CYANOSIS

CYANOSIS

Cyanosis is defined as the diffused bluish coloration of skin and mucus membrane. It is due to the presence of large amount of reduced hemoglobin in the blood. Quantity of reduced hemoglobin should be at least 5 to 7 g/dL in the blood to cause cyanosis.

DISTRIBUTION OF CYANOSIS

When it occurs, cyanosis is distributed all over the body. But, it is more marked in certain regions where the skin is thin. These areas are lips, cheeks, ear lobes, nose and fingertips above the base of the nail.

CONDITIONS WHEN CYANOSIS OCCURS

1. Any condition which leads to arterial hypoxia and stagnant hypoxia. Cyanosis does not occur in anemic hypoxia because the hemoglobin content itself is less. It does not occur in histotoxic hypoxia because of tissue damage.

2. Conditions when altered hemoglobin is formed. Due to poisoning, hemoglobin is altered into methemoglobin or sulfhemoglobin, which causes cyanosis. The cyanotic discoloration is due to the dark color of these compounds only and not due to reduced hemoglobin.

3. Conditions like polycythemia when blood flow is slow. During polycythemia, because of increased

RBC count, the viscosity of blood is increased and it leads to sluggishness of blood flow. So the quantity

of deoxygenated blood increases, which causes bluish discoloration of skin.

CYANOSIS AND ANEMIA

Cyanosis usually occurs only when the quantity of reduced hemoglobin is about 5 g/dL to 7 g/dL. But,

in anemia, the hemoglobin content itself is less. So, cyanosis cannot occur in anemia.

CARBON MONOXIDE POISONING

Carbon monoxide is a dangerous gas since it causes death. This gas was used by Greeks and Romans for the execution of criminals. Carbon monoxide causes more deaths than any other gases.

SOURCES OF CARBON MONOXIDE

Common sources for carbon monoxide are exhaust of gasoline engines, coal mines, gases from guns, deep wells and underground drainage system.

TOXIC EFFECTS OF CARBON MONOXIDE

Carbon monoxide is a dangerous gas because it displaces oxygen from hemoglobin, by binding with same site in hemoglobin for oxygen. So, oxygen transport and oxygen carrying capacity of the blood are decreased. Hemoglobin has got 200 times more affinity for carbon monoxide than for oxygen. So, even with low partial pressure of 0.4 mm Hg of carbon monoxide in alveoli, 50% of hemoglobin is saturated with it. It can be dangerous if the partial pressure increases to 0.6 mm Hg, (1/1,000 of volume concentration in air). Presence of carboxyhemoglobin decreases the release of oxygen from hemoglobin and the oxygen-hemoglobin dissociation curve shifts to left. It is still more dangerous because, during carbon monoxide poisoning, the partial pressure of oxygenin blood may normal in spite of low oxygen content of blood. So, the regular feedback stimulation of respiratory centers by hypoxia does not take place because of normal partial pressure of oxygen. However, low oxygen content in blood affects the

brain, resulting in unconsciousness. The condition becomes fatal if immediate treatment is not given. Carbon monoxide is toxic to the cytochrome system in cells also.

SYMPTOMS OF CARBON MONOXIDE POISONING

Symptoms of carbon monoxide poisoning depend upon its concentration:

1. While breathing air with 1% of carbon monoxide, saturation of hemoglobin with carbon monoxide

becomes 15% to 20%. Mild symptoms like headache and nausea appear.

2. While breathing air containing carbon monoxide more than 1%, the saturation becomes 30% to 40%.

It causes convulsions, cardiorespiratory arrest, loss of consciousness and coma.

3. When hemoglobin saturation is above 50%, death occurs.

TREATMENT FOR CARBON MONOXIDE POISONING

Treatment for carbon monoxide poisoning includes:

1. Immediate termination of exposure to carbon monoxide

2. Providing adequate ventilation and artificial respiration

3. Administration of 100% oxygen if possible. It is to replace carbon monoxide

4. Administration of air with few percent of carbon dioxide, if possible. It is done to stimulate the respiratory centers.

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