Respiratory failure is a pathological syndrome that accompanies a number of diseases, which is based on a violation of gas exchange in the lungs. The basis of the clinical picture is the signs of hypoxemia and hypercapnia (cyanosis, tachycardia, sleep and memory disorders), respiratory muscle fatigue syndrome and shortness of breath. DN is diagnosed on the basis of clinical data, confirmed by indicators of the gas composition of blood, respiratory function. Treatment includes the elimination of the causes of DN, oxygen support, if necessary, mechanical ventilation.
External respiration supports continuous gas exchange in the body: the supply of atmospheric oxygen and the removal of carbon dioxide. Any violation of respiratory function 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 increases in the blood and the oxygen content decreases, which leads to oxygen starvation, first of all, of vital organs – the heart and brain.
In case of respiratory failure (DN), the necessary gas composition of the blood is not provided, or it is maintained due to the overvoltage of the compensatory capabilities of the respiratory system. A threatening condition for the body develops during respiratory failure, characterized by a decrease in the partial pressure of oxygen in arterial blood of less than 60 mm Hg. Art., as well as increasing the partial pressure of carbon dioxide more than 45 mm Hg. Art.
Respiratory failure may develop in various acute and chronic inflammatory diseases, injuries, tumor lesions of the respiratory system; in case of pathology of the respiratory muscles and the heart; in conditions leading to limited mobility of the chest. Disruption of pulmonary ventilation and the development of respiratory failure can result in:
- Obstructive disorders. Obstructive respiratory failure is observed when air is difficult to pass through the airways – the trachea and bronchi due to bronchospasm, inflammation of the bronchi (bronchitis), foreign bodies, stricture (narrowing) of the trachea and bronchi, compression of the bronchi and trachea by the tumor, etc.
- Restrictive violations. Respiratory failure in restrictive (restrictive) type is characterized by limiting the ability of the lung tissue to expand and collapse and occurs in exudative pleurisy, pneumothorax, pneumosclerosis, adhesions in the pleural cavity, limited mobility of the costal framework, kyphoscoliosis, etc.
- Hemodynamic disorders. The reason for the development of hemodynamic respiratory failure may be circulatory disorders (for example, thromboembolism), leading to the impossibility of ventilation of the blocked portion of the lung. Hemodynamic type of respiratory failure also leads to the right-left shunting of blood through an open oval window for heart disease. When this occurs, the mixture of venous and oxygenated arterial blood.
Respiratory failure is classified according to a number of symptoms:
According to pathogenesis (mechanism of occurrence):
- parenchymal (hypoxemic, respiratory or pulmonary insufficiency of type I). Respiratory failure in the 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 failure II type). The leading manifestation of respiratory failure by ventilation type is the increase in the content and partial pressure of carbon dioxide in arterial blood (hypercapnia). Hypoxemia is also present in the blood, but it lends itself well to oxygen therapy. The development of ventilation respiratory failure is observed with weakness of the respiratory muscles, mechanical defects of the muscle and rib cage of the chest, violation of the regulatory functions of the respiratory center.
By etiology (reasons):
- obstructive. In this type, the functionality of the external respiration apparatus suffers: full inhalation and especially exhalation are difficult, the respiration rate is limited.
- restrictive (or restrictive). NAM develops due to the limitation of the maximum possible depth of inhalation.
- combined (mixed). DN according to the combined (mixed) type combines the signs of obstructive and restrictive types with the predominance of one of them and develops with a long course of cardiopulmonary diseases.
- hemodynamic. DN develops in the absence of blood flow or inadequate oxygenation of the lung.
- diffuse. Respiratory failure of the diffuse type develops with violation of the penetration of gases through the capillary-alveolar membrane of the lungs with its pathological thickening.
By the rate of increase of signs:
- Acute respiratory failure develops rapidly, within a few hours or minutes, as a rule, is accompanied by hemodynamic disturbances and represents a danger to the lives 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 DN with its exacerbation or decompensation.
- Chronic respiratory failure may increase over several months and years, often gradually, with a gradual increase in symptoms, and may also be a result of incomplete recovery from acute DN.
In terms of blood gas composition:
- compensated (blood gas composition is normal);
- decompensated (the presence of hypoxemia or arterial blood hypercapnia).
According to the severity of symptoms of DN:
- DN I degree – characterized by shortness of breath with moderate or significant loads;
- DN II degree – shortness of breath occurs with minor exertion, the use of compensatory mechanisms at rest is noted;
- DN III degree – manifested by shortness of breath and cyanosis at rest, hypoxemia.
Symptoms of Respiratory Distress
Signs of DN 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 the partial pressure of oxygen (PaO2) in arterial blood below 60 mm Hg. Art. Hemodynamic disorders are also characteristic of hypoxemia, as expressed in tachycardia and moderate arterial hypotension. With a decrease in PaO2 in arterial blood to 55 mm Hg. Art. there are memory impairments at the events taking place, and when PaO2 is reduced to 30 mm Hg. Art. the patient loses consciousness. Chronic hypoxemia is manifested by pulmonary hypertension.
Manifestations of hypercapnia
Manifestations of hypercapnia are tachycardia, sleep disturbances (insomnia at night and drowsiness during the day), nausea, and headaches. The rapid increase in carbon dioxide partial pressure (PaCO2) in arterial blood can lead to a hypercapnic coma state 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 active involvement in the breathing process of the auxiliary muscles (muscles of the upper respiratory tract, neck muscles, abdominal muscles).
Syndrome of weakness and fatigue of the respiratory muscles
BH more than 25 per min. may be the initial sign of fatigue of the respiratory muscles. BH reduction is less than 12 per min. may foreshadow breathing. The extreme variant of the syndrome of weakness and fatigue of the respiratory muscles is paradoxical breathing.
Dyspnea is subjectively felt by patients as a lack of air due to excessive respiratory effort. Dyspnea with respiratory failure may occur both during physical exertion and in a relaxed state. In the late stages of chronic respiratory failure with the addition of the phenomena of heart failure, patients may experience swelling.