ANEMIA IN PREGNANCY AND ITS ANAESTHETIC IMPLICATIONS

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ANEMIA IN PREGNANCY AND ITS ANAESTHETIC
IMPLICATIONS
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Anemia

• Definition Quantitative or qualitative
  reduction of Hb or circulating RBCs or both.
• As per WHO, Hb conc. Of lt11 gm/dl or Hct lt
  0.33 in 1st 3rd trimester. In developing
  countries, limit brought down to 10 gm/dl.
• Incidence 40 to 60

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Normal Level Of Hb/Hct
Levels vary with age and gender

• AGE
• Newborn
• 1 month
• 3 month
• 12 months
• Adult male
• Adult female

• Hb/Hct
• 16/55
• 12/38
• 10/30
• 12/38
• 14/45
• 12/36

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WHO definition for Chronic Anemia

• AGE
  Hb gm
• 6/12 - 6 yrs
  lt10
• 6 - 14 yrs
  lt12
• Adult male
  lt13
• Non pregnant female
  lt12
• Pregnant female
  lt11/ Hct lt33
• 1st trimester
  lt11
• 2nd trimester
  lt10.5

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Severity of Anemia

• ICMR CATEGORIES
• Category Severity
  Hb levels gm
• 1 Mild
  10 10.9
• 2 Moderate
  7 10.0
• 3 Severe
  lt7.0
• 4 Very
  severe lt4.0

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Physiological anemia of pregnancy
Blood volume ?45 Plasma vol
?55 RBC vol ?30 HCt
?30 Hb
?10.5-11
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Physiological anemia of pregnancy

• ? in RBC mass
• ? demand for
  iron
• ?in total body iron
  stores
• ?in serum ferritin levels
  (28-32 weeks of
• 
  pregnancy)

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Criteria for Physiological anemia

• Hb 10 gm
• RBC 3.2 million/mm3
• PCV 30
• Peripheral smear showing normal morphology of RBC
  with central pallor.

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Regulation of Iron Transfer to fetus

• Maternal circulation
• ?
  Serum transferrin carries Fe
• Transferrin receptors located on apical
• surface of placental synctiotrophoblast
• ?
• Holotransferrin is endocytosed
• ?
• Fe is released apotransferrin
• ?
• Free Fe binds to ferritin in placental cells
• ?
• Transferred to apotransferrin which enters from
  foetal side
• of placenta exits into fetal circulation.

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Pathophysiology

• Oxygen Hemoglobin dissociation curve
• O2 released to the tissues is
• affected by the shape position
• of ODC which can move either to
• right or left. Shift is described in
• terms of P50 O2 tension (Po2) at
• which Hb is 50
• saturated with O2,
• corresponds to 27
• mm Hg.
• 
  
• .

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Parameters Arterial bloood Venous Blood
Po2 (mm Hg) 100 45
O2 carried by Hb/100ml blood(ml) 20 15
O2 in solution/100ml of blood(ml) 0.3 0.15

• 
  
  Normal values of oxygen in arterial
  and Venous blood
• Oxygen content Volume of oxygen carried in 100ml
  of blood.
• Arterial O2 content
• CaO2 (1.34 x Hb x SaO2) (0.003 x
  PaO2)
• Venous O2 content
• CvO2 (1.34 x Hb x SvO2) (0.003 x
  PvO2)
• .

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• Oxygen flux Amount of oxygen leaving the left
  ventricle
• per minute in the arterial
  blood.
• CO x arterial O2 sat x Hb conc. X
  1.31
• Oxygen delivery Amount of oxygen that reaches
  the
• systemic
  capillaries each min.
• Do2 Q x CaO2 x 10 (Q
  Cardiac output)
• Oxygen uptake Volume of oxygen that leaves the
• capillary blood and
  moves into the tissues
• each min.
• Measure of oxygen
  consumption of
• tissues.
• Vo2 Q X (CaO2 CvO2) X 10

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• Oxygen extraction ratio Fraction of oxygen
  delivered
• to the capillaries
  that is taken up into
• the tissues.
• Index of efficiency
  of oxygen.
• O2ER VO2 / DO2

Parameters Absolute Range
Cardiac output 5 6 L/min
O2 delivery 900 1100ml/min
O2 uptake 200 270ml/min
O2 extraction ratio 0.20 0.30
Normal range for oxygen transport parameters
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Acute Anemia
Blood loss gt 20 of blood
volume Hypovolemia
hemodynamic instability.

Signs symptoms of acute Blood loss
Blood loss Volume, ml Symptoms Signs
lt20 lt1000 Restlessness Mild Tachycardia
20-30 1000-1500 Anxiety Tachycardia on exertion ? pulse pressure
30-40 1500-2000 Syncope on sitting or standing Tachycardia at rest, ?RR, Syst. Hypoten.
gt40 gt2000 Confusion, shortness of breath Marked tachycardia, Shock
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• Compensatory mechanism
• Stimulation of adrenergic nervous system
  release of
• vasoactive hormones.
• Sympathetic stimulation leading to ? CO HR.
• Systemic vasoconstriction, ? VR and ? SV.
• Redistribution of blood volume to vital organs.
• Anerobic metabolism, acidosis, hyperventilation.
• Renal conservation of water electrolytes.
• Factors affecting Compensation
• Cardiopulmonary disease
• Left ventricular dysfunction.
• Magnitude of loss, oxygen consumption
• Anaesthesia

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• Anaesthetic considerations
• Management of patient is judged by
  magnitude of hemorrhage and adequacy of volume
  replacement.
• Thiopentone - suitable induction agent for
  normovolemic patients who sustained acute blood
  loss.
• Ketamine or Etomidate - hypovolemic patients.
• Decrease conc. of volatile anaesthetic or
  infusion rate of agents administered i/v.
• Regional anaesthesia not a good option.
• Small doses of midazolam can be given.

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• Anaesthetic management
• Secure 2 large bore cannulas.
• Monitor SpO2,ETCO2,NIBP,temp,UO,CVP,ECG.
• GA with RSI.
• Fluid resuscitation, oxygen by mask, aspiration
  prophylaxis.
• Send blood for CBC, cross matching, coagulation
  profile
• Arrange adequate blood.
• Ensure left uterine placement.
• Transfuse blood if Hb lt 7gm with ongoing blood
  loss.
• If coagulation disorder present, give FFP_at_ 15-20
  ml/kg.
• Prepare for intraop cell salvage if indicated.
• Regional not indicated.

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• Guidelines for Blood Transfusion (By National
  Institutes of Health Consensus Conference)
• Hb gt 10gm/dl transfusion rarely indicated.
• Hb lt 6gm/dl transfusion almost always
  indicated.
• Hb 6 to10gm/dl decision to transfuse is
  determined by patients risk for complications of
  decreased tissue oxygenation ( pt. with IHD ).
• Preoperative autologous donation in selected
  patients.
• Intraoperative blood salvage when appropriate.
• Acute normovolemic hemodilution when appropriate.

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Chronic Anemia

• Includes Iron Deficiency Anemia, Thalassemia,
  sickle cell anemia.
• Symptoms No symptom (unless RBC count is very
  low).
• Fatigue, dyspnoea on exertion, palpitation.
• Nausea, loss of appetite, constipation,
  indigestion.
• Postural hypotension, vertigo, light headedness.
• Angina, heart failure, confusion.
• H/O bleeding (DUB, malena, hematuria).
• Signs
• Vitals - ? HR,RR
• GPE - Pallor of skin mucous membranes, JVP ?,
• pedal edema, generalised
  anasarca,
• glossitis, stomatitis,
  Koilonychia, mouth soreness.
• Resp. system - Tachypnoea
• - Basal crepts, if
  LVF.

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• CVS - Tachycardia, strong peripheral pulses with
  wide
• pulse pressure.
• - Functional cardiac murmur
  (Ejection murmur).
• - Evidence of cardiomegaly, CHF.
• Abd. - Jaundice, hepatosplenomegaly.
• CNS - altered sensorium.
• - Mental disturbances (B12 def).
• Edema (Renal failure).
• Lower leg ulcers (Sickle cell Anemia).
• Compensatory Mechanisms
• ? 2,3 DPG shift of O2Hb dissociation curve to
  right.
• ? Oxygen Extraction ratio.
• Circulatory adjustments - ? CO by increasing SV.
• -
  myocardial hypertrophy.
• Release of erythropoietin which stimulates
  erythroid precursors in bone marrow to produce
  RBCs.

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• Respiratory adjustments - ? physiological
  shunting in
• 
  lungs.
• -
  ? respiratory reserve.
• -
  tachypnoea,
• 
  hyperventilation.
• GIT - reduced splanchnic blood flow.
• Lab Investigations
• Complete blood count
• a) RBC count Hb, Hct.
• b) RBC indices MCV,MCH,MCHC, RDW.
• c) WBC count
• - Cell differential
• - Nuclear segmentation of
  neutrophils.

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• d) Platelet count
• e) Cell morphology
• - Cell size
• - Hb content
• - Anisocytosis,
  Poikilocytosis, Polychromasia
• Reticulocyte count
• Iron supply studies S.Iron, TIBC, S.Ferritin,
  Marrow
• 4. Marrow examination aspirate biopsy

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Iron Deficiency Anemia

• Most common cause of anemia in pregnancy.
• Stored as S.ferritin Hemosiderin.
• Adult male
  Adult female
• Stores 1000mg
  300 500mg
• Losses 1mg/day
  2mg/day
• 
  3mg/day(Pregnancy)
• Daily iron requirement
• 2.5mg early pregnancy.
• 5.5mg from 20 to 22 wks
• 6 to 8mg 32 wks onwards

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• Basal Iron
  280mg
• Transfer to fetus
  200-350mg
• For placenta
  50-150mg
• Blood loss at delievery
  100-250mg
• Expansion of red cell mass
  570mg
• Iron conserved by Amenorrhea
  240-480mg
• TOTAL REQUIREMENT
  800-900mg(4-6mg/d)
• Causes
• Increased iron demand
• Diminished intake of iron
• Disturbed metabolism
• Pre-pregnancy health status
• Excess demand

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• Haematological parameters
• 
  IDA Normal values
• Plasma iron lt30
  50-150ug/dl
• S.Ferritin lt12
  14-150ug/l
• TIBC gt400
  300-350ug/dl
• Transferrin saturation lt15
  30-50
• MCV lt75
  75-93fl
• MCH lt25
  25-36 pg
• MCHC lt30
  30-36g/dl
• RBC Protoporphyhrin gt200
  30-50ug/dl

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• Complications
• During Pregnancy - Pre eclampsia (due to
  malnutrition or
• hypoproteinemia)
• - Intercurrent
  infection (infection impairs
• erythropoiesis by
  BM depression)
• - heart failure (at
  30-32wks or preg)
• - Preterm labour
• During labour - Uterine inertia
• - PPH
• - Cardiac failure
• - shock

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• Puerperium - Puerperal sepsis
• - Subinvolution
• - Failing lactation
• - Puerperal venous thrombosis
• - Pulmonary embolism
• Effects on baby -
• Amount of Fe transferred to fetus
  is
• uneffected even if mother suffers
  from IDA.
• - increased incidence of low
  birth.
• - IUD due to severe maternal
  anoxemia.

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Folic acid Deficiency

• FA is cofactor in nucleic acid synthesis and has
  imp. role in cell division.
• Stores are limited (6-10mg).
• Daily requirement is 300-500mg.
• Def. causes Megaloblastic anemia.
• High incidence in multigravida, twin pregnancy,
  hyperemesis gravidarum, alcohol consumption,
  smoking, malabsorption, antiepileptic drugs.
• Effects on mother Incidence of abortion high.
• Effects on Fetus Premature birth, Neural tube
  defects,
• cleft palate.

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Management

• Prevention
• Avoidance of frequent child birth.
• Supplementary Fe therapy (60mg elemental Iron
  three times a day).
• Dietary prescription.
• Adequate treatment for any infection.
• Early detection of falling Hb level, levels
  should be estimated at 1st A/N visit, 30th
  finally 36th week.

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Pregnancy lt30wks
Pregnancy 30-36wks
Pregnancy gt36wks
IDA FA def. Parenteral Oral
FA I/M iron I/V iron
IDA FA def. Oral
iron Oral FA Intolerance or Non-compliance I/
M iron I/V iron
Blood transfusion
PROTOCOL OF SEVERE ANEMIA IN PREGNANCY
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• Curative
• ORAL THERAPY -
• 200mg (60mg elemental iron) X 3
  times a day.
• WHO 60mg elemental iron 250ug FA
  OD/BD.
• Govt. of India Regimen
• 100mg Fe 500ug FA during 2nd
  half of
• pregnancy X 100 days.
• Drawbacks
• - Intolerance
• - Unpredictable absorption rate.
• - Non Compliant patient.
• - Long time for improvement _at_
  0.3-1gm/100ml/wk.

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• Response to therapy
• - Sense of well being.
• - Increased appetite.
• - Increase in Hb.
• - Reticulocytosis with in 5-10
  days.
• PARENTERAL THERAPY-
• Indications
• - Failure to iron therapy.
• - Non compliant patient.
• - Case seen for the 1st time during
  last 8-10 wks
• with severe anemia.

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• Advantages
• - Certainity of admission.
• - Hb rises _at_1gm/100ml/wk.
• I/V Route
• Iron Dextran (1ml contains 50mg elemental
  iron one
• ampoule contains
  2ml).
• Total dose infusion Deficit of iron calculated
  total
• amount required
  to correct deficit is
• administered in
  single setting I/V
• infusion.
• Elemental Iron Needed (mg)
• (Normal Hb - Patients Hb) X Wt(kg) X
  2.21 1000

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• Given _at_10 drops/min X 30 mins (diluted in normal
• saline or 5 dextrose).
• If no reaction, ? to 40 drops/min.
• Side effects
• - Anaphylactoid reaction.
• - Chest pain, rigors, chills, fall in BP,
  dyspnoea,
• hemolysis.
• Treatment Stop infusion.
• Give antihistaminics,
  corticosteroids
• epinephrine.
• I/M Route
• Iron Sorbitol Citrate (Jactofer)
• Iron Dextran (imferon)
• Oral iron should be suspended at least 24 hrs
  prior to
• therapy to avoid reaction.

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• Drawbacks
• - Painful injection (less with jactofer).
• - Chances of abcess formation
  discolouration of skin
• over injection site.

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• BLOOD TRANSFUSION -
• Transfusion triggers
• Task force 1996, 2006 No uniform transfusion
• trigger
• Patient factors
  Type of surgery
• 
  
• Preg Preg
  Elective Emergency
• lt36wks gt 36wks C/S
  C/S
• -Hb 5gm - Hb 6gm - with H/O
  -Always
• Without CHF without CHF APH,PPH,
  arrange
• -Hb 5-7gm,if -Hb 6-8gm,if previous
  blood.
• CHF,hypoxia, CHF,hypoxia, LSCS.
• Infections. Infections.
• Hb lt8gm,2 units blood should be
  arranged.

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• Guidelines for transfusion
• Prefer fresh Packed cells.
• Do not repeat tranfusion within 24 hrs.
• Effects of Transfusion
• ? O2 carrying capacity of blood.
• Viscosity increases by 33.
• Hb increases by 1gm/unit.
• Heart rate decreases by 7.
• Supplies natural constituents of blood.
• Improvement with in 3 days.
• Drawbacks
• Premature labour (blood reaction).
• CHF
• Transfusion rexn.
• Infections HIV, Hep B etc.

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• Anaesthetic Considerations
• Etiology Chronicity of anemia
• Pt. overall condition
• Pt. ability to compensate for ? O2 delievery.
• Operative procedure.
• Anticipated blood loss.
• Minimize factors interfering with O2 delivery
• - low myocardial contractility,
  CO (careful with
• volatile anesthetic agents
• - left shift of ODC
  (hyperventilation,
• hypothermia, alkalosis)
• Prevent increase in O2 consumption (reduce postop
  pain, fever, shivering).

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• Anaesthetic technique
• Regional anaesthesia
• Spinal or epidural can be given
• Preloading fall in hct by 20 (2lt).
• Exacerbate anemia
• Heart failure.
• General anaesthesia
• Principle
• Avoid hypoxia.
• Maintain cardiovascular stability.
• Minimize factors which produce unwanted shift of
  O2 dissociation curve.

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• Secure 2 large bore cannulas.
• Monitor SpO2,ETCO2,NIBP,temp,UO,CVP,ECG.
• Induction
• Adequate preoxygenation.
• I/V agents administered slowly.
• Maintenance
• Ventilation should be maintained to provide
  normocapnia.
• Possibility of awareness is to be kept in mind as
  O2 conc. is increased.
• Mild tachycardia wide pulse pressure may be
  physiological obtunded by anaesthetic
  agents.
• Tissue perfusion judged by blanching ear lobes,
  nose.
• Change posture cautiously ? BP CO.

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• Postoperative
• Extubate relaxant effect worn off.
• Monitor vitals, fluid intake/output respiratory
  parameters for 12 24 hrs.
• Oxygen enriched air given by mask.
• Prevent shivering.
• Hb should be checked postoperatively
  transfusion accordingly.

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Management during labour

• Adequate oxygenation.
• Avoid sympathetic stimulation and
  hyperventilation prevent rightward shift of ODC.
• Decreased blood loss.
• Avoid maternal stress, patient can go into CHF.
• Improved uterine blood flow.
• PPH should be emergently treated.

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Sickle cell Anemia

• Valine substituted for glutamic acid at 6th
  position on ß chain of Hb molecule.
• Common variants - SS ( sickle cell anemia).
• - SA ( sickle
  cell trait).
• - SC ( sickle
  cell disease).

Hb SS Hb SA Hb SC
Cell trait Homozygous Heterozygous Double heterozygous
HbS 70 90, rest HbF. 10 40, 40-60 HbA. Very low
Hb (g/dl) 6 - 9 13 -15 9 - 12
Life expectancy 30 yrs normal Slightly ?
Propensity for sickling (O2 falls lt 40)
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• Signs symtoms of sickle cell disease
• Vaso-occlusive complications
• a) Painful episodes
• b) Acute chest syndrome
• c) Strokes
• d) Renal insufficieny
• e) Splenic sequestration
• f) Proliferative retinopathy
• g) Priapism
• h) Spontaneous abortion
• i) Bone pains, leg ulcers, Osteonecrosis
• Complications related to hemolysis
• a) Anemia (Hct 15 30)
• b) Cholelithiasis
• c) Acute aplastic episodes

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• Infectious complications
• a) Streptococcus pneumonia sepsis
• b) E.coli sepsis
• c) Osteomyelitis
• Factors favouring Sickling
• Hypoxia
• Acidosis
• Decrease in body temperature
• Dehydration
• Circulatory stasis
• Investigations
• Hb, Hct, Reticulocyte count
• Blood film
• Hb electrophoresis
• Sickle cell test (Na metabisulphite)

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Treatment

• Acute pain
• a)Fluid replacement
• b)Administer opoids NSAIDS.
• Chronic pain
• a)Acetaminophen with codiene
• b)Fentanyl patches
• c)NSAIDS

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• Anaesthetic Management
• Goals -
• Avoidance of acidosis due to hypoventilation of
  lungs.
• Maintenance of optimal oxygenation.
• Prevention of circulatory stasis (improper body
  positioning, use of tourniquets).
• Maintenance of normal body temperature.
• Preoperative period -
• a) Admit to hospital 12 24 hrs
  before surgery to
• permit optimal hydration with I/V
  fluids.
• b) Correction of any coexisting
  infection.
• c) Transfuse RBCs if needed ( keep Hb
  b/w 9-12
• gm Hct of about 35, with
  60-70 HbA).
• Intraoperative period -
• a) Monitor SpO2,ETCO2,NIBP,temp,UO,CVP,
  ECG

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• b) Maintain arterial oxygenation
• c) Hydration.
• d) Body temperature.
• e) Replace blood loss when necessary.
• General anaesthesia
• Preoxygenate for 5 mins before induction to make
  HbS as
• possible is in oxy form.
• After airway is established, give 30 50
  inspired oxygen.
• Regional anaesthesia
• Maintain oxygenation, ventilation, hypotension.
• Prevent stasis of blood flow.

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• Postoperative period
• a) Maintain oxygenation, hydration
• b) Avoid acidosis hypothermia.
• c) Adequate analgesia.
• d) Incentive spirometry.

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Thalassaemia

• Quantitative abnormalities of polypeptide globin
  chain synthesis.

Type Hb Hb electrophoresis Clinical syndrome
a-thalassaemia
1.Hydrops foetalis (deletion of 4 a-genes) 3-10g/dl Hb Barts(100) Fatal in utero or in early infancy
2.HbH disease (deletion of 3 a-genes) 2-12g/dl HbH (2), rest HbA,HbA2,HbF Hemolytic anemia
3.a-thalassaemia trait (deletion of 2 a-genes) 10-14g/dl normal Microcytic hypochromic bloood picture but no anemia
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Type Hb Hb-electrophoresis Clinical syndrome
ß-thallassaemias
1. ß-thallassaemias Major (Cooleys anemia) lt5g/dl HbA(0-50) HbF(50-98) Severe cong. Hemolytic anemia,requ BT
2. ß-thallassaemias Intermedia 5-10g/dl Variable Severe anemia but no regular BT
3. ß-thallassaemias minor 10-12g/dl HbA2(4-9) HbF(1-5) Usually asymptomatic
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• Anaesthetic management
• Management depends on severity of Anemia.
• Preoperative evaluation of cardiac hepatic
  function
• in transfusion dependent patients as a risk
  of Fe toxicity
• or haemochromatosis.
• Extramedullary haematopoiesis
  Hyperplasia of facial bones difficult
  intubation.
• Spinal cord compression massive haemothorax
  also caused by extramedullary haematopoiesis.

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Oxygen Cascade

• Dry atmospheric air PO2 159 mmHg PO2 PB
  x FiO2,
• 
  760 x .21 159
• In Humidified air PiO2 149 mmHg PiO2
  (PB 47) x FiO2
• Alveolar air PAO2 100 mmHg
  PAO2 PiO2 PACO2/RQ
• Arterial blood PaO2 97 mmHg
  PaO2 102 Age/3
• Mixed venous blood PVO2 40 mmHg
• Cell PO2 5 to 40 mmHg
• Mitochondria PO2 1 to 2 mmHg

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Preoxygenation

• Denitrogenation.
• Replacement of the nitrogen volume of the lung
  (upwards of 69 of the FRC) with oxygen to
  provide a
• reservoir for diffusion into alveolar
  capillary blood after the onset of apnoea.
• Three Methods
• 100 O2 via tight fitting mask for 5 mins in a
• spontaneously breathing patient
• 10 mins of oxygen reserve
• 4 vital capacity breaths of 100 O2 over a 30
  secs.
• 8 deep breaths in a 60 sec period.

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Oxygen Stores

• Normal Oxygen Stores in adults -1500 ml.
• (O2 remaining in lungs bound to Hb
  dissolved in body fluids)
• Hemoglobins high affinity and very limited
  quantity in solution restricts the availibility
  of these stores.
• The oxygen contained within the lungs at FRC
  becomes the most important source of oxygen
  during the period of apnea, of which 80 is used
  only.

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Clinical Importance

• Apnea in a patient breathing room air
• Oxygen content fiO2(.21) X
  FRC(2300 ml)480 ml
• Metabolic activity V O2 250ml/min
• Severe hypoxemia in 90 sec.
• Apnea in a patient breathing 100 O2
• Oxygen content fiO2(1) X
  FRC(2300 ml)2300 ml
• Metabolic activity V O2 250ml/min
• Severe hypoxemia in 7-8 Min.

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• Pregnant patients-
• ?FRC (15-20) ?O2 Consumption(20-40)
• Rapid desaturation during period of apnea
• Preoxygenation for 3 - 5
  Min.

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References

• Obstetric Anesthesia- Principles and practice
  David H
• Chestnut 3rd edition
• 2. Anaesthesia Co-existing
  diseases-Stoelting.
• 3. Millers Anesthesia- Ronald D. Miller 6th
  edition.
• 4. Short Practice of Anaesthesia Churchill
  Davidson.
• 5. Textbook of obstetrics- DC Dutta.
• 6. The ICU book Paul. L. Marino.
• 7. Text book of Pathology Robbins.

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Thank you
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