Cyanosis in term neonates – A problem oriented approach

Dr.Gopakumar.HAssistant Professor

Dept of Neonatology AIMS , Kochi

Aims

• To provide a brief approach to cyanosis in term neonates

• Representative case scenarios and discussion

• Fetal circulation and basic physiology

Common presentation of common condition Uncommon presentation of common condition Uncommon presentation of uncommon condition

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Fetal circulation

Placenta – gas exchange

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Changes with onset of respiration • Breathing initiates abrupt fall

in pulmonary vascular resistance

• Gas exchange function transferred from placenta to lungs

• Concurrent increase in blood flow to the lungs . Pulmonary arterioles dilate in response to increased oxygen saturation

• Closure of 3 communicating channels - ductus arteriosus , ductus venosus and foramen ovale

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Pathology of PPHN

• Any condition that interferes with normal perinatal transition

• Hypoxia and acidosis – pulmonary vasoconstriction ( impaired perinatal transition as in birth asphyxia , MAS etc )

• Pulmonary hypoplasia • Premature closure of

ductus arteriosus as in maternal NSAID therapy

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Diagnostic dilemma in hypoxemia in a full term neonate

• Cyanotic congenital heart disease • Persistent pulmonary hypertension

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Identifying right to left shunt

• Obtain ABG from right radial artery ( preductal ) and posterior tibial artery ( postductal ) simultaneously

• A higher PaO2 in right radial artery sample by 20 mm of Hg indicates presence of right to left shunting

• An SpO2 difference may also suggest right to left shunting

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Hyperoxia test

• Place infant in 100% oxygen concentration for 5 to 10 minutes

• Sample arterial blood • Persistent hypoxia after 5 to 10 minutes

of 100% oxygen exposure suggest presence of right to left shunting

• If PaO2 > 100 mm of Hg , CCHD more or less ruled out

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Hyperoxia – hyperventilation test

• Hypoxia and acidosis causes pulmonary vasoconstriction

• Alkalosis and increased blood oxygen can decrease pulmonary vascular resistance

• By increasing minute ventilation – PaCO2 falls and pH rises . This markedly increase pH and may result in dramatic increase in PaO2

• A dramatic increase along with extreme lability of PaO2 is more suggestive of PPHN

• Differentiates PPHN from CCHD • CCHD – fixed right to left shunting ( PaO2 between 40 to

50 mm Hg ) even with inhalation of 100% oxygen and hyperventilation

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Essential diagnosis of PPHN

• Risk factors ( Birth asphyxia / MAS / Pneumonia etc )

• Chest Ray usually normal / underlying lung condition

• ABG – Low PaO2 in the face of high FiO2 • Echo – to rule out congenital cyanotic

heart disease and to diagnose PPHN

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Case scenario

• Term male baby with birth weight of 3.7kg • Born to IDM mother by Elective LSCS at an

outside hospital• ANP uneventful • Baby cried immediately after birth • Tachypneoic - 70/min - shifted to NICU .• Managed in hood oxygen along with other

supportive measures • On Day 2 Baby had increasing tachypnea

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On examination

• Spo2 on 5ltrs O2 -90-92%, not much difference b/n upper and lower limb.

• Other systems – within normal limits

• Chest x-ray –Bronchopneumonia

• Echo done at referring hospital – PPHN

• Referred for further management

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Admission in AIMS • Baby tachypnic • Spo2 on 5ltrs O2 85-88%, No

significant upper and lower limb difference

• Blood pressure – WNL • CVS - S2 appeared loud • Systolic murmur at tricuspid

area• ABG( preductal) - On 100%

Fio2 • pH – 7.23, PO2 –45mmHg,

PCO2 – 55mmHG, HCO3-15mmol

• Chest X-ray – suggestive of Bronchopneumonia

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• Baby had increasing tachypnea and frequent desaturation upto 80% and electively ventilated

• Hyperoxia – hyperventilation - pH – 7.5, PO2 – 50mmHg, PCO2 –32mmHg , HCO3 – 21mmol, Lactate- 3mmol

• Sepsis screen negative

Problems • Tachypnea in a term neonate since

birth • Differentiation between PPHN and

CHD • Discordance between clinical

suspicion of sepsis / pneumonia and lab investigation ( No risk factors of sepsis )

• Low PaO2 in Hyperoxia – hyperventilation test

Detailed cardiac evaluation

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Review echo

Infra-diaphragmatic -Total anomalous pulmonary venous connection .

Emergency corrective surgery done

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TAPVC

Entry of pulmonary veins into systemic venous pathways

Supracardiac Cardiac Infracardiac

Right SVC Right atrium Portal vein

Brachiocephalic vein

Coronary sinus IVC

Azygous vein

Obstruction to venous return – venous hypertension Worsening cyanosis , increasing respiratory distress,No significant cardiomegaly Corrective surgery

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Case scenario

• A Term male baby ( birth weight of 3.5 kg )• Mother with uncontrolled gestational diabetes

mellitus• Elective LSCS at 38wks gestational age at

outside hospital • Cried soon after birth • Developed tachypnea soon after birth • Initially managed with O2 hood • At 4hrs after birth - Tachypnea worsened.Had

desaturation to around 85% in hood oxygen and hence referred to AIMS with suspected CCHD

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On admission in AIMS • Baby had tachypnea . No chest retractions or

grunt • Cyanotic with an Oxygen saturation about 75% • Had tachycardia with low pulse volume • Hyperoxia test –saturation improved to 82%• Chest X-ray from outside – mild cardiomegaly,

Lung fields clear(adequate lung volume )• ABG - pH 7.2, PCO2 – 60mmHg, PO2 –

34mmHG, HCO3 – 14mmol • PCV – 71 %

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Possibilities

• Cyanotic heart disease • Persistent pulmonary hypertension Uncontrolled GDM Elective LSCS without

induction of labour Polycythemia Presumed Chronic hypoxia

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Cardiac evaluation

• Emergency Echo– No structural heart disease

• Mild PPHN – oxygenate well, Treat the precipitating cause –? Polycythemia,

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Management • Baby was ventilated

after 2hrs in view of severe hypoxia and features of respiratory failure

• Hb – 24gm%, PCV – 71% • Chest X-ray- lungs

fields normal , Mild cardiomegaly

• Preductal- 88%, Postductal- 82% on Fio2- 100%

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Management

Ventilatory adjustements were changed based on CXR and ABG results . Standard management for PPHN was instituted

partial exchange

Baby improved with management

Chest –x-ray after 6hrs .

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Highlights – Multiple risk factors for PPHN

• Infant of poorly controlled diabetic mother

• Born without labour pains – delayed clearance of lung fluid

• Delayed administeration of CPAP • Polycythemia

Differentiating PPHN from CCHD PPHN CCHD

History Risk factors( NSAID ) May have positive family history

Delivery Fetal distress / birth asphyxia

Uneventful

Examination Respiratory and / or neurological signs

May have cardiac signs

Chest X ray F/0 resp path Often non specific

ECG Non specific May have clear abnormality ( Usually non specific )

Hyperoxia test Variable response . Fluctuating oxygen tension

Often low fixed PaO2

Upper limb / lower limb saturations

Lower limb saturation often lower

Sometimes discrepent

Echo Rules out structural heart disease

Diagnosis

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Case scenario• Term AGA male baby • Elective LSCS ( persistent breech) in outside

hospital,. • Baby had mild tachypnea initially , which

settled with 2lts of free flow O2 for 2hrs.• At 18hrs of birth , baby had bluish

discoloration of extremities and lips • Shifted the baby to NICU in view obvious

cyanosis, tachypnea and SPO2 of 80%. SPO2 did not improve with hood oxygen

• Systemic examination was within normal limits exept for tachypnea and low SPO2

• Baby shifted to AIMS

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Admission in AIMS

• Supportive measures given • Sepsis screen done –

Negative • Chest X-ray done – Normal • PH- 7.26, PO2 – 300 mmHg ,

PCO2 40 , Lactate – 8 mmol, HCO3 – 17mmol, BE- 15 mmol.- suggestive of Acidosis with lactate build up –( peripheral perfusion problem )

• Echo – reported normal• Arterial blood was dark

brownish

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Problems • Cyanosis • Normal PaO2 • Low SpO2 • Sepsis screen negative • Peripheral perfusion problem• Dark arterial blood

Discordance between clinical suspicion and investigations Normal PaO2 and low SpO2

? Impairment in tissue release

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Clinical progress • Baby worsened over 1hr , Baby

irritablilty increased • Spo2 dropped to 75% on 6ltrsd O2 ,

cyanosis worsened – electively intubated

• Echo – no structural heart disease / PPHN

• ABG – pH – 7.48, PCO2- 35 mm, PO2-300 mmHG , But corresponding overnight Spo2 persisted around 85-88%.Baby still looked cyanotic.

Dark colour of blood – with normal PaO2 ?Hematologic problem

Methemoglobin levels sent

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Methhemoglobin - revealed 21% total Hb%.Hematology consultation done – supportive

measures , correction of metabolic acidosis and Blood transfusion / ET advised

Improved with transfusion ( deferred exchange transfusion )

Methylene blue not availabe Baby gradually improved over the next 2 days

and was off ventilator To repeat Methemoglobin levels at a later date

Methemoglobinemia – probably transient

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Causes of cyanosis

• Relatively high levels of deoxyhemoglobin – generally more than 5 gm / dL

• When nonphysiologic hemoglobin ( eg – Methemoglobin is present more than 1.5 gm / dL )

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Causes of acquired methemoglobinemia

• Metabolic acidosis • Exposure to certain drugs • Nitrites • Nitrate containing compounds

Definitive treatment – Methylene blue

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Neonatal cyanosis Category Details Comments

Respiratory Any respiratory disease

Cardiac Common mixing TAPVC

Especially if obstructed

Truncus arteriosus Cardiac failure

Right to left shunts Pulmonary atresia ( IVS ) Pulmonary atresia ( VSD ) Tricuspid atresia , TGA

PPHN ( includes CNS insult )

Hematologic Methemoglobinemia Grey / blackish blood . Arterial oxygen tension normal

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Summary

• Respect respiratory distress in a term Neonate • Consider early CPAP to recruit lung volume • Differentiate PPHN and CCHD .Role of early

pediatric cardiology evaluation • Discordance between clinical suspicion and

labortary result – think of an alternative diagnosis as well

• Involve experienced specialists at the earliest to guide management decisions

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Acknowledgement

• Dr.Rajiv . P.K• Dr.Mathew Kripail • Dr.Sudheer • Dr.Sivji• Dr.Sunil .B • Dr.Ashwin Prabhu • Dr.Prasanna • Dr.Laxmikanth• All specialists ( Pediatric cardiology and

Hematology ) and Nursing staff involved in the mangement of sick babies

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