5. Healing of a Wound

Tobacco contains about 4000 different chemicals, e.g. nicotine, carbon monoxide, heavy metals, cyanide and other carcinogenic compounds. From one smoked cigarette 2 – 3 mg of nicotine and 20 – 30 ml of carbon monoxide are absorbed into the organs of the smoker. Among the numerous harmful substances nicotine, carbon monoxide and hydrogen cyanide are regarded as the most significant to the healing process of a wound.

Weakened blood circulation in the area of the wound slows down the healing process and enhances the development of infections.

Nicotine

Nicotine affects the peripheral blood circulation. Disorders are brought about through at least two mechanisms.

Nicotine is the most important substance that affects blood vessels, causing narrowing of the peripheral vessels which weakens the flow of blood in the tissues.
In addition, nicotine damages the inner walls of blood vessels. The damaged inner walls increase the tendency of blockage formation in small blood vessels.

Nicotine activates the sympathetic nervous system that regulates the functions of circulatory organs, glands, alimentary canal and urinary organs. This increases the constriction of peripheral blood vessels. The constricted state of peripheral blood vessels lasts 90 minutes from the smoking of a cigarette, and since a smoker normally smokes at 90 – 120 minutes’ intervals, this leads to an almost constant state of blood vessel constriction while a person is awake.

Nicotine affects the blood coagulation system by increasing the amount of thrombocytes and their tendency to adhere. This influence is dose-related: The higher the nicotine level of the tobacco product is, the higher the adhesion of thrombocytes. This presumably increases the formation of micro-blockages in peripheral blood vessels, and thus decreases blood flow in the tissues. In addition, smokers have reduced blood clot dissolving ability and their coagulation factor levels tend to raise, which again increase the risk for micro-blockages. A smoker’s organs tend to repair their lack of oxygen by boosting the production of red blood cells, which increases the formation of blood clots. Furthermore, damages in the inner walls add the adhesion of thrombocytes, thus growing the risk of blockages.

Nicotine influences the healing process of wounds through several different mechanisms, and this synergism leads to lack of oxygen in the tissues and disturbances in the initial stages of the healing.
Smokers have decreased skin elasticity and lower amount of elastic components, and wrinkling of the skin takes place. Reduced amount of collagen in the skin and in the wound raises the risk of wound rupture. The structure of smokers’ skin has been estimated to be 10 years older at middle age compared to non-smokers at the same age.

Because some of the disorders in blood circulation are due to the effect of nicotine, snuff has in this sense the same effect as smoked tobacco products. Most seriously affected are the small blood vessels, which leads to the typical grayish skin colour among those who have been smoking for a long time. The grayish colour is a consequence of continuous constriction of blood vessels close to the surface of the skin.

Carbon monoxide

Through a smoked cigarette large amounts of carbon monoxide enter the blood circulation, binding itself 200 times stronger than oxygen to the hemoglobin in red blood cells. Carbon monoxide displaces the oxygen, which in turn causes lack of oxygen in tissues and cells and finally problems in the healing of a wound.

Hydrogen cyanide

The hydrogen cyanide that tobacco contains inhibits the enzyme activity which is needed for transportation of oxygen. This leads to lack of oxygen in the tissues, decrease in the metabolism connected with oxygenation, and slowing down of cell repair mechanisms. In consequence there is a delay in wound healing process and an increase in the risk for infections.