Sickle Cell Anemia: Etiology and Pathology (Pediatric Nursing)

00:01 Now we will cover sickle cell anemia.

00:03 Sickle cell anemia is an inherited form of anemia which is a condition in which the aren't enough healthy red blood cells to carry the oxygen throughout the body.

00:12 Normally your red blood cells are flexible and round and they move easily through the blood vessels.

00:17 In sickle cell anemia, the red blood cells become malformed, sticky and rigid and they're shaped like crescent moons or sickles.

00:24 These irregularly shaped cells can get stuck in the blood vessels and this is going to cause the blood flow to slow and decreased oxygen delivery to parts of the body.

00:34 There is no cure for most patients with sickle cell anemia but treatments can relieve pain and help prevent problems associated with the disease.

00:42 Sickle cell anemia is also known as sickle cell disease, hemoglobin S, SS disease or sickling disorder due to hemoglobin S.

00:52 Sickle cell anemia is an autosomal recessive disorder due to a genetic homozygous defect that is caused by the presence of hemoglobin S instead of hemoglobin A.

01:03 Hemoglobin A is the normal type of hemoglobin.

01:05 Because it's recessive, both the mother and the father must pass on this defective form of the gene for the child to be affected.

01:12 If only one parent passes on the sickle cell gene to their child, that child will have sickle cell trait and this is a carrier state.

01:19 These patients do not have sickle cell disease.

01:23 A carrier has only one defective hemoglobin gene and they also have one normal hemoglobin gene so they're gonna make both normal and sickled cells.

01:32 These patients are usually asymptomatic but they can pass this defective gene on to their children.

01:38 In this pedigree chart, both parents are carriers because they each have one defective hemoglobin gene.

01:44 They do not have the disease because remember that requires two defective genes.

01:48 You can see the probability that each of their offspring will have sickle cell anemia which is the disease, be a carrier which is sickle cell trait, or be unaffected.

01:57 Now it's possible that this family will have children with the disease, children as carriers, or children who are unaffected, maybe they'll have a mixture of all three because the probability and the risk resets with each pregnancy.

02:11 There's a 25% chance that their child will have sickle cell disease because they would inherit both diseased genes.

02:17 There's a 50% chance that their children will have the sickle cell carrier gene or have the trait by inheriting only one diseased gene.

02:25 And there's a 25% chance that their children will have normal hemoglobin and be unaffected.

02:31 In the United States, most people have sickle cell disease are of African ancestry but the condition is also common in people from Mediterranean countries as well as patients from India, Saudi Arabia and Hispanic countries.

02:43 Because the disease runs in families, couples planning to have children can have genetic testing.

02:49 Sickle cell anemia is caused by mutation in the gene that tells your body to make the red iron-rich compound that gives blood its color, this is the hemoglobin.

02:58 Hemoglobin allows red blood cells to carry oxygen from your lungs to all parts of your body.

03:02 In sickle cell anemia, the abnormal hemoglobin causes the red blood cells to become rigid, sticky and misshapen.

03:09 Sickle cells in the circulation increase the viscosity of blood, the blood becomes thicker.

03:13 this is gonna slow the circulation thereby increasing the time of exposure to a hypoxic injury particularly in the small vasculature of the spleen.

03:22 This repeated sickling of the red blood cells ultimately damages the membrane.

03:26 These cells cannot squeeze freely through the capillaries and they can block the blood vessel in the microvascular tree.

03:33 There are two major features of sickle cell anemia, the first is chronic hemolysis.

03:38 The sickled cells cannot change shaped easily so they tend to become damaged or burst apart.

03:43 A normal healthy red blood cell lives about 120 days but a sickled cell survives for only 10 to 20 days.

03:50 The body is not able to reproduce new red blood cells fast enough to keep up with this rapid destruction of the sickled cells.

03:57 This results in a chronic hemolysis and anemia.

04:01 The second is the acute episodic vaso-occlusive crisis that can result in organ failure and this is when the sickled-shaped cells stick to the vessel wall and create a blockage that's gonna slow or stop the blood flow.

04:13 When the blood supply is blocked, the oxygen can't reach the nearby tissues and this lack of oxygen causes a crisis which is an acute sudden severe pain.

04:22 There are two components to the pathology associated with sickle cell anemia.

04:26 First the person has to have the genetic mutation to make the abnormal hemoglobin and then that hemoglobin needs to be triggered.

04:34 Once it's triggered, the abnormal proteins transform within the red blood cells and they're gonna alter the shape.