Polycythem

iaA Problem of Plenty

• B/O Pooja Venkatesh ,Twin -2, B wt 2.2 kg delivered through NVD in Bapuji hospital,cried immediately after birth.(23/10/2016).

• Twin 1, B.wt-2.1kg Male

• Baby was found to be plethoric hence shifted to NICU at 12 HOL.

• With Diagnosis of: Term/Male/SGA/Twin -2/Polycythemia

• At 14 HOL,Twin 2-Hb-24gm/dl and PCV -74%.

• At 14 HOL Twin 1 :hb-11.5gm%,PCV-39%

• Baby was started on IV fluids ,1.5 times the maintenance.

• Repeat CBC at 36 HOL showed Hb-25.6% and HCT -73.2%.

• TSB at 36 HOL -12.2mg/dl warranting phototheraphy.

• In view persistently high HCT ,Partial exchange transfusion was done at 46 HOL.

• HCT was corrected upto 62%,replacement fluid was Normal saline.

• Post exchange HCT was 65%.

• Baby was started on breast feeding from D3 of life.

• Baby received phototheraphy upto D6 of life.

• No documented hypoglycemic episodes through out NICU stay.

• Baby discharged on D7 with HCT -60%.

Viscosity:

• The viscosity of a fluid is a measure of its resistance to gradual deformation by shear stress or tensile stress.

• For liquids, it corresponds to the informal concept of "thickness"; forexample, honey has a much higher viscosity than water.

• Plasma at 37°C is about 1.8-times more viscous than water at the same temperature; therefore, the relative viscosity of plasma (compared to water) is about 1.8.

Poiseuille Law:

• Viscosity depends on Hematocrit, plasma proteins (especially albumin , fibrinogen), deformability of erythrocytes, erythrocyte aggregation , interaction of cell components with vessel walls .

• The gold standard - measurement of viscosity is a whole blood viscometer that can accurately measure the viscosity of blood (expressed in centipoise)

• Hyperviscosity is blood viscosity >14.6 centipoise, measured at a shear rate of 11.5 per second

• Whole blood viscometers are not universally available • Because the erythrocyte number is the most important factor

affecting viscosity, measurement of the neonatal Hct has been suggested as the best clinical screening test for identifying infants with presumed hyperviscosity

Definition:• Neonatal polycythemia defined in as a Venous HCT

>65%. • Incidence .95%-1.5%• This cut-off has been chosen based on the

observation that blood viscosity exponentially increases above a Hct of 65% or Hemoglobin concentration higher than 22.0 g/dl

- a statistical definition of infants at risk. - neither based upon the risk for symptoms or for

complications.

Factors influence normally HCT

1. Gestational age • HCT increases progressively with increasing

gestational age, thus NP may occur at much higher rates in post term than in preterm infants (Due to normal variation of Hct)

2. Degree of placental transfusion • At term, the total fetoplacental blood volume is about

115 ml/kg fetal weight, and is distributed in the "normal" full-term infant after birth as approximately 70 ml/kg in the infant, with 45 ml/kg remaining in the placenta. This distribution may vary considerably, as more or less blood may remain in the placenta.

• The main factors influencing placental transfusion are time of cord clamping, position of the delivered infant in relation to the placenta, onset of respiration, presence or not of intrauterine hypoxia, and presence or not of cord compression

Degree of placental transfusion..contd

A. Time of cord clamping Within 30 to 45 seconds following birth, the umbilical arteries are functionally closed, while blood flow from placenta to fetus through the umbilical vein may continue for a few additional minutes . When the infant is delivered at or below the introitus level, if the cord is not clamped, her/his blood volume will increase in a stepwise manner, reaching 55% additional volume after 3 minutes

B. Position of the delivered infant in relation to the placenta In vaginally delivered infants who are kept 50 to 60 cm above the placenta, placental transfusion does not occur . In contrast, if they are maintained 40 cm below the placenta, placental transfusion is hastened

Degree of placental transfusion..contd

C. Onset of respiration: Onset of respiration through generating a negative intrathoracic pressure and presumably increasing the placental-fetal transfusion process

D. Presence or not of intrauterine hypoxia Acute intrapartum and intrauterine asphyxia can be accompanied by an increase in hematocrit (presumably through increased transcapillary escape of plasma).

E. Presence or not of cord compression Because the umbilical vein is more compressible than the umbilical arteries, infants born with a tight nuchal cord may actually have low blood volume at birth

F. Dehydration- Relative loss of water from body

3. Site of blood sampling :Capillary HCT is generally higher than venous HCT which in turn is higher than "central" HCT (from umbilical vein) . Capillary HCT from warmed heels correlates well with venous HCT

4. Time of blood sampling Hematocrit rises from values obtained at birth (from cord venous or arterial sampling) to reach a peak at 2 hours of age, staying at a plateau for 2 additional hours, then decreases to go back to values close to cord blood values by 12 to 18 hours of age.

CAUSES OF POLYCYTHEMIA

Classified as:• Normovolemic• Hypervolemic• Hypovolemic

1. Normovolemic Polycythemia condition where normal intravascular volume is present despite an increase in red cell mass. It results from increased RBC production due to placental insufficiency and/or chronic intrauterine hypoxia

-Intrauterine Growth Restriction -Maternal Pregnancy Induced Hypertension -Maternal Diabetes Mellitus -Prolonged Intrauterine Tobacco Exposure -Postmaturity -High Altitude

2. Hypervolemic polycythemia occurs when higher than average blood volume is accompanied by an increased red cell mass acute transfusion to the fetus such as

- maternal-fetal transfusion -twin-to-twin transfusion- Delayed cord clamping 3. Hypovolemic polycythemia occurs secondary to

a relative increase in number of erythrocytes to plasma volume

-intravascular dehydration

EFFECTS AND COMPLICATIONS OF POLYCYTHEMIA

A. Hyperviscosity leads to a reduction in cerebral blood flow decreased blood flow to the brain→ decrease supply to the brain of other substances carried by plasma, such as glucose, amino acids

B. Increased cellular breakdown of the increased red cell mass

Increased breakdown of red cells in NP may be a significant contributing factor of neonatal hyperbilirubinemia

C. Hemodynamic effects of hypervolemia or of hypovolemia hypervolemia may lead to congestive heart failure, pulmonary edema, and cardiorespiratory failure hypovolemia can lead to hypoxic-ischemic injury to vital organs.

A.Central nervous system (CNS): Poor feeding, lethargy, hypotonia, apnea, tremors, jitteriness, seizures,cerebral venous thrombosis.

B. Cardiorespiratory. Cyanosis, tachypnea, heart murmur, congestive heart failure, cardiomegaly, elevated pulmonary vascular resistance, prominent vascular markings on chest x-ray.

C. Renal Decreased glomerular filtration, renal vein thrombosis, hematuria, proteinuria. D. Other. Thrombocytopenia, poor feeding, Increased jaundice, Persistent hypoglycemia, Hypocalcemia, testicular infarcts, Necrotizing enterocolitis (NEC), Priapism, Disseminated intravascular coagulation

Indications for polycythemia screening

Do not routinely screen well term newborns for this syndrome, because there are few data showing that treatment of asymptomatic patients with partial exchange transfusion is beneficial in the long term

• Small for gestational age (SGA) neonates• Large for gestational age (LGA) neonates • Infants of diabetic mothers (IDM)• Newborns with morphological features of growth

restriction• Monochorionic twins especially the recipient twin• Babies looking plethoric

A. Once other causes of illness have been considered and excluded (e.g., sepsis, pneumonia, hypoglycemia), any child with symptoms that could be due to hyperviscosity should be considered for partial exchange transfusion if the peripheral venous hematocrit is >65%.

B. Asymptomatic infants with a peripheral venous hematocrit between 60% and 70% can usually be managed by increasing fluid intake and repeating the hematocrit in 4 to 6 hours.

C. Exchange transfusion when the peripheral venous hematocrit is >70% in the absence of symptoms, but this is a controversial

D. The following formula can be used to calculate the exchange with normal saline that will bring the hematocrit to 50% to 60%. In infants with polycythemia, the blood volume varies inversely with the birth weight.

Volume to be exchanged is calculated by the following equation:

Volume (mL) = (Initial Hct – Desired Hct) x Weight(kg) x 90 mL Initial Hct -Desired Hct should be 55%.-Hypervolemia is common in polycythemia; use

90 mL/kg as estimated blood volume.-Volume to be exchanged in a term infant is

almost always in the range of 25-30 mL/kg. If calculated volume is outside this range, re-check the calculations.

TECHNICAL ASPECTS OF PET

• Which Diluting Fluid Should Be Used- Plasma, 5% Albumin, NS, Or Ringer Solution - It Did Not Find Clinically Differences - NS Is The Optimal Fluid (Cheapest, With Less

Potential Side-effects)• Vessels Used.-UAC,UVC, periphreal vessels• Aim for a target, post PET HCT of 55%.

Conclusions:

1. PCT is a venous hematocrit of at least 65%. Such a number is much more likely to be significant in an infant >6 hours than it is at 2-4 hours of age.

2. Symptoms/complications of polycythemia are unlikely to be related to a hematocrit of < 65%.

3. There is no evidence that PET alters the neurologic or developmental outcomes of asymptomatic polycythemic neonates.

Recommendations:

1. Routine screening for polycythemia is not recommended.

2. Routine performance of PET in asymptomatic infants is not recommended.

3. Screening for symptoms should be performed carefully and documented in all infants with polycythemia.

4. Normality of blood glucose should be documented in all infants found to have polycythemia.

5. PET causes a prompt relief of symptoms. the presence of symptoms (or of hypoglycemia) should lead to perform PET.

6. PET should be performed as early as possible whenever symptoms are present, in view of the potential for more severe symptoms and complications to develop. Before proceeding with PET, it appears that there is a need for thorough, timely, clinical and physical assessment of the newborn.

7. If performed, PET should be done with normal saline

Twin To Twin Transfusion Syndrome

• Monochorionic pregnancy.

• Pathophysiology:-Placental vascular anastomosis-unequal placental sharing-abnormal cord insertions

• Donor and Recipient

Diagnosis:

• Btw 17-26 wks GA

• Monochorionicity.

• USG Findings-Quintero,CHOP,CVPS.

Fetal Treatment:

• Amnioreduction(survival 37%-83%)

• Microseptostomy of intertwin membrane

• Fetoscopic laser photocoagulation.

• Fetoscopic cord coagulation

Neonatal Management:

• Donor- resuscitation at birth , rapid IV acess to treat hypotension,PRBC transfusion for anemia,correction of hypoglycemia.

• Reciepent –PET

• PPHN and TTTS

References:• Dana Mathews,Bertil Glader.Erythrocytes disorders in

infancy.Avery’s diseases of Newborn,9thed:1102-1106.• Deidre O.Polycythemia.Manual of Neonatal Care,7th ed:572-577.• Polycythemia.The PGI Handbook of NICU Protocols 4th ed:171-

175,2010.• Polycythemia.AIIMS Protocols in Neonatology 1st ed:202-211,2016• Habli.Twin to twin transfusion syndrome:A Comprehensive

update.Clin Perinatology2009;391-416• De waal et al.Systematic review of optimal fluid for PET in

polycythemia.Arch disease Child fetal Neonatal ed 2006:F7-F10 • Werner EJ.Neonatal Polycythemia and hyperviscosity.Clin

Perinatology1995:693-710

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