Abnormal Hb

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Abnormal hemoglobinBy Dr. Ehab Khairy

Abnormal HemoglobinMay be due to: 1- Abnormal concentrations High or low concentrations 2- Abnormal Structures Sickle cell disorders 3- Abnormal Synthesis Thalassemias 4- Abnormal Hemoglobin function Met hemoglobin

Abnormally low Hemoglobin Concentration

Iron deficiency Chronic disease Thalassemia Thalassemia Sickle cell A plastic anemia Autoimmune Folic acid deficiency Vit.B12 deficiency Distribution Of Anemia

Physiological compensatory Mechanisms for Low Hemoglobin

Manifestations Of Sever Nutritional AnemiaIron deficiency anemia

Respiratory distress Congestive heart failure Thrombocytopenia Neurologic abnormalities

Vitamin B 12 deficiency anemia1- Neuropathy * Sensory : Bilateral symmetrical parasthesia Loss of propioceptive and vibratory sensations * Motor: Diminished deep tendon reflexes and un steady gait * Mental: Impaired memory and mental depression 2- Thyroid disorders: associated with pernicious anemia

Folic acid deficiency anemia

Smooth tongue Hyper pigmentation Mental depression Peripheral edema Liver dysfunction With or without peripheral neuropathy

Optimization Of Deficiency Anemia Before Elective SurgeryIron Deficiency Anemia # Oral preparations 200 mg # Parenteral preparations must be given under close medical supervision # Human Erythropoietin

Vitamin B12 Deficiency Anemia 1 mg hydroxo-cobolamin Im every three days for six injections Folic Acid Deficiency Anemia Oral 5 mg of folic acid for four months

Preoperative Transfusion Decision making*Causes of anemia *Degree of anemia *Duration of anemia *Urgency of surgery *Intravascular fluid volume *Likely hood of intra operative blood loss *Age of the patient *Co existing diseases - Ischemic heart disease - Lung disease - Cerebrovascular disease

Guide Line For Blood Transfusion- Hb conc.> 10 g/dl Transfusion rarely indicated specially for chronic anemia - Hb conc. < 6g/dl Almost indicate blood transfusion specially for acute anemia - Hb conc. Between 6 9 g/dl Decision of transfusion is determined by patient risk for complications of decreased tissue oxygenation ( patient with ischemic heart)

Adverse Effects Of Anesthesia On AnemiaAnesthesia depress sympathetic nervous system and decrease C.O.P. and offsets An important physiological compensatory mechanism for anemia Nitrous oxide can produce megaloblastic changes even within a short period of administration

Effects of Anemia On Anesthesia and Its Choice

Anemia theoretically reduces Mac of Volatile Anesthetics Neurologic changes of vitamin B12 deficiency detract the choice of Regional anesthesia and peripheral nerve block

Anesthetic Goals1Adequate tissue Oxygen DeliveryAvoid drug induce myocardial depression Avoid factors shifting oxygen dissociation curve to the left (Hyperventilation & Hypothermia)

23-

Minimizing blood Loss Adequate Monitoring

PolycythemiaPathologic excess of hematocrit with or without increased hemoglobin concentration 1- Primary Polycythemia (vera) Increased hematocrit Iron deficiency anemia 2- Relative Polycythemia Increased hematocrit Normal Hb conc. 3- Secondary Polycythemia Increased hematocrit High Hb conc.

Causes Of Secondary Polycythemia 1- Chronic anoxia* High Altitude * Smokers polycythemia * Cardiopulmonary diseases * Obesity hypoventilation & Sleep apnea syndrome

2- Renal DiseasesCalculi, Cysts, Hydronephrosis, Carcinoma

3- Excessive Testosterone production 4- IatrogenicExogenous Testosterone and Erythropoietin

Complications of Increased Hb Conc.Increased Blood Viscosity

Increased peripheral resistance

Thrombosis

Anesthetic GoalsReduction of Hb conc. < 15g/dl prior to elective surgery by 1- Minimizing tissue anoxia and other factors enhancing erythropoietin production 2- Normovolemic hemo- dilution just prior to surgery is much better than repeated phlebotomy a week before. Why?

Structure Of Hemoglobin# Fetal Hemoglobin (Hb F)Consists of 2 chains & 2 Changes to adult Hemoglobin within 3 to 6 months after birth to adult

# Adult Hemoglobin (Hb A)Consists of 2 chains & 2 An other form of adult Hb

# Adult hemoglobin (HB A2)consists of 2 chains & 2

Hereditary Disorder Of Hemoglobin

Hemoglobinopathies consist of abnormal structural variants of hemoglobin , the most important is sickle disorders (Hb S) Thalassemia reflects abnormal synthesis of hemoglobin where chains of hemoglobin are diminished or absent

Sickle Cell DiseasesSickle cell disease is one of the most prevalent genetic disorders affecting millions through out the word It is common in India, Saudia Arabia, Mediterranean countries, South, and center of America Sickle cell disease denotes all genotypes that contain at least 1 sickle gene in which hemoglobin S (HbS) makes up at least half of the hemoglobin present.

Mendelian Trait of Sickle Cell DiseaseHb S is formed of 2 normal alphaand 2 abnormal beta-globin chains

Recessive (Hb S, Hb S)Abnormal hemoglobin

Heterozygous (Hb A, Hb S)Normal and abnormal hemoglobin Normal hemoglobin more abundant

Pathophysiology# chain of Hb S differs form that of Hb A only in the substitution of valine for glutamic acid at the sixth position. # Hb S carries oxygen normally but it unloads oxygen more easily as its P50 is 31mmHg compared to 26 mmHg of normal Hb # Once oxygen is unloaded to the tissues It begins to form semisolid aggregate structures, consequently RBCs acquire sickle shape.

Results of Sickle Cells Erythrostasis Increased blood viscosity Reduced blood flow Hypoxia Increased adhesion of red blood cells Vascular occlusion Further sickling

Pathophysiology of Sickle Cell Disease

Clinical Signs and SymptomsVaso occlusive Painful crisis Acute chest syndrome (a lifethreatening pneumonia-like illness) Cerebrovascular accidents Splenic and renal dysfunction Chronic anemia Susceptibility to infections

Cont. Jaundice Pallor Hand and foot syndrome (warmth and tenderness) Leg ulcers Organomegaly Cardiac failure Abdominal and bone pain (aseptic necrosis)

A plastic crisisCharacterized byprofound anemia Hb is < 3g/dl,

It may be Precipitated byInfection, hypoxia, systemic disease, acidosis, dehydration, trauma, and Folic acid deficiency

Splenic Sequestration CrisisCharacterized bySudden pooling of blood in the spleen due to partial occlusion of its drainage It can cause life threatening hypotension in infants and young children Why? Repeated splenic infarction result in fibrosis -auto spleenectomy.

Managing a CrisisA part of blood transfusion High doses of folic acid Analgesia for pain Hydration Enhance hemoglobin F production of by using hydroxyurea and erythropoietin .. Why?

Anesthetic ManagementsPreoperative preparation- Adequate hydration - Infection control - Prophylactic antibiotics - Optimization of quality and quantity of Hb by partial exchange transfusion - The goal of such transfusion is to achieve a hematocrit of 30-40% with > 50% normal Hb A

Intra operative Managements Avoid 6H & 1SHypoxia Hypotension Hypothermia Stases Hypercarbia Hypovolemia Hyperthermia

Intra Operative MonitoringsCVP PAPis useful to monitor volume state

for monitoring of mixed venous oxygen saturation

Sickling changes do not occur if the VSO2 above 40 mmHg

Post operative Considerations

Supplemental oxygen Pain Control Pulmonary physiotherapy Early ambulation

Thalassemia

Types Of ThalassemiaAlpha Thalassemia Normal Silent carrier Minor /

- / -/- --/ Hb H disease --/- Barts hydrops fetalis --/--

Beta Thalassemia Normal Minor Intermedia Major / /0 /+ 0/+ 0/0 +/+

0 = no production of the chain + = diminished production of the chain

Clinical manifestations1- Anemia : Microcytic and hypochromic 2- Excessive hemolysis 3- Hyperplasia of the bone marrow and extramedullary erythropoiesis

Excessive hemolysis:- Many RBCs fail to mature and early destroyed By the reticuloendothelial system - Excess globins of Thalassemia (Target cell) - This Hb is poorly soluble, highly reactive and cause free radical cellular Injury-

Excess hemolysis result in Splenomegaly, Hepatomegaly, Cholelithiasis, and Jaundice

3- Hyperplasia Of The Bone MarrowCaused by vigorous secretion of erythropoietin Result in

* Skeletal abnormalities and facial dysmorphism. *Development of extramedullary marrow in Pleura Hemothorax Sinuses Epistaxis Epidural space Epidural hematoma

Blood Transfusion Therapy for Thalassemia 1- Palliative transfusion: It is just to keep patient surviving 2- hypertransfusion: Maintain a hemoglobin level of 9 to 10 g/dl To reduce extramedullary erythropoiesis 3- Supertransfusion: Maintain a hemoglobin level >12 g/dl in an effort to suppress all erythropoiesis.

Complications of regular Blood Transfusion

HemosiderosisCardiac and Hepatic iron toxicity (cirrhosis) Require Chelation therapy with Deferoxamine

Expected Anesthetic Difficulties1- Difficult Air Way:Hyperplasia of facial bones and narrowing of nasal passage

2- Hemosiderosis:Resulting in cardiac dysfunction, supra ventricular arrhythmias as well as hepatic dysfunctions

Regional AnesthesiaEpidural, spinal, and intrapleural anesthesia are relatively contraindicated as the presence of extramedullary bone marrow increases the likelihood of bleeding and hematoma formation Patients receiving palliative transfusion therapy are at greatest risk

Met-hemoglobinMet = beyond Ferric iron (fe+3) = one oxidation state beyond ferrous iron (Fe+2)

Ferric form of ironUnable to bind to O