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Cyanosis – Types, Pathophysiology, Symptoms and Causes

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Definition

Cyanosis is the medical term for a bluish color of the skin and the mucous membranes due to an insufficient level of oxygen in the blood. For example, the lips and fingernails may show cyanosis. Cyanosis can be evident at birth due to the presence of a heart malformation that permits blood that is not fully oxygenated to enter the arterial circulation. Cyanosis can also appear at any time later in life and often accompanies conditions in which lung function is compromised (resulting in an inability to fully oxygenate the blood) or conditions in which the heart’s pumping function is compromised.

The presence of abnormal forms of hemoglobin or other abnormalities of the blood cells can also sometimes cause cyanosis. The medical term for lowered oxygen levels is hypoxia; the term anoxia refers to the absence of oxygen. Pseudocyanosis is the appearance of cyanosis that is not associated with reduced oxygen delivery to tissues. Most causes are related to the ingestion of metals (such as silver or lead) or drugs/toxins.

History of Cyanosis

The name cyanosis literally means the blue disease or the blue condition. It is derived from the color cyan, which comes from cyanós (κυανός), the Greek word for blue. It is postulated by Dr. Christen Lundsgaard that cyanosis was first described in 1749 by Jean-Baptiste de Sénac, a French physician who served King Louis XV. De Sénac concluded from an autopsy that cyanosis was caused by a heart defect that led to the mixture of arterial and venous blood circulation. But it was not until 1919 when Dr. Lundsgaard was able to derive the concentration of deoxyhemoglobin (8 volumes percent) that could cause cyanosis.

Pathophysiology

Cyanosis typically occurs when the amount of oxygen bound to hemoglobin is very low. Oxygen in the blood is carried in two physical states. Approximately 2% is dissolved in plasma and the other 98% is bound to hemoglobin. The presence of cyanosis might be an indication of inadequate oxygen delivery to the peripheral tissues. It also could be related to increased oxygen extraction by the peripheral tissues. Several factors play a significant role in oxygen delivery to the end organs. Oxygen delivery is the product of the cardiac output and arterial oxygen content. Cardiac output is determined by the preload, afterload, and contractility. The arterial oxygen content is the sum of oxygen bonded to hemoglobin and dissolved in plasma, approximately 1.34 mL per 1 g of hemoglobin and 0.003 mL of oxygen per 100 mL of plasma.

Typically, when the level of deoxygenated hemoglobin is around 3 to 5 g/dL, cyanosis becomes very evident. The presence of jaundice, skin color, ambient temperature, or light exposure might affect the assessment of cyanosis. Anemia or polycythemia also plays a role in cyanosis. The level of hypoxia required to produce clinically evidenced cyanosis varies for a given level of hemoglobin. Cyanosis is more difficult to discern when the level of hemoglobin is low. In other words, cyanosis might not be clinically evident in a patient with severe anemia.

Types of Cyanosis

Cyanosis is of two types – central and peripheral. The characteristic features of these two types of cyanosis include the following:

Central Cyanosis

This condition occurs due to heart and lung conditions, as well as the occurrence of abnormal forms of hemoglobin, such as methemoglobin and sulfhemoglobin in the blood. These are responsible for the blue-purple discoloration of the tongue and the lining of the oral cavity. It has been observed that central cyanosis can be accompanied by peripheral cyanosis. However, in the absence of peripheral cyanosis, the toes and fingers usually exhibit a warm sensation to touch.

Peripheral Cyanosis

This occurs due to the decreased blood flow to the peripheral parts (extremities) of the body, such as the fingers, toes and especially the nail beds. Peripheral cyanosis is accentuated by the stagnation of arterial blood in the capillaries of the periphery and release of most of the oxygen to the tissues. As a result, the level of deoxygenated blood increases in the capillaries and veins. This can occur due to congestive heart failure and shock, both of which exhibit sluggish blood circulation and rapid fall in blood pressure in the capillaries and veins. Peripheral cyanosis is also precipitated by exposure to extremely cold temperatures such as higher altitudes, as well as vascular diseases. It responds well to warming-up the limbs.

Peripheral Cyanosis

Risk factors          

There are a few factors that can increase the risk of a person developing Cyanosis. Some of the Cyanosis risk factors are written as follows:

Causes of Cyanosis

Oxygen is what makes blood red. Getting enough oxygen through your lungs and circulating it effectively throughout your body is what gives your skin a normal pink or red tinge (regardless of your skin tone).

Blood that doesn’t have much oxygen in it is carrying mainly waste carbon dioxide from your cells to be exhaled from your lungs. This oxygen-poor blood is darker in color and more bluish-red than true red.

It’s normal for your veins to show this bluish color since veins deliver blood with its waste cargo back to the heart and lungs to get rid of the carbon dioxide.

But when parts of your body turn blue or purple due to cyanosis, there’s an underlying issue that’s limiting blood flow or oxygen that must be addressed immediately.

Cyanosis can be caused by a wide variety of medical conditions, such as:

Symptoms

Some heart defects cause major problems right after birth.

The main symptom of cyanosis is a bluish color of the lips, fingers, and toes that is caused by the low oxygen content in the blood. It may occur while the child is resting or only when the child is active.

Some children have breathing problems (dyspnea). They may get into a squatting position after physical activity to relieve breathlessness.

Others have spells, in which their bodies are suddenly starved of oxygen. During these spells, symptoms may include:

Infants may get tired or sweat while feeding and may not gain as much weight as they should.

Fainting (syncope) and chest pain may occur.

Other symptoms depend on the type of cyanotic heart disease, and may include:

A baby with Cyanosis

Complications of Cyanosis

Because cyanosis can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your healthcare professional design specifically for you to reduce the risk of potential complications including:

Diagnosis and test

Bluish skin is usually a sign of something serious. If the normal color does not return when your skin is rubbed or warmed, it is important to get medical attention right away to determine the cause.

The physical examination performed by your doctor will include listening to your heart and lungs. You may also have to undergo a series of other clinical tests.

Apart from the clinical assessment of hypoxemia, the diagnosis of Cyanosis may also include the following investigations:

Treatment and medications

Treating cyanosis completely depends on treating the underlying cause. Timely treatment can help to prevent further complications of low blood oxygen.

Other lifestyle modifications include exercising regularly, keeping extremities warm, reducing stress, and avoiding rapid temperature changes.

Prevention of Cyanosis

Cyanosis can prove fatal if not treated on time. Hence, it is better to have Cyanosis prevention rather than taking any risk. A few preventive methods for this condition are as follows:

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