Lecture No. 5. Emergency conditions in pulmonology

Acute respiratory failure is a pathological condition of the body in which the function of the external respiration apparatus is insufficient to provide the body with oxygen and adequate removal of carbon dioxide.

Normal tidal volume (TO) is 500 ml (alveolar ventilation - 350 ml, dead space 150 ml). Minute volume of ventilation (MOV) - 6-8 l. Oxygen consumption - 300 ml/min. In the exhaled air, oxygen is 16%, in the inhaled - 21%. Oxygen in the inhaled mixture should be at least 20%.

Causes of acute respiratory failure: a violation of the central regulation of breathing or a mismatch between ventilation and blood flow at the level of respirons - the final structural and functional units of the lungs. Overdose of narcotic substances (inhalation), narcotic analgesics, acute cerebral edema, cerebrovascular accident, brain tumors, reduced airway lumen or complete obstruction, retraction of the tongue, a large amount of sputum, especially in patients with suppurative lung diseases (abscess, bilateral bronchiectasis), pulmonary hemorrhage, vomiting and aspiration, laryngospasm and bronchospasm.

When the tongue is retracted, an air duct should be placed or it is most reliable to intubate and artificially ventilate. With the accumulation of sputum, it is necessary to force the patient to expectorate it. If the patient is unconscious, then the respiratory tract is sanitized. In severe patients, anesthesia and active sanitation are performed. Catheterization of the trachea, bronchial tree and removal of the contents are performed.

1. Laryngospasm

Laryngospasm is the closure of the true and false vocal cords. In both cases, control agents (eufillin) are necessarily used. If this does not help, it is necessary to introduce short-acting muscle relaxants, intubate and transfer the patient to mechanical ventilation. Muscle relaxants cause respiratory failure in the postoperative period if sufficient decurarization is not performed. It is usually produced by anticholinesterase drugs (prozerin). By the time of extubation, it is necessary to make sure that strength and muscle tone have recovered (ask to raise a hand, squeeze a hand, raise a head).

With multiple fractures of the ribs, part of the chest sinks during inhalation, the so-called paradoxical breathing develops, so it is necessary to restore the chest frame. For this patient, it is necessary to intubate, after introducing relaxants, with further transfer to mechanical ventilation (until the integrity of the chest is restored).

The following leads to a decrease in the functioning lung parenchyma: atelectasis, lung collapse, pneumonia, the consequences of surgery, pneumo-, hemo-, pyothorax. Differences between atelectasis and collapse: atelectasis is an obstruction in a straightened state. This condition is characterized by the presence of an unventilated lung through which half of the circulating blood passes, the latter is not oxygenated. As a result, acute respiratory failure develops. When the lung collapses, it is compressed by air or fluid in the pleural cavity. At the same time, blood circulation in the compressed lung decreases sharply, and blood circulation in a healthy lung increases. Therefore, collapse is not as dangerous a complication in terms of the development of acute respiratory failure as atelectasis. Before surgery, the function of the intact lung should be assessed (separate spirography).

According to the stage of development, acute respiratory failure is divided into:

1) dysfunction;

2) insufficiency;

3) failure of prosthetic function.

According to the rate of development, acute respiratory failure is divided into:

1) lightning fast (develops within a minute);

2) acute (develops within a few hours);

3) subacute (develops within a few days);

4) chronic (lasts for years).

The main elements of intensive care for acute respiratory failure: oxygen therapy, drainage position of the patient, fibrobronchoscopy, tracheostomy, intubation and mechanical ventilation, bronchodilation, hormone therapy, HBO.

2. Pulmonary embolism

Pulmonary embolism (PE) is a blockage of the main or middle trunk, small vascular trunks of the pulmonary artery, leading to an increase in pressure in the pulmonary circulation, right ventricular failure.

Predisposing factors

Diseases of the cardiovascular system - atherosclerosis, rheumatic heart disease, rheumatic malformations, septic endocarditis. Diseases of the veins of the lower extremities, pathology of the organs and vessels of the small pelvis. Postoperative PE in particular require close attention. Most often, embolism develops during operations on: vessels of the lower extremities, bladder, female genital organs, prostate gland, pelvic bones and hip joint. Changes in the system of hemostasis, spontaneous fibrinolysis, retraction and organization of venous thrombi are essential. Patients with oncological diseases, obesity, circulatory insufficiency, who are forced to stay in bed for various reasons, are also at the greatest risk.

Clinical classification of PE

Form: heavy, medium and light.

Downstream: fulminant, acute, recurrent.

According to the level of damage to the pulmonary artery: trunk or main branches, lobar (segmental) branches, small branches.

Clinic and diagnostics

The clinical course of PE is quite variable. The most common symptoms are sudden onset of shortness of breath (RR ranges from 30 to more than 50 per minute), rapid breathing, pallor, more often cyanosis, swelling of the jugular veins, tachycardia, arterial hypotension (up to shock), retrosternal pain, cough and hemoptysis. Auscultation often determines the strengthening of the II tone over the pulmonary artery.

X-ray signs - an increase in the size of the proximal pulmonary artery, depletion of the peripheral pattern, as well as raising the dome of the diaphragm.

The ECG may reveal overload of the right departments (cor pulmonale):

1) the appearance of Q waves with a simultaneous increase in the amplitude of the R and S waves (QS syndrome);

2) rotation of the heart around the longitudinal axis with the right ventricle forward (shift of the transition zone to the left chest leads);

3) ST segment elevation with negative T wave in leads III, aVF, V1-V3;

4) the appearance or increase in the degree of blockade of the right leg of the bundle of His;

5) high pointed "pulmonary" tooth P with a deviation of its electrical axis to the right;

6) sinus tachycardia or tachysystolic form of atrial fibrillation.

Echocardiography allows detecting acute cor pulmonale, determining the severity of hypertension in the pulmonary circulation, assessing the structural and functional state of the right ventricle, detecting thromboembolism in the heart cavities and in the main pulmonary arteries, visualizing an open foramen ovale, which can affect the severity of hemodynamic disorders and be the cause of paradoxical embolism . However, a negative echocardiographic result by no means rules out the diagnosis of pulmonary embolism.

The most informative diagnostic method is pulmonary artery angiography.

For preventive purposes, anticoagulants are used in the postoperative period. The dose of heparin is 10 IU per day (000 IU 2 times). In the presence of contraindications, anticoagulants are not prescribed. Contraindications include: severe brain damage; oncopathology with the potential for bleeding; thrombocytopenia; pulmonary tuberculosis; severe chronic diseases of the parenchyma of the liver and kidneys with functional insufficiency.

Treatment

Anticoagulant therapy. Anticoagulants can prevent secondary thrombosis in the pulmonary vascular bed and the progression of venous thrombosis. It is advisable to widely use low molecular weight heparins (dalteparin, eioxaparin, fraxiparin), which, in comparison with conventional unfractionated heparin, rarely cause hemorrhagic complications, have less effect on platelet function, have a longer duration of action and high bioavailability.

thrombolytic therapy. In massive PE, thrombolytic therapy is indicated and justified in cases where the volume of the lesion is relatively small, but pulmonary hypertension is pronounced. Most often, streptokinase is used at a dose of 100 units per hour. But one should be aware of severe allergic reactions. The duration of thrombolysis is usually 000-1 days. Urokinase and alteplase are devoid of antigenic properties, but have high resistance.

Surgery. Embolectomy is indicated for patients with thromboembolism of the pulmonary trunk or both of its main branches with an extremely severe degree of impaired lung perfusion, accompanied by pronounced hemodynamic disorders. All manipulations to remove emboli after cross-clamping of the vena cava should last no more than 3 minutes, since this interval is critical for patients who are operated on under conditions of severe initial hypoxia. It is optimal to perform embolectomy under cardiopulmonary bypass using transsternal access.

3. Bronchial asthma

Bronchial asthma is a disease based on chronic inflammation of the airways with an autoimmune component, accompanied by a change in the sensitivity and reactivity of the bronchi, manifested by an attack or the status of suffocation, with constant symptoms of respiratory discomfort, against the background of a hereditary predisposition to allergic diseases.

Classification

The classification of bronchial asthma is as follows.

1. Stages of development of asthma:

1) biological defects in practically healthy people;

2) the state of preastma;

3) clinically pronounced asthma.

2. Clinical and pathogenetic variants:

1) atopic;

2) infectious-dependent;

3) autoimmune;

4) dishormonal;

5) neuro-psychic;

6) aspirated;

7) primary altered bronchial reactivity.

3. The severity of the course of the disease:

1) lung;

2) moderate;

3) heavy.

4. Flow phases:

1) exacerbation;

2) unstable remission;

3) stable remission (more than 2 years).

5. Complications:

1) pulmonary - atelectasis, pneumothorax, acute pulmonary insufficiency;

2) extrapulmonary - cor pulmonale, heart failure.

6. By etiology:

1) atopic (exogenous, allergic, immunological);

2) non-atopic (endogenous, non-immunological).

Clinical criteria for the degree of BA are given in Table 2.

Table 2

Clinical criteria for assessing the severity of asthma

asthmatic status

Asthmatic status is a non-stopping attack of bronchial asthma, characterized by acute obstructive respiratory failure during the day. The main distinguishing features of status asthmaticus are the lack of effect of conventional bronchodilatory therapy and an unproductive debilitating cough.

The classification of status asthmaticus is shown in Table 3.

Table 3

Classification of status asthmaticus (Sorokina T. A., 1987)

AS is characterized by severe shortness of breath of an expiratory nature with the participation of the auxiliary muscles of the chest and anterior abdominal wall in the act of breathing, accompanied by a change in the color of the skin - pallor, hyperemia, cyanosis. The skin may be dry and hot or cold and damp. Tachypnea is characteristic, the respiratory rate is usually more than 30 per 1 min.

Auscultatory listening to the musical sound associated with the passage of air through the narrowed bronchioles. With the progression of the process, the well-known phenomenon of "silent zones" of the lungs occurs, which indicates broncho-obstruction of this region of the lungs. Characterized by tachycardia, increased blood pressure and cardiac output (MOS). Decreased systolic blood pressure during inspiration. Dehydration and hypovolemia develop. Fluid loss occurs mainly through the respiratory tract and skin. The volume of circulating blood (CBV) is usually reduced by an average of 10% and very rarely increased. Significantly increase blood viscosity and hematocrit to 0,50-0,60, which creates a real threat of pulmonary thromboembolism and requires the appointment of heparin. The concentration of proteins is increased, general dehydration is manifested by thirst, dryness of the tongue, increased plasma osmolality, and oliguria. Central venous pressure (CVP) is reduced to 2-5 cm of water. Art. Hypovolemia predisposes to collapse, which is especially important when transferring patients to mechanical ventilation. Initially, there is excitement, then mental disorders and "respiratory panic", which is associated with a feeling of lack of air. In the future, irritability, confusion, lethargy (up to stupor and coma) sets in. Respiratory acidosis develops.

Emergency treatment of status asthmaticus

Oxygen therapy. Moistened oxygen is inhaled₂ through nasal catheters or through a mask at a rate of 1-2 l / min.

Adrenaline stimulates a1-, b1- and b2-adrenergic receptors, dilates the bronchi and reduces airway resistance. It is administered subcutaneously: with a body weight of less than 60 kg - 0,3 ml, with a weight of 60 to 80 kg - 0,4 ml, with a weight of more than 80 kg - 0,5 ml. Eufillin inhibits phosphodiesterase, which contributes to the accumulation of cAMP and the removal of bronchospasm. When prescribing aminophylline, contraindications should be taken into account, which include smoking and childhood, heart failure and acute coronary syndrome, chronic diseases of the lungs, liver and kidneys.

With AS, the loading dose of aminophylline is 3-6 mg/kg, it is administered intravenously over 20 minutes. Then, a maintenance drip infusion of the drug is carried out at the rate of 0,6 mg/kg per 1 hour for a patient without concomitant pathology, 0,8 mg/kg per 1 hour for a smoker, 0,2 mg/kg per 1 hour for congestive heart failure, pneumonia , diseases of the liver and kidneys, 0,4 mg / kg per 1 hour for severe chronic lung diseases.

The effect of corticosteroid therapy is associated with the suppression of airway inflammation and increased sensitivity to b-adrenergic drugs. The more severe the AS, the greater the indication for immediate corticosteroid therapy. A high dose of corticosteroids should be administered initially. The minimum dose is 30 mg of prednisolone or 100 mg of hydrocortisone, or 4 mg of dexamethasone (celeston). If therapy is ineffective, the dose is increased. At least every 6 hours, appropriate equivalent doses of these drugs are administered. Most patients are shown inhalation therapy with b-adrenergic agonists; (fenoterol, alupent, salbutamol). Exceptions are cases of drug overdose of sympathomimetics.

If the ongoing therapy does not give an effect, intravenous administration of b-adrenergic agonists, such as isoproterenol, diluted in a 5% glucose solution, is indicated. Contraindications are heart disease (coronary cardiosclerosis, myocardial infarction), severe tachycardia and symptoms of tachyphylaxis, old age. The rate of administration of isoproterenol is 0,1 μg / kg per 1 min until the onset of tachycardia (HR 130 per 1 min or more).

Infusion therapy is the most important component of the treatment of AS, aimed at replenishing fluid deficiency and eliminating hypovolemia, the total volume of infusion therapy is 3-5 liters per day. Hydration is carried out by introducing solutions containing a sufficient amount of free water (glucose solutions), as well as hypo- and isotonic electrolyte solutions containing sodium and chlorine. Indicators of adequate hydration are the cessation of thirst, a wet tongue, the restoration of normal diuresis, improved sputum evacuation, and a decrease in hematocrit to 0,30-0,40.

Halothane anesthesia can be used in the treatment of a severe asthma attack that is not amenable to conventional therapy.

Artificial ventilation of the lungs. Indications for the transfer of patients with AS to mechanical ventilation should be very strict, since in this state it often causes complications and is characterized by high mortality. At the same time, mechanical ventilation, if it is carried out according to strict indications, is the only method that can prevent further progression of hypoxia and hypercapnia.

Indications for IVL:

1) steady progression of AS, despite intensive therapy;

2) increase in pCO₂ and hypoxemia, confirmed by a series of tests;

3) progression of CNS symptoms and coma;

4) increasing fatigue and exhaustion.

Mucolytics and expectorants are divided into two groups.

1. Proteolytic enzymes (trypsin, chymotrypsin) act by breaking the peptide bonds of glycoproteins, reducing the viscosity and elasticity of sputum. They are effective in mucous and purulent sputum, having an anti-inflammatory effect, but can cause hemoptysis and allergic reactions.

2. Cysteine ​​derivatives stimulate secretory activity in the ciliated epithelium of the tracheobronchial tree (mukosolvan, mukomist), are used as an aerosol of a 20% solution of 2-3 ml 2-3 times a day.

Author: Kolesnikova M.A.

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