Respiratory failure: classification and emergency care
Jun 07, 2018
Respiratory failure is a condition in which the gas composition of the blood suffers from a violation of the respiratory processes that support it in the norm.
For 10 thousand people about 8-10 people suffer from different forms of respiratory failure.In 60-75% of patients with acute or chronic respiratory diseases, it was observed at least once in life.Table of contents:
Causes and classification of respiratory failure
This pathological condition can accompany most diseases of the respiratory system.But most often it occurs in diseases such as:
- cardiogenic pulmonary edema( provoked by heart disease);
- adult respiratory distress syndrome( ARDS) - acute lung damage, in which swelling and edema of their tissues are observed.
Respiratory failure occurs:
- Ventilation - in case of a violation of ventilation of the lungs;In this case, the respiratory tract is mainly affected;
- parenchymatous - due to tissue damage of the lungs themselves.
Ventilation type of pathology most often occurs when:
- disorders from the cerebral respiratory center;
- fatigue, weakening or damage to the muscles involved in the act of breathing;
- mechanical defect in the musculoskeletal of the chest - mainly due to congenital or acquired defects( most often kyphoscoliosis), with trauma, after surgery;
- chronic obstructive diseases of the respiratory system;
Parenchymal respiratory failure occurs in very many lung diseases:
- cystic fibrosis;
and so on.
Respiratory failure is characterized by:
- with a carbon dioxide surplus in the blood( vent type);
- lack of oxygen( parenchymal type ).
The rate of onset and development of respiratory failure is:
Acute respiratory failure is characterized by the following symptoms:
- occurs suddenly - for several days or hours, sometimes even minutes;
- is rapidly progressing;
- is accompanied by impaired blood flow;
- may endanger the life of the patient, which will require intensive care.
Characteristics of chronic respiratory failure:
- begins with inconspicuous or non-specific subjective discomfort;
- can develop for months and years;
- is able to develop if the patient is not fully recovered from acute respiratory failure.
Important! Even if the patient suffers from chronic respiratory failure, its acute form may occur, which means that the body has not coped with chronic respiratory failure, it is not compensated.
Allocate a mild, moderate and severe degree of respiratory failure, which is delimited by the oxygen pressure and the saturation of the blood: at a mild degree, the oxygen pressure is 60-79 mm Hg.The saturation is 90-94%, while the average is 40-59 mm Hg.Art.And 75-89%, in case of severe - less than 40 mm Hg.Art.And less than 75%.
Normally, the oxygen pressure is more than 80 mm Hg.The saturation is more than 95%.
External respiration( that is, the flow of oxygen through the respiratory tract into the lungs) is supported by many links of one adjusted mechanism - this is:
- central nervous system and respiratory center;
- neuromuscular system( in particular, the structure of the chest);
- respiratory tract;
- alveoli of the lungs.
Breakage of any link will lead to respiratory failure.
CNS and respiratory center lesions, which most often lead to respiratory failure:
- overdose of narcotic drugs( including medication);
- reduced thyroid function;
- impairment of cerebral circulation.
Pathological conditions from the side of the neuromuscular system that provoke respiratory failure:
- Guillain-Barre syndrome( a condition in which the immune system responds to its own nerve cells as foreign structures);
- myasthenia gravis( muscle weakness, which in turn can develop for a variety of reasons);
- Duchenne disease( characterized by muscular dystrophy);
- congenital weakness and rapid fatigue of the respiratory muscles.
Chest disorders that may cause respiratory failure:
- kyphoscoliosis( curvature of the spine in two projections);
- condition after thoracoplasty operations;
- pneumothorax( air in the pleural cavity);
- hydrothorax( fluid in the pleural cavity).
Pathological conditions and respiratory diseases due to which respiratory failure occurs:
- laryngospasm( narrowing of the larynx due to contraction of its muscles);
- laryngeal edema;
- obstruction( blockage) by a foreign body at any level of the airway;
- bronchial asthma;
- chronic obstructive diseases of the respiratory system( in particular, obstructive bronchitis with an asthmatic component);
- cystic fibrosis( defeat of all glands of external secretion - including respiratory tract);
- bronchiolitis obliterans( inflammation of small bronchi with their subsequent overgrowing).
Lesions of alveoli leading to respiratory failure:
- different types of pneumonia;
- adult respiratory distress syndrome;
- a decline in the lungs( atelectasis), which can be caused by a variety of causes;
- pulmonary edema of various origin;
- alveolitis( inflammation of the alveoli);
- pulmonary fibrosis( massive growth of pulmonary parenchyma connective tissue);
- sarcoidosis( mass formation in the organs of peculiar nodules - including in the lungs).
The above causes lead to hypoxemia - a decrease in oxygen levels in tissues. Direct mechanisms of its occurrence:
- in the portion of air that a person breathes, the so-called partial pressure of oxygen decreases;
- lung is poorly ventilated;
- gases do not pass well between the walls of the pulmonary alveoli and the walls of the vessels;
- venous blood is discharged into the arteries( this process is called bypass surgery);
- oxygen pressure in mixed venous blood decreases.
Partial oxygen pressure in the air volume that a person inhales can be reduced under the following conditions:
- in close proximity to sources of combustion( it consumes oxygen);
- in case of inhalation of poison gas;
- at high altitude( in particular, in high altitude) as a result of air thinning and reducing atmospheric pressure.
Due to the fact that the lung is poorly ventilated, the pressure of carbon dioxide increases in its alveoli, and this leads to a decrease in the oxygen pressure in the same alveoli.
Deterioration of the passage of gases in the walls of alveoli and vessels occurs most often in such diseases and conditions as:
- proliferation of connective tissue in the lungs;
- asbestosis( occupational disease due to work in asbestos production, resulting in asbestos accumulating in the lungs);
- carcinomatosis( metastasis to the lungs due to malignant tumor of any location);
- age-related changes in the lungs;
- changes the position of the body, which can change the volume of the lungs.
With bypass, the venous blood does not pass through the vascular bed of the lungs, and if it passes, then only in those areas of the lung where gas exchange is not observed.For this reason venous blood does not get rid of carbon dioxide, it continues to circulate in the vascular system, thus preventing the blood from being saturated with oxygen .The lack of oxygen that occurs with such shunting is very difficult to correct with oxygen therapy.
Respiratory failure due to a discharge of blood occurs in conditions such as:
- pulmonary embolism;
- shock conditions of various origins;
- performance of physical work by patients suffering from chronic respiratory diseases.
The increase in the carbon dioxide content is due to:
- worsening of ventilation of the lungs;
- increasing the volume of the so-called dead space( lung segments that do not participate in gas exchange);
- increase in carbon dioxide content in the external environment.
The process of airing the lung depends on the many factors that support it - from the nervous system to the respiratory muscles.
If the volume of those areas of the lung that do not take part in gas exchange increases, compensatory mechanisms are started, due to which the ventilation of the lung is kept at the required level. As soon as these mechanisms are exhausted, the airing deteriorates.
An increase in the amount of carbon dioxide can be observed both because of its excessive intake from the external environment and as a result of its increased production by the tissues. Most often this occurs with such conditions as:
- body temperature increase;Increasing it by 1 degree leads to an increase in the production of carbon dioxide by 10-14%;
- muscular activity - not only physiological( sports, physical labor), but also one that is not normally observed( convulsions, convulsions);
- strengthening parenteral nutrition - nutrient intake in the form of injectable solutions.
Especially parenteral nutrition affects the increase in the production of carbon dioxide, if it increases the carbohydrate content. This mechanism is not so significant for increased production of carbon dioxide - but with other failures exacerbates them.
Clinical symptoms show both oxygen deficiency and excess carbon dioxide. The most common manifestations are:
- feeling of suffocation;
- blueing of the skin and visible mucous membranes;
- changes from the side of the central nervous system;
- weakness, and then muscle fatigue, taking part in the act of breathing.
With shortness of breath, the patient makes an effort to inhale, which is not normally required. The degree of dyspnea is not indicative of a lack of oxygen or an excess of carbon dioxide - it is difficult to conclude from this how much respiratory failure is expressed.
About the level of hypoxemia and hypercapnia( excess carbon dioxide) more clearly signal other clinical signs - a discoloration of the skin, a violation of hemodynamics and manifestations of the central nervous system.
Symptoms of hypoxemia:
- Cyanosis - always appears with her.The cyanotic skin tone appears standard with a partial oxygen pressure below 60 mmHg.Art.And oxygen saturation of blood is less than 90%;
- increased heart rate and pulse, as well as increased blood pressure;
- disorders from the central nervous system: if the oxygen pressure has dropped to 55 mm Hg.The patient begins to have memory problems if up to 30 mm Hg.Art.- loses consciousness;
- if respiratory failure is observed in a patient for a long time, then it manifests itself in the growth of bone marrow cells.This process is aimed at compensating for oxygen starvation( the bone marrow takes part in the blood, and therefore ensures the normal transfer of oxygen by blood elements).
Symptoms that indicate an increase in the amount of carbon dioxide are the result of :
- increased activity of the sympathetic part of the autonomic nervous system( the part that strengthens the activity of the internal organs);
- direct action of carbon dioxide on the fabric.
The most typical clinical symptoms, indicative of an excess of carbon dioxide, are:
- disorders from the hemodynamics( blood flow through the vessels);
- changes from the central nervous system.
With an excess of carbon dioxide, the hemodynamics changes as follows:
- heart rate and pulse increase;
- develops vasodilation throughout the body;
- increases cardiac output.
The central nervous system responds to an increase in the level of carbon dioxide as follows:
- appears tremor( trembling of the trunk and limbs);
- patients suffer from insomnia if they manage to fall asleep - often wake up in the middle of the night, and during the day they can not overcome drowsiness;
- headaches occur( mainly in the morning);
- marked with nausea, not related to eating or changing the position of the body in space.
If the pressure of carbon dioxide increases rapidly, the patient can even fall into a coma.
Due to clinical manifestations, fatigue and weakness of the respiratory muscles can be detected:
- , first the breathing becomes faster( fatigue is fixed if the breathing rate is 25 breaths-in-exhalations per minute);
- further, when the pressure of carbon dioxide increases, respiration becomes less frequent.If the respiratory rate is less than 12 per 1 minute, this should cause medical anxiety: such a black hole may indicate an imminent possible stopping of breathing.
Normally, the respiratory rate is 16-20 acts per minute at rest.
The body tries to provide normal breathing by connecting additional muscles that normally do not participate in the act of breathing.This is manifested by a contraction of the muscles that lead to the swelling of the wings of the nose, the tension of the muscles of the neck, the contraction of the abdominal muscles.
If fatigue and weakening of the respiratory muscles have reached an extreme degree, then paradoxical breathing begins to manifest: during inspiration, the chest will narrow and fall down, exhalation - expand and rise upwards( normally everything happens the other way around).
These symptoms allow us to record the fact of respiratory failure and assess the degree of its development.But for its more accurate assessment it is necessary to investigate the gas composition of the blood and the acid-base balance. The study of such indicators as:
- partial oxygen pressure;Partial pressure of carbon dioxide;
- Blood pH( determination of acid-base balance);
- level of bicarbonates( salts of carbonic acid) in the arterial blood.
In the case of ventilation respiratory failure, the is shifted to the acidic pH of the blood, in the case of lung tissue damage, to alkaline.
The determination of the level of bicarbonates allows us to judge the process's neglect: if their amount is more than 26 mmol per liter, this indicates a prolonged increase in the level of carbon dioxide in the blood.
To assess the violations of gas metabolism, lung radiography is performed.In some cases, X-ray signs may not be fixed, although the clinic speaks of respiratory failure. This happens when:
- dropping venous blood( shunt);
- chronic obstructive diseases;
- bronchial asthma;
On the other hand, 2-sided massive radiographic changes with a moderate clinic can be observed with:
- massive pneumonia;
- edema of the lung;
- of fluid entering the lungs;
- pulmonary hemorrhage.
Also for the study of breathing, in order to understand which particular part it suffers, conduct spirometry - the study of external respiration.For this, the patient is asked to breathe in and out with the prescribed parameters( for example, with varying intensity). Such methods help to analyze:
- how passable the airways are;
- in what state is the lung tissue, its vessels and respiratory muscles;
- what is the severity of respiratory failure.
During the conduct of such methods, the study is primarily determined by the :
- vital capacity of the lungs - the volume of air that can be placed by the lungs at the maximum inspiration;
- forced vital capacity of the lungs is the amount of air that a patient can exhale at the maximum expiratory flow rate;
- the amount of air that the patient exhales in the first second of exhalation
and other parameters.
Treatment and emergency care for respiratory failure
At the heart of the treatment of respiratory failure lie:
- elimination of the causes that provoked it;
- providing airway patency;
- replenishment of missing oxygen in the body.
There are a lot of methods for eliminating the causes of respiratory failure, they depend on the cause of its occurrence:
- if an infection of the respiratory tract is observed - prescribe antibiotics;
- for respiratory failure due to pneumothorax, drain the pleural cavity;
- when the airway is blocked by a foreign body it is removed
and so on.
Chronic respiratory insufficiency is insidious in that it is impossible to affect its course by conservative methods. Recently, such attempts are being made - thanks to lung transplantation.But at the moment this method does not apply to common ones - an overwhelming number of patients are treated with established conservative methods that can ease the manifestations of respiratory failure, but not eliminate it.
The passage of the airways is provided by methods that dilute sputum and help the patient cough out its .First of all it is:
- reception of bronchodilator and mucolytic agents;
- postural drainage( the patient occupies a certain position and begins to cough up phlegm);
- vibromassage of the thorax.
Even not too prolonged hypoxemia can lead to death, so replenishing the missing oxygen in the body is extremely important. To this end, use:
- oxygen therapy;
- taking medications that improve breathing;
- body position change;
- improved cardiac output.
Oxygen in oxygen therapy is delivered to the body in many ways - primarily through:
- the so-called nasal cannula( tube with a special tip);
- simple face mask;
- specially developed Venturi mask;
- mask with a sack.
Pharmaceuticals designed to improve breathing are selected depending on which link of breathing is affected.
Despite the apparent simplicity, the method of changing the position of the body( from the stomach to the side) can significantly improve the flow of oxygen into the blood, and then into the tissue.In this case:
- under the influence of gravity there is a redistribution of blood flow and a decrease in the discharge of venous blood( bypass).The patient can lie on his stomach up to 20 hours a day;
- due to the fact that the compliance of a healthy lung is reduced, ventilation in the affected lung is increased.
Improve cardiac output by using drugs that replenish the volume of circulating blood.
In severe cases, when other methods do not help, resort to hardware artificial ventilation. It is shown with:
- impaired consciousness, indicating significant respiratory failure;
- fatigue of the muscles involved in the act of breathing;
- to unstable hemodynamics;
- complete respiratory arrest.
Inhalation of the helium-oxygen mixture is considered effective.
Measures that prevent the development of respiratory failure are a complex of activities that today can be identified in a separate small section of pulmonology. Prevention of respiratory failure reduces to:
- preventing the diseases that cause it;
- treatment of already occurring diseases, which can be complicated by respiratory failure.
It is very important to prevent the development of chronic respiratory failure, which is difficult to correct.
Even non-sustained hypoxemia can be fatal.Operative diagnostic and medical measures in case of acute respiratory failure help to eliminate it without consequences for the organism.Actions with chronic respiratory failure help to weaken its manifestations, but do not cure it.
Kovtonyuk Oksana Vladimirovna, medical reviewer, surgeon, consulting physician