Combustion - (regardless of the fuel burned) is an exothermic reaction involving the oxidation of the substance being burned. In our environment, the best available oxidant is oxygen present in 21% of atmospheric air. An ideal situation is when complete combustion occurs, in which all the fuel is oxidized according to the formula: C2H4 + 3O2 → 2CO2 + 2H2O, which in practice means that all carbon and hydrogen compounds –i.e. hydrocarbons in the form of commonly available fuels like wood, coal, liquid fuels or gas, burn in the presence of oxygen to carbon dioxide and water with the release of thermal energy. It is clear that none of the products of this reaction (water or carbon dioxide) are toxic to humans. What's more, they are part of the human body. The problem begins when the combustion of fuel occurs in insufficient oxygen in the atmosphere. This can happen during a fire or when the oven we are using is technically out of order. In this situation, incomplete or semi-combustion occurs. As a result of incomplete combustion, carbon forms instead of carbon dioxide. This phenomenon is usually known as "soot". However, the worst situation is when there is half-burning. Carbon monoxide (CO) is produced instead of carbon or carbon dioxide. Carbon monoxide is a silent killer with a direct threat to life and health for those around him. A gas stove in a small bathroom without a chimney flue (or with a non-permeable duct) can produce up to 29 dm3 of CO in 1 minute, and thus a lethal dose of this gas for humans.

Let's consider what carbon monoxide is and how it affects the human body. CO is a simple molecule formed by the combination of oxygen and carbon. In the Earth's atmosphere it is a colorless, odorless gas, slightly lighter than air, which makes it easy to disperse and mix with it. Above all, however, this gas is highly toxic to all mammals and its toxicity is due to its strong binding to hemoglobin in blood vessels. The same hemoglobin, which physiologically is responsible for the transport of oxygen from the lungs to body tissues in the human body. The impairment of this transport increases with the increase in the concentration of carbon monoxide in the blood, which just like oxygen penetrates unrestrictedly through the alveoli. Let's look at the typical symptoms of carbon monoxide poisoning depending on its concentration in the inhaled air:

The numbers speaks for themselves - a small amount of carbon monoxide in the inhaled air leads to death in a short time. This is because it binds to hemoglobin about 250 times more strongly than oxygen. Therefore, each inhalation, even with a small amount of carbon monoxide, gradually displaces oxygen from hemoglobin, replacing it. This explains why the symptoms correlate with the concentration of carbon monoxide in the inhaled air and the time of exposure.

Since the mechanism of action of carbon monoxide on the human body is already known, it will be easier to understand the procedure of providing first aid to the victim in case of poisoning with this gas. In a situation where we suspect carbon monoxide poisoning, the priority (as always) will be to ensure our own, the witnesses and the place of incident safety. If we make sure it is safe at the scene, the next step will be to stop the victim's exposure to carbon monoxide. For example: the injured person lies in the bathtub, the stove has worked in the bathroom, and we as rescuers are able to safely intervene - we should evacuate the injured from the bathtub (a dangerous place due to the risk of flooding), cut off the fuel supply to the stove (limiting exposure to carbon monoxide), open all windows, doors, ventilation grilles (further reducing exposure to toxic gas) and dry the wet victim (reducing the risk of hypothermia). The next step in the first aid procedure should be to assess the vital parameters of the victim. It is best to do this by assessing consciousness, and in the absence of it - by assessing breath. These are procedures known to both rescuers and qualified first aid rescuers. A typical picture of an injured person with acute carbon monoxide poisoning will primarily manifest as fatigue, weakness, vomiting, and later disturbances of consciousness of varying severity, convulsions, generalized cyanosis. It is worth noting that in children, the most common first symptom will be vomiting. The next step should be to call the emergency medical team because CO poisoning is a life-threatening condition and requires hospital treatment. If the injured person is unconscious, he should be placed in a safe side position, whose advantages are well known to rescuers trained by the Centrum Ratownictwa. While waiting for the arrival of the emergency medical team, if it is possible, active or passive oxygen therapy (depending on the condition of the injured) should be implemented. The oxygen therapy kit should be equipped with a reservoir to achieve the highest oxygen concentration in the breathing mixture. This is important because it increases the chance of hemoglobin-associated carbon monoxide displacement and allows better oxygen supply to tissues. Many rescuers use a pulse oximeter while using oxygen therapy- is a tool for non-invasive measurement of oxygen saturation of hemoglobin. The device works by measuring the absorption of electromagnetic waves of two different lengths by hemoglobin molecules. The level of electromagnetic wave absorption depends on what the hemoglobin molecule is associated with.

A pulse oximeter is always indicated when giving first aid to a person suspected of any type of respiratory failure. We must remember that pulse oximetry measurement in situations of carbon monoxide poisoning is made with a big mistake - it will always be overstated. This is due to the molecular similarity of hemoglobin associated with oxygen and hemoglobin associated with carbon monoxide. This similarity means that the absorption of electromagnetic waves with a shorter wavelength is similar, which means that the pulse oximeter "does not distinguish" hemoglobin combined with oxygen or carbon monoxide (fig.). In recent years, more modern "pulse-CO-oximeter" devices have appeared on the market, which, based on many measurements, at various wavelength ranges and using mathematical algorithms, can indicate the concentration of individual hemoglobin fractions. Currently, these devices are quite expensive and available only in hospitals or emergency medical teams. Therefore, providing first aid throughout the care of the patient should constantly monitor his vital functions, because the toxic concentration of carbon monoxide in the blood can lead to respiratory arrest and sudden cardiac arrest, which would oblige us to apply the procedure of cardiopulmonary resuscitation.

Summarizing ; a rescuer when giving first aid to a poisoned CO person should apply oxygen therapy as soon as possible, remembering all points in the safe first aid algorithm. In severe cases of carbon monoxide poisoning, a hyperbaric chamber is recommended. The necessity of its use is decided by the doctor who providing assistance to the injured, after considering factors such as the degree of poisoning, prognosis, distance to the nearest hyperbaric chamber. Oxygen therapy is important because breathing a mixture with a high concentration of oxygen shortens the half-life (the time it takes for half the number of molecules to be metabolized or removed from the body) COHb to 320 minutes and 100% oxygen to 80 minutes. What is more feeding oxygen under increased pressure in a hyperbaric chamber reduces this time to 25 minutes.