Complications of prolonged IVL. Connection to a ventilator - indications and treatment

In addition to knowledge of the methodological and (patho-) physiological foundations, first of all, some experience is necessary.

In the hospital, ventilation is carried out through an endotracheal or tracheostomy tube. If ventilation is expected for more than one week, a tracheostomy should be performed.

To understand ventilation, the different modes and possible ventilation settings, the normal respiratory cycle can be considered as a basis.

When considering the pressure/time graph, it becomes clear how changes in a single breath parameter can affect the respiratory cycle as a whole.

IVL indicators:

• Respiratory rate (strokes per minute): each change in respiration rate with the same inspiratory duration affects the inspiratory/expiratory ratio
• Inhale/exhale ratio
• Tidal volume
• Relative minute volume: 10-350% (Galileo, ASV mode)
• Inspiratory pressure (P insp), approximate settings (Drager: Evita/Oxylog 3000):
  • IPPV: PEEP = lower pressure level
  • BIPAP: P tief = lower pressure level (=PEEP)
  • IPPV: P plat = upper pressure level
  • BIPAP: P hoch = upper pressure level
• Flow (volume/time, tinspflow)
• "Rise rate" (rate of pressure rise, time to plateau): in obstructive disorders (COPD, asthma) a higher initial flow ("rise") is needed to rapidly change the pressure in the bronchial system
• Duration of plateau flow → = plateau → : the plateau phase is the phase during which widespread gas exchange occurs in different areas of the lung
• PEEP (Positive End Expiratory Pressure)
• Oxygen concentration (measured as a fraction of oxygen)
• Peak respiratory pressure
• Maximum upper pressure limit = stenosis limit
• Pressure difference between PEEP and P reac (Δp) = pressure difference required to overcome the compliance (= elasticity = resistance to compression) of the respiratory system
• Flow/Pressure Trigger: The flow trigger or pressure trigger serves as the “trigger point” for initiating pressure-assisted/pressure-assisted breaths in assisted ventilation techniques. When triggered by flow (l/min), a certain air flow rate in the patient's lungs is required to inhale through the breathing apparatus. If the trigger is pressure, a certain negative pressure (“vacuum”) must first be reached in order to inhale. The desired trigger mode, including the trigger threshold, is set on the breathing apparatus and must be selected individually for the period of artificial ventilation. The advantage of the flow trigger is that the “air” is in a state of motion and the inspiratory air (=volume) is delivered to the patient more quickly and easily, which reduces the work of breathing. When initiating flow before flow occurs (=inspiration), a negative pressure must be reached in the patient's lungs.
• Breathing periods (using Evita 4 as an example):
  • IPPV: inspiratory time - T I expiratory time = T E
  • BIPAP: inspiratory time - T hoch , expiratory time = T tief
• ATC (automatic tube compensation): flow-proportional pressure maintenance to compensate for tube-related turbodynamic drag; to maintain calm spontaneous breathing, a pressure of about 7-10 mbar is needed.

Artificial lung ventilation (ALV)

Negative pressure ventilation (NPV)

The method is used in patients with chronic hypoventilation (eg, poliomyelitis, kyphoscoliosis, muscle diseases). Exhalation is passive.

The most famous are the so-called iron lungs, as well as pectoral cuirass devices in the form of a semi-rigid device around the chest and other handicraft devices.

This mode of ventilation does not require tracheal intubation. However, patient care is difficult, so VOD is the method of choice only in an emergency. The patient can be switched to negative pressure ventilation as a method of weaning from mechanical ventilation after extubation, when the acute period of the disease has passed.

In stable patients requiring prolonged ventilation, the "turning bed" method can also be used.

Intermittent positive pressure ventilation

Artificial ventilation of the lungs (ALV): indications

Impaired gas exchange due to potentially reversible causes of respiratory failure:

• Pneumonia.
• Worsening course of COPD.
• Massive atelectasis.
• Acute infectious polyneuritis.
• Cerebral hypoxia (for example, after cardiac arrest).
• Intracranial hemorrhage.
• intracranial hypertension.
• Massive traumatic or burn injury.

There are two main types of ventilators. Pressure-controlled machines blow air into the lungs until the desired pressure is reached, then the inspiratory flow stops and after a short pause, passive exhalation occurs. This type of ventilation has advantages in patients with ARDS, as it allows to reduce peak airway pressure without affecting the performance of the heart.

Volume-controlled devices deliver a predetermined tidal volume into the lungs for a set inspiratory time, maintain that volume, and then passive expiration occurs.

Nasal ventilation

Nasal intermittent ventilation with CPAP creates patient-triggered positive airway pressure (CPAP) while allowing exhalation to the atmosphere.

Positive pressure is generated by a small machine and delivered through a tight-fitting nasal mask.

Often used as a home night ventilation method in patients with severe musculoskeletal chest disease or obstructive sleep apnea.

It can be successfully used as an alternative to conventional mechanical ventilation in patients who do not need to create CPAP, for example, with an attack of bronchial asthma, COPD with CO2 retention, and also with difficult weaning from mechanical ventilation.

In the hands of experienced staff, the system is easy to operate, but some patients use this equipment as well as medical professionals. The method should not be used by inexperienced personnel.

Positive Airway Pressure Ventilation

Permanent forced ventilation

Continuous mandatory ventilation delivers a set tidal volume at a set respiratory rate. The duration of inspiration is determined by the respiratory rate.

The minute volume of ventilation is calculated by the formula: TO x respiratory rate.

The ratio of inhalation and exhalation during normal breathing is 1:2, but in pathology it can be disturbed, for example, in bronchial asthma, due to the formation of air traps, an increase in expiratory time is required; in adult respiratory distress syndrome (ARDS), accompanied by a decrease in lung compliance, some lengthening of the inspiratory time is useful.

Complete sedation of the patient is required. If the patient's own breathing is maintained against the background of constant forced ventilation, spontaneous breaths can overlap with hardware breaths, which leads to overinflation of the lungs.

Prolonged use of this method leads to atrophy of the respiratory muscles, which creates difficulties in weaning from mechanical ventilation, especially if combined with proximal myopathy on the background of glucocorticoid therapy (for example, in bronchial asthma).

Ventilator cessation can occur quickly or by weaning, when the function of breathing control is gradually transferred from the device to the patient.

Synchronized Intermittent Mandatory Ventilation (SIPV)

PWV allows the patient to breathe spontaneously and effectively ventilate the lungs, while gradually switching the function of breathing control from the ventilator to the patient. The method is useful in weaning patients with reduced respiratory muscle strength. And also in patients with acute lung diseases. Continuous mandatory ventilation in the presence of deep sedation reduces oxygen demand and work of breathing, providing more efficient ventilation.

Synchronization methods differ between ventilator models, but they have in common that the patient independently initiates breathing through the ventilator circuit. Typically, the ventilator is set so that the patient receives the minimum sufficient number of breaths per minute, and if the spontaneous breathing rate falls below the set ventilation rate, the ventilator delivers mandatory breaths at the set rate.

Most ventilators that ventilate in the CPAP mode have the ability to perform several modes of positive pressure support for spontaneous breathing, which makes it possible to reduce the work of breathing and ensure effective ventilation.

Pressure support

Positive pressure is created at the moment of inspiration, which allows you to partially or completely help the implementation of inspiration.

This mode can be used in conjunction with synchronized mandatory intermittent ventilation or as a means of maintaining spontaneous breathing in assisted ventilation modes during the weaning process.

The mode allows the patient to set their own breathing rate and ensures adequate lung expansion and oxygenation.

However, this method is applicable in patients with adequate lung function while maintaining consciousness and without fatigue of the respiratory muscles.

Positive end-expiratory pressure method

PEEP is a predetermined pressure that is applied only at the end of exhalation to maintain lung volume, prevent alveolar and airway collapse, and open atelectatic and fluid-filled lungs (eg, in ARDS and cardiogenic pulmonary edema).

The PEEP mode allows you to significantly improve oxygenation by including more lung surface in gas exchange. However, the trade-off for this advantage is an increase in intrathoracic pressure, which can significantly reduce venous return to the right side of the heart and thus lead to a decrease in cardiac output. At the same time, the risk of pneumothorax increases.

Auto-PEEP occurs when air is not completely out of the respiratory tract before the next breath (for example, with bronchial asthma).

The definition and interpretation of DZLK against the background of PEEP depends on the location of the catheter. DZLK always reflects the venous pressure in the lungs, if its values ​​exceed the values ​​of PEEP. If the catheter is in an artery at the apex of the lung where pressure is normally low due to gravity, the pressure detected is most likely alveolar pressure (PEEP). In dependent zones, the pressure is more accurate. The elimination of PEEP at the time of DPLV measurement causes significant fluctuations in hemodynamics and oxygenation, and the obtained PDEP values ​​will not reflect the state of hemodynamics when switching to mechanical ventilation again.

Cessation of ventilation

Termination of mechanical ventilation according to the schedule or protocol reduces the duration of ventilation and reduces the rate of complications, as well as costs. In mechanically ventilated patients with neurologic injury, the re-intubation rate was reduced by more than half (12.5 vs. 5%) with a structured technique for stopping ventilation and extubation. After (self-)extubation, most patients do not develop complications or require re-intubation.

Attention: It is in neurological diseases (for example, Guillain-Barré syndrome, myasthenia gravis, a high level of spinal cord injury) that stopping mechanical ventilation can be difficult and prolonged due to muscle weakness and early physical exhaustion or due to neuronal damage. In addition, high-level damage to the spinal cord or brainstem can lead to impaired protective reflexes, which, in turn, greatly complicates the termination of ventilation or makes it impossible (damage at C1-3 altitude → apnea, C3-5 → respiratory failure of varying degrees expressiveness).

Pathological types of breathing or violations of the mechanics of breathing (paradoxical breathing when the intercostal muscles are turned off) can also partially impede the transition to spontaneous breathing with sufficient oxygenation.

The termination of mechanical ventilation includes a step-by-step decrease in the intensity of ventilation:

• F i O 2 reduction
• Normalization of the ratio of inhalation - and doha (I: E)
• Decreased PEEP
• Reducing the holding pressure.

Approximately 80% of patients stop mechanical ventilation successfully. In about 20% of cases, termination fails at first (- difficult cessation of mechanical ventilation). In certain groups of patients (for example, with damage to the structure of the lungs in COPD), the failure rate is 50-80%.

There are the following methods of stopping IVL:

• Training of atrophied respiratory muscles → enhanced forms of ventilation (with a step-by-step decrease in machine breathing: frequency, maintenance pressure or volume)
• Recovery of exhausted/overworked respiratory muscles → controlled ventilation alternates with a spontaneous phase of breathing (eg, 12-8-6-4 hour rhythm).

Daily attempts at spontaneous intermittent breathing immediately after waking up can have a positive effect on the duration of ventilation and stay in the ICU and not become a source of increased stress for the patient (due to fear, pain, etc.). In addition, you should adhere to the rhythm of "day / night."

Prognosis of cessation of mechanical ventilation can be done based on various parameters and indexes:

• Rapid shallow breathing index
• This indicator is calculated based on the respiratory rate/inspiratory volume (in liters).
• RSB<100 вероятность прекращения ИВЛ
• RSB > 105: Termination unlikely
• Oxygenation index: target P a O 2 /F i O 2 > 150-200
• Airway occlusive pressure (p0.1): p0.1 is the pressure on the closed valve of the respiratory system during the first 100 ms of inspiration. It is a measure of the basic respiratory impulse (= patient effort) during spontaneous breathing.

Normally, the occlusal pressure is 1-4 mbar, with pathology > 4-6 mbar (-> cessation of mechanical ventilation / extubation is unlikely, the threat of physical exhaustion).

extubation

Criteria for performing extubation:

• A conscious, cooperative patient
• Confident spontaneous breathing (eg, "T-connection/tracheal ventilation") for at least 24 hours
• Stored defensive reflexes
• Stable condition of the heart and circulatory system
• Respiratory rate less than 25 per minute
• Vital capacity of lungs more than 10 ml/kg
• Good oxygenation (PO 2 > 700 mm Hg) with low F i O 2 (< 0,3) и нормальном PСО 2 (парциальное давление кислорода может оцениваться на основании насыщения кислородом
• No significant comorbidities (eg, pneumonia, pulmonary edema, sepsis, severe traumatic brain injury, cerebral edema)
• Normal state of metabolism.

Preparation and holding:

• Inform the conscious patient about extubation
• Before extubation, conduct a blood gas analysis (guidelines)
• Approximately one hour before extubation, give 250 mg of prednisolone intravenously (prevention of glottic edema)
• Aspirate contents from the pharynx/trachea and stomach!
• Loosen the fixation of the tube, unlock the tube and, while continuing to suck the contents, pull the tube out
• Administer oxygen to the patient through a nasal tube
• Over the next hours, carefully monitor the patient and monitor blood gases regularly.

Complications of artificial ventilation

• Increasing incidence of nosocomial or ventilator-related pneumonia: The longer the patient is ventilated or intubated, the greater the risk of nosocomial pneumonia.
• Deterioration of gas exchange with hypoxia due to:
  • right-to-left shunt (atelectasis, pulmonary edema, pneumonia)
  • violations of the perfusion-ventilation ratio (bronchoconstriction, accumulation of secretions, dilation of the pulmonary vessels, for example, under the influence of drugs)
  • hypoventilation (insufficient own breathing, gas leakage, incorrect connection of the breathing apparatus, increase in physiological dead space)
  • violations of the function of the heart and blood circulation (syndrome of low cardiac output, a drop in blood flow volumetric velocity).
• Damage to lung tissue due to the high concentration of oxygen in the inhaled air.
• Hemodynamic disorders, primarily due to changes in lung volume and intrathoracic pressure:
  • decreased venous return to the heart
  • increase in pulmonary vascular resistance
  • a decrease in ventricular end-diastolic volume (reduction in preload) and a subsequent decrease in stroke volume or volumetric blood flow velocity; hemodynamic changes due to mechanical ventilation are influenced by the characteristics of the volume and pumping function of the heart.
• Reduced blood supply to the kidneys, liver, and spleen
• Decreased urination and fluid retention (with resulting edema, hyponatremia, reduced lung compliance)
• Respiratory muscle atrophy with weakened respiratory pump
• During intubation - bedsores of the mucous membrane and damage to the larynx
• Ventilation-related lung injury due to cyclic collapse and subsequent opening of atelectatic or unstable alveoli (alveolar cycle) and alveolar hyperdistension at the end of inspiration
• Barotrauma/volumetric lung injury with "macroscopic" lesions: emphysema, pneumomediastinum, pneumoepicardium, subcutaneous emphysema, pneumoperitoneum, pneumothorax, bronchopleural fistulas
• Increased intracranial pressure due to impaired venous outflow from the brain and reduced blood supply to the brain due to vasoconstriction of cerebral vessels with (permissible) hypercapnia

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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 various. So, the problem can occur 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.

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:

1. 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.
2. 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).
3. 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).

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Mechanical ventilation is mainly used to treat ventilatory insufficiency, pulmonary congestion and edema, and low cardiac output syndrome.

ventilation failure. There are three main groups of patients with ventilation insufficiency requiring mechanical ventilation. The first group consists of patients with relatively normal lungs, but with depression of the respiratory center. The range of this group is quite wide: from patients with postoperative depression of the respiratory center (caused by drugs), requiring mechanical ventilation for several hours, to patients whose respiratory center is affected by embolism, an episode of hypoxia or cardiac arrest, and requiring mechanical ventilation for a period of many days. The best indicator that determines the need for artificial ventilation is the level of arterial pCO 2 above 55-60 mm Hg. st., although other factors may influence the decision of this issue. For example, many patients develop metabolic alkalosis after cardiopulmonary bypass, associated with the preoperative use of diuretics (causing potassium loss) and the utilization of large amounts of citrate from preserved blood. With severe metabolic alkalosis, respiratory depression occurs, which leads to normalization of pH. Under these conditions (for example, with BE+ 10 mEq/l and pCO 2 60 mmHg), resorting to artificial ventilation of the patient would be an obvious mistake.

The second group, related to ventilation insufficiency, includes elderly and middle-aged patients with chronic pulmonary diseases. They often have increased physiological dead space, venous admixture, and airway resistance. The treatment of such patients presents a certain problem, since the use of unguided oxygen therapy can lead to hypercapnia, and controlled oxygen therapy does not always completely normalize the reduced arterial pCO 2 . The use of isoprenaline * and other bronchodilators increases the risk of hypercapnia and hypoxemia (Fordham, Resnekoy, 1968). Therefore, it may be necessary to transfer the patient to artificial ventilation earlier than in patients without concomitant lung diseases. In such cases, the decision on the use of mechanical ventilation should be based on a thorough analysis of the functions of the heart and breathing.

Assessment of the condition of patients in the third group also encounters certain difficulties. These patients usually clearly show signs of respiratory failure, however, changes in blood gases are much less pronounced than one would expect, judging by the clinical condition of the patients. This is explained by the fact that a large number of factors are involved in the occurrence of ventilation failure. The production of a significant amount of secretion, scattered areas of atelectasis, congestion in the lungs, pleural effusion and a large heart - all this leads to a significant increase in the work of breathing. At the same time, a decrease in cerebral blood flow, hypoxemia, sedatives and toxemia can cause depression of the respiratory center. In the end, there comes a point when the resistance to breathing exceeds the patient's ability to provide adequate ventilation - ventilation failure occurs. Therefore, setting indications for mechanical ventilation in such patients is determined mainly by clinical signs and largely depends on the presence of external manifestations of respiratory disorders. These signs include an increase in the respiratory rate (over 30-35 per minute in an adult and over 40-45 per minute in children), which acquires a "grunting" difficult character with the use of auxiliary muscles. The patient looks exhausted, hardly pronounces more than a few words, loses interest in the environment. Increased heart rate (over 100-120 beats per minute in adults and over 130 beats per minute in children) and some dimming of consciousness indicate the need for urgent action. Blood gases in these cases often do not reflect the severity of the patient's condition. Arterial pCO 2 rarely exceeds 50-55 mm Hg. Art. However, sometimes low arterial pO 2 indicates a marked increase in right-to-left shunting and possibly a fall in cardiac output. The latter can usually be determined from the low pO 2 of mixed venous blood.

When establishing indications for mechanical ventilation, it is necessary to take into account the history, the nature of the operation performed, the general course of the postoperative period and the presence of respiratory disorders. In general, mechanical ventilation is resorted to earlier in patients with previous lung diseases and a complex nature of the defect, especially if there is doubt about the radicalness of the operation. The occurrence of pulmonary edema also serves as an indication for an earlier start of treatment. Thus, mechanical ventilation should be used earlier in a patient undergoing radical correction of Fallot's tetrad than in a patient operated on for a simple ventricular septal defect. Similarly, tracheostomy and mechanical ventilation may be used prophylactically at the end of surgery in a patient with severe left atrial pressure and a history of chronic lung disease undergoing mitral valve replacement surgery. It should be noted that the respiratory disorders that have appeared can subsequently progress extremely quickly.

Pulmonary edema. Identification of stagnation in the lungs or their edema during X-ray examination cannot be considered a sufficient indication for mechanical ventilation. The situation should be assessed taking into account the anamnesis, changes in pressure in the left atrium and A - apO 2 . In a patient with a long-term increase in pressure in the left atrium, edema develops relatively rarely. However, an increase in pressure in the left atrium above the initial level can be considered as the most important indicator in favor of the start of mechanical ventilation. Very useful information is also given by the value of A - apO 2 when breathing pure oxygen. This indicator should be used to assess the effectiveness of treatment. If A - apO 2 while breathing 100% oxygen, despite all the measures taken, continues to grow or if under the same conditions arterial pO 2 falls below 100-200 mm Hg. Art., undoubtedly should resort to artificial ventilation.

Syndromes of "small cardiac output" and "postperfusion lungs". Since the correct selection of patients for surgery and surgical technique have improved significantly in recent years, the first of these syndromes is less common. A patient with low cardiac output has cyanosis, peripheral vasoconstriction, and low arterial pressure combined with high venous pressure. Urination is reduced or absent. Metabolic acidosis is often observed. Gradually there comes a darkening of consciousness. pO 2 of mixed venous blood is usually low. Sometimes the peripheral circulation is so limited that most peripheral tissues are not perfused. In this case, mixed venous pO 2 may be normal despite low cardiac output. These patients, almost as a rule, have completely clear lungs and there is no indication for mechanical ventilation ** except for the possibility of a decrease in the work of breathing. Since its increase in such patients is unlikely, the need for artificial ventilation is highly doubtful.

On the other hand, data have been obtained that make it possible to consider mechanical ventilation unconditionally expedient in "postperfusion pulmonary syndrome". As already mentioned, a characteristic feature of this syndrome is a pronounced increase in venous admixture and intrapulmonary shunting from right to left. Similar phenomena occur in all patients operated under cardiopulmonary bypass, but their severity varies greatly from patient to patient. To a large extent, shunting is due to the presence of exudate in the alveoli, which determines a rather slow rate of normalization. However, there is always another component associated with the occurrence of atelectasis. In this case, vigorous physical therapy and prolonged mechanical ventilation can help. The effect of the remaining shunts can be attenuated by the application of 100% oxygen. Since the work of breathing is known to be increased in this condition, its reduction will further improve arterial oxygenation. This increases the saturation of the mixed venous blood and thus blunts the effect of shunting on arterial oxygenation. Thus, it can be concluded that although mechanical ventilation can reduce cardiac output (Grenvik, 1966), the reduction in work of breathing and total venous admixture usually more than compensates for this shift. As a result, the general condition of the patient improves significantly.

* β-Stimulator. The drug is also known by other names: isuprel, isoproterenol, isadrin, novodrin.

** The point of view of the authors seems to us at least controversial, since both our experience and the observations of other authors (V. I. Burakovsky et al., 1971) indicate the undoubted benefits of artificial ventilation in the syndrome of "low cardiac output", naturally combination with other therapeutic measures (approx. transl.).

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

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

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.

Artificial lung ventilation- provides gas exchange between the surrounding air (or a specially selected mixture of gases) and the alveoli of the lungs.

Modern methods of artificial lung ventilation (ALV) can be divided into simple and hardware. Simple methods are usually used in emergency situations: in the absence of spontaneous breathing (apnea), with acutely developed respiratory rhythm disturbance, its pathological rhythm, agonal type breathing: with an increase in breathing of more than 40 in 1 min, if it is not associated with hyperthermia (body temperature above 38.5 °) or severe uncorrected hypovolemia; with increasing hypoxemia and (or) hypercapnia, if they do not disappear after anesthesia, restoration of airway patency, oxygen therapy, elimination of a life-threatening level of hypovolemia and severe metabolic disorders. Simple methods primarily include expiratory methods of mechanical ventilation (artificial respiration) from mouth to mouth and from mouth to nose. In this case, the head of the patient or the victim must necessarily be in the position of maximum occipital extension to prevent retraction of the tongue and ensure airway patency; the root of the tongue and the epiglottis are displaced anteriorly and open the entrance to the larynx. The caregiver stands on the side of the patient, with one hand compresses the wings of his nose, tilting his head back, with the other hand slightly opens his mouth by the chin. Taking a deep breath, he presses his lips tightly to the patient's mouth and makes a sharp energetic exhalation, after which he turns his head to the side. The exhalation of the patient occurs passively due to the elasticity of the lungs and chest. It is desirable that the assisting person's mouth be insulated with a gauze pad or a piece of bandage, but not with a dense cloth. With mechanical ventilation from mouth to nose, air is blown into the nasal passages of the patient. At the same time, his mouth is closed, pressing the lower jaw to the upper one and trying to pull his chin up. Air blowing is usually carried out with a frequency of 20-25 per 1 min; when combined with mechanical ventilation and cardiac massage - With frequency 12-15 in 1 min. Carrying out simple mechanical ventilation is greatly facilitated by the introduction of an S-shaped air duct into the oral cavity of the patient, the use of Ruben's bag ("Ambu", RDA-1) or RPA-1 fur through the oral mask. In this case, it is necessary to ensure the patency of the respiratory tract and tightly press the mask to the face of the patient.

Hardware methods (with the help of special respirators) are used if necessary for long-term ventilation (from several hours to several months and even years). In the USSR, the most common are RO-6A in its modifications (RO-6N for anesthesia and RO-6R for intensive care), as well as a simplified model of RO-6-03. The Phase-50 respirator has great potential. For pediatric practice, the apparatus "Vita-1" is produced. The first domestic device for jet high-frequency ventilation is the Spiron-601 respirator

The respirator is usually attached to the patient's airway through an endotracheal tube or tracheostomy cannula. More often, hardware ventilation is carried out in the normal frequency mode - 12-20 cycles per 1 min. The practice also includes mechanical ventilation in high-frequency mode (more than 60 cycles per 1 min), in which the tidal volume is significantly reduced (up to 150 ml and less), positive pressure in the lungs at the end of inspiration and intrathoracic pressure decrease, blood flow to the heart is less obstructed. In addition, with mechanical ventilation in high-frequency mode, the patient's adaptation to the respirator is facilitated.

There are three methods of high-frequency ventilation (volumetric, oscillatory and jet). Volumetric is usually carried out with a respiratory rate of 80-100 in 1 min, oscillatory - 600-3600 in 1 min, providing vibration of a continuous or discontinuous (in the standard frequency mode) gas flow. The most widely used jet high-frequency ventilation with a respiratory rate of 100-300 per 1 min, in which into the respiratory tract through a needle or catheter with a diameter of 1-2 mm a jet of oxygen or a gas mixture is blown under pressure 2-4 atm. Jet ventilation can be carried out through an endotracheal tube or tracheostomy (in this case, injection occurs - atmospheric air is sucked into the respiratory tract) and through a catheter inserted into the trachea through the nasal passage or percutaneously (puncture). The latter is especially important in cases where there are no conditions for tracheal intubation or the medical staff do not have the skill to perform this procedure.

Artificial lung ventilation can be carried out in automatic mode, when the patient's spontaneous breathing is completely suppressed by pharmacological preparations or specially selected parameters of lung ventilation. It is also possible to carry out auxiliary ventilation, in which the patient's independent breathing is preserved. Gas supply is carried out after a weak attempt by the patient to inhale (trigger mode of auxiliary ventilation), or the patient adapts to an individually selected mode of operation of the apparatus.

There is also an Intermittent Mandatory Ventilation (PMV) mode, commonly used during the gradual transition from mechanical ventilation to spontaneous breathing. In this case, the patient breathes on his own, but a continuous stream of heated and humidified gas mixture is supplied to the airways, which creates some positive pressure in the lungs throughout the entire respiratory cycle. Against this background, with a given frequency (usually from 10 to 1 time per 1 min), the respirator produces an artificial breath, coinciding (synchronized PPVL) or not coinciding (non-synchronized LLVL) with the next independent breath of the patient. The gradual reduction of artificial breaths allows you to prepare the patient for spontaneous breathing.

The mode of ventilation with positive end-expiratory pressure (PEEP) from 5 to 15 has become widespread. see aq. Art. and more (according to special indications!), at which the intrapulmonary pressure during the entire respiratory cycle remains positive relative to atmospheric pressure. This mode contributes to the best distribution of air in the lungs, reducing blood shunting in them and reducing the alveolar-arterial oxygen difference. With artificial ventilation of the lungs with PEEP, atelectasis is straightened out, pulmonary edema is eliminated or reduced, which helps to improve arterial blood oxygenation at the same oxygen content in the inhaled air.

The relatively rarely used method of mechanical ventilation, electrical stimulation of the diaphragm, has not lost its significance. Periodically irritating either the phrenic nerves or directly to the diaphragm through external or needle electrodes, it is possible to achieve its rhythmic contraction, which ensures inspiration. Diaphragm electrical stimulation is more often used as a method of auxiliary ventilation in the postoperative period, as well as in preparing patients for surgical interventions.

With the modern anesthetic aid, mechanical ventilation is carried out primarily due to the need to ensure muscle relaxation with curare-like drugs. Against the background of mechanical ventilation, it is possible to use a number of analgesics in doses sufficient for full anesthesia, the introduction of which in conditions of spontaneous breathing would be accompanied by arterial hypoxemia. By maintaining good oxygenation of the blood, mechanical ventilation helps the body cope with the surgical injury. In a number of surgical interventions on the organs of the chest (lungs, esophagus), separate bronchial intubation is used, which makes it possible to turn off one lung from ventilation during the operation to facilitate the work of the surgeon. Such intubation also prevents the contents from the operated lung from flowing into the healthy lung. In surgical interventions on the larynx and respiratory tract, transcatheter jet high-frequency ventilation is successfully used, which facilitates the examination of the surgical field and allows maintaining adequate gas exchange with the trachea and bronchi opened. Given that under conditions of general anesthesia and muscle relaxation, the patient cannot respond to hypoxia and hypoventilation, control over the content of blood gases is of particular importance, in particular, constant monitoring of the partial pressure of oxygen (pO 2) and partial pressure of carbon dioxide (pCO 2) percutaneous through special sensors. When performing general anesthesia in malnourished, debilitated patients, especially in the presence of respiratory failure before surgery, with severe hypovolemia, the development of any complications during general anesthesia that contribute to the occurrence of hypoxia (decrease in blood pressure, cardiac arrest, etc.), continuation of mechanical ventilation in within a few hours after the end of surgery. In case of clinical death or agony, mechanical ventilation is a mandatory component of resuscitation. It can be stopped only after a complete recovery of consciousness and full independent breathing.

In complex intensive care IVL is the most powerful means of dealing with acute respiratory failure. It is usually carried out through a tube that is inserted into the trachea through the lower nasal passage or tracheostomy. Of particular importance is the careful care of the respiratory tract, their full drainage. At pulmonary edema, pneumonia, adult respiratory distress syndrome artificial ventilation of the lungs is indicated with PEEP sometimes up to 15 see aq. st. and more. If hypoxemia persists even with high PEEP, the combined use of traditional and jet high-frequency ventilation is indicated.

Auxiliary ventilation is used in sessions up to 30-40 min in the treatment of patients with chronic respiratory tract. It can be used in outpatient clinics and even at home after appropriate training of the patient.

ALV is used in patients who are in a coma (trauma, brain surgery), as well as with peripheral damage to the respiratory muscles (polyradiculoneuritis, spinal cord injury, lateral amyotrophic). In the latter case, mechanical ventilation has to be carried out for a very long time - months and even years, which requires especially careful patient care. ALV is also widely used in the treatment of patients with chest trauma, postpartum eclampsia, various poisonings, cerebrovascular accidents, om, om.

Control of adequacy of IVL. When carrying out emergency ventilation using simple methods, it is sufficient to observe the color of the skin and movements of the patient's chest. The chest wall should rise with each inhalation and fall with each exhalation. If instead the epigastric region rises, then the blown air does not enter the respiratory tract, but into the esophagus and stomach. The cause is most often the wrong position of the patient's head.

When conducting long-term mechanical ventilation, its adequacy is judged by a number of signs. If the patient's spontaneous breathing is not pharmacologically suppressed, one of the main signs is the patient's good adaptation to the respirator. With a clear mind, the patient should not have a feeling of lack of air, discomfort. Breath sounds in the lungs should be the same on both sides, the skin has a normal color, dry. Signs of inadequacy of mechanical ventilation are increasing, a tendency to arterial hypertension, and when using artificial ventilation with PEEP - to hypotension, which is a sign of a decrease in blood flow to the heart. It is extremely important to control pO 2 , pCO 2 and the acid-base state of the blood, pO 2 during mechanical ventilation should be maintained at least 80 mmHg st. In severe hemodynamic disorders (massive blood loss, traumatic or cardiogenic), it is desirable to increase pO 2 to 150 mmHg st. and higher. pCO 2 should be maintained by changing the minute volume and respiratory rate, at the maximum level at which the patient fully adapts to the respirator (usually 32-36 mmHg st.). In the process of prolonged mechanical ventilation, metabolic acidosis or metabolic alkalosis should not occur. . The first most often indicates violations of the peripheral circulation and microcirculation, the second - about hypokalemia and cellular hypohydration.