ANEMIA IN NEONATES
ANEMIA,POLYCYTHEMIA IN A NEWBORN-Dr.ApoorvaPediatrics pg
ANEMIA IN NEONATES
Physiologic Anemia Of Infancy
In utero,due to high oxygen saturation(45%) in fetal aorta,erythropoietin levels are high &hence,RBC production is rapid.
At one week postnatally, all RBC indices begin declining to a minimum value reached at about 8-12 weeks of age (11g/dl)decreased RBC production plasma dilution associated with increasing blood volumeshorter life span of neonatal RBCs (50-70 days)more fragile RBCs
Liver-erythropoietin.due to low oxygen sat95% low eryhtropoietin3
Switch from HbF to HbA (switch to HbA provides for greater unloading of oxygen to tissues d/t lower oxygen affinity of HbA relative to HbF.)
Seldom produces symptoms.
As the hemoglobin levels reach nadir,oxygen delivery to tissues is impaired,erythropoietin stimulated,RBC production increases.
Iron stores rapidly utilized for this process. Hence,iron has to be supplied.
Anemia of Prematurity Occurs in low birth weight infants. The nadir is lower and is reached sooner. Average nadir is 7-9 g/dL and is reached at 4-8 weeks of age.
Due to a combination of :
decreased RBC mass at birth, increased iatrogenic losses from lab draws, shorter RBC life span, inadequate erythropoietin production, low iron stores,rapid rate of growth,Vitamin E deficiency.
Exaggeration of normal physiologic anemia 5
Signs and Symptoms :apneapoor weight gainpallordecreased activityTachycardia.
Iron administration does not alter nadir reached or its rate of reduction.
PathophysiologyAnemia in the newborn results from three processesLoss of RBCs: hemorrhagic anemiaMost common causeIncreased destruction: hemolytic anemiaUnderproduction of RBCs: hypoplastic anemia
Hemorrhagic anemiaAntepartum periodLoss of placental integrityAbruption, previa, traumatic amniocentesis.Anomalies of the umbilical cord or placental vesselsVelamentous insertion of the cord , communicating vessels, cord hematoma, entanglement of the cord,vasa previa.Twin-twin transfusion syndromeOnly in monozygotic multiple births13-33% of twin pregnancies have TTTSDifference in hemoglobin usually > 5 g/dLCongestive heart disease common in anemic twin and hyperviscosity common in plethoric twin
Due to blood loss8
Hemorrhagic anemiaIntrapartum periodFetomaternal hemorrhage Increased risk with ECV,ICV,breech delivery,placental malformationsTraumatic rupture of the cordFailure of placental transfusion due to cord occlusion (nuchal or prolapsed cord)Obstetric trauma causing occult visceral or intracranial hemorrhage
Hemorrhagic anemiaNeonatal periodEnclosed hemorrhage: suggests obstetric trauma or severe perinatal hypoxiaHemorrhagic caput succedaneum, cephalhematoma, intracranial hemorrhage, visceral hemorrhageDefects in hemostasisCongenital coagulation factor deficiencyConsumption coagulopathy: DIC, sepsisVitamin K dependent factor deficiencyThrombocytopenia: immune, or congenital with absent radiiIatrogenic blood loss due to blood draws
Hemolytic anemiaImmune hemolysis: Rh/ ABO /minor blood group incompatibility or autoimmune hemolysisNonimmune: sepsis, TORCH infectionCongenital erythrocyte defectG6PD, thalassemia, membrane defects (hereditary spherocytosis,elliptocytosis)Systemic diseases: galactosemia, osteopetrosisNutritional deficiency: vitamin E
Maternal lupus RA11
Hypoplastic anemiaCongenital Diamond-Blackfan syndrome, congenital leukemia, sideroblastic anemiaAcquiredInfection: Rubella and parvovirus are the most commonDrug induced
Clinical presentationDetermine the following factors :Age at presentationAssociated clinical featuresHemodynamic status of the infantPresence or absence of compensatory reticulocytosisFamily history,obstetric history
Presentation of hemorrhagic anemiaAcute hemorrhagic anemiaPallor without jaundice,cyanosis unrelieved by oxygenTachypnoea Decreased perfusion progressing to hypovolemic shockAcidosisNormocytic or normochromic RBC indicesReticulocytosis within 2-3 days of event
ChronicPallorMinimal signs of respiratory distressMicrocytic or hypochromic RBC indicesCompensatory reticulocytosisEnlarged liver d/t extramedullary erythropoiesis
Presentation of hemolytic anemiaJaundice is usually the first symptomCompensatory reticulocytosisPallorHepatosplenomegaly
Presentation of hypoplastic anemiaUncommonPresents after 48 hours of ageAbsence of jaundiceReticulocytopenia
Presentation of other formsTwin-twin transfusionGrowth failure in the anemic twinOccult internal hemorrhageIntracranial: bulging anterior fontanelle and neurologic signs (altered mental status, apnea, seizures)Visceral hemorrhage: most often liver is damaged and leads to abdominal massPulmonary hemorrhage: radiographic opacification of a hemithorax with bloody tracheal secretions
DiagnosisInitial studiesHemoglobinRBC indicesMicrocytic or hypochromic suggest chronic hemorrhage or thalassemiaNormocytic or normochromic suggest acute hemorrhage, systemic disease, intrinsic RBC defect or hypoplastic anemiaReticulocyte countelevation suggests chronic hemorrhage or hemolytic anemia while low count is seen with hypoplastic anemia
DiagnosisBlood smear to look for spherocytes (hereditary spherocytosis,immune hemolysis)elliptocytes (hereditary elliptocytosis)pyknocytes ,bite cells,heinz bodies(G6PD)Schistocytes,fragmented RBCs (consumption coagulopathy)Direct Coombs test: positive in isoimmune or autoimmune hemolysis
Other diagnostic studiesBlood type and Rh in isoimmune hemolysisKleihauer-Betke test on maternal blood to look for fetomaternal hemorrhageCXR for pulmonary hemorrhageBone marrow aspiration for congenital hypoplastic or aplastic anemiaTORCH: IgM levels, urine for CMVDIC panel, platelets looking for consumptionOccult hemorrhage: cranial or abdominal ultrasoundIntrinsic RBC defects: enzyme studies, globin chain ratios, membrane studies
ManagementSimple replacement transfusionIndications: acute hemorrhageUse 15-20 ml/kg O, RH- packed RBCs or blood cross-matched to mother and adjust hct to 50%Give via UVCDraw diagnostic studies before transfusionongoing deficit replacementmaintenance of effective oxygen-carrying capacityHct >35% in severe cardiopulmonary diseaseHct >40% in mild-moderate cardiopulmonary disease, apnea, symptomatic anemia, need for surgery
ManagementExchange transfusionIndicationsChronic hemolytic anemiaSevere isoimmune hemolytic anemiaConsumption coagulopathyNutritional replacement: iron, folate, vitamin E
ErythropoietinIncreased erythropoiesis without significant side effects
POLYCYTHEMIA IN NEONATES
Polycythemia is increased total RBC massCentral venous hematocrit > 65%Polycythemic hyperviscosity is increased viscosity of the blood resulting from increased numbers of RBCsNot all polycythemic infants have symptoms of hyperviscosity
IncidencePolycythemia occurs in 2-4% of newbornsHalf of these are symptomaticHyperviscosity occurs in 25% of infants with hematocrit 60-64%
PathophysiologyClinical signs result from regional effects of hyperviscosity and from the formation of microthrombiTissue hypoxiaAcidosisHypoglycemia in the substrateOrgans affected: CNS, kidneys, adrenals, cardiopulmonary system, GI tract
What affects hyperviscosity?HematocritIncreased hct is the most important single factorResults from increase in circulating RBCs or decreased plasma volume (dehydration)Plasma viscosityHigher plasma proteins = increased viscosityEspecially fibrinogen (typically low in neonates)Not usually an issue in neonatesRBC aggregationOccurs in areas of low blood flow = venous microcirculationNot a large factor in neonatesDeformability of RBC membrane: usually normal
Conditions that alter incidenceAltitude: increased RBC massNeonatal agePhysiologic increase in hematocrit due to fluid shifts away from intravascular compartment with maximum at 2-4 hours of ageObstetric factors: delayed cord clamping or stripping of the umbilical cordHigh-risk delivery, especially if precipitous
Perinatal processesEnhanced fetal erythropoiesis usually related to fetal hypoxiaPlacental insufficiencyMaternal hypertension, abruption, post-dates, IUGR, maternal smokingEndocrine disorders: due to increased oxygen consumptionIDM (>40% incidence), congenital thyrotoxicosis, CAH, Beckwith-Wiedemann syndrome (hyperinsulinism)
DUE TO : HypertransfusionDelayed cord clampingShould be done within 1 minuteGravity: positioning below the placenta will increase placental transfusionMeds: oxytocin can increase contractions and thus transfusionDecreased in c-section ( no contractions )Twin-twin transfusionIntrapartum asphyxiaEnhances net umbilical flow toward the infant, while acidosis increases capillary leak leading to reduced plasma volume
Clinical presentationSymptoms are non-specific!CNS: lethargy, hyperirritability, proximal muscle hypotonia, vasomotor instability, vomiting, seizures, cerebral infarction (rare)Cardiopulmonary: respiratory distress, tachycardia, CHF, pulmonary hypertensionGI: feeding intolerance, sometimes NECGU: oliguria, ARF, renal vein thrombosis, priapismMetabolic: hypo-glycemia/-calcemia/-magnesemiaHeme: hyperbili, thrombocytopeniaSkin: ruddiness
DiagnosisCentral venous hematocrit > 65%ALWAYS draw a central venous sample if the capillary hematocrit is > 65%Warmed capillary hematrocrit > 65% only suggestive of polycythemia
ManagementAsymptomatic infantsExpectant observation unless central venous hematocrit >75% (consider partial exchange transfusion)Can do a trial of rehydration over 6-8 hr if dehydrated Give 130-150 ml/kg/dCheck central hematocrit q6 hourly
ManagementSymptomatic infants with central hct > 65%Partial exchange transfusion is advisable but debatableFor exchange can use normal saline, 5% albumin, or FFPVolume exchanged = (Weight (kg) x blood volume) x (hct - desired hct) / hct
Other investigationsSerum glucoseHypoglycemia is common with polycythemiaSerum bilirubinIncreased bilirubin due to increased RBC turnoverSerum sodium, BUN, urine specific gravityUsually high if baby is deyhdratedBlood gas to rule-out inadequate oxygenation as cause of symptomsPlatelets, as thyrombocytopenia can be presentSerum calcium-hypocalcemia can be seen
PrognosisIncreased risk of GI disorders and NEC with partial exchange transfusion (PET)Older trials show decreased neurologic complications from hyperviscosity with PET, but newer trials show no real benefitPET is controversial!Infants with asymptomatic polycythemia have an increased risk for neurologic sequelaeNormocythemic controls with the same perinatal history have a similarly increased risk