Respiratory Distress in Respiratory Distress in the Delivery roomthe Delivery room

NICU Night CurriculumUniversity of Chicago Comer Children’s Hospital

““Code White” Code White” • 2222 234

““Code White”Code White”

• You arrive in the DR• What do you want to know

• Gestational Age: 40 weeks • Why was code called?: Meconium Stained

fluid• Serologies: Negative• Vaginal delivery, ROM 20 hours

• Mom is 30 y/o G1P0, no PMH• ROM 20 hours, green/yellow color noted in

amniotic fluid• Late decels were noted• Nuchal cord x 1• Male baby is born limp, cyanotic, not crying

What do you do next?What do you do next?

ResuscitationResuscitationLaryngoscopy firstMeconium aspiratorCheck heart rateEvaluate Respiratory rateCheck PulsesAre there Breath sounds?Give PPV if necessary

EquipmentEquipment• What size blade and Endotracheal size tube would you

use?• How far would you insert the ETT?

• Appropriate Blade:–Preterm: 0–Term: 1

• Endotracheal tube Size<1kg = 2.5 1 2 kg = 3.02 3 kg = 3.5> 3 kg = 4

• Insertion Depth:6 + (wt in kg) = cm at lip

What do you want to know when What do you want to know when

looking at the baby (Name 4 looking at the baby (Name 4

things)?things)?

• Crying/breathing or not• Respiratory effort, retractions, grunting• Heart rate, pulses• Murmur?• Airway obstruction? (pass suction catheter)• Obvious anomalies/dysmorphic features (i.e.

micrognathia, macroglossia)

What’s your What’s your differential?differential?

• Pulmonary diseaseso Meconium Aspiration Syndromeo Repsiratory distress syndromeo Pneumoniao Pulmonary hemorrhage

• Congenital Heart Diseaseso Transposition of the great vesselso Hypoplastic left ventricleo Critical pulmonary stenosiso Severe coarctation of the aortao Total anomalous pulmonary venous return

• Sepsis

Physical ExamPhysical Exam

• HR 100, not crying -> intubate, suction 3 mL of green fluid

• Baby starts crying, HR 140• Subcostal retractions, RR 65• Tone and color improve, retractions resolve• Apgars??• To NICU or not?

You did not bring baby back to the NICU, You did not bring baby back to the NICU,

but you are called to GCN a little while but you are called to GCN a little while

later….later….

• Baby is tachypneic, grunting, and still retracting, SpO2 80%

• What do you do next?

InterventionsInterventions• Oxygen therapy• Consider PPV on way back to NICU• Place on conventional ventilator if needed• Chest Xray• ABG, CBC, BMP, blood culture, antibiotics• How would you describe the CXR on the

next slide?.....

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CXR Findings:CXR Findings:

• Patchy opacities in both lung fields• ETT in place• Atelectasis• Poor heart borders• Air trapping

Meconium Aspiration Meconium Aspiration

SyndromeSyndrome

• MSAF in 10-15% of births, usually term or post-term

• Meconium aspirated in utero or with first breath

• Thick, particulate meconium causes small airway obstruction; ball-valve effect

• Presents with tachypnea, retractions, grunting in first hours of life

• Usually improves within 72 hours except for those that require mechanical ventilation

• Some are refractory to conventional ventilation; need HFOV, iNO, and even ECMO

Persistent Pulmonary Persistent Pulmonary

HypertensionHypertension

• Suspected with hypoxia refractory to conventional ventilation

• Occurs with MAS due to hypoxia that triggers pulmonary vasculature remodeling

• Normal decline in pulmonary vascular resistance does not occur

• Estimated by measuring tricuspid regurgitation on Echocardiogram

EpidemiologyEpidemiology

• Predisposing factors for PPHN: birth asphyxia, meconium aspiration pneumonia, RDS, polycythemiaOften idiopathic, can be geneticIncidence 1/500-1,500 live births

• MAS:MSAF in 10-15% of births, 5% of those develop MAS, 30% require mechanical ventilation, 3-5% mortality

PathophysiologyPathophysiology• PPHN is defined as sustained elevation of

the pulmonary vascular resistance after birth, causing right to left extrapulmonary shunting of blood (PDA, foramen ovale) resulting in severe hypoxemia.

• Result of increased pulmonary artery medial muscle thickness and extension of smooth muscle layers into the non-muscular peripheral arterioles

Diagnosis of PPHNDiagnosis of PPHN

• Hyperoxia Test: o Distinguishes cyanotic heart disease from

pulmonary diseaseo Check PaO2 before and after

administering 100% oxygeno Should rise to 400-500; If rises above

150, usually can exclude heart lesiono PPHN does not respond to 100% oxygen

Severity of PPHNSeverity of PPHN• Oxygenation index (OI) can be used to

measure severity of PPHN.

Oxygenation Index: (Mean Airway Pressure x FiO2 x 100)/Pao2

More details on how to interpret these numbers later…

Clinical presentationClinical presentation• Infants with PPHN are usually delivered at near

term, term, or post term, and are commonly AGA.

• Clinical findings include tachypnea, grunting, retraction, and cyanosis, especially with stimulation. The hypoxemia in PPHN is labile and disproportionate to the extent of the pulmonary parenchymal disease.

• Arterial blood gas shows severe hypoxemia with relatively normal pH and PCO2.

• In infants with ductal level shunting, there is a gradient of 10mm Hg between right arm and lower extremity oxygen pressure. If the shunting is intrapulmonary or via PFO, there is no difference in oxygenation of the right arm and the umbilical artery blood.

CXRCXR• Chest X-ray reflects the underlying

parenchymal lung disease. In infants with idiopathic PPHN, the lung fields are clear and appear undervascularized

• For MAS, patchy infiltrates, coarse streaking, increased AP diameter and flattening of diaphragm

Treatment Treatment • The underlying causes of PPHN, such as

hyperthermia, hypoglycemia, hypocalcemia, polycythemia, hypoxia, and acidosis, must be aggressively treated.

• Goal of therapy in patients with PPHN is to lower the Pulmonary vascular resistance, maintain systemic blood pressure, reverse the right to left shunts, and improve tissue oxygenation.

Treatment continued:Treatment continued:• Response often unpredictable

(nonresponders vs responders)• If severe, require mechanical ventilation and

100% FiO2• Consider Surfactant initially• Inhaled Nitric oxide = pulmonary vasodilation• Inhaled or IV prostacyclin if no response to

iNO• PO Sildenafil and Bosentan once off vent if

still having PHTN• ECMO necessary in 5-10% of cases

SeveritySeverity• If Oxygenation index (OI) is greater than 25,

begin iNO, usually at 20 ppm but can go to 40 ppm if poor response

• If OI continues to worsen, consider ECMO• Potential Side Effects of iNO includes

methemoglobinemia secondary to excess iNO

PrognosisPrognosis• Survival varies with underlying cause

of PPHN• Long-term outcome related to HIE and

ability to reduce pulmonary vascular resistance

• 70-80% survival for those treated with ECMO and 60-75% appear normal at 1-3.5 yrs of age

Review QuestionsReview Questions• Neonatal resuscitation• Typical presentation of MAS• MAS can lead to PPHN• Treatment• Prognosis

PREP 2011 #242PREP 2011 #242“You are called to attend the c/s delivery of a 42

weeks’ gestation infant because of FTP complicated by severe oligohydramnios. Maternal screens are unremarkable. ROM at delivery reveals scant meconium-stained fluid.

Under the warmer, the infant is vigorous and has good respiratory effort, a HR of >100, central cyanosis and meconium staining of peeling ‘post dates’ skin. You begin blow-by oxygen which improves his color, but he develops tachypnea and grunting. He is transferred to SCN where he is intubated and an UVC is placed. Pre- and postductal saturations are 97% while receiving 60% oxygen.”

Chest radiography is provided which shows patchy opacification and hyperinflation

Of the following, the infant’s clinical presentation is MOST consistent with

A. Group B streptococcal pneumoniaB. Meconium aspiration syndromeC. Persistent pulmonary hypertensionD. Retained fetal lung liquid syndromeE. Transposition of the great vessels

Answer: B. MASAnswer: B. MAS“The history of post dates pregnancy with severe

oligohydramnios, the findings of meconium staining at birth and early-onset respiratory distress, and the CXR make MAS most likely.

Congenital cyanotic heart disease is less likely due to this infant’s response to oxygen. Although the infant is at high risk for PPHN, the similar pre- and postductal saturations do not demonstrate shunting at the ductal level.

The CXR does not demonstrate diffuse infiltrates or fluid in the fissures which would suggest retained fetal lung fluid syndrome (TTN).”

PREP 2010 #130PREP 2010 #130“You are called to the operative delivery of a 42-weeks’

gestation male following a pregnancy complicated by oligohydramnios and poor fetal growth. MSAF was noted upon AROM. Fetal bradycardia resulted in a decision for c/s delivery. Resuscitation of the infant requires intubation, tracheal suctioning, assisted ventilation, chest compressions, and IV epinephrine. Apgar scores are 1, 3, and 5.

You transfer the newborn to the NICU, where he appears cyanotic, in respiratory distress, and agitated. Systemic BP is 35/17. On 100% O2, pulse oximetry in the right upper and left lower extremities reveals sats of 94% and 80%, respectively”…..

Chest XR provided reveals atelectasis in the RUL, hyperinflation and patchy infiltrates.

Of the following, the MOST likely diagnosis is

A. Congenital diaphragmatic herniaB. Congenital pneumoniaC. Cyanotic congenital heart diseaseD. Persistent pulmonary hypertensionE. Respiratory distress syndrome

Answer: D. PPHNAnswer: D. PPHN“The growth restriction, 42-week GA, oligohydramnios,

and depressed condition requiring vigorous resuscitation at birth strongly indicate fetal compromise due to chronic hypoxemia. Although meconium expression does not always equate with fetal stress and may be a normal finding…, the risk for meconium aspiration must be acknowledged when fetal stress is accompanied by abnormal HR and perinatal depression…

The difference in pre- and postductal sats indicates that the newborn has a right-to-left shunt and PPHN….”

PREP 2009 #194PREP 2009 #194“You admit a 39 weeks’ GA male who has respiratory

distress to the intensive care nursery. His mother had a negative GBS screening culture and did not require antibiotics in labor. She did not have chorioamnionitis or PROM. However, amniotic fluid was meconium-stained at the time of delivery, and the infant required tracheal intubation, with resultant meconium suctioned from below the vocal cords. Apgars scores were 3 and 7. On PE, he has marked work of breathing with tachypnea and retractions and episodic cyanosis when agitated. Breath sounds are coarse and equal. There is no heart murmur. While receiving hood oxygen at an FiO2 of 0.50, his oxygen saturation is 85%. You obtain a CXR.”

The radiographic findings most expected for this infant are….”

A. Air bronchograms, diffusely hazy lung fields, and low lung volume

B. Cardiomegaly, hazy lung fields, and pulmonary vascular engorgement

C. Fluid density in the horizontal fissure, hazy lung fields with central vascular prominence, and normal lung volume

D. Gas-filled loops of bowel in the left hemithorax and opacification of the right lung field

E. Patchy areas of diffuse atelectasis, focal areas of air-trapping, and increased lung volumes

Answer: EAnswer: E“The infant described has respiratory distress and hypoxemia.

Air bronchograms in diffusely hazy low volume lungs are most consistent with surfactant deficiency-related respiratory distress syndrome.

Cardiomegaly with hazy lung fields and pulmonary vascular engorgement is seen in left-sided obstructive cardiac disease states or with pulmonary overcirculation (eg, truncus arteriosus, aortic stenosis, transposition, anomalous pulmonary venous return)

When gas filled loops of bowel are seen in the chest, diaphragmatic hernia is the diagnosis.”

““Specialty Board Review: Specialty Board Review:

Pediatrics” Pediatrics” • Which medication used by the mother

during pregnancy is the most likely to cause PPHN in the newborn

A. phenobarbitalB. captoprilC. aspirinD. bupropionE. levothyroxine

AnswerAnswer : aspirin: aspirin• “constriction of the fetal ductus arteriosis

may lead to PPHN. Of the medications listed, only aspirin does this. Other NSAIDS can also do this.”

Learning ObjectivesLearning Objectives• Review assessment/resuscitation of neonate

in delivery room• Review pathogenesis of meconium

aspiration syndrome and PPHN• Review treatment and prognosis for MAS

and PPHN

ReferencesReferences• Nelson Textbook of Pediatrics• Nadas’ Pediatric Cardiology• PREP 2009, 2010, 2011• Specialty Board Review: Pediatrics• www.learningradiology.com• www.uptodate.com