Medicine 5th year, 8th lecture/part three (Dr. Sabir)
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Medicine 5th year, 8th lecture/part three (Dr. Sabir)

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The lecture has been given on Apr. 3rd, 2011 by Dr. Sabir.

The lecture has been given on Apr. 3rd, 2011 by Dr. Sabir.

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    Medicine 5th year, 8th lecture/part three (Dr. Sabir) Medicine 5th year, 8th lecture/part three (Dr. Sabir) Presentation Transcript

    • Sickle Cell Anemia Dr. Sabir
    • What is Sickle Cell Anemia (SCA)?
      • an inherited condition that results in a decrease in the ability of red blood cells to carry oxygen throughout the body
        • Sickle red blood cells become hard and irregularly shaped (resembling a sickle)
        • Become clogged in the small blood vessels and therefore do not deliver oxygen to the tissues.
        • Lack of tissue oxygenation can cause excruciating pain, damage to body organs and even death.
    • Pathogenesis
      • Normal hemoglobin
      • 2 alpha and 2 beta chains
      • form a 4 chain tetramer
      • HbS:
      • Valine substituted for glutamic acid in both beta chains (HbSS).
      • This occurs due to single point mutation at sixth position of beta globin chain which has thymine instead of adenine.
    • PATHOGENESIS Arterial pO 2 oxyHbS(soluble) Stiff,viscous sickle cell Venous pO 2 deoxyHbS polymerised) Membrane changes Ca 2+ influx,K + leakage Capillary venule occlusion Shortened red cell survival Microinfarction Ischemic tissue pain Ischemic organic malfn. Anemia, jaundice
    • Mechanism -HbS
      • When sickle haemoglobin (HbS) gives up its oxygen to the tissues, HbS sticks together
        • Forms long rods inside RBC
        • RBC become rigid, inflexible, and sickle-shaped
        • Unable to squeeze through small blood vessels, instead blocks small blood vessels
        • Less oxygen to tissues of body
      • RBCs containing HbS have a shorter lifespan
        • Normally 120 days
        • Chronic state of anaemia
      • Sickle Cell Trait
      • Sickle haemoglobin (S) + Normal haemoglobin (A) in RBC
        • Adequate amount of normal Hb (A) in red blood cells
          • RBC remain flexible
          • Carrier
          • Do Not have the symptoms of the sickle cell disorders, with 2 exceptions
          • Pain when Less Oxygen than usual (scuba diving, activities at high altitude (12,000ft), under general anaesthesia)
          • Minute kidney problems
    • LAB DIAGNOSIS
      • SICKLE TEST: Red cells with HbS take a sickle shape when mixed with a freshly prepared solution of the reducing agent sodium metabisulphite.(2%) Giving an appearance of turbidity.
      • SOLUBILITY TEST: Hb added to solution of sodium dithionite(reducing agent) in phosphate buffer.Turbidity shows presence of HbS.
      • Hb ELECTROPHORESIS
    • BLOOD PICTURE
      • Hb : 6-9gm%, may be lower
      • Anemia: normocytic, normochromic
      • MCV,MCH: Normal
      • Stained film:Moderate anisopoikilocytosis, sickle cells, oval cells, occ target cells, Howell-Jolly bodies
      • Reticulocytosis (10-20%)
    •  
    • Screening
      • Haemoglobin Electrophoresis
        • Simple Blood test
        • Routine screening in high risk groups
            • During pregnancy
            • Before anaesthesia
      • Prenatal Testing
        • Amniocentesis
          • 16 and 18 weeks of the pregnancy
          • small risk of causing a miscarriage (1 in 100)
        • Chorionic villus sampling (CVS)
          • 9th or 10th week of pregnancy
          • very small amount of material from the developing placenta
          • slightly higher chance of miscarriage
    • Early Symptoms and Complications
      • Typically appear during infant's first year
          • 1 st symptom: dactylitis and fever (6 mo-2 yrs)
          • Pain in the chest, abdomen, limbs and joints
          • Enlargement of the heart, liver and spleen nosebleeds
          • Frequent upper respiratory infections
          • Chronic anemia as children grow older
      • Over time Sickle Cell sufferers can experience damage to organs such as liver, kidney, lungs, heart and spleen
      • Can result in death
    • Medical Complications
      • pain episodes
      • strokes
      • increased infections
      • leg ulcers
      • bone damage
      • jaundice
      • early gallstones
      • lung blockage
      • kidney damage and
      • loss of body water in urine
      • painful erections (priapism)
      • blood blockage in the spleen or liver (sequestration)
      • eye damage
      • low red blood cell counts (anemia)
      • delayed growth
    • Serious Complications: PAIN Recurrent Pain Episodes or Sickling Crises
      • Occur at any age but appear to be particularly frequent during late adolescence and early adult life
        • Unpredictable
        • Red Blood Cells get stuck in the small veins and prevent normal blood flow
        • Characterized by severe pain in the back, chest, abdomen, extremities, and head
        • Highly disruptive to life
        • Most common reasons for individuals to seek health care
      • Fever
      • Chest pain
      • Shortness of Breath
      • Increasing tiredness
      • Abdominal swelling
      • Unusual headache
      Danger Signs of a Crisis
      • Any sudden weakness or
      • loss of feeling
      • Pain that will not go away
      • with home treatment
      • Priapism (painful erection
      • that will not go down)
      • Sudden vision change
      SEEK URGENT HOSPITAL TREATMENT IF IN CRISIS
    • Crises
      • During a crisis
        • severe pain in the fingers, toes,
        • arms, joints,legs, back, abdomen, and bones.
      • Decrease in oxygen to the chest and lungs
        • May lead to acute chest syndrome
          • Damage to the lungs
            • Severe pain and fever
            • airways narrowing, further reducing O 2
          • Leads to an increased risk of potentially
          • fatal infections
      • Infections
      • Thirst and dehydration caused by not drinking enough( even if thirst is not felt )
      • Over-exertion
      • Over-excitement
      • Cold weather and cold drinks and swimming
      • Bangs, bumps, bruises and strains
      • Stress triggers pain in adults, but does not seem to do so in children.
      Triggers of Pain
    • Alleviating Pain
      • Warmth: increases blood flow
      • Massaging and rubbing
      • Heat from hot water bottles and deep heat creams
      • Bandaging to support the painful region
      • Resting the body
      • Getting the sufferer to relax
        • deep breathing exercises
        • distracting the attention
      • Pain-killing medicines (analgesics): paracetamol, codeine non-steroidal anti-inflammatory, morphine if necessary
      • Taking folic acid daily to help make new red cells
      • Daily penicillin until age six to prevent serious infection
      • Drinking plenty of water daily (8-10 glasses for adults)
      • Avoiding too hot or too cold temperatures
      • Avoiding over exertion and stress
      • Getting plenty of rest
      • Getting regular check-ups from knowledgeable health care providers
      Daily Preventive Measures
    • Treating Complications
      • Pain-killing drugs and oral and intravenous fluids
        • To reduce pain and prevent complications.
      • Transfusions
        • Correct anemia
        • Treat spleen enlargement in children before the condition becomes life-threatening
        • Regular transfusion therapy also can help prevent recurring strokes in children at high risk of crippling nervous system complications.
      • Hydroxyurea
        • The first effective drug treatment for adults with severe sickle cell anemia reported in early 1995
        • Daily doses of the anticancer drug, hydroxyurea, reduced the frequency of painful crises, acute chest syndrome, needed fewer blood transfusions
        • Increases production of fetal hemoglobin in the blood
          • Fetal hemoglobin seems to prevent sickling of red cells
          • cells containing fetal hemoglobin tend to survive longer in the bloodstream
      Developing Treatments
      • Bone marrow transplantation
        • Shown to provide a cure for severely affected children with sickle cell disease
        • Only about 18 percent of children with sickle cell anemia are likely to have a matched sibling.
      Developing Treatments
      • The Ultimate Cure?
      • Gene Therapy
      • Correcting the “defective gene” and inserting it into the bone marrow
      • Turning off the defective gene and simultaneously reactivating another gene that turns on production of fetal hemoglobin.
      • No real cure for Sickle Cell Anemia at this time.
      • “ In the past 30 years, the life expectancy of people with sickle cell anemia has increased. Many patients with sickle cell anemia now live into their mid-forties and beyond.”