A person who spends a long time in closed premises often complains of unpleasant symptoms. After contacting a medical facility, 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 poisoning (CO2).
There are two types of hypercapnia:
- exogenous – characterized by an increase in the amount of carbon dioxide in the body, which develops as a result of the victim’s stay in a room with an increased level;
- endogenous - appears as a result of deviations in the human respiratory system.
If the disease develops, you need to consult a qualified doctor who will explain how the pathology appeared and how to eliminate the symptoms.
Causes
Hypercapnia can develop for various reasons, but there is a list of factors that increase the likelihood of its occurrence:
- periodic epileptic urges;
- traumatic effects on the brain stem;
- damage to the brain stem as a result of cancer, stroke or other inflammatory processes;
- presence of bronchial asthma;
- pathological changes in the spinal cord that occur with poliomyelitis;
- the use of pharmacological drugs that can disrupt the functioning of the respiratory system;
- the presence of myasthenia gravis in the body;
- 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 deep immersion under water (improper breathing, hyperventilation and intense exercise are factors that can provoke the development of such an illness);
- 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 surgery.
Symptoms
Symptoms of hypercapnia can be acute or 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 there is shortness of breath;
- blood pressure increases significantly;
- the person feels drowsy and becomes lethargic;
- the rhythm of the heart muscle accelerates;
- pain occurs in the chest area;
- periodic gag reflex and nausea appear;
- the patient is bothered by frequent convulsions;
- the victim’s consciousness is confused, speech is slurred;
- Possible 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 blood supply and soft tissues, the more clearly the signs of the disease appear.
If the acute form of hypercapnia is not detected and eliminated, it can provoke the appearance of many negative complications and a complete disruption of the respiratory and cardiovascular systems, and the consequence of such a process is the most dangerous consequence - the death of the victim.
Symptoms of chronic course:
- feeling lethargic and tired (after normal sleep);
- psychological disorders (depression, stress, hypersensitivity, agitation and irritability);
- reduced blood pressure;
- the occurrence of abnormalities in respiratory and heart rhythm;
- the presence of shortness of breath with minor exertion;
- deterioration of vital functions and brain activity.
If there are 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 increases gradually, and the negative effect on the victim’s body 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 be restored, and the cardiovascular system begins to function much faster. Thanks to adaptation processes in the human body, the disease does not require therapy or the attention of doctors.
First aid
In case of external exposure to carbon dioxide, first medical aid is provided to the victim:
- 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 device supporting the patient’s respiratory process, the resulting disorder is stopped and the patient’s condition is stabilized;
- when the resulting poisoning threatens human life, tracheal intubation is performed;
- in case of exogenous pathology, oxygen therapy and artificial ventilation are performed.
When the victim is taken to a medical facility to confirm the diagnosis and prescribe treatment measures.
Diagnostic technique
During diagnosis, a qualified doctor examines the patient, interviews him about the present symptoms and types of precise studies. The presence of carbon dioxide poisoning can be confirmed or refuted using diagnostic techniques:
- studying the level of carbon dioxide in the arterial blood of the victim. The established PCO2 norm is 4.6-6.0 kPa or 35-45 mm Hg. Art. In case of poisoning, PCO2 levels rise to 55-80 mm Hg. Art., and the oxygen level 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 device 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. Its calculation method can determine the amount of gases present in the circulatory system.
After conducting a diagnostic examination and carefully studying the results obtained, a qualified medical professional, 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 levels). In fact, it is an integral part of 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 rate of carbon dioxide accumulation (partial pressure) in arterial blood exceeds the norm of 40–45 mmHg. 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 hemoglobin of erythrocytes, forming carbohemoglobin, which is unable to transport oxygen to the 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 carbon dioxide gas in tissues and blood is due to external causes. For example, by inhaling air saturated with carbon dioxide (more than 5%). In this case, the person develops 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 impaired gas exchange in the alveoli (the final vesicular structures of the lungs) and developing due to respiratory diseases (obstruction, inflammation, trauma, foreign objects, operations);
- impaired 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 “provoker” of hypercapnia
Separately, we should highlight hyperventilation of the lungs, which is the opposite of hypoventilation and develops with intense breathing, during which the body is oversaturated with oxygen. Often this condition subsequently leads to an increase in the amount of carbon dioxide in the tissues and blood. This happens, for example, during diving (deep diving), when a person in front of him actively and quickly breathes, trying to saturate his lungs with oxygen, but does it incorrectly.
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, and special forces soldiers maintain a breathing rhythm in which the exhalation is 2 or 3 times longer than the inhalation. In this case, the person completely frees the lungs of carbon dioxide, but does not provoke hyperventilation.
Endogenous factors
The causative factors causing 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 rib joints;
- spinal deformity (scoliosis, kyphosis);
- tuberculous spondylitis, previous rickets;
- extreme obesity (Pickwickian syndrome);
- congenital defects of the osteochondral apparatus;
- limited mobility of the chest due to muscular dystrophy and pain due to intercostal neuralgia;
- damage and damage to the structures of the brain and spinal cord - strokes, encephalitis, trauma, tumor, poliomyelitis;
- myasthenia gravis (neuromuscular genetic disease);
- acidosis, metabolic alkalosis;
- atherosclerosis;
- epileptic seizures;
- apnea (sudden uncontrolled stop 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 carbon dioxide accumulation;
- prolonged stay in stuffy rooms, smoking, including passive smoking;
- long stay in closed and sealed spaces (wells, mines, submarines, space suits, closed garages), where carbon dioxide accumulates;
- improper operation of furnaces and boilers;
- damage by phosgene, ammonia, hydrochloric, sulfuric acid;
- poisoning with anticholinesterase drugs;
- technical problems in breathing equipment during surgical interventions when the patient is under anesthesia.
Symptoms
Based on 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 gas acidosis
Signs of hypercapnia also vary depending on whether the condition of abnormally high carbon dioxide levels is acute (short-term) or chronic.
Normal outdoor CO2 concentrations are about 0.04%, or 380–400 ppm in parts per million units. Thus, 0.1% carbon dioxide corresponds to 1 thousand ppm.
Adaptation of the body to respiratory acidosis
If a person spends a long time in an environment with a constant moderately increased level of carbon dioxide in the air or with a slow increase in CO 2 concentration, gradual adaptation to environmental changes occurs.
Thanks to compensation mechanisms, the body, to some extent, has the internal strength to eliminate emerging breathing 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, when the partial pressure of carbon dioxide in the blood increases by 1 mm Hg. Art. the volume of breath 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 hypercapnia in children
In children, respiratory failure due to carbon dioxide poisoning develops faster and is more severe than in adults.
The specifics of the course and consequences of hypercapnia in childhood are associated with the anatomy and functionality of the respiratory system:
- narrow airways (cause disruption of their patency even with slight swelling or accumulation of mucus);
- rapid reaction of respiratory tract tissues to irritants (swelling, spasm, increased secretion);
- weakness of the respiratory muscles in children;
- anatomical features - abduction of the ribs from the sternum almost at a right angle reduces the depth of inspiration.
In a child’s body, a strong excess of carbon dioxide causes a slowdown in metabolic processes, dystrophic and irreversible changes against the background of oxygen starvation of the tissues of the heart, liver, brain, and kidneys.
An increased level of carbon dioxide in the blood of a pregnant woman is a dangerous condition for both mother and child. Features that aggravate or provoke the development of hypercapnia:
- while carrying a baby, a woman’s need for oxygen increases by approximately 18–22%;
- as a result of the growth of the uterus, the abdominal type of breathing is replaced by the thoracic one, in which the abdominal muscles, as auxiliary ones, are excluded from participating in breathing, which leads to incomplete exhalation and the accumulation of carbon dioxide in the lungs;
- the growing uterus puts pressure on the liver, stomach, raises the diaphragm, reducing the tidal volume of the lungs and preventing the possibility of deepening 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.
Consequences:
- 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;
- disturbance 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:
- disorders of organ formation in the embryo;
- delayed mental and physical development in a newborn;
- cerebral palsy;
- epilepsy.
If the baby survives childbirth safely, then later he may develop severe chronic disorders. As a result, all newborns with respiratory acidosis require intensive treatment.
Diagnostics
Hypercapnia is diagnosed based on:
- subjective feelings 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 to determine the concentration of carbon dioxide in arterial blood. Normal carbon dioxide levels are observed at partial pressures ranging from 4.7 to 6 kPa, which corresponds to 35–45 mmHg. Art.
With the development of hypercapnia, an increase in the partial pressure of carbon dioxide is detected to 55–100 mm Hg. Art., a decrease in oxygen content, an increase in blood acidity (acidosis) against the background of a shift in the acid-base balance downward (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 (renewal of the gas composition in the pulmonary alveoli during breathing) is also carried out to identify the state of hypoventilation, that is, insufficient ventilation of the lungs, in which a deficiency of oxygen and an excess of carbon dioxide are formed in the blood.
To track the development of gas 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.
Recently, the pulse oximeter device has become very popular. It is used to determine the pulse and assess the oxygen saturation of hemoglobin. The latter indicator allows us 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 gas acidosis develops under the influence of external factors (exogenous hypercapnia), it is necessary:
- ventilate the room or go out into the open air;
- drink plenty of fluids to prevent blood clotting and reduce toxicity
For 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, set up anesthesia equipment;
- if a coma develops and breathing stops, immediately begin forced ventilation of the lungs so that inhaling air into the patient’s mouth or nose lasts twice as long as exhaling;
- in case of special severity and the patient cannot breathe independently, for example, when the airways are blocked, perform tracheal intubation.
Drug 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 cause respiratory acidosis;
- to restore normal gas exchange in the pulmonary alveoli.
Mechanical ventilation is often performed. They resort to its help in cases where:
- the person is not breathing or 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 drops below 45 mm Hg);
- arterial blood pH is 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 artificial ventilation. In this case, the patient breathes a balanced oxygen-nitrogen mixture with an oxygen content of up to 40%.
Incompetent oxygen therapy (especially with pure oxygen under pressure) leads to an increase in carbon dioxide levels 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 during drug overdose, poisoning with anesthetics and other pathological conditions.
In addition, with oxygen therapy it is easy to miss the development of a “reverse” critical condition - hypocapnia (carbon dioxide deficiency in the blood) and alkalosis (alkalization 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 mucus using a catheter or endotracheal tube;
- saline solution is administered through droppers to liquefy and remove bronchial secretions and 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 case of acute respiratory failure or an asthma attack, Prednisolone is administered intravenously, which quickly relieves swelling of the mucous membrane;
- in case of severe respiratory acidosis, alkaline solutions (Carbicarb, Tromethamine), sodium bicarbonate are infused drip-wise to compensate for respiratory acidosis;
- Diuretics are used to relieve edema and improve the compliance of the lungs;
- Doxopram and bronchodilators (Theophylline, Salbutamol, Fenoterol, Ipratropium bromide, Aminophylline) are used to stimulate breathing, expand the bronchi, and enhance pulmonary ventilation.
Further therapy depends on the disease causing hypercapnia and may include:
- antibacterial, anti-inflammatory, hormonal, immunostimulating drugs;
- bronchodilators in patients with pulmonary obstruction (Adrenaline, Isoproteronol) together 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, Izadrin 1%);
- injections of sodium hydroxybutyrate 20%, Sibazon 0.5% (relieves spasms), Cocarboxylase (maintains blood pH normal during acidosis) and Essentiale to eliminate oxygen starvation accompanying hypercapnia and acute respiratory failure.
Folk remedies
Home therapy using folk remedies does not have the “arsenal” to fully combat hypercapnia and acute respiratory failure. However, decoctions of medicinal plants can provide a certain positive result in chronic pathology. As a rule, the effect is expected if the cause of respiratory acidosis is bronchopulmonary diseases.
Many of them help to partially relax the bronchi, relieve swelling, reduce the viscosity of sputum and improve the removal of purulent mucus from the lungs.
When using folk recipes independently 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 swelling of the larynx, when inhaling with them there is a danger of bronchospasm, sudden swelling, respiratory burn ways and even activation of the proliferation of pathogenic microbes. For example, oregano, anise or licorice root, which are useful for breathing problems, can provoke uterine bleeding in pregnant women and allergies.
“Chest” herbs that make breathing easier in diseases that provoke gas acidosis include plantain, coltsfoot, licorice, marshmallow, sage, pine buds, anise, mint, wild rosemary (poisonous), chamomile, violet, calendula.
Usually, 2 tablespoons of herbal mixture are poured into 250–300 ml of boiling water, boiled slowly for 15 minutes, left for about 30–40 minutes, and filtered. The resulting decoction 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.
Products prepared with milk are also considered effective:
- Carrot juice with milk. Warm boiled milk is poured into fresh carrot juice in a 1:1 ratio. The medicinal drink is drunk 100–150 ml three times a day (warm). Removes phlegm well.
- Decoction of leek root in milk. Take raw materials from 2-3 plants, removing the lower white part. Crush, pour in 250–300 ml of milk and boil over low heat for 10 minutes. Leave for up to 6–7 hours. Strain and drink “onion milk” 5 times a day, a tablespoon. It relaxes the bronchi and makes breathing easier.
Treatment prognosis and possible complications
Hypercapnia can go unnoticed when the carbon dioxide content in the air is low. But it can also lead to the development of severe complications, depending on the concentration of CO 2, physiology, age of the person, and internal diseases.
With a mild degree of respiratory acidosis (up to 50 mm Hg), the condition does not have too negative an effect on the body even with prolonged exposure due to the adaptive capabilities of a person and a person’s adaptability to such conditions. Tolerance to 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 mmHg. Art. causes severe lack of oxygen, which in the absence of medical care and further development of hypercapnia leads to the patient’s 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 failure of respiratory function;
- regular and prolonged stay in the open air;
- compliance with the rules for working with professional breathing apparatus, which are used by miners, firefighters, divers, pilots, and 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 and workshop premises (exchange with the external atmosphere is calculated at a rate of 30 m 3 per hour per person), ensuring a comfortable concentration of carbon dioxide in the air for people (no more than 450–500 ppm);
- provision of sealed premises with CO 2 absorber devices;
- checking and troubleshooting equipment for anesthesia and artificial pulmonary ventilation;
- competent administration of general anesthesia.
Both short-term carbon dioxide intoxication and its long-term effects on the body can have an extremely negative effect on a person. Early recognition of symptoms in acute carbon dioxide poisoning and monitoring for 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) that 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., what happened during the patient’s anesthesia.
Etiology
Hypercapnia has a wide variety of causes, 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 characteristics - bakers, divers and steelworkers are at risk;
- air pollution;
- prolonged stay of a person in an unventilated room;
- long-term addiction to cigarettes;
- passive smoking;
- inhalation of carbon dioxide during a fire;
- diving to great depths during diving;
- excess nutrition;
- improper operation of special breathing 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 injury, oncological process, inflammatory lesion or stroke;
- the course of bronchial asthma;
- pathologies of the spinal cord, for example, polio;
- irrational use of drugs;
- sleep apnea syndrome - there is a sudden cessation of breathing movements;
- muscle tissue dystrophy;
- deformational changes in the chest, in particular kyphosis;
- sepsis;
- severe obesity;
- myasthenia gravis;
- chronic bronchopulmonary diseases accompanied by obstructive syndrome;
- damage to the central nervous system;
- fever;
- disturbance of gas exchange in the lung tissue - the disorder may occur due to Mendelssohn syndrome, Hamman-Rich disease, pneumothorax, respiratory distress syndrome, pulmonary edema or inflammation;
- 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 occurs:
- acute - characterized by a sudden appearance of clinical signs and a significant deterioration of the condition, most often found in children;
- chronic - the clinic is expressed in a slow increase in symptoms over a long time.
There are several degrees of severity 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 is:
- 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. The processes of adaptation to the new environment are activated in the body - this is compensation for the condition with increased respiratory movements.
Not a single classification includes permissive hypercapnia - a targeted limitation of the volume of ventilation of the lungs, which is necessary to avoid excessive stretching of the alveoli, despite an increase in CO2 beyond normal limits, up to 50–100 millimeters Hg. Art.
Symptoms
Usually the disease develops slowly, with a gradual increase in the intensity of clinical manifestations. It is extremely rare for symptoms to develop at lightning speed.
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;
- increased blood tone;
- increased 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;
- swelling;
- decreased visual acuity;
- rare and shallow breathing;
- cyanosis of the skin;
- strong cold sweat;
- increased heart rate up to 150 beats per minute;
- increased blood pressure values;
- dizziness;
- difficulty urinating.
Acidotic coma is expressed by the following symptoms:
- decreased reflexes;
- hyperhidrosis;
- a sharp decrease in blood tone;
- loss of consciousness;
- cyanotic skin tone;
- convulsive seizures.
In case of chronic disease, symptoms include:
- constant fatigue;
- decreased ability to work;
- decreased blood pressure;
- excitement followed by depression of consciousness;
- dyspnea;
- breathing problems;
- sleep disturbance;
- headaches and dizziness.
In children, the symptoms are practically no different. It should be remembered that in this category of patients, hypercapnia develops much faster and is much more severe than in adults.
In situations where the disease develops against the background of other diseases, the possibility of appearance of external signs of the underlying pathology cannot be ruled out.
If symptoms occur, it is very important to provide emergency assistance to the victim. You should call a medical team to your home, and then follow these steps:
- remove or remove a person from a room with a high content of carbon dioxide;
- perform tracheal intubation (only if the patient’s condition is serious) - this can be done by an experienced clinician;
- administer emergency oxygen therapy.
The only measure of assistance to a person who has fallen into an acidotic coma is artificial ventilation.
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 search for a possible underlying disease;
- collect and analyze your life history to identify external causes, which will allow you to 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 draw up 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 biological fluid;
- CBS analysis.
As for instrumental procedures, the following tests are performed:
- chest x-ray;
- ultrasonography;
Treatment
Treatment tactics depend on the sources behind which hypercapnia occurred. If the pathology is exogenous in nature, it is necessary:
- ventilate the room;
- go out into the fresh air;
- take a break from work;
- drink plenty of liquid.
If the malaise has become a secondary phenomenon, to eliminate the pathology it is necessary to eliminate the underlying disease. You may need to take the following medications:
- bronchodilators;
- antibiotics;
- anti-inflammatory drugs;
- hormonal medications;
- immunostimulants;
- diuretics;
- bronchodilators;
- medications to relieve symptoms.
You can eliminate the negative effects of carbon dioxide on the body in the following ways:
- infusion therapy;
- artificial ventilation;
- oxygen therapy;
- chest massage;
Possible complications
Violation of the normal composition of the blood can cause the formation of a large number of complications:
- delay of the child in mental and psychomotor development;
- epilepsy;
- hypoxia without hypercapnia in newborns;
- miscarriage;
- pulmonary hypertension;
- malignant hypertension;
- acute respiratory failure.
It is well known how oxygen deficiency and excess carbon dioxide have equally bad effects on human health. The supply of oxygen to the body must be regular and in the required quantity. A disruption 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 (RF), often occurring simultaneously.
There are two types of ODN:
- hypercapnic, caused by excess carbon dioxide;
- hypoxemic, caused by oxygen deficiency.
Both types of respiratory failure must be considered separately from each other, since each of them is individual.
Hypercapnia is an increase in carbon dioxide levels in the human circulatory system.
- this is a decrease in the level of oxygen in the blood ().
The mechanism of oxygen transport through the bloodstream to tissues has been known since school. Transport is carried out in which O2 is bound to hemoglobin.
Hemoglobin delivers oxygen to tissues and organs and 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 enters the lungs with venous blood and is removed from the body. attaches CO2, thus turning into carbohemoglobin, which in the lungs breaks down into hemoglobin and carbon dioxide, which is removed from the body when exhaled.
Gas exchange according to this scheme occurs 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 it 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 inextricably from each other.
Hypoxia
According to the method of occurrence, oxygen deficiency in 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 a deficiency of oxygen in the blood. This is especially evident when flying at high altitudes, during mountain hikes, when diving to great depths, and also when inhaling heavily polluted air.
- Endogenous hypoxia associated with pathology of the respiratory organs and circulatory system.
There are 4 groups of hypoxia:
- respiratory, when there is insufficient ventilation of the lungs, which occurs after injury, depression of the respiratory center, after various diseases, for example, pneumonia, COPD, and when inhaling toxic substances;
- circulatory, which occurs during acute and chronic insufficiency of the circulatory system caused by;
- 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 bluish skin, tachycardia, and hypotension, which often leads to death.
Hypercapnia
The development of hypercapnia is influenced by changes in the ratio of pulmonary ventilation and the accumulation of carbon dioxide in tissues and blood. Normally, this figure is no more than forty-five millimeters of mercury.
Reasons for the development of hypercapnia:
- impaired gas exchange caused by disease of the respiratory system or forced holding of breath to relieve pain inside the chest;
- suppression of the function of the respiratory center and changes in breathing regulation due to injuries, tumors, intoxication;
- decreased 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 cholesterol deposition on their walls;
- occupational diseases in people whose working conditions involve inhaling polluted air;
- inhalation of oxygen-depleted air.
Symptoms of hypercapnia:
- insomnia at night and drowsiness during the day;
- dizziness and headaches;
- nausea and vomiting;
- increased intracranial pressure;
- labored breathing;
A rapid increase in the level of CO2 in the blood causes coma, which leads to.
Severity of hypercapnia:
- Moderate– accompanied by euphoria, increased sweating, redness of the skin, changes in breathing, increased blood pressure, and insomnia.
- Deep– characterized by increased excitability of the nervous system, increased intracranial pressure, shallow breathing, difficulty urinating, and tachycardia.
- Acidotic coma– is aggravated by the lack of consciousness and reflexes, pronounced cyanosis, which in the absence of medical care leads to death.
Impaired oxygen saturation of the blood in the lungs causes hypoxemia. The main indicator that is used to determine oxygen deficiency is partial tension. Its normal value should not be below eighty millimeters of mercury.
The causes of hypoxemia may be the following:
- decreased 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 blood flow volume, which occurs in chronic lung diseases;
- shunting due to changes in the circulatory system and venous blood entering the left atrium;
- functional disorders in the capillary membrane.
The exchange of oxygen and carbon dioxide occurs in the lungs and tissues, but not all areas function equally. 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 in 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:
- blueness of the skin with severe manifestations of the disease, and pallor of the skin with minor changes;
- tachycardia, when the heart tries to help the body provide it with oxygen;
- hypotension;
- loss of consciousness.
Lack of oxygen in the blood causes memory impairment, decreased attention, insomnia, and severe 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 diagnosis is the patient’s complaints, his examination by the attending doctor and analysis of the examination results.
The examination of the patient's condition includes:
- blood test for gas ratio, that is, measuring the amount of O2 in the blood after treatment procedures;
- electrolyte analysis, which determines the presence of chronic diseases in the lungs;
- general blood test, reflecting the amount of hemoglobin;
- measuring blood levels using a unique device;
- X-rays to exclude bronchopulmonary diseases;
- ECG and heart to detect disturbances in its functioning 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 prescriptions for taking medications must be made by the attending physician. Experts recommend conducting laboratory tests to monitor blood composition while taking medications.
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 monitored by the doctor, taking into account the origin of the disease);
- artificial ventilation, which is used even when the patient is in a coma;
- antibiotics, bronchodilators, diuretics;
- physical therapy, thoracic massage.
When treating hypoxia, the causes of its occurrence should be taken into account. Experts recommend starting therapy by eliminating these particular problems. It is recommended to minimize the influence of negative factors on the development of hypercapnia and hypoxemia.
Prevention
Hypercapnia and hypoxemia are quite unpleasant diseases for humans, so following simple rules will help prevent the active development of:
- walks every day for 2 hours;
- ban on active and passive smoking;
- competent diagnosis of heart and lung diseases;
- moderate physical activity;
- well-designed diet.
To prevent the development of hypercapnia, it is necessary to promptly treat diseases of the bronchopulmonary system, which are accompanied by respiratory failure.
Prevention of hypercapnia includes:
- organization of uninterrupted operation of equipment for divers, miners, astronauts and other professions associated with differences in temperature and pressure;
- keeping 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 arterial blood and body tissues.
It can develop during space flight when the concentration of carbon dioxide in the cabin atmosphere or in the pressure helmet of a spacesuit increases due to partial or complete disruption of the carbon dioxide removal and absorption system. Excess carbon dioxide in the cabin can be provided for by the flight program for reasons of weight saving, reducing the size and energy intensity of the life support system, as well as to enhance oxygen regeneration, prevent hypocapnia, or to reduce the damaging effects of cosmic radiation.
Depending on the ventilated volume of the spacesuit 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. Long-term (days, weeks, months) exposure to an atmosphere with moderate carbon dioxide content leads to chronic hypercapnia.
If the backpack carbon dioxide absorption system 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 regeneration system has completely failed.
Even severe hypercapnia worsens well-being and general condition, depleting the reserves of the body’s basic vital functions. Human behavior becomes inadequate, mental, especially physical performance, and the body’s resistance to stress factors - overload, orthostasis, overheating, hyperoxia, decompression - decrease.
It is important that hypercapnia in space flight is fraught with serious complications due to the “reverse” effect of carbon dioxide. After switching 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 subside, but even intensify or new symptoms of carbon dioxide poisoning appear. This condition can persist for minutes, hours, and sometimes even a day after the normal gas composition of the inhaled air is restored.
An increase in the concentration of carbon dioxide in the inhaled air to 0.8-1% does not cause disturbances in physiological functions and performance during 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 in a spacesuit for several hours, the carbon dioxide content in the pressure helmet should not exceed 2% (RCO 15 mm Hg - 2 kPa). Once this concentration of carbon dioxide is reached, complaints of shortness of breath and fatigue will appear, but the work will be completed in full.
In a spacecraft cabin with only light work periodically performed, an astronaut can complete a task within several hours when the carbon dioxide concentration increases to 3% (PCO, 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, tension in physiological functions and depletion of functional reserves occur, which are detected by stress tests.
The state of acute hypercapnia can be established by an increase in PCO 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, bluishness of the face, severe sweating. Chronic hypercapnia is accompanied by phasic changes in psychomotor activity (excitement followed by depression), which manifest themselves in behavior and during mental and muscular work. Headache, fatigue, nausea and vomiting are less pronounced. Persistent hypotension is common. Violations of electrolyte balance and acid-base status, as well as tension in the function of the adrenal cortex, are determined only by biochemical methods.
There are no specific treatments for hypercapnic acidosis or ways to increase the body's resistance to elevated concentrations of carbon dioxide. The most effective help for an astronaut in case of disruption of the regeneration system will be the fastest restoration of the normal gas composition of the inhaled air. If problems with the main regeneration system cannot be corrected, then subsystems and emergency systems, as well as emergency oxygen supplies on board or in the suit, should be used.
In the spacesuit, the astronaut can also isolate himself from the hypercapnic environment of the cabin by closing the visor of the pressure helmet. To promptly prevent hypercapnia on board a ship, a device is needed to indicate dangerous levels of carbon dioxide.
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