth to nose | Follow the same steps as with the previous technique with one difference: breathe into the victim's nose with the mouth tightly closed. The technique is relevant for jaw injuries, convulsions and spasms. |
| Using the C-tube |
|
These techniques are applicable before medical care, do not require special medical education and are easy to perform.
Hardware modes and types of artificial lung ventilation
Hardware ventilation of the lungs is carried out only by specialists using special equipment in a hospital after clinical studies: measuring the respiratory rate, the presence of consciousness, measuring the respiratory volume. Types of mechanical ventilation carried out using the equipment are classified according to the mechanism of action (Table 2).
Table 2 - Types of hardware artificial lung ventilation
| Mode Type | Main characteristics | Indications |
|---|---|---|
| IVL with volume control | Represents the delivery of a fixed volume of air to the lungs, regardless of respiratory pressure | Hypoxemic respiratory failure |
| Ventilator with pressure control | The volume of air is not fixed, but depends on the difference between the operating pressure of the apparatus and the pressure in the patient's lungs, as well as on the duration of inspiration and the person's respiratory efforts. | Bronchopleural fistula, childhood (patients who cannot be sealed) |
Procedure modes
The modes of artificial ventilation of the lungs differ in the way the equipment is used:
The advantage of assisted ventilation is the synchronization of the operation of the equipment and the person, the ability to refuse the use of sedatives and hypnotics during resuscitation.
This mode responds to changes in lung mechanics and is comfortable for the patient. Ventilation modes are determined depending on the following factors:
- the presence (absence) of spontaneous breathing;
- insufficiency of respiratory activity;
- apnea (stop breathing);
- hypoxia (oxygen starvation of the body).
Types of equipment for ventilation
In modern resuscitation practice, the following artificial respiration apparatuses are widely used, which carry out the forced delivery of oxygen to the respiratory tract and the removal of carbon dioxide from the lungs:
Table 3 - The action of high-frequency equipment for ventilation
Possible complications of mechanical ventilation and conduct in newborns
Artificial lung ventilation has no contraindications for use, except for the presence of foreign bodies in the patient's airways. However, artificial ventilation can have some negative consequences. The most common complications of IVL are:
This type of resuscitation has found its application in neonatal departments and pediatric resuscitation. Its use is shown for:
The absolute basics of ventilators include:
- convulsions;
- pulse less than 100 beats per minute;
- persistent cyanosis (blue skin and mucous membranes of the child).
Clinical indicators of the need for ventilation of the lungs:
- arterial hypotension;
- lung bleeding;
- bradycardia;
- recurrent apnea;
- developmental defects.
Resuscitation actions are carried out under the control of heart rate, respiratory rate and blood pressure. To avoid the development of pneumonia and tracheobronchitis, vibration massage of the child's chest, disinfection of the endotracheal tube and conditioning of the respiratory mixture are carried out.
In newborns, a pressure-assisted ventilation mode is used, which neutralizes air leakage during ventilation. This mode synchronizes and supports every breath of a small patient. No less popular is the synchronized mode, which allows the equipment to adapt to the spontaneous breathing of a newborn. This significantly reduces the risk of developing pneumothorax and cardiac hemorrhages.
Currently, children's intensive care units are equipped with neonatal ventilation devices that meet all the requirements of the child's body and control blood pressure, evenly distribute oxygen in the lungs, maintain air flow, and neutralize air leakage.
If breathing is disturbed, the patient is artificially ventilated or mechanically ventilated. It is used when the patient cannot breathe on his own or when he lies 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, the second one requires an understanding of the design of medical equipment.
In medicine, mechanical ventilation is understood as the artificial blowing of air into the lungs in order to ensure gas exchange between the environment and the alveoli. Artificial ventilation can be used as a resuscitation measure when a person has serious violations of spontaneous breathing, or as a means to protect against lack of oxygen. The latter condition occurs during anesthesia or diseases of a spontaneous nature.
Forms of artificial ventilation are hardware and direct. The first uses a gas mixture for breathing, which is pumped into the lungs by a machine through an endotracheal tube. Direct implies rhythmic contraction and unclenching of the lungs to ensure passive inhalation-exhalation without the use of a device. If an "electric lung" is applied, the muscles are stimulated by the impulse.
Indications for IVL
To carry out artificial ventilation and maintain the normal functioning of the lungs, there are indications:
- sudden cessation of blood circulation;
- mechanical asphyxia of breath;
- injuries of the chest, brain;
- acute poisoning;
- a sharp decrease in blood pressure;
- cardiogenic shock;
- asthma attack.
After operation
The endotracheal tube of the ventilator 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:
- exclusion of expectoration of sputum and secretions from the lungs, which reduces the frequency of infectious complications;
- reducing the need for support of the cardiovascular system, reducing the risk of lower deep venous thrombosis;
- creating conditions for feeding through a tube to reduce the frequency 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 the state of sleep and wakefulness.
With pneumonia
If the patient develops severe pneumonia, this quickly leads to the development of acute respiratory failure. Indications for the use of artificial ventilation in this disease are:
- disorders of consciousness and psyche;
- lowering blood pressure to a critical level;
- intermittent breathing more than 40 times per minute.
Artificial ventilation is carried out in the early stages of the development of the disease in order to increase work efficiency and reduce the risk of death. IVL lasts 10-14 days, 3-4 hours after insertion of the tube, a tracheostomy is performed. If the pneumonia is massive, it is carried out with positive end-expiratory pressure (PEEP) for better lung distribution and reduced venous shunting. Together with the intervention of mechanical ventilation, intensive antibiotic therapy is carried out.
With a stroke
The connection of mechanical ventilation in the treatment of stroke is considered a rehabilitation measure for the patient and is prescribed for indications:
- internal bleeding;
- lung damage;
- pathology in the field of respiratory function;
- coma.
During an ischemic or hemorrhagic attack, shortness of breath is observed, which is restored by a ventilator in order to normalize the lost brain functions and provide the cells with a sufficient amount of oxygen. They put artificial lungs for a stroke for up to two weeks. During this time, a change in the acute period of the disease passes, swelling of the brain decreases. Get rid of the ventilator if possible, as soon as possible.
Types of IVL
Modern methods of artificial ventilation are divided into two conditional groups. Simple ones are used in emergency cases, and hardware ones - in a hospital setting. The former can be used if a person does not have independent breathing, he has an acute development of respiratory rhythm disturbance or a pathological regimen. Simple methods include:
Ventilation modes in intensive care
The artificial respiration apparatus 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 an adult and a child, different devices are used, differing in the size of the device being inserted and in the adjustable respiratory rate. Hardware ventilation is carried out in a high-frequency mode (more than 60 cycles per minute) in order to reduce the respiratory 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 continuous or intermittent flow vibration;
- jet - 100-300 per minute, is the most popular, with it oxygen or a mixture of gases under pressure is blown into the airways using a needle or a thin catheter, other options are an endotracheal tube, tracheostomy, a catheter through the nose or skin.
In addition to the considered methods, which differ in the frequency of breathing, ventilation modes are distinguished according to the type of apparatus used:
Ventilator
In the resuscitation mode or postoperative ward, a ventilator is used. This medical equipment is needed to supply a gas mixture of oxygen and dry air to the lungs. Forced mode is used to saturate cells and blood with oxygen and remove carbon dioxide from the body. There are several types of ventilators:
- by type of equipment used - endotracheal tube, tracheostomy, mask;
- according to the applied algorithm of work - manual, mechanical, with neuro-controlled lung ventilation;
- by age - for children, adults, newborns;
- by drive - pneumomechanical, electronic, manual;
- by appointment - general, special;
- in the applied field - intensive care unit, resuscitation, postoperative department, anesthesiology, newborns.
Technique for artificial lung ventilation
Doctors use ventilators to perform artificial ventilation. After examining the patient, the doctor sets the frequency and depth of breaths, selects the gas mixture. Gases for constant breathing are supplied through a hose connected to the 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. With prolonged ventilation, the endotracheal tube is inserted into the hole through the anterior wall of the trachea.
Problems during mechanical ventilation
After installing the ventilator and during its operation, problems may arise:
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 artificial ventilation as soon as possible, taking into account the clinical situation. The indication for weaning is the positive dynamics of recovery with 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 fever or infection, apnea;
- blood counts are stable.
Before weaning from the respirator, the remnants of muscle blockade are checked, and the dose of sedatives is reduced to a minimum. There are the following modes of weaning from artificial ventilation:
- spontaneous breathing test - temporary shutdown of the device;
- synchronization with one's own attempt to inhale;
- pressure support - the device picks up all attempts to inhale.
If the patient has the following symptoms, it cannot be disconnected from artificial ventilation:
- anxiety;
- chronic pain;
- convulsions;
- dyspnea;
- decrease in respiratory volume;
- tachycardia;
- high blood pressure.
Consequences
After using a ventilator or other method of artificial ventilation, side effects are not excluded:
- bronchitis, bedsores of the bronchial mucosa, fistulas;
- pneumonia, bleeding;
- pressure reduction;
- sudden cardiac arrest;
- urolithiasis disease;
- mental disorders;
- pulmonary edema.
Complications
Dangerous complications of mechanical ventilation during the use of a special device or long-term therapy with it are not excluded:
- worsening of the patient's condition;
- loss of spontaneous breathing;
- pneumothorax - accumulation of fluid and air in the pleural cavity;
- compression of the lungs;
- slippage of the tube into the bronchi with the formation of a wound.
Video
The information presented in the article is for informational purposes only. The materials of the article do not call for self-treatment. Only a qualified doctor can make a diagnosis and give recommendations for treatment based on the individual characteristics of a particular patient.
- Classical and fractional duodenal sounding are procedures in which bile secretions are taken from a patient for analysis using a probe. Properly conducted fluid sampling helps to identify pathologies, detect helminthiasis inside ......
- Urological massage of the prostate, urethra and other pelvic organs in men is necessary for prostatitis, congestion, chronic inflammatory diseases. An unpleasant procedure should be carried out under strict control ......
- Respiratory diseases are one of the most common diseases today. People who have a predisposition to such diseases should definitely know about pneumosclerosis of the lungs, because the disease requires the right approach to treatment, ......
- Inflammation of the lungs is a very serious disease, which in medicine is officially called pneumonia. The disease ranks 4th in mortality after strokes, heart attacks and oncology. The hottest question today....
- The most common symptoms that bronchiectasis causes are a persistent cough and purulent sputum from the respiratory organs. The development of the inflammatory process leads to irreversible deformation and functional impairment.
- Today, due to the variety of antibacterial drugs, diseases of the lungs and bronchi are less common than even 20-30 years ago. If the disease still affects a person, then it is difficult, ......
- Active influence on certain zones - acupressure helps to cope with many diseases and pathological conditions that are harmful to the human body. Oriental doctors are sure that massaging BAT (biologically active...
- The cosmetology industry does not stand still, periodically replenishing its stock of unique techniques. Most women who are dissatisfied with age-related skin changes do not want to go under the surgical knife and are looking for alternative options.......
- This type of surgical intervention is perhaps the most common in proctology. In a situation where you are assigned a hemorrhoidectomy - what is it you can find out from your doctor, who ......
- A pleasant period of waiting for a baby for a future mother is often associated with vascular problems complicated by a headache. The use of the popular drug Citramon during pregnancy can have a negative impact on a woman's health.
- With extensive pathologies of the knee joint, surgery is recommended. Arthroscopy is not only a surgical intervention, but also a diagnostic measure aimed at determining the real state of the articular structures, the contents of the cavity...
0
One of the main tasks of the intensive care unit (ICU) is to provide adequate respiratory support. In this regard, for specialists working in this field of medicine, it is especially important to correctly navigate the indications and types of artificial lung ventilation (ALV).
Indications for mechanical ventilation
The main indication for artificial lung ventilation (ALV) is the patient's respiratory failure. Other indications include prolonged awakening of the patient after anesthesia, impaired consciousness, lack of protective reflexes, and fatigue of the respiratory muscles. The main goal of artificial lung ventilation (ALV) is to improve gas exchange, reduce the work of breathing and avoid complications when the patient wakes up. Regardless of the indication for mechanical ventilation (ALV), the underlying disease must be potentially reversible, otherwise weaning from mechanical ventilation (ALV) is not possible.
Respiratory failure
Respiratory failure is the most common indication for respiratory support. This condition occurs in situations where there is a violation of gas exchange, leading to hypoxemia. may occur alone or be associated with hypercapnia. The causes of respiratory failure can be different. So, the problem can arise at the level of the alveolocapillary membrane (pulmonary edema), the airways (rib fracture), etc.
Causes of respiratory failure
Inadequate gas exchange
Causes of inadequate gas exchange:
- pneumonia,
- pulmonary edema,
- acute respiratory distress syndrome (ARDS).
Inadequate breathing
Causes of inadequate breathing:
- chest wall injury
- rib fracture,
- floating segment;
- respiratory muscle weakness
- myasthenia gravis, poliomyelitis,
- tetanus;
- depression of the central nervous system:
- psychotropic drugs,
- dislocation of the brain stem.
Airway obstruction
Causes of airway obstruction:
- upper airway obstruction:
- croup,
- edema,
- tumor;
- obstruction of the lower respiratory tract (bronchospasm).
In some cases, indications for artificial lung ventilation (ALV) are difficult to determine. In this situation, clinical circumstances should be taken into account.
The main indications for mechanical ventilation
There are the following main indications for artificial lung ventilation (ALV):
- Respiratory rate (RR) >35 or< 5 в мин;
- Fatigue of the respiratory muscles;
- Hypoxia - general cyanosis, SaO2< 90% при дыхании кислородом или PaO 2 < 8 кПа (60 мм рт. ст.);
- Hypercapnia - PaCO 2 > 8 kPa (60 mm Hg);
- Decreased level of consciousness;
- Severe chest injury;
- Tidal volume (TO)< 5 мл/кг или жизненная емкость легких (ЖЕЛ) < 15 мл/кг.
Other indications for mechanical ventilation (ALV)
In a number of patients, artificial lung ventilation (ALV) is performed as a component of intensive care for conditions not associated with respiratory pathology:
- Control of intracranial pressure in traumatic brain injury;
- Respiratory protection ();
- Condition after cardiopulmonary resuscitation;
- The period after long and extensive surgical interventions or severe trauma.
Types of artificial lung ventilation
Intermittent positive pressure ventilation (IPPV) is the most common mode of mechanical ventilation (ALV). In this mode, the lungs are inflated by positive pressure generated by a ventilator, and gas flow is delivered through an endotracheal or tracheostomy tube. Tracheal intubation is usually performed through the mouth. With prolonged artificial lung ventilation (ALV), patients in some cases better tolerate nasotracheal intubation. However, nasotracheal intubation is technically more difficult to perform; in addition, it is accompanied by a higher risk of bleeding and infectious complications (sinusitis).
Tracheal intubation not only allows IPPV, but also reduces the amount of "dead space"; in addition, it facilitates the toilet of the respiratory tract. However, if the patient is adequate and available for contact, mechanical ventilation (ALV) can be performed non-invasively through a tightly fitting nasal or face mask.
In principle, two types of ventilators are used in the intensive care unit (ICU) - adjustable according to a pre-set tidal volume (TO) and inspiratory pressure. Modern artificial lung ventilation (ALV) devices provide various types of artificial lung ventilation (ALV); From a clinical point of view, it is important to choose the type of artificial lung ventilation (ALV) that is most suitable for this particular patient.
Types of mechanical ventilation
Artificial lung ventilation (ALV) by volume
Artificial lung ventilation (ALV) by volume is carried out in those cases when the ventilator delivers a predetermined tidal volume to the patient's airways, regardless of the pressure set on the respirator. Airway pressure is determined by the compliance (stiffness) of the lungs. If the lungs are rigid, the pressure rises sharply, which can lead to the risk of barotrauma (rupture of the alveoli, which leads to pneumothorax and mediastinal emphysema).
Artificial lung ventilation (ALV) by pressure
Artificial lung ventilation (ALV) by pressure means that the ventilator (ALV) reaches a predetermined pressure level in the airways. Thus, the delivered tidal volume is determined by lung compliance and airway resistance.
Modes of artificial lung ventilation
Controlled mechanical ventilation (CMV)
This mode of artificial lung ventilation (ALV) is determined solely by the settings of the respirator (airway pressure, tidal volume (TO), respiratory rate (RR), inspiratory to expiratory ratio - I: E). This mode is not very often used in intensive care units (ICUs), as it does not provide synchronization with the patient's spontaneous breathing. As a result, CMV is not always well tolerated by the patient, requiring sedation or the administration of muscle relaxants to stop the "fight with the ventilator" and normalize gas exchange. As a rule, the CMV mode is widely used in the operating room during anesthesia.
Assisted mechanical ventilation (AMV)
There are several modes of ventilation to support the patient's attempts at spontaneous respiratory movements. In this case, the ventilator catches the attempt to inhale and supports it.
These modes have two main advantages. First, they are better tolerated by patients and reduce the need for sedative therapy. Secondly, they allow you to save the work of the respiratory muscles, which prevents their atrophy. The patient's breathing is supported by a predetermined inspiratory pressure or tidal volume (TO).
There are several types of auxiliary ventilation:
Intermittent mechanical ventilation (IMV)
Intermittent mechanical ventilation (IMV) is a combination of spontaneous and mandatory breaths. Between forced breaths, the patient can breathe independently, without ventilator support. The IMV mode provides the minimum minute ventilation, but may be accompanied by significant variations between mandatory and spontaneous breaths.
Synchronized intermittent mechanical ventilation (SIMV)
In this mode, mandatory breaths are synchronized with the patient's own breathing attempts, which provides him with greater comfort.
Pressure-support ventilation - PSV or assisted spontaneous breaths - ASB
When you try your own breathing movement, a pre-set pressure breath is delivered into the airways. This type of assisted ventilation provides the patient with the greatest comfort. The degree of pressure support is determined by the level of airway pressure and may gradually decrease during weaning from mechanical ventilation (ALV). Forced breaths are not given, and ventilation depends entirely on whether the patient can attempt spontaneous breathing. Thus, PSV mode does not provide apnea ventilation; in this situation, its combination with SIMV is shown.
Positive end expiratory pressure (PEEP)
Positive end expiratory pressure (PEEP) is used in all types of IPPV. During expiration, positive airway pressure is maintained to inflate collapsed lung regions and prevent distal airway atelectasis. As a result, they improve. However, PEEP leads to an increase in intrathoracic pressure and can reduce venous return, which leads to a decrease in blood pressure, especially in the presence of hypovolemia. When using PEEP up to 5-10 cm of water. Art. these negative effects, as a rule, can be corrected by infusion loading. Continuous positive airway pressure (CPAP) is effective to the same extent as PEEP, but is used primarily in the context of spontaneous breathing.
Start of artificial ventilation
At the beginning of artificial lung ventilation (ALV), its main task is to provide the patient with the physiologically necessary tidal volume (DO) and respiratory rate (RR); their values are adapted to the initial state of the patient.
| Fio 2 | At the beginning of artificial lung ventilation (ALV) 1.0, then a gradual decrease |
| PEEP | 5 cm aq. Art. |
| Tidal volume (TO) | 7-10 ml/kg |
| Inspiratory pressure | |
| Respiratory rate (RR) | 10-15 per min |
| Pressure support | 20 cm w.c. Art. (15 cm wg above PEEP) |
| I:E | 1:2 |
| Flow Trigger | 2 l/min |
| pressure trigger | -1 to -3 cm aq. Art. |
| "Sighs" | Previously intended for the prevention of atelectasis, currently their effectiveness is disputed |
| These settings are changed depending on the clinical condition and comfort of the patient. | |
Optimization of oxygenation during mechanical ventilation
When transferring a patient to artificial lung ventilation (ALV), as a rule, it is recommended to initially set FiO 2 = 1.0, followed by a decrease in this indicator to the value that would allow maintaining SaO 2 > 93%. In order to prevent lung damage due to hyperoxia, it is necessary to avoid maintaining FiO 2 > 0.6 for a long time.
One strategy to improve oxygenation without increasing FiO 2 may be to increase mean airway pressure. This can be achieved by increasing the PEEP to 10 cmH2O. Art. or, in pressure-controlled ventilation, by increasing peak inspiratory pressure. However, it should be remembered that with an increase in this indicator\u003e 35 cm of water. Art. dramatically increases the risk of pulmonary barotrauma. Against the background of severe hypoxia (), it may be necessary to use additional methods of respiratory support aimed at improving oxygenation. One of these directions is a further increase in PEEP > 15 cm of water. Art. In addition, a low tidal volume strategy (6-8 ml/kg) can be used. It should be remembered that the use of these techniques may be accompanied by arterial hypotension, which is most common in patients receiving massive fluid therapy and inotropic / vasopressor support.
Another direction of respiratory support against the background of hypoxemia is an increase in inspiratory time. Normally, the ratio of inhalation to exhalation is 1:2; in case of oxygenation disorders, it can be changed to 1:1 or even 2:1. It should be remembered that an increase in inspiratory time may not be well tolerated by those patients who require sedation. A decrease in minute ventilation may be accompanied by an increase in PaCO 2 . This situation is called "permissive hypercapnia". From a clinical point of view, it does not present any special problems, except for those moments when it is necessary to avoid an increase in intracranial pressure. In permissive hypercapnia, it is recommended to maintain an arterial blood pH above 7.2. In severe ARDS, the prone position can be used to improve oxygenation by mobilizing collapsed alveoli and improving the balance between ventilation and lung perfusion. However, this provision makes it difficult to monitor the patient, so it must be applied with sufficient caution.
Improving the elimination of carbon dioxide during mechanical ventilation
Carbon dioxide removal can be improved by increasing minute ventilation. This can be achieved by increasing the tidal volume (TO) or respiratory rate (RR).
Sedation during mechanical ventilation
Most patients who are on mechanical ventilation (ALV) require in order to adapt to the stay of the endotracheal tube in the airways. Ideally, only light sedation should be administered, while the patient should remain contactable and at the same time adapted to ventilation. In addition, it is necessary that the patient be able to attempt spontaneous respiratory movements while under sedation in order to eliminate the risk of atrophy of the respiratory muscles.
Problems during mechanical ventilation
"Fan Fight"
When desynchronized with a respirator during artificial lung ventilation (ALV), a drop in tidal volume (TO) is noted, due to an increase in inspiratory resistance. This leads to inadequate ventilation and hypoxia.
There are several causes of desynchronization with a respirator:
- Factors due to the patient's condition - breathing directed against inhalation by the artificial lung ventilation apparatus (ALV), holding the breath, coughing.
- Reduced lung compliance - lung pathology (pulmonary edema, pneumonia, pneumothorax).
- Increased resistance at the level of the respiratory tract - bronchospasm, aspiration, excessive secretion of the tracheobronchial tree.
- Ventilator disconnection or , leakage, equipment failure, blockage of the endotracheal tube, torsion or dislocation.
Diagnosing ventilation problems
High airway pressure due to obstruction of the endotracheal tube.
- The patient could pinch the tube with his teeth - enter the air duct, prescribe sedatives.
- Airway obstruction due to excessive secretion - suction the contents of the trachea and, if necessary, lavage the tracheobronchial tree (5 ml saline NaCl). If necessary, reintubate the patient.
- The endotracheal tube has shifted into the right main bronchus - pull the tube back.
High airway pressure as a result of intrapulmonary factors:
- Bronchospasm? (wheezing on inhalation and exhalation). Make sure that the endotracheal tube is not inserted too deep and does not stimulate the carina. Give bronchodilators.
- Pneumothorax, hemothorax, atelectasis, pleural effusion? (uneven chest excursions, auscultatory picture). Take a chest x-ray and prescribe appropriate treatment.
- Pulmonary edema? (Foamy sputum, bloody, and crepitus). Give diuretics, treat heart failure, arrhythmias, etc.
Sedation / analgesia factors:
- Hyperventilation due to hypoxia or hypercapnia (cyanosis, tachycardia, arterial hypertension, sweating). Increase FiO2 and mean airway pressure using PEEP. Increase minute ventilation (for hypercapnia).
- Cough, discomfort or pain (increased heart rate and blood pressure, sweating, facial expression). Assess for possible causes of discomfort (located endotracheal tube, full bladder, pain). Assess the adequacy of analgesia and sedation. Switch to the ventilation mode that is best tolerated by the patient (PS, SIMV). Muscle relaxants should be prescribed only in cases where all other causes of desynchronization with the respirator have been excluded.
Weaning from mechanical ventilation
Artificial lung ventilation (ALV) can be complicated by barotrauma, pneumonia, decreased cardiac output, and a number of other complications. In this regard, it is necessary to stop artificial lung ventilation (ALV) as soon as possible, as soon as the clinical situation allows.
Weaning from the respirator is indicated in cases where there is a positive trend in the patient's condition. Many patients receive mechanical ventilation (ALV) for a short period of time (for example, after prolonged and traumatic surgical interventions). In a number of patients, in contrast, mechanical ventilation (ALV) is carried out for many days (for example, ARDS). With prolonged artificial lung ventilation (ALV), weakness and atrophy of the respiratory muscles develop; therefore, the rate of weaning from the respirator largely depends on the duration of artificial lung ventilation (ALV) and the nature of its modes. Assisted ventilation modes and adequate nutritional support are recommended to prevent respiratory muscle atrophy.
Patients recovering from critical conditions are at risk for the occurrence of "polyneuropathy of critical conditions". This disease is accompanied by weakness of the respiratory and peripheral muscles, decreased tendon reflexes, and sensory disturbances. Treatment is symptomatic. There is evidence that long-term use of muscle relaxants from the group of aminosteroids (vecuronium) can cause persistent muscle paralysis. In this regard, vecuronium is not recommended for long-term neuromuscular blockade.
Indications for weaning from mechanical ventilation
The decision to initiate weaning from a respirator is often subjective and based on clinical experience.
However, the most common indications for weaning from mechanical ventilation (ALV) are the following conditions:
- Adequate therapy and positive dynamics of the underlying disease;
- Breathing function:
- BH< 35 в мин;
- Fio 2< 0,5, SaO2 >90% PEEP< 10 см вод. ст.;
- DO > 5 ml/kg;
- VC > 10 ml/kg;
- Minute ventilation< 10 л/мин;
- No infection or hyperthermia;
- Hemodynamic stability and EBV.
There should be no evidence of residual neuromuscular block before weaning begins, and the dose of sedatives should be kept to a minimum to maintain adequate contact with the patient. In the event that the patient's consciousness is depressed, in the presence of arousal and the absence of a cough reflex, weaning from artificial lung ventilation (ALV) is ineffective.
Weaning Modes
It is still unclear which of the methods of weaning from artificial lung ventilation (ALV) is the most optimal.
There are several main modes of weaning from a respirator:
- Spontaneous breathing test without ventilator support. Temporarily turn off the ventilator (ALV) and connect a T-piece or breathing circuit to the endotracheal tube for CPAP. The periods of spontaneous breathing gradually lengthen. Thus, the patient gets the opportunity for a full-fledged work of breathing with periods of rest when artificial lung ventilation (ALV) is resumed.
- Weaning using the IMV mode. The respirator delivers to the patient's airways a set minimum volume of ventilation, which is gradually reduced as soon as the patient is able to increase the work of breathing. In this case, the hardware breath can be synchronized with the own attempt to inspire (SIMV).
- Weaning with pressure support. In this mode, the device picks up all attempts to inhale the patient. This weaning method involves a gradual reduction in pressure support. Thus, the patient becomes responsible for increasing the volume of spontaneous ventilation. With a decrease in the level of pressure support to 5-10 cm of water. Art. above PEEP, you can start a spontaneous breathing test with a T-piece or CPAP.
Impossibility of weaning from artificial lung ventilation
In the process of weaning from artificial lung ventilation (ALV), it is necessary to closely monitor the patient in order to promptly identify signs of fatigue of the respiratory muscles or inability to wean from the respirator. These signs include restlessness, dyspnea, decreased tidal volume (TR) and hemodynamic instability, primarily tachycardia and hypertension. In this situation, it is necessary to increase the level of pressure support; it often takes many hours for the respiratory muscles to recover. It is optimal to start weaning from the respirator in the morning to ensure reliable monitoring of the patient's condition throughout the day. With prolonged weaning from mechanical ventilation (ALV), it is recommended to increase the level of pressure support for the night period to ensure adequate rest for the patient.
Tracheostomy in the intensive care unit
The most common indication for tracheostomy in the ICU is to relieve prolonged mechanical ventilation (ALV) and the process of weaning from the respirator. Tracheostomy reduces the level of sedation and thus improves the possibility of contact with the patient. In addition, it provides an effective toilet of the tracheobronchial tree in those patients who are unable to self-drain sputum as a result of its excess production or weakness of muscle tone. A tracheostomy can be done in the operating room like any other surgical procedure; in addition, it can be performed in the ICU at the patient's bedside. For its implementation is widely used. The time to switch from an endotracheal tube to a tracheostomy is determined individually. As a rule, a tracheostomy is performed if the likelihood of prolonged mechanical ventilation (ALV) is high or there are problems with weaning from the respirator. Tracheostomy can be accompanied by a number of complications. These include tube blockage, tube disposition, infectious complications, and bleeding. Bleeding can directly complicate surgery; in the late postoperative period, it can be erosive in nature due to damage to large blood vessels (for example, the innominate artery). Other indications for tracheostomy are obstruction of the upper respiratory tract and protection of the lungs from aspiration when the laryngeal-pharyngeal reflexes are suppressed. In addition, a tracheostomy may be performed as part of an anesthetic or surgical management for a number of interventions (eg laryngectomy).
Liked a medical article, news, lecture on medicine from the category
