A person who stays indoors for a long time often complains of unpleasant symptoms. After contacting a medical institution, doctors diagnose "hypercapnia".
Hypercapnia (sometimes hypercarbia) is the name of a pathological process that occurs as a result of an excess of carbon dioxide in the circulatory system and soft tissues of the human body, or, more simply, carbon dioxide (CO2) poisoning.
There are two types of hypercapnia:
- exogenous - characterized by an increase in the amount of carbon dioxide in the body, developing as a result of the victim's stay in a room with an increased level of it;
- endogenous - appears as a result of deviations of the human respiratory system.
If the disease develops, you need to contact a qualified doctor who will explain how the pathology appeared and how to eliminate the symptoms.
Causes
Hypercapnia can develop due to various reasons, but there is a list of factors that increase the likelihood of its occurrence:
- periodic epileptic urges;
- traumatic effect on the brain stem;
- damage to the brain stem as a result of cancer, stroke or other inflammatory processes;
- the presence of bronchial asthma;
- pathological changes in the spinal cord that occur with poliomyelitis;
- the use of pharmacological drugs that can disrupt the respiratory system;
- the presence in the body of myasthenia gravis;
- muscular dystrophy;
- all kinds of pathological changes in the structure of the sternum;
- serious stage of obesity;
- chronic diseases of the bronchi, in which the patency of the respiratory system is impaired.
Exogenous hypercapnia occurs due to:
- inhaling excessive amounts of carbon monoxide;
- diving and strong diving under water (improper breathing, hyperventilation and intense exercise - factors can provoke the development of such an ailment);
- prolonged stay in miniature enclosed spaces (well, mine, submarine and spacesuit);
- technical failures in the device, is responsible for maintaining the respiratory rhythm at the time of the surgical intervention.
Symptoms
Symptoms of hypercapnia are acute and chronic. Common signs of an acute form of the disease:
- the skin acquires a reddish tint;
- sudden headache and dizziness;
- even with minor physical exertion, shortness of breath is present;
- blood pressure rises significantly;
- the person feels drowsy and becomes lethargic;
- the rhythm of the heart muscle accelerates;
- pain in the chest area;
- there are periodic urges of a gag reflex and nausea;
- the patient is disturbed by frequent convulsions;
- the consciousness of the victim is confused, speech is slurred;
- possibly fainting.
The severity of the above symptoms depends entirely on the stage and nature of the disease. The higher the level of carbon dioxide in the circulatory system and soft tissues, the more pronounced the signs of the disease.
If you do not detect and eliminate the acute form of hypercapnia, then you can provoke the appearance of many negative complications and a complete disruption of the respiratory and cardiovascular systems, and the consequence of this process is the most dangerous consequence - the death of the victim.
Symptoms of a chronic course:
- feeling sluggish and tired (after normal sleep);
- psychological disorders (depression, stress, hypersensitivity, agitation and irritability);
- reduced blood pressure;
- the occurrence of deviations in the respiratory and cardiac rhythm;
- the presence of shortness of breath with minor exertion;
- deterioration of vital functions and brain activity.
Existing signs of carbon dioxide poisoning, it is possible to prevent the occurrence of complications in a timely manner. If you have several of the described symptoms, you must visit a medical facility or call an ambulance.
However, there are cases when the pathology is called chronic compensated hypercapnia, and it does not threaten human health and does not require prompt medical intervention.
This is explained by the fact that when the level of carbon dioxide in the room rises gradually, and the negative effect on the body of the victim occurs slowly, due to his prolonged stay in such an environment, the body begins to adapt to the changes.
The respiratory system begins to work faster, the acid-base balance in the circulatory system begins to recover, and the work of the cardiovascular system begins to function much faster. Due to adaptive processes in the human body, the disease does not require therapy and the attention of doctors.
First aid
In the event of external exposure to carbon dioxide, the victim is given first aid:
- an ambulance is called;
- a person with suspected hypercapnia is removed from a closed room that contains an increased level of an unfavorable gas;
- in the event of a malfunction of the apparatus that supports the patient's respiratory process, they stop the violation that has arisen and stabilize the patient's condition;
- when the resulting poisoning threatens human life, then tracheal intubation is performed;
- with pathology of the exogenous type, oxygen therapy and artificial ventilation of the lungs are performed.
When the victim is taken to a medical facility for confirmation of the diagnosis and the appointment of therapeutic measures.
Diagnosis technique
During the diagnosis, a qualified doctor conducts an examination of the patient, a survey about the symptoms present and types of accurate studies. You can confirm or refute the presence of carbon dioxide poisoning using diagnostic methods:
- study of the level of carbon dioxide in the arterial blood of the victim. The established norm of РСО2 is 4.6-6.0 kPa or 35-45 mm Hg. Art. In case of poisoning, the PCO2 indicators rise to 55-80 mm Hg. Art., and the level of oxygen decreases (CO2 indicator);
- examination of alveolar ventilation to determine the state of lack of pulmonary ventilation, which provokes a decrease in oxygen levels and an increase in carbon dioxide;
- in order to detect gas acidosis, a specialized apparatus is used - a capnograph. With its help, an experienced doctor is able to determine the presence and amount of carbon dioxide by the partial pressure contained in the exhaled air;
- diagnostics can be carried out using aerotonometry. Her calculation technique is able to determine the amount of gases present in the circulatory system.
After a diagnostic examination and a thorough study of the results obtained, a qualified medical worker, taking into account the possible and individual characteristics of the victim's body, prescribes the most effective method of therapy.
What is hypercapnia
Hypercapnia is a pathological condition that occurs when there is an excess of carbon dioxide (CO 2) in the blood and tissues, with signs of poisoning, hypoventilation (breathing disorders due to insufficient ventilation of the lungs) and hypoxia (low oxygen content). In fact, it is an integral part of the oxygen starvation of the body against the background of oxygen deficiency in the blood and respiratory acidosis.
Gas (respiratory) acidosis is a synonymous name for hypercapnia. It is used when the accumulation of carbon dioxide (partial pressure) in arterial blood exceeds the norm of 40-45 mm Hg. Art. (in the venous - 51), and its acidity increases, which is expressed in a decrease in the pH parameter, which ideally should be in the range from 7.35 to 7.45.
Signs of carbon dioxide poisoning are formed as a result of damage to oxygen carriers - red blood cells. Carbon dioxide binds erythrocyte hemoglobin, forming carbohemoglobin, unable to carry oxygen to organs, causing, along with hypercapnia, acute oxygen starvation - hypoxia.
The nature of hypercapnia is:
- endogenous;
- exogenous.
The exogenous form means that the abnormal increase in gaseous carbon dioxide in the tissues and blood is due to external causes. For example, inhalation of air saturated with carbon dioxide (more than 5%). In this case, a person has signs of obvious intoxication.
The endogenous nature is associated with internal factors - pathological changes in certain diseases, accompanied by signs of respiratory failure.
Carbon dioxide poisoning - video
Causes and risk factors
The following conditions lead to the development of hypercapnia:
- pulmonary hypoventilation, accompanied by a violation of gas exchange in the alveoli (the end bubble structures of the lungs) and developing due to respiratory diseases (obstruction, inflammation, trauma, foreign objects, operations);
- violation of respiratory function due to depression of the respiratory center due to brain injuries, neoplasms, cerebral edema, poisoning with certain medications - morphine derivatives, barbiturates, anesthetics and others;
- inability of the chest to carry out full respiratory movements.
Hyperventilation as a "provocateur" of hypercapnia
Separately, hyperventilation of the lungs should be singled out, which is the opposite of hypoventilation and develops with intensive breathing, during which the body is oversaturated with oxygen. Often this condition leads to an increase in the amount of carbon dioxide in the tissues and blood. This happens, for example, when diving (deep diving), when a person in front of him is actively and quickly breathing, trying to saturate his lungs with oxygen, but does it wrong.
During neurological hyperventilation (for example, during panic attacks), which provokes frequent but shallow breathing in the patient, poisoning can also occur - first with excess oxygen, then with carbon dioxide. The fact is that during superficial inhalations and exhalations, carbon dioxide is not completely removed from the lungs, accumulating in them. For this reason, experienced runners, hunters, special forces maintain a breathing rhythm in which exhalation is 2 or 3 times longer than inhalation. In this case, a person completely frees the lungs from carbon dioxide, but does not provoke hyperventilation either.
Endogenous factors
The causative factors that cause the occurrence of endogenous hypercapnia include the following diseases and pathological conditions:
- respiratory diseases: pneumonia, asthma, emphysema, pneumosclerosis, airway obstruction;
- chest injuries, including rib fractures, arthritis of the costal joints;
- spinal deformity (scoliosis, kyphosis);
- tuberculous spondylitis, rickets;
- extreme obesity (Pickwick syndrome);
- congenital defects of the bone and cartilage apparatus;
- restriction of mobility of the chest with muscular dystrophy and pain against the background of intercostal neuralgia;
- defeat and damage to the structures of the brain and spinal cord - strokes, encephalitis, trauma, tumor, poliomyelitis;
- myasthenia gravis (a neuromuscular genetic disease);
- acidosis, metabolic alkalosis;
- atherosclerosis;
- epileptic seizures;
- apnea (sudden uncontrolled cessation of breathing).
Exogenous factors
External (exogenous) causes of hypercapnia are:
- professional activities associated with frequent inhalation of carbon monoxide or prolonged breath holding (divers, firefighters, bakers, miners, foundry workers);
- heavy physical activity in conditions of accumulation of carbon dioxide;
- prolonged stay in stuffy rooms, smoking, including passive;
- long stay in closed and sealed spaces (wells, mines, submarines, space suits, closed car garages), where carbon dioxide accumulates;
- improper operation of furnaces, boilers;
- defeat by phosgene, ammonia, hydrochloric, sulfuric acid;
- poisoning with anticholinesterase drugs;
- technical problems in the respiratory equipment during surgical interventions, when the patient was given anesthesia.
Symptoms
According to the time of manifestation, early and late clinical symptoms are distinguished, the severity of which is directly related to the level of carbon dioxide in the body and the degree of hypercapnia.
Early and late symptoms of gaseous acidosis
Signs of hypercapnia also differ depending on whether the condition of abnormally high carbon dioxide is acute (short-term) or chronic.
The normal concentration of CO 2 in the open air is about 0.04% or 380-400 ppm in units of measurement meaning "number of carbon dioxide particles per million particles of atmospheric air" or "parts per million". Thus, 0.1% carbon dioxide corresponds to 1 thousand ppm.
Body adaptation to respiratory acidosis
If a person stays for a long time in an environment with a constant moderately high level of carbon dioxide in the air or with a slow increase in the concentration of CO 2, a gradual adaptation to changes in the environment occurs.
Thanks to the mechanisms of compensation, the body to some extent has internal forces to eliminate the resulting respiratory disorders. Thus, an increase in carbon dioxide in the blood causes a reflex increase and deepening of respiratory movements to optimize lung ventilation, remove excess carbon dioxide and normalize the acid-base balance of the blood. For example, with an increase in the partial pressure of carbon dioxide in the blood by 1 mm Hg. Art. breathing volume per minute (MOD) increases by 2-4 liters.
The heart and blood vessels also adapt to new conditions by increasing cardiac output and increasing blood pressure. This phenomenon in medicine is called "chronic compensated hypercapnia" and does not require hospital treatment.
Features of the state of hypercapnia in children
In children, respiratory failure due to carbon dioxide poisoning develops faster and is more severe than in adults.
The specificity of the course and consequences of hypercapnia in childhood are associated with the anatomy and functionality of the respiratory system:
- narrow airways (cause a violation of their patency even with a slight edema or accumulation of mucus);
- rapid reaction of the tissues of the respiratory tract to irritants (edema, spasm, increased secretion);
- weakness of the respiratory muscles in children;
- anatomical features - the abduction of the ribs from the sternum at almost a right angle reduces the depth of inspiration.
In the body of a child, a strong excess of carbon dioxide causes a slowdown in metabolic processes, degenerative and irreversible changes against the background of oxygen starvation of the tissues of the heart, liver, brain, and kidneys.
The increased content of carbon dioxide in the blood of a pregnant woman is a dangerous condition for both the mother and the child. Features that aggravate or provoke the development of hypercapnia:
- during the bearing of the baby, the need for oxygen in a woman increases by about 18–22%;
- as a result of the growth of the uterus, the abdominal type of breathing is replaced by the chest, in which the abdominal muscles, as auxiliary, are excluded from participation in breathing, which leads to incomplete expiration and accumulation of carbon dioxide in the lungs;
- the growing uterus puts pressure on the liver, stomach, raises the diaphragm, reducing the respiratory volume of the lungs and making it impossible to deepen the breath with the help of its movement.
All these changes contribute to the rapid development of respiratory acidosis even with minor disorders in the respiratory system.
Effects:
- respiratory failure, increased blood pressure, increased viscosity or, conversely, its dilution with the risk of bleeding;
- high risk of developing eclampsia, early placental abruption;
- miscarriage, premature birth;
- hypoxia, respiratory failure in the fetus, newborn;
- violation of placental gas exchange;
the negative impact of carbon dioxide on the central nervous system and cerebral cortex of an infant, leading to the development of the following pathologies:
- violations of the formation of organs in the embryo;
- delayed mental and physical development in a newborn;
- cerebral palsy;
- epilepsy.
If the baby survives the birth safely, then later he may develop severe chronic disorders. As a result, all newborns with respiratory acidosis require intensive treatment.
Diagnostics
Diagnosis of hypercapnia is based on:
- subjective sensations of the patient;
- objective signs of hypercapnia corresponding to the early or late development of poisoning and its severity;
- laboratory test results.
The most reliable method is the determination of the concentration of carbon dioxide in arterial blood. The normal content of carbon dioxide is noted at a partial pressure ranging from 4.7 to 6 kPa, which corresponds to 35–45 mm Hg. Art.
With the development of hypercapnia, an increase in the partial pressure of carbon dioxide to 55 - 100 mm Hg is detected. Art., a decrease in oxygen content, an increase in blood acidity (acidosis) against the background of a downward shift in the acid-base balance (pH less than 7.35) or, conversely, alkalization (pH more than 7.45), which occurs, for example, during hyperventilation before diving.
A study of alveolar ventilation is also carried out (updating the gas composition in the pulmonary alveoli during breathing) to identify the state of hypoventilation, that is, insufficient ventilation of the lungs, in which oxygen deficiency and an excess of carbon dioxide are formed in the blood.
To track the development of gaseous acidosis, a medical analyzer is used - a capnograph, which determines the content of carbon dioxide in the blood by its partial pressure in the air during exhalation.
In recent years, the pulse oximeter has become very popular. It is used to determine the pulse and estimate the oxygen saturation of hemoglobin. The latter indicator allows you to indirectly judge whether a person has oxygen starvation, and therefore an excess of carbon dioxide in the blood. Such diagnostics can be carried out at home by the patient himself, if he has this device.
Treatment
Treatment for hypercapnia is primarily aimed at improving pulmonary ventilation.
First aid
If the state of gaseous acidosis develops under the influence of external factors (exogenous hypercapnia), it is necessary:
- ventilate the room or go outside;
- drink plenty of fluids to prevent blood clots and reduce toxicity
In acute respiratory acidosis, you should:
- immediately remove the patient from the place where the concentration of carbon dioxide in the air is increased;
- during surgical interventions, establish equipment for anesthesia;
- with the development of a coma and respiratory arrest, immediately begin forced ventilation of the lungs so that the inhalation of air into the patient's mouth or nose lasts twice as long as exhalation;
- in case of particular severity and impossibility of independent breathing of the patient, for example, when the airways are blocked, intubate the trachea.
Medical and instrumental therapy
Therapy for hypercapnia and respiratory failure that develops against its background is aimed at:
- to eliminate the causes that provoked the pathology;
- for the treatment of internal diseases that caused respiratory acidosis;
- to restore normal gas exchange in the pulmonary alveoli.
Often carry out hardware ventilation of the lungs. Her help is resorted to in cases where:
- a person is not breathing, or he has severe shortness of breath with a frequency of more than 40 breaths per minute;
- oxygen therapy does not give a positive result (the partial pressure of oxygen falls below 45 mm Hg);
- arterial blood pH less than 7.3.
They also resort to oxygen therapy, which is used only for acute exogenous hypercapnia (caused by external conditions) in combination with mechanical ventilation. In this case, the patient breathes a balanced oxygen-nitrogen mixture with an oxygen content of up to 40%.
Illiterate oxygen therapy (especially with pure oxygen under pressure) leads to an increase in the content of carbon dioxide in the blood and even more pronounced respiratory disorders. Particular attention should be paid to the state of depression of the respiratory center, which occurs with drug overdose, poisoning with anesthetics and other pathological conditions.
In addition, with oxygen therapy, it is easy to miss the development of the "reverse" critical state - hypocapnia (carbon dioxide deficiency in the blood) and alkalosis (alkalinization of the blood). Therefore, oxygen treatment requires constant monitoring of blood gases and pH (acid-base balance).
If necessary, the following activities are carried out:
- the airways are regularly cleared of viscous sputum using a catheter or endotracheal tube;
- physiological saline is injected through droppers to dilute and remove bronchial secretions, activate blood flow;
- 0.5–1 ml of a solution of Atropine sulfate 0.1% is injected subcutaneously with profuse salivation and sputum production;
- in acute respiratory failure, an asthma attack, Prednisolone is administered intravenously, which quickly relieves mucosal edema;
- with a severe degree of respiratory acidosis, alkaline solutions (Carbicarb, Tromethamine), sodium bicarbonate are dripped in to compensate for respiratory acidosis;
- diuretics are used to relieve edema, improve lung compliance;
- to stimulate breathing, expand the bronchi, enhance pulmonary ventilation, Doxopram, bronchodilators (Theophylline, Salbutamol, Fenoterol, Ipratropium bromide, Aminophylline) are used.
Further therapy depends on the disease provocateur of hypercapnia and may include:
- antibacterial, anti-inflammatory, hormonal, immunostimulating drugs;
- bronchodilators in patients with pulmonary obstruction (adrenaline, isoproteronol) in conjunction with careful therapy with small doses of oxygen;
- aerosol therapy to improve airway patency, including inhalation with a solution of sodium bicarbonate 3%, the composition of aerosols includes bronchodilators (Salbutamol, Novodrin 1%, Solutan, Euspiran, Isadrin 1%);
- injections of sodium hydroxybutyrate 20%, Sibazon 0.5% (relieves spasms), Cocarboxylase (maintains blood pH in normal conditions during acidosis) and Essentiale to eliminate oxygen starvation accompanying hypercapnia and acute respiratory failure.
Folk remedies
Home therapy using folk remedies does not have an "arsenal" for a full fight against hypercapnia and acute respiratory failure. However, decoctions of medicinal plants can give a certain positive result in the chronic course of pathology. As a rule, the effect is expected if bronchopulmonary diseases become the cause of respiratory acidosis.
Many of them help to partially relax the bronchi, relieve swelling, reduce the viscosity of sputum and improve the excretion of purulent mucus from the lungs.
With the independent use of folk recipes without a specified diagnosis, it is impossible to predict the patient's reaction to a specific remedy, and the condition can only worsen: certain herbs, foods, medicinal substances cause allergies with laryngeal edema, when inhaled with them, there is a danger of bronchospasm, sudden swelling, burns of the respiratory ways and even activation of reproduction of pathogenic microbes. For example, oregano, anise or licorice root, useful for breathing problems, can provoke uterine bleeding in pregnant women, allergies.
The “thoracic” collections, which facilitate breathing in diseases provocateurs of gaseous acidosis, include plantain, coltsfoot, licorice, marshmallow, sage, pine buds, anise, mint, wild rosemary (poisonous), chamomile, violet, calendula.
Usually, 2 tablespoons of herbs are poured into 250-300 ml of boiling water, boiled slowly for 15 minutes, insisted for about 30-40 minutes, filtered. The resulting broth is brought to a volume of 200 ml by adding boiled water, and taken warm in half a glass up to 4 times a day for 2 weeks.
Milk-based products are also considered effective:
- Carrot juice with milk. Warm boiled milk is poured into fresh carrot juice in a ratio of 1:1. The medicinal drink is drunk 100-150 ml three times a day (warm). Removes moisture well.
- Leek root decoction in milk. They take raw materials from 2-3 plants, removing the lower white part. Crush, pour 250-300 ml of milk and simmer for 10 minutes over low heat. Insist up to 6-7 hours. Filter and drink "onion milk" 5 times a day for a tablespoon. It relaxes the bronchi, makes breathing easier.
Treatment prognosis and possible complications
Hypercapnia can go unnoticed with a low content of carbon dioxide in the air. But it can also lead to the development of severe complications, depending on the concentration of CO 2 , physiology, human age, and internal diseases.
With a mild degree of respiratory acidosis (up to 50 mm Hg), the condition does not have a too negative effect on the body even with prolonged exposure due to the adaptive capabilities of a person and the adaptability of a person to such conditions. Tolerance of a higher content of carbon dioxide in the blood is associated with the general condition of a person, the presence of chronic pulmonary and heart diseases. Partial pressure of 70–90 mm Hg. Art. causes a severe lack of oxygen, which, in the absence of medical care and the further development of hypercapnia, leads the patient to death.
The most serious complication of acute respiratory acidosis is hypercapnic coma, which, without intensive emergency treatment, ends in respiratory and cardiac arrest.
Prevention
To prevent hypercapnia, you need:
- timely and correct treatment of diseases of the bronchi and lungs, especially those accompanied by acute or chronic insufficiency of respiratory function;
- regular and prolonged exposure to the open air;
- compliance with the rules for working with professional breathing apparatus used by miners, firefighters, divers, pilots, astronauts;
- active and regular ventilation of home and office premises (especially with installed plastic windows that do not have valves);
- provision of supply ventilation and exhaust in working, workshop premises (exchange with the external atmosphere is calculated at a rate of 30 m 3 per hour per person), providing a comfortable concentration of carbon dioxide in the air for people (no more than 450–500 ppm);
- provision of airtight rooms with CO 2 absorbers;
- checking, troubleshooting equipment for anesthesia, artificial pulmonary ventilation;
- proper administration of general anesthesia.
Both short-term carbon dioxide intoxication and its long-term effect on the body can have an extremely negative effect on a person. Early detection of symptoms in acute carbon dioxide poisoning and monitoring of manifestations in hypercapnia caused by internal diseases can prevent many serious conditions. Immediate treatment can prevent the death of the patient even in the case of prolonged acidotic coma (hours, days), which develops with carbon dioxide poisoning. Medical statistics confirm cases of a successful outcome with severe respiratory acidosis, when the carbon dioxide tension in the blood reached 160–200 mm Hg. Art., which occurred during anesthesia of the patient.
Etiology
In hypercapnia, the causes of origin are very diverse, divided into external and internal. The first category is the increased content of carbon dioxide in the air - if a person is in such an environment for a long time, a pathological condition develops. This group includes:
- some professional features are at risk for bakers, divers and steelworkers;
- air pollution;
- prolonged stay of a person in an unventilated room;
- long-term addiction to cigarettes;
- second hand smoke;
- inhalation of carbon dioxide during a fire;
- diving to great depths while diving;
- excess nutrition;
- improper operation of special respiratory equipment, which is used during surgical operations - when the patient is under anesthesia.
Internal provocateurs are represented by the following list:
- convulsive or epileptic seizures;
- violation of the integrity of the brain stem, which can occur against the background of trauma, the course of an oncological process, an inflammatory lesion, or a stroke;
- the course of bronchial asthma;
- spinal cord pathologies, for example, poliomyelitis;
- irrational use of drugs;
- sleep apnea syndrome - there is a sudden cessation of respiratory movements;
- dystrophy of muscle tissue;
- deformation changes in the chest, in particular kyphosis;
- sepsis;
- severe form of obesity;
- myasthenia gravis;
- chronic bronchopulmonary diseases accompanied by obstructive syndrome;
- damage to the central nervous system;
- fever;
- violation of gas exchange in the lung tissue - the disorder may occur due to Mendelsohn's syndrome, Hamman-Rich disease, pneumothorax, respiratory distress syndrome, edema or pneumonia;
- the period of bearing a child - often the disease develops in the 3rd trimester, when any breathing problems can cause hypercapnia;
- respiratory acidosis;
- malignant hyperthermia;
- atherosclerosis.
The condition is closely related to hypoxia - insufficient oxygen in the blood or oxygen starvation of the body.
Classification
Based on the nature of the course, hypercapnia happens:
- acute - characterized by a sharp appearance of clinical signs and a significant deterioration in the condition, most often occurs in children;
- chronic - the clinic is expressed in a slow increase in symptoms for a long time.
There are several degrees of severity of the course of the disease:
- moderate;
- deep - symptoms from the central nervous system appear and manifestations of acute respiratory failure increase;
- acidotic coma.
Depending on the causes of development, the disease happens:
- endogenous - internal sources act as provocateurs;
- exogenous - develops against the background of external factors.
Separately, chronic compensated hypercapnia is distinguished - it occurs when a person is in conditions of a slow increase in the level of carbon dioxide in the air for a long period of time. In the body, the processes of adaptation to a new environment are activated - this is a compensation for the state with increased respiratory movements.
None of the classifications includes permissive hypercapnia - a purposeful restriction of the volume of ventilation of the lungs, which is necessary to avoid excessive stretching of the alveoli, despite an increase in CO2 beyond the normal range, up to 50-100 millimeters of mercury. Art.
Symptoms
Usually the disease develops slowly, with a gradual increase in the intensity of clinical manifestations. Extremely rarely there is a lightning-fast development of symptoms.
The symptoms of hypercapnia will vary slightly depending on the severity of the problem. For example, the moderate form is characterized by:
- sleep problems;
- euphoria;
- increased sweating;
- skin hyperemia;
- increased respiratory movements;
- increase in blood tone;
- increase in heart rate.
The deep stage is expressed by the following symptoms:
- increased aggressiveness and agitation;
- severe headache;
- nausea and weakness;
- the appearance of bruises under the eyes;
- puffiness;
- decreased visual acuity;
- rare and shallow breathing;
- cyanosis of the skin;
- strong allocation of cold sweat;
- increased heart rate up to 150 beats per minute;
- increase in blood pressure values;
- dizziness;
- difficulty urinating.
Acidotic coma is expressed by such signs:
- decreased reflexes;
- hyperhidrosis;
- a sharp decrease in blood tone;
- loss of consciousness;
- cyanotic skin tone;
- convulsive seizures.
In the case of a chronic course of the disease, symptoms include:
- constant fatigue;
- decrease in working capacity;
- lowering blood pressure;
- excitation, replaced by oppression of consciousness;
- dyspnea;
- breathing problems;
- sleep disturbance;
- headaches and dizziness.
In children, the symptoms are practically the same. It should be remembered that in this category of patients, hypercapnia develops much faster and is much more severe than in adults.
In those situations when the disease develops against the background of other diseases, the possibility of the appearance of external signs of the underlying pathology is not excluded.
If symptoms occur, it is very important to provide emergency assistance to the victim. You should call a team of doctors at home, and then perform the following actions:
- remove or remove a person from a room with a high content of carbon dioxide;
- carry out tracheal intubation (only in a serious condition of the patient) - an experienced clinician can do this;
- administer emergency oxygen therapy.
The only measure of assistance to a person who has fallen into an acidotic coma is artificial ventilation of the lungs.
Diagnostics
An experienced clinician will be able to make the correct diagnosis based on symptoms and laboratory results.
The doctor needs:
- study the medical history - to look for a possible underlying disease;
- collect and analyze a life history - to identify external causes, which will determine whether there was a need for a procedure such as permissive hypercapnia;
- assess the condition of the skin;
- measure pulse, heart rate and blood tone;
- interview the patient in detail (if the person is conscious) or the one who delivered the victim to a medical facility - to compile a complete symptomatic picture and determine the severity of the condition.
Laboratory research:
- general clinical blood test;
- blood biochemistry;
- assessment of the gas composition of the biological fluid;
- analysis for KOS.
As for instrumental procedures, the following tests are performed:
- chest x-ray;
- ultrasonography;
Treatment
The tactics of therapy depends on the sources against which hypercapnia arose. If the pathology is exogenous, it is necessary:
- ventilate the room;
- go out into the fresh air;
- take a break from work
- drink plenty of fluids.
If the malaise has become a secondary phenomenon, in order to eliminate the pathology, it is necessary to eliminate the underlying disease. You may need to take these medications:
- bronchodilators;
- antibiotics;
- anti-inflammatory drugs;
- hormonal drugs;
- immunostimulants;
- diuretics;
- bronchodilators;
- medications to relieve symptoms.
You can eliminate the negative effect of carbon dioxide on the body in the following ways:
- infusion therapy;
- artificial ventilation of the lungs;
- oxygen therapy;
- chest massage;
Possible Complications
Violation of the normal composition of the blood can cause the formation of a large number of complications:
- delayed child in mental and psychomotor development;
- epilepsy;
- hypoxia without hypercapnia in newborns;
- miscarriage;
- pulmonary hypertension;
- malignant hypertension;
- acute respiratory failure.
Hypoxemia is a decrease in the level of oxygen in the blood. Hypercapnia is the accumulation of carbon dioxide in the blood. Both of these conditions develop under the condition that the inhaled air contains an insufficient amount of oxygen. If its level is not restored to normal, then hypoxemia and hypercapnia will provoke hypoxia. It is these two conditions that are considered the main symptoms that indicate the development of respiratory failure.
In the acute form, respiratory failure can be hypercapnic and hypoxemic. In the first case, respiratory failure develops with an increase in the level of carbon dioxide in the blood, and in the second case, an insufficient supply of oxygen to the blood leads to it. Often, a person with acute respiratory failure has both hypercapnia and hypoxemia, but it is important for the doctor to determine which condition prevails, since the tactics of managing the patient depend on this.
The pathogenesis of hypercapnia and hypoxemia
So, if the level of carbon dioxide in the blood is elevated, then a person is diagnosed with hypercapnia. With a decrease in the oxygen content in the blood, they speak of hypoxemia.
Oxygen, which enters the lungs along with the inhaled air, is carried with the blood flow through the body with the help of red blood cells, binding to hemoglobin. Hemoglobin that carries oxygen to tissues is called oxyhemoglobin. When it reaches its destination, oxyhemoglobin gives up oxygen, after which it becomes deoxyhemoglobin, which can again attach oxygen, or carbon dioxide, or water to itself. However, normally, in the tissues where hemoglobin has delivered oxygen, carbon dioxide is already waiting for it. He picks it up and brings it out of the tissues into the lungs, which, during exhalation, rid the body of carbon dioxide. The hemoglobin that carries carbon dioxide is called carbohemoglobin.
If we consider this process in the form of a diagram, then it will look like this:
Hb found in red blood cells + O2 from the air = HbO2 (this reaction occurs in the lungs, from which oxygen-enriched hemoglobin is sent to the tissues).
HbO2> Hb + O2, while oxyhemoglobin gives oxygen to tissues.
Hb + CO2 (deoxyhemoglobin takes carbon dioxide from the tissues) = HbCO2 (this carohemoglobin is sent back to the lungs to get rid of carbon dioxide).
HbCO2 from tissues breaks down in the lungs into Hb and CO2. In this case, CO2 is removed, and Hb takes a new O2 molecule to again deliver oxygen to the tissues.
The cycle repeats again.
In this formula:
Hb - hemoglobin.
HbO2 is unstable oxyhemoglobin.
O2 is oxygen.
CO2 is carbon dioxide.
HbO2 is an unstable carbohemoglobin.
Such a reaction of the exchange of oxygen and carbon dioxide occurs on the condition that a person inhales clean air, in this case, the tissues do not experience oxygen starvation. However, it is known that reduced hemoglobin can attach any molecule to itself, since it does not have strong bonds. In simple terms, it attaches any component that it comes across. If there are few oxygen molecules in the lungs, then hemoglobin will take carbon dioxide molecules and send them to the tissues along with arterial blood. As a result, a person develops hypoxia, that is, oxygen starvation.
Hypoxia, hypoxemia and hypercapnia are the three symptoms that are characteristic of acute respiratory failure.
Hypoxia can be caused by many factors.
However, depending on the nature of its origin, two types of hypoxic reactions are distinguished:
Hypoxia is exogenous. In this case, hypoxia develops as a result of the fact that the level of oxygen in the inhaled air becomes low. Therefore, human blood is not saturated with O2, which leads to oxygen starvation of tissues. Exogenous hypoxia develops in people who fly at high altitudes, climbers, conquerors of mountain peaks, scuba divers. Also, exogenous hypoxia develops in any person who inhales air with harmful inclusions.
Hypoxia, which develops against the background of various pathologies of the respiratory or circulatory system.
Such hypoxia is divided into 4 subspecies:
Respiratory hypoxia, which manifests itself in violation of the function of external respiration. At the same time, the actual volume of ventilation of the alveoli per unit of time is lower than what the body needs. Respiratory hypoxia is caused by chest injuries, impaired airway patency, a decrease in the working surface of the lung tissue, and inhibition of the respiratory center (against the background of taking medications, with, with inflammation of the lung tissues). Respiratory hypoxia may be the result of diseases such as emphysema, pneumosclerosis, chronic obstructive pulmonary disease. It can also develop against the background of poisoning the body with toxic substances.
Circulatory form of hypoxia, which develops against the background of acute or chronic insufficiency of the circulatory system. Congenital, for example, an open oval window, can lead to such disorders.
Tissue hypoxia develops with poisoning. In this case, the tissues simply refuse to take in oxygen from the blood.
Blood hypoxia, which develops against the background of a drop in the level of red blood cells or hemoglobin in the blood. Most often, the cause is, which is a consequence of acute blood loss or other pathological conditions.
Symptoms such as cyanosis of the skin, tachycardia, drop in blood pressure, convulsions, and fainting indicate severe hypoxia. In severe hypoxia, the patient's symptoms rapidly increase. If the victim is not provided with emergency assistance, he will die.
With hypercapnia, carbon dioxide accumulates in the tissues of the body and in the blood. The indicator of such accumulation of PaCO2. The level of this indicator should not exceed 45 mm. rt. Art.
Causes of hypercapnia can be as follows:
Violation of ventilation of the lungs against the background of airway obstruction. Sometimes a person deliberately takes a breath less deep, for example, if he experiences pain during breathing (with a chest injury, with operations on the peritoneal organs, etc.).
Violations in the functioning of the respiratory center, which affects the regulation of respiratory function. This can occur with brain injury, with its destructive lesions, with drug poisoning.
Weak muscle tone of the chest, which happens in various pathological conditions.
So, the main pathologies that can cause hypercapnia are:
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Chronic obstructive pulmonary disease.
Infectious diseases of the respiratory system.
Also, the peculiarities of a person’s professional activity can cause hypercapnia. So, bakers, divers, steelworkers often suffer from it. An unfavorable ecological situation in the area where a person lives, inhalation of tobacco smoke and a long time spent in unventilated rooms can lead to excessive accumulation of carbon dioxide in tissues and blood.
Hypercapnia is indicated by the following symptoms:
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Pain in the chest area.
Increased heart rate.
Difficulty in falling asleep. Daytime sleepiness.
Increased intracranial pressure, up to cerebral edema.
If the level of carbon dioxide in the blood significantly exceeds the permissible limits of the norm, then the development of hypercapnic coma is possible. It is dangerous by stopping the heart and breathing.
Hypoxemia develops when arterial blood is not saturated with oxygen in the lungs. The level of oxygen in the blood is indicated by such an indicator as PaO2. Its normal level is 80 mm. rt. Art., but no less.
Causes of hypoxemia:
Alveolar hypoventilation, which most often develops when there is insufficient oxygen in the air. However, other reasons may also lead to it.
Violations of ventilation-perfusion connections, which is observed in various lung diseases.
Right-to-left shunting, when venous blood enters the left atrium, bypassing the lungs. The cause of this condition is often one or another heart disease.
Violation of diffusion in the alveolar-capillary membrane.
Causes of impaired ventilation-perfusion connections in the lungs and diffusion capacity of the alveolar-capillary membrane
Gas exchange in the lungs is provided by ventilation of the lungs and blood flow in a small circle. But perfusion and ventilation occur in different proportions. So, some parts of the lungs are better ventilated, but not supplied with blood. In some areas, on the contrary, the blood is actively coming, but there is no ventilation, for example, this is observed in the alveoli of the tops of the lungs. If there are many such areas that take part in gas exchange, but are not sufficiently washed by the blood, then this entails first hypoxemia, and then hypercapnia. Such relationships are called ventilation-perfusion.
Violation of this ratio can be observed in the following cases:
Pulmonary hypertension.
Sudden loss of blood in large volumes.
Shock of various origins.
DIC syndrome with the formation of small blood clots in the bloodstream.
Pulmonary embolism.
The diffuse capacity of the alveolar-capillary membrane can increase and decrease depending on the specific circumstances. For example, what is the intensity of compensatory-adaptive mechanisms in a particular person during physical activity, with a change in body position, etc. The diffuse ability of the alveolar-capillary membrane begins to decrease in people after 20 years, which is a physiological norm for each person. Its significant decrease is observed in pathologies of the respiratory organs, for example, with inflammation of the lungs, with emphysema or obstructive pulmonary disease. All this becomes prerequisites for the development of hypoxemia, hypercapnia and hypoxia.
Hypoxemia can increase rapidly or gradually.
Its symptoms are:
Cyanosis of the skin. The more intense it is, the lower the level of oxygen in the blood. If hypoxemia is weak, then cyanosis of the skin does not develop, the person just looks paler than usual.
Tachycardia or palpitations is a compensatory mechanism of the body, which tries to compensate for the lack of oxygen in this way.
Drop in blood pressure.
It is well known how oxygen deficiency and excess carbon dioxide are equally bad for human health. The supply of oxygen to the body must be regular and in the required quantity. A violation in the supply of oxygen and a decrease in its level in the body is called hypoxemia. The accumulation of carbon dioxide leading to hypoxia is called hypercapnia. Hypercapnia and hypoxemia are important symptoms of respiratory failure (ARF), often occurring simultaneously.
There are two types of ODN:
- hypercapnic, caused by excess carbon dioxide;
- hypoxemic due to oxygen deficiency.
Both types of respiratory failure must be considered separately from each other, since each of them is individual.
Hypercapnia- this is an increase in carbon dioxide in the human circulatory system.
- This is a decrease in the level of oxygen in the blood ().
The mechanism of transporting oxygen through the bloodstream to the tissues is known from school. Transport is carried out in which O2 is associated with hemoglobin.
Hemoglobin delivers oxygen to tissues and organs, becomes reduced, that is, capable of attaching any chemical compound, including carbon dioxide. And in the tissues at this time there is carbon dioxide, which with venous blood enters the lungs and is excreted from the body. attaches CO2, thus turning into carbohemoglobin, which in the lungs breaks down into hemoglobin and carbon dioxide, which is excreted from the body when exhaled.
Gas exchange according to this scheme takes place when the ratio of O2 and CO2 in the body is optimal: when a person inhales, he absorbs air enriched with oxygen, and when he exhales, he releases air saturated with carbon dioxide.
When the air is depleted of O2, and CO2 accumulates in the body, hemoglobin, adding carbon dioxide, delivers it to the tissues, causing hypoxia, that is, oxygen starvation. Hypercapnia and hypoxemia in this case cause ARF. Both of these phenomena, together with hypoxia, are considered inseparably from each other.
hypoxia
According to the method of occurrence, oxygen deficiency of the body is divided into two groups: exogenous and endogenous:
- Exogenous hypoxia occurs due to a decrease in the partial pressure of oxygen in the surrounding air, which results in an oxygen deficiency in the blood. This is especially pronounced when flying at high altitude, when hiking in the mountains, when diving to great depths, as well as when inhaling heavily polluted air.
- Endogenous hypoxia associated with the pathology of the respiratory and circulatory system.
There are 4 groups of hypoxia:
- respiratory, when there is an insufficiency of lung ventilation that occurs after an injury, depression of the respiratory center, after various diseases, for example, pneumonia, COPD, and when inhaled toxic substances;
- circulatory, arising from acute and chronic insufficiency of the circulatory system caused;
- tissue, which occurs during intoxication;
- blood, as a result of a decrease in red blood cells in the blood, which is determined by anemia of various origins.
A complex form of hypoxia is characterized by cyanosis of the skin, tachycardia, hypotension, which often leads to death.
Hypercapnia
The development of hypercapnia is affected by a change in the ratio of pulmonary ventilation and the accumulation of carbon dioxide in the tissues and blood. Normally, this indicator is no more than forty-five millimeters of mercury.
Reasons for the development of hypercapnia:
- violation of gas exchange caused by a disease of the respiratory system or forced breath holding to relieve pain inside the chest;
- suppression of the function of the respiratory center and a change in the regulation of breathing due to injuries, tumors, intoxication;
- decrease in muscle tone of the thoracic region due to pathological changes;
- chronic obstructive pulmonary disease,
- violation of the acid-base balance in the body;
- infectious diseases of the respiratory system;
- chronic vascular disease with deposition of cholesterol on their walls;
- occupational diseases in people whose working conditions are associated with the inhalation of polluted air;
- inhalation of oxygen-depleted air.
Symptoms of hypercapnia:
- insomnia at night and drowsiness during the day;
- dizziness and headaches;
- nausea and vomiting;
- increase in intracranial pressure;
- labored breathing;
A rapid increase in the level of CO2 in the blood causes a coma, which leads to.
The severity of hypercapnia:
- Moderate- accompanied by euphoria, increased sweating, redness of the skin, changes in breathing, increased blood pressure, insomnia.
- deep- characterized by increased excitability of the nervous system, increased intracranial pressure, shallow breathing, difficulty urinating, tachycardia.
- acidotic coma- aggravated by the lack of consciousness and reflexes, pronounced cyanosis, which in the absence of medical care leads to death.
Violation of oxygen saturation of the blood in the lungs causes hypoxemia. The main indicator that is guided by when determining oxygen deficiency is partial tension. Its normal value should not be below eighty millimeters of mercury.
The causes of hypoxemia can be as follows:
- decrease in ventilation in the alveoli of the lungs, when the oxygen content in the inhaled air is very low;
- violation of the ratio of ventilation volume to the volume of blood flow, which occurs in chronic lung diseases;
- shunting in case of changes in the circulatory system and ingress of venous blood into the left atrium;
- functional disorders in the capillary membrane.
The exchange of oxygen with carbon dioxide occurs in the lungs and tissues, but not all areas function in the same way. For example, with normal ventilation of some areas in the lungs, the supply of blood is worse, and in some areas the blood flow is excellent, but they are poorly ventilated and also do not participate in gas exchange. This leads to hypoxemia, which is associated with hypercapnia.
Changes in blood flow occur due to disease of other organs, especially the blood.
These disorders also lead to a lack of oxygen in the blood:
- bleeding;
- acute fluid loss;
- shock of various origins;
- vasculitis.
Symptoms of hypoxemia:
- blue skin with a strong manifestation of the disease, and pallor of the skin with minor changes;
- tachycardia, when the heart tries to help the body in providing it with oxygen;
- hypotension;
- loss of consciousness.
The lack of oxygen in the blood is the cause of memory impairment, decreased attention, insomnia, pronounced chronic fatigue. The serious impact of hypercapnia and hypoxemia on the human body is due to the special role of the respiratory and cardiovascular systems.
Diagnostics
The basis of the diagnosis is the patient's complaints, his examination by the attending doctor and analysis of the examination results.
The study of the patient's condition includes:
- a blood test for the ratio of gases, that is, a measurement of the amount of O2 in the blood after medical procedures;
- electrolyte analysis, which determines the presence of chronic diseases in the lungs;
- a general blood test, reflecting the amount of hemoglobin;
- blood level measurement using a unique device;
- x-rays to exclude broncho-pulmonary diseases;
- ECG and heart to detect violations in his work and the presence of congenital anomalies.
Treatment
Treatment of hypercapnia and hypoxemia is carried out in parallel, but there is a difference in therapeutic measures. Any prescription for medication should be made by the attending physician. Experts recommend in the process of taking drugs to conduct laboratory tests to monitor blood composition.
Treatment suitable for both conditions is:
- inhalation of a mixture of gases with a high content of O2, and sometimes pure oxygen (the treatment regimen is developed and controlled by the doctor, taking into account the origin of the disease);
- artificial ventilation of the lungs, which is used even in a state of coma in a patient;
- antibiotics, bronchodilators, diuretics;
- physiotherapy exercises, massage of the thoracic region.
When treating hypoxia, the causes of its occurrence should be considered. Experts recommend starting therapy with the elimination of precisely these problems. The influence of negative factors on the development of hypercapnia and hypoxemia is advised to be minimized.
Prevention
Hypercapnia and hypoxemia are quite unpleasant diseases for a person, so following simple rules will help prevent active development:
- walks every day for 2 hours;
- a ban on active and passive smoking;
- competent diagnosis of diseases of the heart and lungs;
- moderate physical activity;
- well-formulated diet.
To prevent the development of hypercapnia, it is necessary to treat diseases of the broncho-pulmonary system, which are accompanied by respiratory failure, in time.
Prevention of hypercapnia includes:
- organization of uninterrupted operation of equipment for divers, miners, astronauts and other professions associated with temperature and pressure differences;
- maintenance of anesthesia machines in perfect condition;
- daily walks;
- ventilation of the premises, and, if necessary, additional ventilation.
Hypercapnia is an increased tension of carbon dioxide in the arterial blood and tissues of the body.
It can develop in space flight with an increase in the concentration of carbon dioxide in the cabin atmosphere or in the pressure helmet of the spacesuit due to partial or complete disruption of the carbon dioxide removal and absorption system. An excess of carbon dioxide in the cabin can be provided for by the flight program for reasons of weight saving, reduction in size and power consumption of the life support system, as well as in order to enhance oxygen regeneration, prevent hypocapnia, or to reduce the damaging effect of cosmic radiation.
Depending on the ventilated volume of the suit and cabin, damage to the regeneration system and the amount of carbon dioxide produced by the crew, its concentration in the inhaled air can increase to a toxic level (more than 1%, or 7.5 mm Hg - 1 kPa) in a few minutes or hours. In this case, a state of acute hypercapnia develops. Prolonged (days, weeks, months) stay in an atmosphere with a moderate content of carbon dioxide leads to chronic hypercapnia.
If the knapsack system for absorption of carbon dioxide in a space suit fails during intensive work, the concentration of carbon dioxide in the pressure helmet reaches a toxic level in 1-2 minutes. In a spacecraft cabin with 3 cosmonauts doing their usual work, this will happen more than 7 hours after the complete failure of the regeneration system.
Even tired hypercapnia worsens the state of health and general condition, depletes the reserves of the basic vital functions of the body. Human behavior becomes inadequate, mental, especially physical performance decreases, the body's resistance to stress factors - overload, orthostasis, overheating, hyperoxia, decompression.
It is important that hypercapnia in space flight is also fraught with serious complications due to the "reverse" action of carbon dioxide. After the transition from breathing in a hypercapnic environment to a normal gas mixture, as well as to air or oxygen, the noted disturbances in the body often not only do not weaken, but even intensify or new symptoms of carbon dioxide poisoning appear. This state can persist for minutes, hours, and sometimes days after the restoration of the normal gas composition of the inhaled air.
An increase in the concentration of carbon dioxide in the inhaled air up to 0.8-1% does not cause violations of physiological functions and performance in acute and chronic effects. The admissibility of high concentrations is determined primarily by taking into account the duration of stay in such an atmosphere and the intensity of the work performed. If an astronaut has to work for several hours in a space suit, the content of carbon dioxide in a pressure helmet should not exceed 2% (RDO 15 mm Hg - 2 kPa). Upon reaching this concentration of carbon dioxide, complaints of shortness of breath and fatigue will appear, but the work will be completed in full.
In the cockpit of a spacecraft with periodic performance of only light work, an astronaut can cope with the task for several hours with an increase in carbon dioxide concentration up to 3% (RCO, 22.5 mm Hg - 3 kPa). However, severe shortness of breath and headache will occur, which may remain in the future.
Signs of chronic hypercapnia develop with prolonged exposure to an atmosphere with a carbon dioxide content of 0.9 to 2.9%. Under these conditions, the electrolyte balance and acid-base state change, physiological functions are stressed and functional reserves are depleted, which are detected by exercise tests.
The state of acute hypercapnia can be established by an increase in RCO 2 in arterial blood (more than 40 mm Hg, or 5.33 kPa), as well as by subjective and clinical signs: shortness of breath, especially at rest, nausea and vomiting, fatigue at work, headache pain, dizziness, visual disturbances, cyanosis of the face, severe sweating. Chronic hypercapnia is accompanied by phase changes in psychomotor activity (excitation followed by depression), which manifest themselves in behavior and during mental and muscular work. Headache, fatigue, nausea and vomiting are less pronounced. There is often persistent hypotension. Violation of the electrolyte balance and acid-base state, as well as the stress of the function of the adrenal cortex are determined only by biochemical methods.
So far, there are no specific treatments for hypercapnic acidosis or ways to increase the body's resistance to the action of elevated concentrations of carbon dioxide. The most effective help to the cosmonaut in case of violation of the regeneration system will be the fastest restoration of the normal gas composition of the inhaled air. If failures in the main regeneration system cannot be corrected, then subsystems and emergency systems, as well as emergency oxygen supplies on board or in a spacesuit, should be used.
In a spacesuit, an astronaut can also isolate himself from the hypercapnic environment of the cabin by closing the visor of the pressure helmet. For the timely prevention of hypercapnia on board the ship, a device indicating a dangerous level of carbon dioxide is needed.
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