STUDY - Technical - New Dacian's Medicine
Hypoxia,
Polycythemia and Cyanosis (2)
Translation Draft
It's time for the polycytemia approach. The term polycytemia signifies an above-normal increase in the number of erythrocytes in circulating blood. This increase is usually, though not always, accompanied by a corresponding increase in the amount of hemoglobin and an increase in haematocrit levels. Policitemia may or may not be associated with an increase in the total amount of erythrocytes in the body.
It is important to distinguish between absolute polycytemia (an increase in total erythrocytes) and relative (sometimes called false) polycytemia that occurs when, due to blood plasma loss, the concentration of hematoids in circulating blood increases above the normal limit. This may be the consequence of abnormally low fluid intake, loss of plasma in the interstitial fluid or marked loss of fluids in the body, as is the case in persistent vomiting, severe diarrhoea, heavy sweating or acidosis.
Because the term polycytemia is a generic term that refers to all types of increase in the number of erythrocytes, the terms erythrocytosis and erythremia are preferred to describe two forms of absolute polycytemia. Erythrocytosis is the absolute polycytemia that occurs in response to some known stimuli, most often hypoxemia (secondary polycytemia) and erythremia refers to a disease of unknown etiology (policitemia vera).
In secondary polycytemia, but not in polycytemia vera, the absolute increase in erythrocytic mass is due to an increased synthesis of erythropoietin. Erythrocytosis occurs as a response to a variety of factors and represents a physiological response to hypoxia. An approach to differential diagnosis of erythrocytosis should begin with the clarification of its mechanisms of occurrence.
Interesting is addressed, here, stress erythrocytosis (Gaisbock syndrome). These terms were applied to polycytemia occasionally observed in white and middle-aged men, generally hyperactive, hypertensive, obese and anxious, with reddish skin, but who have no characteristic signs of polycytemia vera, i.e. do not exhibit splenomegaly or leukocytosis with immature leukocytes.
In these individuals, the total erythrocytic mass is normal and the plasma volume is below normal. Thus, a relatively increased hematocrit, usually 50-60%, and relative polycytemia. The politithemia of smokers is a condition very close to the above, but the high concentration of carboxyhemoglobin can produce an absolute small increase in erythrocytic mass that is frequently associated with a low plasma volume. Smoking should be discontinued.
Secondary polycytemia occurs especially in high-altitude exposure which leads to incomplete saturation of arterial blood with oxygen and stimulates the production of erythrocytes. Oxygen saturation, rather than oxygen pressure, seems to be more important in determining the erythropoietic response to chronic hypoxia.
A disease known as chronic mountain disease or soroche (Monge disease) can be insidiously established after several years of living at high altitudes. This condition appears to be caused by the development of alveolar hypoventilation, which is added to a lower inspired O2 concentration.
The main manifestations are the reddish coloration of the skin, which become cyanotic at medium exertion, altered mental capacity, fatigue and headache. Those affected are generally between the ages of 40 and 60. Returning to low altitude promptly relieves symptoms. Exposure to high altitudes also causes a number of compensatory reactions, which are designed to increase oxygen intake to tissues.
These include hyperventilation (which reduces the oxygen gradient between inspired air and alveolar air), erythrocytosis, an increase in blood volume in the pulmonary capillaries, an increase in lung diffusion capacity and cardiac output.
Any lung disease that causes chronic hypoxia can lead to erythrocytosis. Increased blood viscosity, secondary to polycytemia, increases pulmonary arterial pressure and, in combination with increased pulmonary vascular resistance resulting from hypoxia, causes increased right ventricular pressure, contributing to the development or worsening of the pulmonary heart.
Abnormal ventilation states, present in individuals with high-grade obesity, can cause alveolar hypoventilation and cause arterial saturation deficiency, erythrocytosis, hypercapnia and drowsiness (Pickwick syndrome). The syndrome is also observed in people who are not obese (sleep-apnea syndrome), where low sensitivity of the respiratory center to CO2 may play a role.
Partial blood singing in the pulmonary circulation (right-left strains), as it occurs in congenital heart disease, causes the most impressive erythrocytosis, caused by abnormalities of the heart or lungs.
The number of erythrocytes increases to values from 12 x 10 to 6/ mm cube strength, a situation possible only when the hematoids are lower than normal, which occurs in these patients with a hematocrit up to 86%. With the advent of polycytemia, there is a gradual increase in blood viscosity, which begins to increase logarithmically when the volume of erythrocytes exceeds 55%.
The most common diseases that cause such polycytemia in adults are tetralogy Offaltoand and Eisenmenger syndrome. Other congenital heart defects are responsible for polycytemia, but occur more frequently in newborns, include transposition of large vessels, tricuspid atresia and persistence of the arterial canal.
Rarely, patients with cirrhosis of the liver will be hypoxemic, secondary to intrapulmonary shunts or right-left shunts from the portal vein to the pulmonary veins. Policitemia from congenital cyanogen heart disease can lead to spontaneous thrombosis in any territory, including the central nervous system.
Increased haematocrit levels and significant increase in blood viscosity, which occur when patients with congenital heart disease, broad right-left shunt or secondary polycytemia become dehydrated, are particularly risky. Symptoms due to increased blood viscosity include slowing down mental processes, headaches, fatigue, visual disturbances and dizziness.
These situations may be accompanied by a variety of clotting defects, including reduced levels of fibrinogen and prothrombin, as well as thrombocytopenia. Reducing the volume of hematoids (plasma re-infusion phlebotomy) is sometimes practiced in some patients with severe symptoms and extremely high levels, usually more than 65%, of hematocrit. It should be done slowly, with caution, without forgetting that polycytemia is an important compensatory mechanism.
However, reducing erythrocytic volume may reduce blood viscosity, with improved blood circulation. Excessive use of coal derivatives and other forms of chronic intoxication, by abnormal production of hemoglobin pigments such as methemoglobin and sulphurphemoglobin, can also cause erythrocysis. In patients with abnormal haemoglobin, which moves the oxygen dissociation curve to the left and interferes with the discharge of oxygen into tissues, the production of erythropoietin is stimulated and secondary erythrocytosis not associated with leukocytosis or thrombocytosis occurs. The reduction of 2,3-bisphosphoglycerate synthesis also causes the hemoglobin dissociation curve to the left.
Moderate erythrocytosis sometimes occurs in Cushing syndrome and can be produced by taking large amounts of corticosteroids and androgens. In particular, we are intrigued by erythrocytosis observed in combination with various tumors, which produce erythropoietin or substances similar to it. These include vascular tumors (hemangioblastomas) of posterior fossa, renal tumors (carcinoma, adenoma and renal sarcoma), uterine myoma, hepatic carcinoma and pheochromocytoma.
Erythrocytosis occurs occasionally in patients with solitary renal cysts or polycystic kidneys, hydronephrosis and renal artery stenosis. Plasma levels of erythropoietin are increased in some of these patients with tumors and in all forms of secondary polycytemia. The activity of substances similar to erythropoietin was demonstrated on tumor extracts and in the fluid in renal cysts, and erythrocytosis disappeared after the associated tumor was removed.
To complete this post with some elements about clinical characteristics and differential diagnosis. Patients with polycytemia present (in combination with the symptoms of the underlying disease) a characteristic "rumen" cyanosis, dizziness, headache, epistaxis and an increased frequency of thrombotic complications. Differential diagnosis of absolute polycytemia takes into account the determination of total hematocrit with many types of secondary analyses and special confirmatory studies.
In polycytemia vera, the level of erythropoietin is usually absent or below normal, alkaline phosphatase leukocyte, binding capacity and level of vitamin B12, the number of platelets and total leukocytes are usually increased, and splenomegaly is commonly present. Serum uric acid and lactic-dehydrogenase (LDH) can be increased. Bone marrow is hyperplaic for all elements.
In secondary polycytemia with hypoxia, the level of erythropoietin is increased, and the level of alkaline leukocytic phosphatase, serum vitamin B12, the number of platelets and total leukocytes are normal. The liver and spleen are not enlarged, and the bone marrow has only hyperplasia of the erythrocytic series. In the absence of signs of polycytemia vera or polycytemia secondary to hypoxia or a tumor, a hemoglobin with a high affinity for oxygen should be sought.
Investigation of a patient with polycytemia should include chest X-ray, electrocardiogram, determination of arterial saturation in oxygen, to highlight a disease of the lungs or heart. In addition, imaging examination of the spleen should be performed to determine its size, as well as of the kidneys, to look for lesions producing erythropoietin (such as renal carcinoma, hydronephrosis or renal cyst).
In patients who do not appear to have polycytemia vera or hypoxemia, the oxygen affinity of the patient's haemoglobin, i.e. PO2 at which 50% of hemoglobin is reduced, should be measured to detect hemoglobins that do not normally release oxygen.
I finished this post. Tomorrow we'll talk about cyanosis... If something special doesn't come up...
It's time for the polycytemia approach. The term polycytemia signifies an above-normal increase in the number of erythrocytes in circulating blood. This increase is usually, though not always, accompanied by a corresponding increase in the amount of hemoglobin and an increase in haematocrit levels. Policitemia may or may not be associated with an increase in the total amount of erythrocytes in the body.
It is important to distinguish between absolute polycytemia (an increase in total erythrocytes) and relative (sometimes called false) polycytemia that occurs when, due to blood plasma loss, the concentration of hematoids in circulating blood increases above the normal limit. This may be the consequence of abnormally low fluid intake, loss of plasma in the interstitial fluid or marked loss of fluids in the body, as is the case in persistent vomiting, severe diarrhoea, heavy sweating or acidosis.
Because the term polycytemia is a generic term that refers to all types of increase in the number of erythrocytes, the terms erythrocytosis and erythremia are preferred to describe two forms of absolute polycytemia. Erythrocytosis is the absolute polycytemia that occurs in response to some known stimuli, most often hypoxemia (secondary polycytemia) and erythremia refers to a disease of unknown etiology (policitemia vera).
In secondary polycytemia, but not in polycytemia vera, the absolute increase in erythrocytic mass is due to an increased synthesis of erythropoietin. Erythrocytosis occurs as a response to a variety of factors and represents a physiological response to hypoxia. An approach to differential diagnosis of erythrocytosis should begin with the clarification of its mechanisms of occurrence.
Interesting is addressed, here, stress erythrocytosis (Gaisbock syndrome). These terms were applied to polycytemia occasionally observed in white and middle-aged men, generally hyperactive, hypertensive, obese and anxious, with reddish skin, but who have no characteristic signs of polycytemia vera, i.e. do not exhibit splenomegaly or leukocytosis with immature leukocytes.
In these individuals, the total erythrocytic mass is normal and the plasma volume is below normal. Thus, a relatively increased hematocrit, usually 50-60%, and relative polycytemia. The politithemia of smokers is a condition very close to the above, but the high concentration of carboxyhemoglobin can produce an absolute small increase in erythrocytic mass that is frequently associated with a low plasma volume. Smoking should be discontinued.
Secondary polycytemia occurs especially in high-altitude exposure which leads to incomplete saturation of arterial blood with oxygen and stimulates the production of erythrocytes. Oxygen saturation, rather than oxygen pressure, seems to be more important in determining the erythropoietic response to chronic hypoxia.
A disease known as chronic mountain disease or soroche (Monge disease) can be insidiously established after several years of living at high altitudes. This condition appears to be caused by the development of alveolar hypoventilation, which is added to a lower inspired O2 concentration.
The main manifestations are the reddish coloration of the skin, which become cyanotic at medium exertion, altered mental capacity, fatigue and headache. Those affected are generally between the ages of 40 and 60. Returning to low altitude promptly relieves symptoms. Exposure to high altitudes also causes a number of compensatory reactions, which are designed to increase oxygen intake to tissues.
These include hyperventilation (which reduces the oxygen gradient between inspired air and alveolar air), erythrocytosis, an increase in blood volume in the pulmonary capillaries, an increase in lung diffusion capacity and cardiac output.
Any lung disease that causes chronic hypoxia can lead to erythrocytosis. Increased blood viscosity, secondary to polycytemia, increases pulmonary arterial pressure and, in combination with increased pulmonary vascular resistance resulting from hypoxia, causes increased right ventricular pressure, contributing to the development or worsening of the pulmonary heart.
Abnormal ventilation states, present in individuals with high-grade obesity, can cause alveolar hypoventilation and cause arterial saturation deficiency, erythrocytosis, hypercapnia and drowsiness (Pickwick syndrome). The syndrome is also observed in people who are not obese (sleep-apnea syndrome), where low sensitivity of the respiratory center to CO2 may play a role.
Partial blood singing in the pulmonary circulation (right-left strains), as it occurs in congenital heart disease, causes the most impressive erythrocytosis, caused by abnormalities of the heart or lungs.
The number of erythrocytes increases to values from 12 x 10 to 6/ mm cube strength, a situation possible only when the hematoids are lower than normal, which occurs in these patients with a hematocrit up to 86%. With the advent of polycytemia, there is a gradual increase in blood viscosity, which begins to increase logarithmically when the volume of erythrocytes exceeds 55%.
The most common diseases that cause such polycytemia in adults are tetralogy Offaltoand and Eisenmenger syndrome. Other congenital heart defects are responsible for polycytemia, but occur more frequently in newborns, include transposition of large vessels, tricuspid atresia and persistence of the arterial canal.
Rarely, patients with cirrhosis of the liver will be hypoxemic, secondary to intrapulmonary shunts or right-left shunts from the portal vein to the pulmonary veins. Policitemia from congenital cyanogen heart disease can lead to spontaneous thrombosis in any territory, including the central nervous system.
Increased haematocrit levels and significant increase in blood viscosity, which occur when patients with congenital heart disease, broad right-left shunt or secondary polycytemia become dehydrated, are particularly risky. Symptoms due to increased blood viscosity include slowing down mental processes, headaches, fatigue, visual disturbances and dizziness.
These situations may be accompanied by a variety of clotting defects, including reduced levels of fibrinogen and prothrombin, as well as thrombocytopenia. Reducing the volume of hematoids (plasma re-infusion phlebotomy) is sometimes practiced in some patients with severe symptoms and extremely high levels, usually more than 65%, of hematocrit. It should be done slowly, with caution, without forgetting that polycytemia is an important compensatory mechanism.
However, reducing erythrocytic volume may reduce blood viscosity, with improved blood circulation. Excessive use of coal derivatives and other forms of chronic intoxication, by abnormal production of hemoglobin pigments such as methemoglobin and sulphurphemoglobin, can also cause erythrocysis. In patients with abnormal haemoglobin, which moves the oxygen dissociation curve to the left and interferes with the discharge of oxygen into tissues, the production of erythropoietin is stimulated and secondary erythrocytosis not associated with leukocytosis or thrombocytosis occurs. The reduction of 2,3-bisphosphoglycerate synthesis also causes the hemoglobin dissociation curve to the left.
Moderate erythrocytosis sometimes occurs in Cushing syndrome and can be produced by taking large amounts of corticosteroids and androgens. In particular, we are intrigued by erythrocytosis observed in combination with various tumors, which produce erythropoietin or substances similar to it. These include vascular tumors (hemangioblastomas) of posterior fossa, renal tumors (carcinoma, adenoma and renal sarcoma), uterine myoma, hepatic carcinoma and pheochromocytoma.
Erythrocytosis occurs occasionally in patients with solitary renal cysts or polycystic kidneys, hydronephrosis and renal artery stenosis. Plasma levels of erythropoietin are increased in some of these patients with tumors and in all forms of secondary polycytemia. The activity of substances similar to erythropoietin was demonstrated on tumor extracts and in the fluid in renal cysts, and erythrocytosis disappeared after the associated tumor was removed.
To complete this post with some elements about clinical characteristics and differential diagnosis. Patients with polycytemia present (in combination with the symptoms of the underlying disease) a characteristic "rumen" cyanosis, dizziness, headache, epistaxis and an increased frequency of thrombotic complications. Differential diagnosis of absolute polycytemia takes into account the determination of total hematocrit with many types of secondary analyses and special confirmatory studies.
In polycytemia vera, the level of erythropoietin is usually absent or below normal, alkaline phosphatase leukocyte, binding capacity and level of vitamin B12, the number of platelets and total leukocytes are usually increased, and splenomegaly is commonly present. Serum uric acid and lactic-dehydrogenase (LDH) can be increased. Bone marrow is hyperplaic for all elements.
In secondary polycytemia with hypoxia, the level of erythropoietin is increased, and the level of alkaline leukocytic phosphatase, serum vitamin B12, the number of platelets and total leukocytes are normal. The liver and spleen are not enlarged, and the bone marrow has only hyperplasia of the erythrocytic series. In the absence of signs of polycytemia vera or polycytemia secondary to hypoxia or a tumor, a hemoglobin with a high affinity for oxygen should be sought.
Investigation of a patient with polycytemia should include chest X-ray, electrocardiogram, determination of arterial saturation in oxygen, to highlight a disease of the lungs or heart. In addition, imaging examination of the spleen should be performed to determine its size, as well as of the kidneys, to look for lesions producing erythropoietin (such as renal carcinoma, hydronephrosis or renal cyst).
In patients who do not appear to have polycytemia vera or hypoxemia, the oxygen affinity of the patient's haemoglobin, i.e. PO2 at which 50% of hemoglobin is reduced, should be measured to detect hemoglobins that do not normally release oxygen.
I finished this post. Tomorrow we'll talk about cyanosis... If something special doesn't come up...
A week of the best and
most full of understanding, love and gratitude!
Dorin, Merticaru