Respiratory failure is a pathological syndrome accompanying a number of diseases, which is based on a violation of gas exchange in the lungs. The clinical picture is based on signs of hypoxemia and hypercapnia (cyanosis, tachycardia, sleep and memory disorders), respiratory muscle fatigue syndrome and shortness of breath. RF is diagnosed on the basis of clinical data confirmed by indicators of blood gas composition, FRS. Treatment includes elimination of the cause of RF, oxygen support, if necessary, ventilation.
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External respiration supports continuous gas exchange in the body: the intake of atmospheric oxygen and the removal of carbon dioxide. Any violation of the function of external respiration leads to a violation of gas exchange between the alveolar air in the lungs and the gas composition of the blood. As a result of these disorders, the content of carbon dioxide in the blood increases and the oxygen content decreases, which leads to oxygen starvation, primarily of vital organs – the heart and brain.
In case of respiratory failure (RF), the necessary gas composition of the blood is not provided, or it is maintained due to overstrain of the compensatory capabilities of the external respiratory system. A threatening condition for the body develops with respiratory insufficiency, characterized by a decrease in the partial pressure of oxygen in arterial blood less than 60 mmHg, as well as an increase in the partial pressure of carbon dioxide more than 45 mmHg.
Respiratory insufficiency can develop in various acute and chronic inflammatory diseases, injuries, tumor lesions of the respiratory organs; in pathology from the respiratory muscles and the heart; in conditions leading to limited mobility of the chest. The violation of pulmonary ventilation and the development of respiratory failure can lead to:
- Obstructive disorders. Respiratory insufficiency of the obstructive type is observed when it is difficult to pass air through the airways – the trachea and bronchi due to bronchospasm, inflammation of the bronchi (bronchitis), ingestion of foreign bodies, stricture (narrowing) of the trachea and bronchi, compression of the bronchi and trachea by a tumor, etc.
- Restrictive violations. Respiratory insufficiency of the restrictive (restrictive) type is characterized by a limitation of the ability of the lung tissue to expand and subside and occurs with exudative pleurisy, pneumothorax, pneumosclerosis, adhesive process in the pleural cavity, limited mobility of the rib cage, kyphoscoliosis, etc.
- Hemodynamic disorders. The cause of the development of hemodynamic respiratory failure may be circulatory disorders (for example, thromboembolism), leading to the inability to ventilate the blocked area of the lung. Right-left blood bypass surgery through an open oval window in heart disease also leads to the development of hemodynamic respiratory failure. In this case, venous and oxygenated arterial blood is mixed.
Respiratory failure is classified according to a number of signs:
1. By pathogenesis (mechanism of occurrence):
- parenchymal (hypoxemic, respiratory or pulmonary insufficiency type I). Respiratory insufficiency of parenchymal type is characterized by a decrease in the content and partial pressure of oxygen in arterial blood (hypoxemia), which is difficult to correct with oxygen therapy. The most common causes of this type of respiratory failure are pneumonia, respiratory distress syndrome (shock lung), cardiogenic pulmonary edema.
- ventilation (“pumping”, hypercapnic or respiratory insufficiency of type II). The leading manifestation of respiratory insufficiency by ventilation type is an increase in the content and partial pressure of carbon dioxide in arterial blood (hypercapnia). Hypoxemia is also present in the blood, but it responds well to oxygen therapy. The development of ventilation respiratory insufficiency is observed with weakness of the respiratory muscles, mechanical defects of the muscular and rib cage of the chest, violation of the regulatory functions of the respiratory center.
2. For etiology (reasons):
- obstructive. With this type, the functionality of the external breathing apparatus suffers: full inhalation and especially exhalation is difficult, the respiratory rate is limited.
- restrictive (or restrictive). RF develops due to the limitation of the maximum possible depth of inspiration.
- combined (mixed). RF of the combined (mixed) type combines signs of obstructive and restrictive types with the predominance of one of them and develops with a prolonged course of cardiopulmonary diseases.
- hemodynamic. RF develops against the background of lack of blood flow or inadequate oxygenation of a part of the lung.
- diffuse. Respiratory insufficiency of the diffuse type develops when the penetration of gases through the capillary-alveolar membrane of the lungs is impaired with its pathological thickening.
3. By the rate of increase of signs:
- Acute respiratory failure develops rapidly, in a few hours or minutes, as a rule, is accompanied by hemodynamic disorders and poses a danger to the life of patients (emergency resuscitation and intensive therapy are required). The development of acute respiratory failure can be observed in patients suffering from a chronic form of RF with its exacerbation or decompensation.
- Chronic respiratory failure can increase over several months and years, often gradually, with a gradual increase in symptoms, may also be a consequence of incomplete recovery after acute RF.
4. According to the indicators of the gas composition of the blood:
- compensated (blood gas composition is normal);
- decompensated (presence of hypoxemia or hypercapnia of arterial blood).
5. According to the severity of symptoms of RF:
- I degree – characterized by shortness of breath with moderate or significant loads;
- II degree – shortness of breath is observed with minor loads, the involvement of compensatory mechanisms at rest is noted;
- III degree – manifested by shortness of breath and cyanosis at rest, hypoxemia.
Signs of RF depend on the causes of its occurrence, type and severity. The classic signs of respiratory failure are:
manifestations of hypoxemia
Hypoxemia is clinically manifested by cyanosis (cyanosis), the degree of which expresses the severity of respiratory failure and is observed with a decrease in partial oxygen pressure (PaO2) in arterial blood below 60 mm Hg. Hypoxemia is also characterized by hemodynamic disorders, expressed in tachycardia and moderate arterial hypotension. With a decrease in RaO2 in arterial blood up to 55 mm Hg. there are memory disorders for events, and with a decrease in RaO2 up to 30 mm Hg. the patient loses consciousness. Chronic hypoxemia is manifested by pulmonary hypertension.
manifestations of hypercapnia
Manifestations of hypercapnia are tachycardia, sleep disorders (insomnia at night and drowsiness during the day), nausea, headaches. A rapid increase in the partial pressure of carbon dioxide (RaSO2) in arterial blood can lead to a state of hypercapnic coma associated with increased cerebral blood flow, increased intracranial pressure and the development of cerebral edema. The syndrome of weakness and fatigue of the respiratory muscles is characterized by an increase in the respiratory rate (BH) and the active involvement of auxiliary muscles (upper respiratory tract muscles, neck muscles, abdominal muscles) in the breathing process.
syndrome of weakness and fatigue of the respiratory muscles
BH more than 25 in min. it can serve as an initial sign of fatigue of the respiratory muscles. Reduction of BH less than 12 v min. may portend respiratory arrest. Paradoxical breathing is an extreme variant of the syndrome of weakness and fatigue of the respiratory muscles.
shortness of breath
Shortness of breath is subjectively felt by patients as a lack of air with excessive breathing efforts. Shortness of breath with respiratory insufficiency can be observed both with physical exertion and in a calm state. In the late stages of chronic respiratory failure with the addition of the phenomena of heart failure, edema may appear in patients.
Respiratory failure is an urgent, life-threatening condition. If timely resuscitation is not provided, acute respiratory failure can lead to the death of the patient. The prolonged course and progression of chronic respiratory failure leads to the development of right ventricular heart failure as a result of a shortage of oxygen supply to the heart muscle and its constant overload. Alveolar hypoxia and inadequate ventilation of the lungs with respiratory insufficiency causes the development of pulmonary hypertension. Hypertrophy of the right ventricle and a further decrease in its contractile function lead to the development of the pulmonary heart, manifested in stagnation of blood circulation in the vessels of the large circle.
At the initial diagnostic stage, an anamnesis of life and concomitant diseases is carefully collected in order to identify possible causes of respiratory failure. When examining the patient, attention is drawn to the presence of cyanosis of the skin, the frequency of respiratory movements is calculated, the involvement of auxiliary muscle groups in breathing is evaluated.
In the future, functional tests are carried out to study the function of external respiration (spirometry, peak flowmetry), which allows an assessment of the ventilation capacity of the lungs. At the same time, the vital capacity of the lungs, the minute volume of respiration, the speed of air movement through various parts of the respiratory tract during forced breathing, etc. are measured.
A mandatory diagnostic test for the diagnosis of respiratory insufficiency is a laboratory analysis of the gas composition of blood, which allows to determine the degree of saturation of arterial blood with oxygen and carbon dioxide (RaO2 and RaSO2) and acid-base state (CBS of blood). During lung radiography, lesions of the chest and parenchyma of the lungs, blood vessels, bronchi are detected.
Treatment of patients with respiratory insufficiency provides for:
- restoration and maintenance of optimal lung ventilation and blood oxygenation for life support;
- treatment of diseases that were the root cause of the development of respiratory failure (pneumonia, exudative pleurisy, pneumothorax, chronic inflammatory processes in the bronchi and lung tissue, etc.).
With pronounced signs of hypoxia, oxygen therapy (oxygen therapy) is performed first. Oxygen inhalations are given in concentrations that ensure maintenance of RaO2 = 55— 60 mmHg, with careful monitoring of pH and RaSO2 of the blood, the patient’s condition. When the patient is breathing independently, oxygen is supplied massively or through a nasal catheter, in a comatose state, intubation and supportive artificial ventilation of the lungs are performed.
Along with oxygnotherapy, measures are taken to improve the drainage function of the bronchi: antibacterial drugs, bronchodilators, mucolytics, chest massage, ultrasound inhalations, physical therapy, active aspiration of bronchial secretions through an endobronchoscope are prescribed. In case of respiratory failure complicated by a pulmonary heart, diuretics are prescribed. Further treatment of respiratory failure is aimed at eliminating the causes that caused it.
Prognosis and prevention
Respiratory failure is a formidable complication of many diseases and often leads to death. In chronic obstructive pulmonary diseases, respiratory failure develops in 30% of patients.Prognostically unfavorable is the manifestation of respiratory failure in patients with progressive neuromuscular diseases (myotonia, etc.). Without appropriate therapy, a fatal outcome may occur within one year.
With all other pathologies leading to the development of respiratory failure, the prognosis is different, but it is impossible to deny that RF is a factor that reduces the life expectancy of patients. Prevention of the development of respiratory failure provides for the exclusion of pathogenetic and etiological risk factors.
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