EM@3AM: Blue Baby

Author: Amber Cibrario, DO (EM Attending Physician, San Antonio, TX), Zachary Baker, DO (EM Attending Physician, San Antonio, TX), Rachel Bridwell, MD (@rebridwell, EM Resident Physician, SAUSHEC / San Antonio, TX) // Reviewed by: Alex Koyfman, MD (@EMHighAK) and Brit Long, MD (@long_brit)

Welcome to EM@3AM, an emDOCs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.


A 6-day-old male presents with increased work of breathing for last 4 hours and an episode of turning blue, which concerned the family. Mom had a normal pregnancy with no complications, and the baby was born full term with a normal APGAR at birth. Mom denies vomiting and diarrhea.  He was breastfeeding well until earlier this afternoon.

Triage vital signs (VS): BP 64/42, HR 178, RR 48, SpO2 73% on room air, rectal temp 37.2 F (rectal). The baby is lethargic and cyanotic, with a weak cry to stimulation. There is a sunken fontanelle, perioral cyanosis with purple intra-oral mucosa, and blue tongue. He is tachypneic and has mild retractions, clear lung sounds, and dullness to percussion 4 cm past right costal margin. There is poor tone and mottled extremities.

What should you consider?


Answer: Right Obstructive Ductal Dependent Pathology1-13

Epidemiology:

  • CHD is the most common major congenital anomaly and is the most common cause of mortality from birth defects in infants.1,2
  • Prevalence
    • 1:1000 live births Worldwide.3,4
    • 2:1000 of live births in the US ~ 40,000 births/year have hemodynamically significant CHD.3,4
      • 50% are discharged from the nursery with missed congenital heart lesion.3,4
      • 25% have critical lesions that end up in the ED shortly after.3
      • These critical congenital lesions are often missed both at discharge from delivery and in the ED leading to death.3–5
    • The number of congenital heart lesions is increasing.3,4
    • Risk Factors:6–8
      • Genetics: Family history especially siblings, chromosomal abnormalities (e.g. Trisomy 13, 18, Turner Syndrome, DiGeorge, CHARGE, VACTERL).
      • Environmental:
        • Maternal factors: phenylketonuria, advanced maternal age, febrile illness during pregnancy
        • Infections: Influenza, rubella
        • Medications: NSAIDs, Lithium, Sulfasalazine, TMP-SMX, phenytoin
        • Toxins: Marijuana, Organic Solvents

Anatomy and Pathophysiology: Right Obstructive Ductal Dependent Lesions

  • Common Causes:5,9,13
    • Tetralogy of Fallot
    • Truncus Arteriosus
    • Transposition of the Great Vessels
    • Tricuspid Atresia
    • TAPVR4-7
  • Pathophysiology:9,13
    • Lesions above have some type of structural obstruction of blood flow to the lungs with a septal defect and resulting shunt.
    • PDA provides supplemental oxygenated systemic blood supply.
    • With PDA closure, there is limited to no pulmonary blood flow, which precipitates cyanosis and hypoxia.

 

Clinical Presentation:

  • Utilize pediatric assessment triangle: Appearance, work of Breathing, Color.12
  • On history: cyanosis, fussiness, tachypnea and poor feeding.9
  • While this is a right obstructive lesion, the differential for a cyanotic neonate should be considered:
    • 4 causes of cyanosis in neonate:13
      • Congenital Heart Disease
      • Sepsis
      • Respiratory Disorders
        • RSV, Pneumonia, ARDS, Aspiration
      • Hematological Disorder
        • Polycythemia – autotransfusion from placenta
        • Methemoglobinopathies
          • Ask for recent medication exposures (e.g. moth balls, lidocaine, benzocaine gels, hurricaine spray)
    •  Physical Exam Pearls:9,13
      • General: profoundly hypoxic (SpO2 70%)
      • Skin: Cyanotic appearing – Signs of Central Cyanosis
        • Cyanosis: >5gm/dL of desaturated hemoglobin13,14
          • Peripheral cyanosis
            • Perioral cyanosis
            • Extremities blue
          • Central cyanosis
            • Purple or blue color of the mouth, tongue, mucous membranes.
      •  Respiratory: Differentiate between respiratory vs. cardiac13,14
        • Cardiac disease presents with silent tachypnea.
          • Tachypnea without increased work of breathing secondary to acidosis.
        • Respiratory disease presents with struggling tachypnea.
          • Tachypnea with hard work of breathing presents with primary respiratory etiology.
      •  Cardiac: Tachycardic, possible murmur but will be difficult to auscultate with a heart rate >160 bpm.
      •  Abdominal
        • Hepatomegaly on exam.13,14
          • Percussion is more effective than palpation in infants as they tend to contract muscles while in distress.
          • Liver > 2cm below right costal margin is abnormal.

 

Evaluation:

  • Grouping congenital heart diseases based on simplifies recognition and management13
    • Age
    • Color
    • 4 Extremity BPs, 4 Extremity pulse Oxs, Hyperoxia test, CXR

  • Initial critical actions
    • Glucose:
      • Critically ill neonates have limited glycogen stores and thus are often hypoglycemic.15
    • IV/IO – 2 IV attempts then place an IO.
      • Need 2 access points if CHD is suspected.
    • Monitor
    • 4 extremity BPs
      • Blood pressure differential:Delta of preductal (right arm) BP and lower extremity blood pressure of > 10 mmHg, consider obstructive process.16
    • 4 extremity pulse ox
      • O2 saturation differential:17
        • Difference in O2 saturation > 3% between preductal (right upper) and post ductal (right lower extremity)
        • <94% in lower extremities
        • < 90% in any extremity require further investigation.
      • Differentiates a systemic obstructive process (e.g. critical coarctation) expediently.
    • What if you are not sure if this is Pulmonary vs. Cardiac cause?13
      • Hyperoxia test for ~5 min
        • Pulse Ox or ABG looking at PaO2
        • Place infant on ~100% FiO2 using NRB for ~5-10min
          • If SpO2 or PaO2 improves, likely respiratory cause.
          • If SpO2 or PaO2 does not improve, likely cardiac cause.
        • iSTAT or Cap Gas can help immediately narrow THE MISFITS differential, especially electrolyte derangements and congenital adrenal hyperplasia if normal glucose, K, and Na.15
  •  What diagnostic test should we order?
    • Labs13,15
      • Full Sepsis Evaluation – CBC, CMP, lactate, Blood Cultures, UA, Urine CX, CSF (LP once stabilized)
      • Ketones, Ammonia, Lactate – help us determine if there is inborn error of metabolism to rule out THEMISFITS
      • Serum and urine drug screen
        • Caregivers often rub winter green oil on infants, precipitating salicylate toxicity, which may present with tachypnea and poor feeding
      • BNP:18
        • <100 pg/mL 100% sensitivity and 98% specificity for detection of significant congenital heart disease.
        • <132.5 pg/mL to detect physiologically significant L to R shunts, 93% SN and 100% SP.
        • >40 pg/mL accuracy of 84% to differentiate cardiac from pulmonary etiologies of respiratory distress.
      • TSH – helps determine endocrine abnormalities.
    • EKG
      • Evaluate for fatal arrhythmia, especially prolonged QT > 500 ms.
      • Newborn ECGs are different:13
        • Newborns are still right heart dominant, so right axis deviation is normal.
        • Signs of LVH in a newborn is never normal.
          • Consider Right Obstructive Ductal Dependent Lesion.
        • Normal Pediatric ECG: Persistent juvenile T wave inversions in V1-V3.
        • Signs of severe RVH are abnormal.13
          • Upright T wave in V1 after 1 week is abnormal, suggestive of left obstructive ductal dependent lesion.
    •  Chest X-ray
      • Abnormal findings
        • Cardiomegaly13,14,19
          • Boot Shaped Heart
          • Eggs on a String Sign, not always present
          • Snowman Sign
        • Clear black lungs19
          • Obstructive pulmonary blood flow
    •  POCUS20
      • Assess for the following features:
        • Number of cardiac chambers
        • Pericardial effusion
        • Poor global cardiac function
        • Septum present
        • Plethoric IVC (if not on positive pressure)
        • B lines suggestive of pulmonary edema

Treatment:

  • Oxygen13,14
    • Oxygen is a potent pulmonary vasodilator, decreasing PVR and increasing pulmonary blood flow, which can improve oxygenation. However, titrate to effect; not 100% SpO2. Over titration can lead to worsening right sided failure due to pulmonary blood flow obstruction.
    • Remember neonates still have fetal Hb circulating which can carry oxygen with a higher affinity resulting in less distress at lower oxygen saturations.
    • Goal oxygen > 85%. If congenital heart disease is suspected, do not empirically place on 100% oxygen13
  • IVF13,14
    • Judicious fluid resuscitation is key.
    • 5ml/kg is the starting recommended fluid bolus in patients with CHD to balance their metabolic demands with their obstructive physiology.
    • POCUS with a plethoric IVC or if obvious hepatomegaly should key the provider in for a relatively fluid overloaded state.
  • Prostaglandin is the crucial intervention.
    • Alprostadil 0.05-0.1 mcg/kg/min (titrate slowly to effect or a maximum of 0.4 mcg/kg/min).21,22
      • Do not bolus, as a bolus with precipitate side effects.23
      • Complications/adverse effects:23
        • Apnea – prepare for intubation
        • Hypotension – have vasopressors ready
        • Hyperthermia
        • Complications may not be immediate
      • Contraindications:
        • TAPVR: worsens shunt physiology with patency of ductus arteriosus
      • Give in any neonate in first 30 days of life with cyanosis or circulatory collapse.22
  •  RSI for Intubation
    • Intubate with caution and be deliberate with medication selection as the wrong choice can precipitate cardiac collapse.
      • Induction:
        • While pretreatment with atropine remains controversial, consider in neonates with cardiac etiology.
        • Ketamine 2mg/kg13,21
        • Etomidate 0.3 mg/kg13,21
        • Fentanyl 1-2mcg/kg13,21
          • High doses can cause cardiac depression, so be cautious
        • Avoid benzodiazepines21
          • Adverse effects of cardiac depressant
      •  Paralytics: Better to paralyze to improve 1st pass success
        • Rocuronium or succinylcholine13
  •  Push dose vasopressors13
    • Push dose vasopressor ready for intubation, if preintubation blood pressure is hypotensive, or have vasopressors already on board.
    • Phenylephrine is a good choice in right obstructive lesions.
      • It increases SVR, which increases L to R shunt leading to improved pulmonary blood flow, decreased obstruction and better oxygenation.
    • EPI is also good choice because also increase SVR
  •   Ventilator Settings13
    • Lung protective tidal volume
    • Titrate O2 ~88-90% to avoid pulmonary recirculation.
    • Low PEEP = 3
      • Positive pressure ventilation increases PVR, decreasing preload and SVR which can affect shunting flow.
    • RR 30-40 (normal for neonates)
  •   Vasopressors, inotropes, chronotropes in their preferred order9,13
    • True vasopressor preferred because can increase SVR, which increases L to R shunt leading to improved pulmonary blood flow, decreased obstruction and better oxygenation
    • Phenylephrine
      • Dose: 0.1-10mcg/kg/min IV continuous infusion initially and titrate21
    • Norepinephrine
      • Dose: 0.02-2mcg/kg/min IV continuous infusion initially and titrate21
    • Epinephrine
      • Dose: 5-1 mcg/kg/min IV continuous infusion initially and titrate21
      • Titrate for alpha effects – it has some increase in SVR, especially at higher doses
    • Avoid dopamine – difficult to titrate
      • Still controversial
      • Recommend discussion with receiving PICU
      •  Push dose vasopressors13
  •  Antibiotics9,13
    • Critically ill neonate still requires empiric sepsis coverage.
    • IV Ampicillin 50 mg/kg/Gentamicin 4 mg/kg or Ampicillin 50 mg/kg/Cefotaxime 25 mg/kg
  • Antivirals
    • Cover for HSV with IV Acyclovir: 20mg/kg Antivirals13 

 

Disposition:

  • PICU with Peds Cardiothoracic Surgery and Peds Cardiology consults often requires transfer to tertiary facility with above consultants available.
  • Critical things the PICU and Cardiothoracic Surgeon needs to know at minimum:13
    • Age
    • Shock or Cyanotic
    • 4 extremity blood pressures
    • 4 extremity pulse ox
    • CXR findings
    • Interventions

 

Pearls:

  • With a cyanotic neonate, consider the 4 common etiologies: Cardiac, Infectious, Respiratory, Hematologic.
  • Silent tachypnea is more likely to be a cardiac etiology than struggling tachypnea, which is more likely respiratory in nature.
  • Hyperoxia test can help determine if this is a respiratory cause or cardiac cause.
  • Neonate that is cyanotic with hypoxia and black lungs on x-ray is more likely to have a right obstructive ductal dependent lesion than primary respiratory illness.
  • In every sick neonate need to obtain: POC glucose, 4 extremity BPs, 4 extremity pulse ox, CXR, EKG, Beside US, Labs to assess for obstructive lesions
  • You need a reason NOT to give prostaglandins in a sick neonate (< 30 days old)
    • Be prepared for apnea, hypotension, hyperthermia
    • 2 IVs or IOs are critical
  • All sick neonates need full septic work up and treatment even if likely CHD.
    • Broad spectrum antibiotics, antivirals, labs, cultures, etc.
  • Empiric sepsis resuscitation can kill cardiac obstructive pathology so carefully evaluate the sick neonate.

From Dr. Katy Hanson at Hanson’s Anatomy:


A 12-day-old boy presents with his mother for respiratory distress and lethargy. The patient was born at home with minimal prenatal care via spontaneous vaginal delivery. He is minimally responsive and cyanotic around the lips and on his tongue, with thready pulses in all four extremities and a capillary refill time > 5 seconds. Vital signs are remarkable for a BP of 50/30 mm Hg, HR of 100 bpm, RR of 50/min, and pulse oximetry of 70%. The patient is placed on oxygen without improvement of his oxygenation. Which of the following is the most likely diagnosis?

A) Coarctation of the aorta

B) Patent ductus arteriosus

C) Transposition of the great vessels

D) Ventricular septal defect

 

 

 

 

Answer: C

Cyanosis is a bluish color of the skin and mucous membranes resulting from an increased amount of reduced hemoglobin or hemoglobin derivatives. Cyanosis is determined by the absolute amount of deoxygenated hemoglobin, not the amount of oxygenated hemoglobin. Central cyanosis is manifested by cyanosis of the mucous membranes and tongue. It is due to inadequate pulmonary oxygenation, whereas peripheral cyanosis is secondary to vasoconstriction and diminished peripheral blood flow. Cyanosis is usually visible when deoxygenated blood exceeds 5 g/dL. Central cyanosis can be a result of hypoventilation, ventilation-perfusion mismatch, right-to-left shunt, congenital heart disease, arteriovenous fistulas, and hemoglobinopathies. This patient is presenting with concerning features for congenital heart disease with associated cyanosis. Infants with congenital heart disease often present with poor feeding, lethargy, breathing disturbances, and cyanosis. Congenital heart lesions that cause cyanosis are best known by the “five Ts”: tetralogy of Fallot, tricuspid atresia, truncus arteriosus, total anomalous pulmonary return, and transposition of the great vessels. Survival of patients with transposition of the great vessels relies on intercirculatory mixing of blood, either by a patent ductus arteriosus, a patent foramen ovale, or a ventricular septal defect. Prostaglandin infusion is often required for the majority of cyanotic and several of the acyanotic congenital heart lesions. Prostaglandin infusion works by causing vasodilation on vascular and ductus arteriosus smooth muscle. This is a temporizing measure that allows the patient enough time before undergoing corrective surgery or surgeries by a pediatric cardiothoracic surgeon.

Coarctation of the aorta (A), patent ductus arteriosus (B) and ventricular septal defect (D) are all congenital heart disorders, however, they are all types of acyanotic heart lesions. The patient above is presenting with cyanosis, which makes all of these less likely.

Rosh Review Free Qbank Access


Further Reading:

FOAM Resources

EM CASES Congenital Heart Disease

EMRAP: Neonatal Cardiology Part 1

EMRAP: Neonatal Cardiology Part 2

PEM PLAYBOOK: Undifferentiated Sick Neonate

PedsEM MORSELS ALCAPA

emDOC: sick neonate

References

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