Carbon monoxide poisoning
Carbon monoxide, or carbon monoxide (chemical formula CO), is an extremely toxic, colorless gas. It is an indispensable product of incomplete combustion of carbon-containing substances: it is determined in automobile exhaust gases, cigarette smoke, in smoke during fires, etc. There is no smell of carbon monoxide, therefore, it is impossible to detect its presence and estimate the concentration in the inhaled air without devices.
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Once in the blood, carbon monoxide displaces oxygen from the connection with the respiratory protein hemoglobin and inhibits the functioning of active centers responsible for the formation of new hemoglobin, thereby causing acute oxygen starvation of tissues. In addition, carbon monoxide disrupts the course of oxidative processes in the body.
Carbon monoxide, which has a high affinity for the respiratory protein, binds to it much more actively than oxygen. For example, if the concentration of CO in the inhaled air is only 0.1% of the total volume (the ratio of carbon monoxide and oxygen is 1: 200, respectively), hemoglobin will bind equal amounts of both gases, i.e., half of the respiratory protein circulating in the systemic circulation will be occupied by carbon monoxide gas.
The breakdown of the carboxyhemoglobin molecule (hemoglobin-carbon monoxide) occurs approximately 10,000 times slower than the molecule of oxyhemoglobin (hemoglobin-oxygen), which determines the danger and severity of poisoning.
The exhaust gases of a car contain a maximum of 13.5% carbon monoxide, on average 6-6.5%. So, a low-power motor of 20 liters. from. produces up to 28 liters of CO per minute, creating a lethal concentration of gas in the air in a closed room (garage, repair box) within 5 minutes.
Typical symptoms of poisoning appear after 2-6 hours of inhalation of air containing 0.22-0.23 mg of carbon monoxide per 1 liter; severe poisoning with loss of consciousness and death can develop in 20-30 minutes at a carbon monoxide concentration of 3.4–5.7 mg / l and in 1-3 minutes at a poison concentration of 14 mg / l.
How does carbon monoxide poisoning happen?
Carbon monoxide poisoning most often occurs in the following cases:
- improper operation or malfunction of furnace equipment, gas heating appliances;
- stay in an unventilated closed room with the car engine running;
- fire;
- smoldering electrical wiring, household appliances, interior parts and furniture;
- violation of safety regulations when working in a chemical production where carbon monoxide is used.
The likelihood of poisoning is directly proportional to the concentration of carbon monoxide in the inhaled air and the time it is exposed to the body.
Poisoning symptoms
The nervous system is most sensitive to changes in the level of oxygen in the blood. The degree of damage can vary from mild reversible to generalized, resulting in temporary or permanent disability, and in especially severe cases, the death of the victim.
In addition to the nervous system, the respiratory (tracheitis, tracheobronchitis, pneumonia) and cardiovascular (dystrophy and necrotization of the myocardium, degenerative changes in the walls of blood vessels) systems are most often involved in the pathological process.
Depending on the concentration of CO in the air and, accordingly, carboxyhemoglobin in the blood, several degrees of carbon monoxide poisoning are emitted.
Symptoms of mild poisoning (the content of carboxyhemoglobin in the blood does not exceed 30%):
- consciousness is preserved;
- constricting, pressing headache, reminiscent of being pulled together in a hoop;
- dizziness, noise, ringing in the ears;
- lacrimation, profuse discharge from the nose;
- nausea, vomiting;
- possible light transient visual impairment;
- difficulty breathing;
- sore throat, dry cough.
Poisoning of moderate severity (develops when the concentration of carboxyhemoglobin in the blood is from 30 to 40%):
- short-term loss or other impairment of consciousness (stunning, soporosis or coma);
- difficulty breathing, intense shortness of breath;
- persistent pupil dilation, anisocoria (pupils of different sizes);
- hallucinations, delusions;
- tonic or clonic seizures;
- tachycardia, pressing pain in the chest;
- hyperemia of the skin and visible mucous membranes;
- discoordination;
- visual impairment (decreased acuity, flashing flies);
- decreased hearing acuity.
In severe poisoning (concentration of carboxyhemoglobin 40-50%):
- coma of varying depth and duration (up to several days);
- tonic or clonic seizures, paralysis, paresis;
- involuntary urination and / or defecation;
- weak threadlike pulse;
- shallow, intermittent breathing;
- cyanosis of the skin and visible mucous membranes.
In addition to the classic manifestations of carbon monoxide poisoning, atypical symptoms may develop in one of the following forms:
- fainting - characterized by a sharp decrease in blood pressure (up to 70/50 mm Hg and below) and loss of consciousness;
- euphoric - sharp psychomotor agitation, decreased criticism, disorientation in time and space, hallucinations and delirium are possible;
- lightning-fast - develops when the concentration of CO in the inhaled air is 1.2% or more, the content of carboxyhemoglobin in the systemic circulation in this case exceeds 75%. The death of the victim occurs rapidly, after 2-3 minutes.
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First aid for carbon monoxide poisoning
If you suspect carbon monoxide poisoning, you must immediately evacuate the victim from the CO exposure zone, call an ambulance team, and provide first aid while awaiting its arrival.
- Provide fresh air by unbuttoning tight clothing, open windows.
- If the victim is conscious, give a warming caffeine-containing drink (tea, coffee) to activate the respiratory and vasomotor centers.
- If the victim is unconscious, bring cotton wool soaked in ammonia to the nose, in the absence of effect, vigorously rub the limbs, chest, face to stimulate blood circulation.
- If there are signs of clinical death (lack of consciousness, breathing and pulse on the carotid arteries, dilated pupils that do not respond to light), cardiopulmonary resuscitation should be started immediately.
It is important to remember: when entering a room where carbon monoxide poisoning is suspected, you must hold your breath and leave it as soon as possible after the evacuation of the victims.
When is medical attention required?
In case of carbon monoxide poisoning, qualified medical care is needed in 100% of cases. Treatment is carried out in a hospital, in the intensive care unit and intensive care unit. The victim is injected with an antidote (Acizol), provided breathing with oxygen or carbogen, further therapy is aimed at maintaining vital functions, eliminating symptoms and preventing the development of complications.
Possible consequences
After carbon monoxide poisoning, both early (in the first 2 days) and late (from 2 to 40 days) complications may develop.
The early ones include:
- swelling of the brain;
- toxic pulmonary edema;
- heart rhythm disturbances;
- visual and hearing impairment;
- neuritis.
Late complications:
- decreased cognitive function;
- amnesia;
- psychosis;
- movement disorders, paralysis, paresis;
- pneumonia;
- myocardial infarction;
- myocarditis;
- acute heart failure.
Prevention
To prevent carbon monoxide poisoning, you must:
- use only serviceable gas equipment, ensure its timely preventive maintenance;
- in houses with stove heating, ensure adequate ventilation, control the position of the stove damper;
- do not work with the car in the garage, repair box with the engine running;
- When working with carbon monoxide, observe safety precautions at the workplace.
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Olesya Smolnyakova Therapy, clinical pharmacology and pharmacotherapy About the author
Education: higher, 2004 (GOU VPO "Kursk State Medical University"), specialty "General Medicine", qualification "Doctor". 2008-2012 - Postgraduate student of the Department of Clinical Pharmacology, KSMU, Candidate of Medical Sciences (2013, specialty "Pharmacology, Clinical Pharmacology"). 2014-2015 - professional retraining, specialty "Management in education", FSBEI HPE "KSU".
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
