Cyanosis

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Cyanosis
Cynosis.JPG
Cyanosis of the hand of a patient with low oxygen saturations
Specialty Pulmonology, cardiology
TypesCentral, peripheral

Cyanosis is the change of body tissue color to a bluish-purple hue, as a result of decrease in the amount of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. [1] Cyanosis is apparent usually in the body tissues covered with thin skin, including the mucous membranes, lips, nail beds, and ear lobes. [1] Some medications may cause discoloration such as medications containing amiodarone or silver. Furthermore, mongolian spots, large birthmarks, and the consumption of food products with blue or purple dyes can also result in the bluish skin tissue discoloration and may be mistaken for cyanosis. [2] [3] Appropriate physical examination and history taking is a crucial part to diagnose cyanosis. Management of cyanosis involves treating the main cause, as cyanosis isn’t a disease, it is a symptom. [1]

Contents

Cyanosis is further classified into central cyanosis and peripheral cyanosis.

Pathophysiology

The mechanism behind cyanosis is different depending on whether it is central or peripheral.

Central cyanosis

Central cyanosis occurs due to decrease in arterial oxygen saturation (SaO2), and begins to show once the concentration of deoxyhemoglobin in the blood reaches a concentration of ≥ 5.0 g/dL (≥ 3.1 mmol/L or oxygen saturation of ≤ 85%). [4] This indicates a cardiopulmonary condition. [5]

Causes of central cyanosis are discussed below.

Peripheral cyanosis

Peripheral cyanosis happens when there is increased concentration of deoxyhemoglobin on the venous side of the peripheral circulation. In other words, cyanosis is dependent on the concentration of deoxyhemoglobin. Patients with severe anemia may appear normal despite higher-than-normal concentrations of deoxyhemoglobin. While patients with increased amounts of red blood cells (e.g., polycythemia vera) can appear cyanotic even with lower concentrations of deoxyhemoglobin. [6] [7]

A baby with a heart condition. Note purple nailbeds. Cyanotic neonate.jpg
A baby with a heart condition. Note purple nailbeds.

Causes

Central cyanosis

Central cyanosis is often due to a circulatory or ventilatory problem that leads to poor blood oxygenation in the lungs. It develops when arterial oxygen saturation drops below 85% or 75%. [6]

Acute cyanosis can be a result of asphyxiation or choking and is one of the definite signs that ventilation is being blocked.

Child with congenital heart disease with central cyanosis that is worsened by measles. Note the bluish-purple discoloration of the fingernails, lips, eyelids, and nose, along with prominent nail clubbing. Child with measles modified by cyanosis Wellcome L0061496.jpg
Child with congenital heart disease with central cyanosis that is worsened by measles. Note the bluish-purple discoloration of the fingernails, lips, eyelids, and nose, along with prominent nail clubbing.

Central cyanosis may be due to the following causes:

  1. Central nervous system (impairing normal ventilation): [6]
  2. Respiratory system: [1] [6]
  3. Cardiovascular system: [1] [6]
  4. Hemoglobinopathies: [6]
  5. Others:
  1. ↑ Note this causes "spurious" cyanosis, in that, since methemoglobin appears blue, the patient can appear cyanosed even in the presence of a normal arterial oxygen level.
  2. ↑ Note a rare condition in which there is excess sulfhemoglobin (SulfHb) in the blood. The pigment is a greenish derivative of hemoglobin which cannot be converted back to normal, functional hemoglobin. It causes cyanosis even at low blood levels.

Peripheral cyanosis

Peripheral cyanosis is the blue tint in fingers or extremities, due to an inadequate or obstructed circulation. [6] The blood reaching the extremities is not oxygen-rich and when viewed through the skin a combination of factors can lead to the appearance of a blue color. All factors contributing to central cyanosis can also cause peripheral symptoms to appear, but peripheral cyanosis can be observed in the absence of heart or lung failures. [6] Small blood vessels may be restricted and can be treated by increasing the normal oxygenation level of the blood. [6]

Initial direction of blood flow in patients with patent ductus arteriosus. Once the pressure of the pulmonary arteries increases more than the aorta due to right heart hypertrophy, the direction of blood flow reverses, sending deoxygenated blood through the patent duct directly into the descending aorta while sparing the brachiocephalic trunk, left common carotid, and left subclavian artery, therefore causing the differential cyanosis. Blausen 0707 PatentDuctusArteriosus.png
Initial direction of blood flow in patients with patent ductus arteriosus. Once the pressure of the pulmonary arteries increases more than the aorta due to right heart hypertrophy, the direction of blood flow reverses, sending deoxygenated blood through the patent duct directly into the descending aorta while sparing the brachiocephalic trunk, left common carotid, and left subclavian artery, therefore causing the differential cyanosis.

Peripheral cyanosis may be due to the following causes: [6]

Differential cyanosis

This illustration depicts a self-induced local (tissue) hypoxia on the right hand (right side of the picture) versus a normal left hand (left side of the picture). The cyanosis was achieved by inflating and tightening the blood pressure cuff on the right arm. Local hypxia.jpg
This illustration depicts a self-induced local (tissue) hypoxia on the right hand (right side of the picture) versus a normal left hand (left side of the picture). The cyanosis was achieved by inflating and tightening the blood pressure cuff on the right arm.

Differential cyanosis is the bluish coloration of the lower but not the upper extremity and the head. [6] This is seen in patients with a patent ductus arteriosus. [6] Patients with a large ductus develop progressive pulmonary vascular disease, and pressure overload of the right ventricle occurs. [9] As soon as pulmonary pressure exceeds aortic pressure, shunt reversal (right-to-left shunt) occurs. [9] The upper extremity remains pink because deoxygenated blood flows through the patent duct and directly into the descending aorta while sparing the brachiocephalic trunk, left common carotid, and left subclavian arteries.

Evaluation

A detailed history and physical examination (particularly focusing on the cardiopulmonary system) can guide further management and help determine the medical tests to be performed. [1] Tests that can be performed include pulse oximetry, arterial blood gas, complete blood count, methemoglobin level, electrocardiogram, echocardiogram, X-Ray, CT scan, cardiac catheterization, and hemoglobin electrophoresis.

In newborns, peripheral cyanosis typically presents in the distal extremities, circumoral, and periorbital areas. [10] Of note, mucous membranes remain pink in peripheral cyanosis as compared to central cyanosis where the mucous membranes are cyanotic. [10]

An example of cyanosis in an individual with darker skin pigmentation. Note the pale purple (instead of the typical bluish-purple hue) nail beds. This patient also had prominent digital clubbing due to a congenital heart disease with right-to-left shunting (this patient had Tetralogy of Fallot). CongenitalHeartCase-133.jpg
An example of cyanosis in an individual with darker skin pigmentation. Note the pale purple (instead of the typical bluish-purple hue) nail beds. This patient also had prominent digital clubbing due to a congenital heart disease with right-to-left shunting (this patient had Tetralogy of Fallot).

It is important to note that skin pigmentation and hemoglobin concentration can affect the evaluation of cyanosis. Cyanosis may be more difficult to detect on people with darker skin pigmentation. However, cyanosis can still be diagnosed with careful examination of the typical body areas such as nail beds, tongue, and mucous membranes where the skin is thinner and more vascular. [1] As mentioned above, patients with severe anemia may appear normal despite higher than normal concentrations of deoxyhemoglobin. [6] [7] Signs of severe anemia may include pale mucosa (lips, eyelids, and gums), fatigue, lightheadedness, and irregular heartbeats.

An example of cyanosis in an elderly individual with darker skin pigmentation. Note the dark purple hue of the lips. Cyanoza .jpg
An example of cyanosis in an elderly individual with darker skin pigmentation. Note the dark purple hue of the lips.

Management

Cyanosis is a symptom not a disease itself, so management should be focused on treating the underlying cause.

If it is an emergency, management should always begin with securing the airway, breathing, and circulation. In patients with significant respiratory distress, supplemental oxygen (in the form of nasal canula or continuous positive airway pressure depending on severity) should be given immediately. [11] [12]

If the methemoglobin levels are positive for methemoglobinemia, first-line treatment is to administer methylene blue. [1]

History

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. [13]

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. [14] 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 per cent) that could cause cyanosis. [14]

See also

Related Research Articles

<span class="mw-page-title-main">Blood</span> Organic fluid which transports nutrients throughout the organism

Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the circulatory system is also known as peripheral blood, and the blood cells it carries, peripheral blood cells.

<span class="mw-page-title-main">Hypoxia (medical)</span> Medical condition of lack of oxygen in the tissues

Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. Hypoxia may be classified as either generalized, affecting the whole body, or local, affecting a region of the body. Although hypoxia is often a pathological condition, variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise.

<span class="mw-page-title-main">Hemoglobin</span> Oxygen-transport metalloprotein in red blood cells of most vertebrates

Hemoglobin, is the iron-containing oxygen-transport protein present in erythrocytes of almost all vertebrates as well as the tissues of some invertebrate animals. Hemoglobin in the blood carries oxygen from the respiratory organs to the other tissues of the body, where it releases the oxygen to enable aerobic respiration which powers the animal's metabolism. A healthy human has 12 to 20 grams of hemoglobin in every 100 mL of blood. Hemoglobin is a metalloprotein, a chromoprotein, and globulin.

<span class="mw-page-title-main">Respiratory failure</span> Inadequate gas exchange by the respiratory system

Respiratory failure results from inadequate gas exchange by the respiratory system, meaning that the arterial oxygen, carbon dioxide, or both cannot be kept at normal levels. A drop in the oxygen carried in the blood is known as hypoxemia; a rise in arterial carbon dioxide levels is called hypercapnia. Respiratory failure is classified as either Type 1 or Type 2, based on whether there is a high carbon dioxide level, and can be acute or chronic. In clinical trials, the definition of respiratory failure usually includes increased respiratory rate, abnormal blood gases, and evidence of increased work of breathing. Respiratory failure causes an altered mental status due to ischemia in the brain.

<span class="mw-page-title-main">Methemoglobinemia</span> Condition of elevated methemoglobin in the blood

Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). Complications may include seizures and heart arrhythmias.

<span class="mw-page-title-main">Arterial blood gas test</span> A test of blood taken from an artery that measures the amounts of certain dissolved gases

An arterial blood gas (ABG) test, or arterial blood gas analysis (ABGA) measures the amounts of arterial gases, such as oxygen and carbon dioxide. An ABG test requires that a small volume of blood be drawn from the radial artery with a syringe and a thin needle, but sometimes the femoral artery in the groin or another site is used. The blood can also be drawn from an arterial catheter.

<span class="mw-page-title-main">Ischemia</span> Restriction in blood supply to tissues

Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism. Ischemia is generally caused by problems with blood vessels, with resultant damage to or dysfunction of tissue i.e. hypoxia and microvascular dysfunction. It also implies local hypoxia in a part of a body resulting from constriction. Ischemia causes not only insufficiency of oxygen, but also reduced availability of nutrients and inadequate removal of metabolic wastes. Ischemia can be partial or total blockage. The inadequate delivery of oxygenated blood to the organs must be resolved either by treating the cause of the inadequate delivery or reducing the oxygen demand of the system that needs it. For example, patients with myocardial ischemia have a decreased blood flow to the heart and are prescribed with medications that reduce chronotrophy and ionotrophy to meet the new level of blood delivery supplied by the stenosed vasculature so that it is adequate.

dextro-Transposition of the great arteries Medical condition

dextro-Transposition of the great arteries is a potentially life-threatening birth defect in the large arteries of the heart. The primary arteries are transposed.

<span class="mw-page-title-main">Blue baby syndrome</span> Two situations that lead to cyanosis in infants

Blue baby syndrome can refer to conditions that cause cyanosis, or blueness of the skin, in babies as a result of low oxygen levels in the blood. This term has traditionally been applied to cyanosis as a result of:

  1. Cyanotic heart disease, which is a category of congenital heart defect that results in low levels of oxygen in the blood. This can be caused by either reduced blood flow to the lungs or mixing of oxygenated and deoxygenated blood.
  2. Methemoglobinemia, which is a disease defined by high levels of methemoglobin in the blood. Increased levels of methemoglobin prevent oxygen from being released into the tissues and result in hypoxemia.
<span class="mw-page-title-main">Methemoglobin</span> Type of hemoglobin

Methemoglobin (British: methaemoglobin) (pronounced "met-hemoglobin") is a hemoglobin in the form of metalloprotein, in which the iron in the heme group is in the Fe3+ (ferric) state, not the Fe2+ (ferrous) of normal hemoglobin. Sometimes, it is also referred to as ferrihemoglobin. Methemoglobin cannot bind oxygen, which means it cannot carry oxygen to tissues. It is bluish chocolate-brown in color. In human blood a trace amount of methemoglobin is normally produced spontaneously, but when present in excess the blood becomes abnormally dark bluish brown. The NADH-dependent enzyme methemoglobin reductase (a type of diaphorase) is responsible for converting methemoglobin back to hemoglobin.

<span class="mw-page-title-main">Haemodynamic response</span>

In haemodynamics, the body must respond to physical activities, external temperature, and other factors by homeostatically adjusting its blood flow to deliver nutrients such as oxygen and glucose to stressed tissues and allow them to function. Haemodynamic response (HR) allows the rapid delivery of blood to active neuronal tissues. The brain consumes large amounts of energy but does not have a reservoir of stored energy substrates. Since higher processes in the brain occur almost constantly, cerebral blood flow is essential for the maintenance of neurons, astrocytes, and other cells of the brain. This coupling between neuronal activity and blood flow is also referred to as neurovascular coupling.

<span class="mw-page-title-main">Eisenmenger syndrome</span> Medical condition

Eisenmenger syndrome or Eisenmenger's syndrome is defined as the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect causes pulmonary hypertension and eventual reversal of the shunt into a cyanotic right-to-left shunt. Because of the advent of fetal screening with echocardiography early in life, the incidence of heart defects progressing to Eisenmenger syndrome has decreased.

<span class="mw-page-title-main">Hypoxemia</span> Abnormally low level of oxygen in the blood

Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, and often causes hypoxia as the blood is not supplying enough oxygen to the tissues of the body.

<span class="mw-page-title-main">CO-oximeter</span>

A CO-oximeter is a device that measures the oxygen carrying state of hemoglobin in a blood specimen, including oxygen-carrying hemoglobin (O2Hb), non-oxygen-carrying but normal hemoglobin (HHb), as well as the dyshemoglobins such as carboxyhemoglobin (COHb) and methemoglobin (MetHb). The use of 'CO' rather than 'Co' or 'co' is more appropriate since this designation represents a device that measures carbon monoxide (CO) bound to hemoglobin, as distinguished from simple oximetry which measures hemoglobin bound to molecular oxygen—O2Hb—or hemoglobin capable of binding to molecular oxygen—HHb. Simpler oximeters may report oxygen saturation alone, i.e. the ratio of oxyhemoglobin to total 'bindable' hemoglobin. CO-oximetry is useful in defining the causes for hypoxemia, or hypoxia,.

<span class="mw-page-title-main">Oxygen–hemoglobin dissociation curve</span> Visual tool used to understand how human blood carries and releases oxygen

The oxygen–hemoglobin dissociation curve, also called the oxyhemoglobin dissociation curve or oxygen dissociation curve (ODC), is a curve that plots the proportion of hemoglobin in its saturated (oxygen-laden) form on the vertical axis against the prevailing oxygen tension on the horizontal axis. This curve is an important tool for understanding how our blood carries and releases oxygen. Specifically, the oxyhemoglobin dissociation curve relates oxygen saturation (SO2) and partial pressure of oxygen in the blood (PO2), and is determined by what is called "hemoglobin affinity for oxygen"; that is, how readily hemoglobin acquires and releases oxygen molecules into the fluid that surrounds it.

A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles.

<span class="mw-page-title-main">Acrocyanosis</span> Vascular disease

Acrocyanosis is persistent blue or cyanotic discoloration of the extremities, most commonly occurring in the hands, although it also occurs in the feet and distal parts of face. Although described over 100 years ago and not uncommon in practice, the nature of this phenomenon is still uncertain. The very term "acrocyanosis" is often applied inappropriately in cases when blue discoloration of the hands, feet, or parts of the face is noted. The principal (primary) form of acrocyanosis is that of a benign cosmetic condition, sometimes caused by a relatively benign neurohormonal disorder. Regardless of its cause, the benign form typically does not require medical treatment. A medical emergency would ensue if the extremities experience prolonged periods of exposure to the cold, particularly in children and patients with poor general health. However, frostbite differs from acrocyanosis because pain often accompanies the former condition, while the latter is very rarely associated with pain. There are also a number of other conditions that affect hands, feet, and parts of the face with associated skin color changes that need to be differentiated from acrocyanosis: Raynaud phenomenon, pernio, acrorygosis, erythromelalgia, and blue finger syndrome. The diagnosis may be challenging in some cases, especially when these syndromes co-exist.

Sulfhemoglobinemia is a rare condition in which there is excess sulfhemoglobin (SulfHb) in the blood. The pigment is a greenish derivative of hemoglobin which cannot be converted back to normal, functional hemoglobin. It causes cyanosis even at low blood levels.

<span class="mw-page-title-main">Oxygen saturation (medicine)</span> Medical measurement

Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal arterial blood oxygen saturation levels in humans are 97–100 percent. If the level is below 90 percent, it is considered low and called hypoxemia. Arterial blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, and should be promptly addressed. Continued low oxygen levels may lead to respiratory or cardiac arrest. Oxygen therapy may be used to assist in raising blood oxygen levels. Oxygenation occurs when oxygen molecules enter the tissues of the body. For example, blood is oxygenated in the lungs, where oxygen molecules travel from the air and into the blood. Oxygenation is commonly used to refer to medical oxygen saturation.

<span class="mw-page-title-main">Hemoglobin M disease</span> Medical condition

Hemoglobin M disease is a rare form of hemoglobinopathy, characterized by the presence of hemoglobin M (HbM) and elevated methemoglobin (metHb) level in blood. HbM is an altered form of hemoglobin (Hb) due to point mutation occurring in globin-encoding genes, mostly involving tyrosine substitution for proximal (F8) or distal (E7) histidine residues. HbM variants are inherited as autosomal dominant disorders and have altered oxygen affinity. The pathophysiology of hemoglobin M disease involves heme iron autoxidation promoted by heme pocket structural alteration.

References

  1. 1 2 3 4 5 6 7 8 9 Adeyinka, Adebayo; Kondamudi, Noah P. (2021), "Cyanosis", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID   29489181 , retrieved 2021-10-28
  2. ↑ Dereure, Olivier (2001). "Drug-Induced Skin Pigmentation: Epidemiology, Diagnosis and Treatment". American Journal of Clinical Dermatology. 2 (4): 253–262. doi:10.2165/00128071-200102040-00006. ISSN   1175-0561. PMID   11705252. S2CID   22892985.
  3. ↑ Conlon, Joseph D; Drolet, Beth A (2004). "Skin lesions in the neonate". Pediatric Clinics of North America. 51 (4): 863–888. doi:10.1016/j.pcl.2004.03.015. PMID   15275979.
  4. ↑ Mini Oxford Handbook of Clinical Medicine (7th ed.). p. 56.
  5. ↑ Adeyinka, Adebayo; Kondamudi, Noah P. (2023), "Cyanosis", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID   29489181 , retrieved 2023-09-24
  6. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Pahal P, Goyal A (July 2020). "Central and Peripheral Cyanosis". StatPearls. PMID   32644593.{{cite journal}}: Cite journal requires |journal= (help)
  7. 1 2 McMullen, Sarah M.; Patrick, Ward (2013-03-01). "Cyanosis". The American Journal of Medicine. 126 (3): 210–212. doi:10.1016/j.amjmed.2012.11.004. ISSN   0002-9343. PMID   23410559. S2CID   244083635.
  8. ↑ Basit, H.; Wallen, T. J.; Dudley, C. (2021). "Frostbite". StatPearls. StatPearls. PMID   30725599.
  9. 1 2 Gillam-Krakauer, Maria; Mahajan, Kunal (2021), "Patent Ductus Arteriosus", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID   28613509 , retrieved 2021-11-19
  10. 1 2 Lees, Martin H. (1970). "Cyanosis of the newborn infant". The Journal of Pediatrics. 77 (3): 484–498. doi:10.1016/S0022-3476(70)80024-5. PMID   5502102.
  11. ↑ Ramji, Siddarth (2013), "Neonatal Resuscitation", IAP Textbook of Pediatrics, Jaypee Brothers Medical Publishers (P) Ltd., p. 28, doi:10.5005/jp/books/11894_109, ISBN   9789350259450 , retrieved 2021-11-05
  12. ↑ Sasidharan, Ponthenkandath (2004). "An approach to diagnosis and management of cyanosis and tachypnea in term infants". Pediatric Clinics of North America. 51 (4): 999–1021. doi:10.1016/j.pcl.2004.03.010. ISSN   0031-3955. PMID   15275985.
  13. ↑ Mosby's Medical, Nursing & Allied Health Dictionary . Mosby-Year Book (4th ed.). 1994. p. 425.
  14. 1 2 Lundsgaard, C. (1919-09-01). "Studies on Cyanosis". The Journal of Experimental Medicine. 30 (3): 259–269. doi:10.1084/jem.30.3.259. ISSN   0022-1007. PMC   2126682 . PMID   19868357.
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