Presentation on theme: "ANEMIA IN PREGNANCY AND ITS ANAESTHETIC IMPLICATIONS"— Presentation transcript:
1ANEMIA IN PREGNANCY AND ITS ANAESTHETIC IMPLICATIONS
2AnemiaDefinition: Quantitative or qualitative reduction of Hb or circulating RBC’s or both.As per WHO, Hb conc. Of <11 gm/dl or Hct < 0.33 in 1st & 3rd trimester. In developing countries, limit brought down to 10 gm/dl.Incidence = 40 to 60 %
8Physiological anemia of pregnancy ↑ in RBC mass↑ demand for iron↓in total body iron stores↓in serum ferritin levels (28-32 weeks ofpregnancy)
9Criteria for Physiological anemia Hb = 10 gm%RBC = 3.2 million/mm3PCV = 30%Peripheral smear showing normal morphology of RBC with central pallor.
10Regulation of Iron Transfer to fetus Maternal circulation↓ Serum transferrin carries FeTransferrin receptors located on apicalsurface of placental synctiotrophoblast↓Holotransferrin is endocytosedFe is released & apotransferrinFree Fe binds to ferritin in placental cellsTransferred to apotransferrin which enters from foetal sideof placenta & exits into fetal circulation.
11Pathophysiology Oxygen Hemoglobin dissociation curve: O2 released to the tissues isaffected by the shape & positionof ODC which can move either toright or left. Shift is described interms of P50 – O2 tension (Po2) atwhich Hb is 50%saturated with O2,corresponds to 27mm Hg..
120.3 0.15 Oxygen content: Volume of oxygen carried in 100ml of blood. ParametersArterial blooodVenous BloodPo2 (mm Hg)10045O2 carried by Hb/100ml blood(ml)2015O2 in solution/100ml of blood(ml)0.30.15Normal values of oxygen in arterial and Venous bloodOxygen 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).
13Oxygen flux: Amount of oxygen leaving the left ventricle per minute in the arterial blood.CO x arterial O2 sat x Hb conc. X 1.31Oxygen delivery: Amount of oxygen that reaches thesystemic capillaries each min.Do2 = Q x CaO2 x (Q = Cardiac output)Oxygen uptake: Volume of oxygen that leaves thecapillary blood and moves into the tissueseach min.Measure of oxygen consumption oftissues.Vo2 = Q X (CaO2 – CvO2) X 10
14Parameters Absolute Range Oxygen extraction ratio: Fraction of oxygen deliveredto the capillaries that is taken up intothe tissues.Index of efficiency of oxygen.O2ER = VO2 / DO2ParametersAbsolute RangeCardiac output5 – 6 L/minO2 delivery900 – 1100ml/minO2 uptake200 – 270ml/minO2 extraction ratio0.20 – 0.30Normal range for oxygen transport parameters
15Acute Anemia Blood loss > 20% of blood volume Hypovolemia & hemodynamic instability.Signs & symptoms of acute Blood lossBlood loss %Volume, mlSymptomsSigns<20<1000RestlessnessMild Tachycardia20-30AnxietyTachycardia on exertion & ↓ pulse pressure30-40Syncope on sitting or standingTachycardia atrest, ↑RR,Syst. Hypoten.>40>2000Confusion, shortness of breathMarked tachycardia, Shock
16Compensatory mechanism: Stimulation of adrenergic nervous system & release ofvasoactive 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 diseaseLeft ventricular dysfunction.Magnitude of loss, oxygen consumptionAnaesthesia
17Anaesthetic 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.
18Anaesthetic 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 profileArrange adequate blood.Ensure left uterine placement.Transfuse blood if Hb < 7gm % with ongoing blood loss.If coagulation disorder present, give ml/kg.Prepare for intraop cell salvage if indicated.Regional not indicated.
19Guidelines for Blood Transfusion (By National Institutes of Health Consensus Conference): Hb > 10gm/dl – transfusion rarely indicated.Hb < 6gm/dl – transfusion almost always indicated.Hb 6 to10gm/dl – decision to transfuse is determined by patient’s 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.
20Chronic AnemiaIncludes 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,RRGPE - Pallor of skin & mucous membranes, JVP ↑,pedal edema, generalised anasarca,glossitis, stomatitis, Koilonychia, mouth soreness.Resp. system - Tachypnoea- Basal crepts, if LVF.
21CVS - 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 RBC’s.
24Iron Deficiency Anemia Most common cause of anemia in pregnancy.Stored as S.ferritin & Hemosiderin.Adult male Adult femaleStores mg – 500mgLosses 1mg/day mg/day3mg/day(Pregnancy)Daily iron requirement2.5mg – early pregnancy.5.5mg – from 20 to 22 wks6 to 8mg – 32 wks onwards
25Basal Iron 280mg Transfer to fetus 200-350mg For placenta 50-150mg Blood loss at delievery mgExpansion of red cell mass mgIron conserved by Amenorrhea mgTOTAL REQUIREMENT mg(4-6mg/d)Causes:Increased iron demandDiminished intake of ironDisturbed metabolismPre-pregnancy health statusExcess demand
26Haematological parameters: IDA Normal valuesPlasma iron < ug/dlS.Ferritin < ug/lTIBC > ug/dlTransferrin saturation <15% %MCV < flMCH < pgMCHC < g/dlRBC Protoporphyhrin > ug/dl
27Complications:During Pregnancy - Pre eclampsia (due to malnutrition orhypoproteinemia)- Intercurrent infection (infection impairserythropoiesis by BM depression)- heart failure (at 30-32wks or preg)- Preterm labourDuring labour Uterine inertia- PPH- Cardiac failure- shock
28Puerperium - Puerperal sepsis - Subinvolution- Failing lactation- Puerperal venous thrombosis- Pulmonary embolismEffects on baby -Amount of Fe transferred to fetus isuneffected even if mother suffers from IDA.- increased incidence of low birth.- IUD due to severe maternal anoxemia.
29Folic acid DeficiencyFA is cofactor in nucleic acid synthesis and has imp. role in cell division.Stores are limited (6-10mg).Daily requirement is mg.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.
30Management 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.
31Pregnancy <30wksPregnancy30-36wksPregnancy >36wksIDA FA def.Parenteral OralFAI/M iron I/V ironIDA FAdef.Oral iron Oral FAIntolerance orNon-complianceI/M iron I/V ironBlood transfusionPROTOCOL OF SEVERE ANEMIA IN PREGNANCY
32Curative: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 ofpregnancy X 100 days.Drawbacks:- Intolerance- Unpredictable absorption rate.- Non Compliant patient.- Long time for 0.3-1gm/100ml/wk.
33Response 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 wkswith severe anemia.
34Advantages:- Certainity of admission.- HbI/V Route:Iron Dextran (1ml contains 50mg elemental iron & oneampoule contains 2ml).Total dose infusion – Deficit of iron calculated & totalamount required to correct deficit isadministered in single setting I/Vinfusion.Elemental Iron Needed (mg) =(Normal Hb - Patients Hb) X Wt(kg) X
35Given @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 totherapy to avoid reaction.
36Drawbacks:- Painful injection (less with jactofer).- Chances of abcess formation & discolouration of skinover injection site.
37BLOOD TRANSFUSION -Transfusion triggers:Task force 1996, 2006 – No uniform transfusiontriggerPatient factors Type of surgeryPreg Preg Elective Emergency<36wks > 36wks C/S C/S-Hb ≤ 5gm% Hb ≤ 6gm% with H/O AlwaysWithout CHF without CHF APH,PPH, arrange-Hb 5-7gm%,if -Hb 6-8gm%,if previous blood.CHF,hypoxia, CHF,hypoxia, LSCS.Infections Infections.Hb <8gm%,2 units blood should be arranged.
38Guidelines 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).CHFTransfusion rexn.Infections: HIV, Hep B etc.
39Anaesthetic Considerations: Etiology & Chronicity of anemiaPt. overall conditionPt. ability to compensate for ↓ O2 delievery.Operative procedure.Anticipated blood loss.Minimize factors interfering with O2 delivery- low myocardial contractility, CO (careful withvolatile anesthetic agents- left shift of ODC (hyperventilation,hypothermia, alkalosis)Prevent increase in O2 consumption (reduce postop pain, fever, shivering).
40Anaesthetic technique: Regional anaesthesia –Spinal or epidural can be givenPreloading fall in hct by 20% (2lt).Exacerbate anemiaHeart failure.General anaesthesia –Principle:Avoid hypoxia.Maintain cardiovascular stability.Minimize factors which produce unwanted shift of O2 dissociation curve.
41Secure 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.
42Postoperative: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.
43Management 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.
44Sickle cell AnemiaValine 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 SSHb SAHb SCCell traitHomozygousHeterozygousDouble heterozygousHbS70 – 90%, rest HbF.10 – 40%, 40-60% HbA.Very lowHb (g/dl)6 - 913 -159 - 12Life expectancy30 yrsnormalSlightly ↓Propensity for sickling+++++ (O2 falls < 40%)++
46Signs & symtoms of sickle cell disease: Vaso-occlusive complicationsa) Painful episodesb) Acute chest syndromec) Strokesd) Renal insufficienye) Splenic sequestrationf) Proliferative retinopathyg) Priapismh) Spontaneous abortioni) Bone pains, leg ulcers, OsteonecrosisComplications related to hemolysisa) Anemia (Hct 15 – 30%)b) Cholelithiasisc) Acute aplastic episodes
47Infectious complications a) Streptococcus pneumonia sepsisb) E.coli sepsisc) OsteomyelitisFactors favouring Sickling:HypoxiaAcidosisDecrease in body temperatureDehydrationCirculatory stasisInvestigations:Hb, Hct, Reticulocyte countBlood filmHb electrophoresisSickle cell test (Na metabisulphite)
49Anaesthetic 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 topermit optimal hydration with I/V fluids.b) Correction of any coexisting infection.c) Transfuse RBC’s if needed ( keep Hb b/w 9-12gm% & Hct of about 35%, with 60-70% HbA).Intraoperative period -a) Monitor SpO2,ETCO2,NIBP,temp,UO,CVP,ECG
50b) 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 aspossible is in oxy form.After airway is established, give 30 – 50% inspired oxygen.Regional anaesthesia:Maintain oxygenation, ventilation, hypotension.Prevent stasis of blood flow.
51Postoperative period – a) Maintain oxygenation, hydrationb) Avoid acidosis & hypothermia.c) Adequate analgesia.d) Incentive spirometry.
52ThalassaemiaQuantitative abnormalities of polypeptide globin chain synthesis.TypeHbHb electrophoresisClinical syndromeα-thalassaemia1.Hydrops foetalis(deletion of 4 α-genes)3-10g/dlHb Barts(100%)Fatal in utero or in early infancy2.HbH disease (deletion of 3 α-genes)2-12g/dlHbH (2%), rest HbA,HbA2,HbFHemolytic anemia3.α-thalassaemia trait (deletion of 2 α-genes)10-14g/dlnormalMicrocytic hypochromic bloood picture but no anemia
53TypeHbHb-electrophoresisClinical syndromeß-thallassaemias1. ß-thallassaemiasMajor (Cooley’s anemia)<5g/dlHbA(0-50%)HbF(50-98)Severe cong. Hemolytic anemia,requ BT2. ß-thallassaemiasIntermedia5-10g/dlVariableSevere anemia but no regular BT3. ß-thallassaemiasminor10-12g/dlHbA2(4-9%)HbF(1-5)Usually asymptomatic
54Anaesthetic management: Management depends on severity of Anemia.Preoperative evaluation of cardiac & hepatic functionin transfusion dependent patients as a risk of Fe toxicityor haemochromatosis.Extramedullary haematopoiesis Hyperplasia of facial bones difficult intubation.Spinal cord compression & massive haemothorax also caused by extramedullary haematopoiesis.
55Oxygen Cascade Dry atmospheric air PO2 = 159 mmHg PO2= PB x FiO2, In Humidified air PiO2 = 149 mmHg PiO2 = (PB – 47) x FiO2Alveolar air PAO2= 100 mmHg PAO2 = PiO2 – PACO2/RQArterial blood PaO2 = 97 mmHg PaO2 = 102 – Age/3Mixed venous blood PVO2 = 40 mmHgCell PO2= 5 to 40 mmHgMitochondria PO2 = 1 to 2 mmHg
56Preoxygenation Denitrogenation. Replacement of the nitrogen volume of the lung (upwards of 69% of the FRC) with oxygen to provide areservoir for diffusion into alveolar capillary blood after the onset of apnoea.Three Methods:100% O2 via tight fitting mask for 5 mins in aspontaneously breathing patient10 mins of oxygen reserve4 vital capacity breaths of 100% O2 over a 30 secs.8 deep breaths in a 60 sec period.
57Oxygen Stores Normal Oxygen Stores in adults -1500 ml. (O2 remaining in lungs + bound to Hb + dissolved in body fluids)Hemoglobin’s 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.
58Clinical Importance Apnea in a patient breathing room air Oxygen content= fiO2(.21) X FRC(2300 ml)=480 mlMetabolic activity =V O2 =250ml/minSevere hypoxemia in 90 sec.Apnea in a patient breathing 100% O2Oxygen content= fiO2(1) X FRC(2300 ml)=2300 mlSevere hypoxemia in 7-8 Min.
59↓FRC (15-20%) +↑O2 Consumption(20-40%) Pregnant patients-↓FRC (15-20%) +↑O2 Consumption(20-40%)Rapid desaturation during period of apneaPreoxygenation for Min.
60References Obstetric Anesthesia- Principles and practice David H Chestnut 3rd edition2. Anaesthesia & Co-existing diseases-Stoelting.3. Miller’s 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.