Acute Anemia In Children

Dr.Osama Arafa Abd EL HameedM. B.,B.CH - M.Sc Pediatrics - Ph. D.

Consultant

of

Pediatrics & Neonatology

Head of Pediatrics Department - Port-Fouad Hospital

By

Anemia:

is characterized by a reduction in the number of circulating red blood cells (RBCs), the amount of hemoglobin, or the volume of packed red blood cells (hematocrit).

Anemia is classified as acute or chronic.

Acute anemia denotes a sudden drop in the RBC population due to hemolysis or acute hemorrhage. In the emergency department (ED), acute hemorrhage is by far the most common etiology.

Etiology• The common pathway in life-threatening acute

anemia is a sudden reduction in the oxygen-carrying capacity of the blood.

• Depending on the etiology, this may occur with or without reduction in the intravascular volume.

• It is generally accepted that an acute drop in hemoglobin to a level of 7-8 g/dL is symptomatic, whereas levels of 4-5 g/dL may be tolerated in chronic anemia, as the body is able to gradually replace the loss of intravascular volume.

Blood loss

• Blood loss is the most common cause of acute anemia seen in the emergency department (ED).

• Iron deficiency anemia is due to chronic slow bleeding and nutritional deficits.

• Some life-threatening causes include:

• Traumatic injury

• Massive upper or lower gastrointestinal (GI) hemorrhage, ruptured aneurysm, and disseminated intravascular coagulation

Hemoglobinopathy

• Sickle cell anemia is caused by a point mutation on the DNA of the beta-globin chain. Valine is substituted for glutamine in the sixth position of the amino acid sequence. In response to oxidative stress, hemoglobin S polymerizes, leading to sickling and hemolysis .

• Patients with sickle cell anemia may have life-threatening complications during acute splenicsequestration and aplastic crisis. An aplastic crisis is due to cessation of erythropoiesis, which is caused by the human parvovirus B19

• Thalassemias

are characterized by decreased production of globin (alpha and beta) chains. Patients with thalassemia major (homozygous for beta thalassemia) develop severe anemia that requires transfusion in the first year of life. Other forms of thalassemia may cause acute anemia during periods of oxidative stress.

Red blood cell enzyme abnormality

• Glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase (PK) deficiency are the 2 most common enzyme defects that cause hemolytic anemia.

• The 2 variants of G6PD deficiencies are African and Mediterranean. The Mediterranean variant has decreased enzyme activity in nearly all circulating RBCs. When cells are exposed to oxidant stress, a life-threatening hemolytic crisis ensues. In the African variant, only a limited portion of the RBC population is vulnerable at a given time; therefore, life-threatening complications are rare.

Congenital coagulopathy

• Von Willebrand disease

• is the most common congenital bleeding disorder. The disease is characterized by deficient or defective von Willebrand factor (vWF), which is essential for platelet adhesion. Transmission is by an autosomaldominant pattern.

• Hemophilia A

• (classic hemophilia) is caused by factor VIII deficiency. Severe bleeding is common. Transmission is autosomal recessive. Hemophilia B(Christmas disease) is due to a factor IX deficiency. Only males are affected.

Autoimmune hemolytic anemia

• Autoimmune hemolytic anemia may be life threatening. The disorder is seen in association with autoimmune diseases (eg, lupus, certain types of lymphomas and leukemias), or it may be drug induced.

• Hemolysis is caused when immunoglobulin G (IgG) autoantibody binds to RBCs, which then lose part of the plasma membrane because of the interaction of the autoantibodies with macrophages. With loss of their plasma membrane, affected RBCs become spherocytes.

Acquired platelet disorder

• Thrombotic thrombocytopenic purpura (TTP) is rare. Arteriolar lesions with localized platelet thrombi and fibrin deposits lead to thrombocytopenia and hemolytic anemia.

• Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disease often precipitated by viral infections.IgG autoantibodies bind to platelets, which then undergo destruction in the spleen. The platelet count may fall as low as 10,000/µL, leading to bleeding.

Hemolytic-uremic syndrome

• Acute anemia from hemolytic-uremic syndrome (HUS) is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and renal failure. The disorder is similar to TTP, but arteriolar lesions are limited to the kidney. In children, the disease is sometimes seen after diarrheal illness caused byEscherichiacoli, Shigella and Salmonella species, or viral gastroenteritis.

• Uremia may also lead to bleeding as a consequence of abnormal platelet function.

Disseminated intravascular coagulation

• DIC can be caused by systemic infection, massive transfusions, severe head injury, trauma, thermal injury, sepsis, or cancer.

• It initially causes thrombosis due to excess release of thrombin; this is followed by bleeding due to consumption of coagulation factors.

History• In the critically ill patient, the emergency physician

should attempt to obtain a focused history per the mnemonic AMPLE (A llergies; M edications, including over-the-counter drugs such as nonsteroidal anti-inflammatory drugs [NSAIDs]; P ast medical and surgical history;L ast meal; and E vents preceding incident).

• For noncommunicative patients, caretakers, paramedics, or primary physicians are a valuable source of information. For injured patients, paramedics should be questioned about the circumstances of the accident, mechanism of the injury, initial vital signs, estimated blood loss in the field, prehospital treatment initiated, and response.

• Important specific queries should address gastrointestinal (GI) and menstrual histories (where applicable)..

• When concern for GI hemorrhage exists, obtain a full GI history including stool color, consistency, and frequency. Black, tarry, malodorous, and frequent stools characterize upper GI bleeding proximal to the ligament of Treitz. Maroon, lumpy, irregular stools characterize lower GI bleeding.

• Consider constitutional symptoms of chronic illnesses (eg, weight loss, night sweats, rashes, bowel changes). Consider family history of malignancy or hematologic problems.

Physical examination• Monitor initial vital signs and address any

abnormality. Periodic measurement of vital signs and examinations of appropriate organ.

• In patients with multiple traumas, presume that every body cavity contains blood until investigation suggests otherwise. The chest, abdomen, pelvis, and extremities must undergo thorough physical examination with imaging, as clinically indicated.

• In early hemorrhagic shock, capillary refill time may increase and the skin may feel cool to the touch. With progressive shock, the skin is cold to the touch, and it appears pale and mottled.

• Patients with jaundice may have liver disease, hemoglobinopathies, or other forms of hemolysis. Purpura and petechiae suggest platelet disorders, and hemarthrosis may be due to hemophilia. Diffuse bleeding from intravenous (IV) sites and mucous membranes may be due to disseminated intravascular coagulation (DIC). In patients with alcoholic liver disease, spider angiomata, caput medusae, umbilical hernias, and hemorrhoids may be appreciated.

• Agitation may present secondary to acute blood loss. When blood loss exceeds 40% of total volume, the patient may lose consciousness.

• With chronic anemia, a hyperdynamic heart, with a prominent point of maximal impulse (PMI), a systolic flow murmur, and occasionally an S3, may be present.

• Advanced trauma life support classifies shock into 4 levels; particular findings are associated with each level, as follows.

• In class I (< 15% blood loss), mild tachycardia may be present, but blood pressure is normal.

• In class II (15-30% blood loss), tachycardia, tachypnea, and a decreased pulse pressure are seen.

• Class III (30-40% blood loss) always leads to a measurable decrease in blood pressure as well as a significant tachycardia and a narrow pulse pressure.

• Class IV (≥40% blood loss) leads to patient demise unless prompt resuscitative measures are taken. Marked tachycardia and significantly decreased blood pressure are common findings.

• Patients with exacerbations of chronic anemia occasionally may present with signs and symptoms of congestive heart failure.

• Organomegaly is a common finding in patients with chronic blood disorders. A palpable spleen and an enlarged hepatic inferior border (more than 3 cm below the right midclavicular costal margin) may suggest chronic anemia.

C B C

• The most important index is the mean corpuscular volume (MCV), on the basis of which anemias can be classified as microcytic, normocytic, or macrocytic.

• Microcytic anemias (usually defined as MCV < 80) include anemias of chronic disease, iron deficiency, lead poisoning, and the hemoglobinopathies (ie, sickle cell disease, sideroblastic anemia, thalassemias).

• Normocytic anemias (MCV 80-100) include anemias of acute blood loss, hemolysis, uremia, and cancer

• Macrocytic anemias (usually defined as MCV >100) include anemias related to alcoholism, folate and vitamin B-12 deficiencies (pernicious anemia), and some preleukemic conditions.

Reticulocyte count

• The reticulocyte count may suggest an inadequate bone marrow response to anemia, which can occur in patients with aplastic anemia or hematologic cancers or can be due to drugs or toxins.

• For patients with hemolytic anemias, use a Finch reticulocyte count, which corrects for the anemia and the 2-day lifespan (versus 1-d lifespan, typically) of immature reticulocytes. The Finch count is the measured reticulocytecount multiplied by the measured hematocrit level, divided by 45, and then divided by 2.

• A simple corrected reticulocyte count is sufficient in patients with sickle cell disease. This is the measured reticulocyte count multiplied by the measured hematocritlevel, divided by 45. Normal reticulocyte counts are 0.5-1%.

Additional Laboratory Studies

• Other studies that may be helpful in evaluating anemia but may not be applicable to the acute ED setting include the following:

• Iron studies

• Folate and vitamin B-12 levels

• Lead levels

• Hemoglobin electrophoresis

• Factor deficiency tests

• Bleeding time

• Bone marrow aspiration

• Coombs test

Urine & stool studies

•Urinalysis should be performed for detection of hemoglobinuria or urobilinogen could indicate hemolysis. •Stool analysis for fresh & occult blood

Ultrasonography

• Ultrasonography is a quick, noninvasive, and relatively simple bedside test useful for diagnosing intraperitoneal bleeding. The focused abdominal sonography for trauma (FAST) examination is commonly performed to diagnose intra-abdominal hemorrhage in unstable trauma patients. When performed by experienced providers.

• In pregnant females with suspected ectopic pregnancy, correlate the sonogram with the serum beta human chorionic gonadotropin (β-hCG) level. It is important to remember that most ectopic pregnancies occur 5-8 weeks after the last normal menses.

Principles of Therapy

• Therapeutic approaches to treat anemia include blood and blood products, immunotherapies, hormonal/nutritional therapies, and adjunctive therapies.

• The goal of therapy in acute anemia is to restore the hemodynamics of the vascular system and to replace lost red blood cells (RBCs). To achieve this, the practitioner may use mineral and vitamin supplements, blood transfusions, vasopressors, histamine (H2) antagonists, and glucocorticosteroids.

Use of blood and blood products• Correction of acute anemia often requires blood, blood products, or both.

• Multiple studies have reported worse outcomes (eg, higher mortality and morbidity rates) in transfused patients compared with non-transfused (or less-transfused) patients.

• Consequently, a conservative approach is indicated. Although the specific threshold is uncertain, restricting transfusion to patients with hemoglobin levels <6-8 g/dL may be associated with better outcomes.

• Whole blood contains RBCs, platelets, and coagulation factors; however, it is rarely used as a treatment option. Packed red blood cells (PRBCs) are the remaining components of whole blood after the plasma and platelets are removed.

• One unit of PRBCs is the product of 1 unit of whole blood and has a volume of 250-300 mL. Each unit of PRBCs is expected to raise the hematocrit level by 3 points.

• Each unit of platelets contains 50 mL of plasma and has normal amounts of fibrinogen and coagulation factors. Some decrease in factors V and VII is noted in comparison with whole blood. Each unit of platelets raises the platelet count by approximately 10,000/µL. The usual pediatric dose is 10-20 ml /kg do not exceed 300 ml .

• Fresh frozen plasma (FFP) is the medium that suspends RBCs and platelets and contains all the coagulation factors. The coagulation factors are diluted. Patients with factor V and XI deficiency and those with coagulopathies due to liver disease are the best candidates for FFP administration; most of the other coagulation factors are now available in concentrated forms.

• Cryoprecipitate is derived from the precipitate collected from thawed FFP. It contains fibrinogen, factor VIII, von Willebrandfactor (vWF), and factor XIII. It is ideal for treatment of mild hemophilia A and conditions that lead to afibrinogenemia.

Management of Acute Anemia by Etiology

• In the emergency department (ED), the first steps are to evaluate the ABCs (Airway, B reathing, and C irculation) and to treat any life-threatening conditions immediately. Crystalloid is the initial fluid of choice.

• Transfer may be considered for patients who are hemodynamically and neurologically stable or when a higher level of care is required. The benefits of transfer must outweigh the risks.

Patients with ongoing hemorrhage or ongoing hemolysisare unstable and should not be transferred unless the initial facility cannot adequately care for the patient. Specific management varies, depending on the etiology of the acute anemia and the patient’s condition.

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