Chapter 13 pathophysiology alterations in oxygen transport

Erythrocyte disorders

Anemia, which is the deficit of red blood cells

Polycythemia which is excess of red blood cells

Importance of RBC’s

Crucial for oxygen delivery, disorders affect oxygen transport, blood viscosity, tissue function

Erythropoiesis requirements

Proteins, vitamins, such as B12, folate, B6, riboflavin, vitamin E, C, and minerals like iron

Iron

Essential for hemoglobin synthesis

Vitamin B 12 and folate

Needed for DNA synthesis in RBCs

Erythropoietin

Produced by kidney in response to hypoxia, stimulates, bone marrow stem cells

RBC metabolism

Relies on glucose, anaerobic Glycolysis. Maintains ion pumps and membrane flexibility.

Hemoglobin contains

Four polypeptide chains, and each one binds an oxygen molecule

Developmental changes regarding hemoglobin

Fetal HB, which is equivalent to high O2 affinity

At birth, switch to adult Hb

Small amount of HBA 2 persist in adult

Developmental change regarding O2 transport

95 to 98% bound to HB, 2 to 5% dissolved in plasma

HB plus O2 equals oxyhemoglobin

O2 disassociation curve

Shift left equals higher hb Affinity for O2, Alkalosis, hypothermia, lower than two, three – DPG

Shift right means lowered HB affinity, acidosis, fever or higher two, three – DPG

General effects of anemia

Lower O2 carrying capacity means, hypoxia, fatigue, dyspnea, tachycardia, pallor

Compensation means higher, HR, cardiac output, respiratory rate

Severity depends on HP level, speed of onset, underlying disease

Mild anemia

HB is 8 to 10 G/D, and often asymptomatic

Severe anemia

HB is less than 7G/DL, and there is weakness, fainting, angina, and dyspnea at rest

Aplastic anemia

Cause is bone marrow failure, which leads to lowering of all blood cells, pancytopenia

Etiology is radiation, chemo, toxins, drugs, viruses

Features is normocytic, normalchromic RBC

S – S is fatigue, infections, and bleeding

Treatment is removed cause, bone marrow transplant, immunosuppression

Anemia of chronic kidney disease

Causes is lower EPO from kidney failure

Features include normocytic, normochronic

S/S: weakness, pallor

Treatment: EPO therapy, iron

Vitamin B 12, cobalamin, deficiency

Cause, impaired absorption. Lack of intrinsic factor led to pernicious anemia.

Features include macrocytic normochromic

S/S equals neurological changes. Paresthesias, Memory loss, ataxia, glossitis, Fatigue.

Treatment includes B12 replacement like injections are high dose oral

Folate deficiency

Causes include poor diet, alcohol, alcoholism, pregnancy

Features include macrocytic, normochromic

S/S: fatigue, no neurologic symptoms

Treatment: folate supplementation

Iron deficiency anemia

Most common world wide

Causes include blood loss, such as G.I. bleed, or administration, poor intake, and higher demand or pregnancy

Features are microcytic and hypochromic RBCs

S/S: fatigue, pallor, spoon, nails, pics

Labs show lowered, ferritin, lowered iron, and higher TIBC

Treatment: iron replacement through oral or IV

Thalassemia

Genetic defect is lowered or absence a or B chains of Hb

Pathophys, Excess unmatched, globin chains, precipitation, RBC destruction.

FEATURES ARE MICROCYTIC, HYPOCHROMIC

S/S: ANEMIA, SPLENOMegaly, BONE, DEFORMITIES, LIKE FRONTAL, BOSSING OR CHIPMUNK FACIES

treatment includes transfusions, chelation for iron overload, Possible bone marrow transplant

Sickle cell anemia

Cause includes mutation and B globin gene which leads to HBS

Pathophysiology: when O2 is low, HBS polymerizes, and then the RBC sickles and then vasso Occlusion and hemolysis occurs

Features include normocytic, normochromic, sickle cells

Complications include Vasoocclusive crisis, or pain, Acute chest syndrome, stroke, Priapism, infections

Treatment includes hydroxyurea Which leads to high HBF, Transfusions, and Stem cell transplant

Hereditary spherocytosis

Cause is RBC membrane defect

Features include spherocytes, normocytic/normochromic

S/S, anemia, splenomegaly, jaundice

Treatment include splenectomy

G6PD deficiency

Cause includes X-linked enzyme effect which leads to RBC is being vulnerable to oxidative stress, drugs, infection, and fava beans are examples

Features include Heinz bodies, bite cells

S/S: episodic hemolysis, Jaundice, dark urine

Treatment includes avoiding triggers, supportive care

Hemolytic disease of the newborn HDN

Cause is maternal antibodies, RH or ABO Incompatibility, Attack fetal RBC

S/S: Jaundice, hepatosplenomegaly, Hydrops Fetalis

Prevention: RHOGAM , antiD-IgG

Acute blood loss anemia

Cause: hemorrhage

Feature: Normocytic, normochromic (early)

S/S, shock tachycardia, hypertension

Treatment is blood/volume replacement

Relative polycythemia

Causes are dehydration or diuretics

Labs show normal RBC mass, but lowered plasma volume

Absolute polycythemia

Primary, polycythemia, vera, neoplastic, bone marrow, stem cell disorder, leads to higher RBCs, WBC’s, and platelets

S/S: Rudy complexation, spleno Magali, thrombosis, pruritus

Complication can progress to acute leukemia

TX: phlebotomy chemo radiation

Secondary: hired EPO, due to chronic hypoxia, (lung disease, high altitude, heart disease)

Transfusion reactions

Acute hemolytic is fever, chills, flank pain, and DIC

Febrile is fever, chills like antibodies to donor WBC

Allergic is hives, wheezing

TRALI is acute lung injury, Hypoxemia within six hours of transfusion

TACO is circulatory overload, hypertension, pulmonary edema

Bacterial sepsis is fever and shock