Cyanosis in newborns

Cyanosis in newborns Microchapters
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Epidemiology and Demographics
Risk factors
Natural History, Complications, and Prognosis
Diagnosis
Treatment
Prevention

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2] Associate Editor(s)-in-Chief: Ifeoma Anaya, M.D.[3]

Synonyms and keywords: Acrocyanosis; central cyanosis

Overview

Cyanosis is coined from the word kuaneos which is greek for dark blue. It is classified into two major types: peripheral and central cyanosis. Cyanosis results when there is an increase in the absolute concentration of deoxygenated hemoglobin to a level of 3-5g/dl. A systematic way of classifying the common causes of cyanosis in newborns is by using the ABC which stands for Airway, Breathing, and Circulation. Congenital heart diseases (CHD) affecting 8-9 per 1000 live births and Persistent pulmonary hypertension of the newborn are the common causes of newborn cyanosis. In older kids, respiratory diseases tend to be more common. Common risk factors in the development of cyanosis in newborns are evident in the pregnancy and labor period. Complications and prognosis are dependent on the actual cause of the cyanosis, prompt recognition, and administration of treatment modalities with appropriate referral to the ideal hospital setting equipped to manage the diagnosis. The primary symptom is the bluish/dark colored lips, mucous membrane, and/or hands and feet. Breathing difficulties such as nasal flaring, chest retractions. Exam findings include lethargy, conjunctival injection, features of shock, tachypnea. Laboratory findings include a Complete blood count and differentials showing ↑Packed cell volume(PCV) suggesting polycythemia, ↑White cell count (Septicemia). Although seldom helpful, an ECG may aid in the diagnosis of arrhythmias and dextrocardia. X-rays can show pulmonary causes like pulmonary hypoplasia and increased lung vascular markings in pulmonary edema, bronchopneumonia. Echocardiography is employed when physical exam findings and/or failed hyperoxia test suggests the presence of congenital heart disease or when the diagnosis is uncertain. Other imaging modalities are used as adjuncts in making diagnoses. The priority in the immediate term will be to optimize the neonate, especially in severe cyanosis. Surgery is employed for more definitive treatment. The following preventive measures can be adopted; pre-conceptual counseling for expectant mothers especially women who are above the age of 35 years, routine prenatal and postnatal care for early detection of congenital anomalies, and adequate preparedness for its management during pregnancy, labor, and delivery.

Historical Perspective

• Cyanosis is coined from the word kuaneos which is greek for dark blue. This is as a result of the bluish discoloration of the skin or mucous membranes depending on etiology.

Classification

• Cyanosis is classified into two major types:
  • Peripheral Cyanosis (acrocyanosis) which is located on the hands and feet. It is mostly physiological and relatively common.
  • Central cyanosis which is considered to be pathological and requiring immediate evaluation until proven otherwise.

Pathophysiology

• Central cyanosis results when there is a rise in the absolute concentration of deoxygenated hemoglobin to a 3-5g/dl. Deoxygenated hemoglobin is dusky blue or purple which causes the discoloration seen in skin and mucous membranes compared to bright red oxyhemoglobin.
• Oxygen is transported in blood predominantly attached to hemoglobin while an insignificant amount is transported dissolved in plasma. Sufficient tissue perfusion relies on the concentration of saturated hemoglobin.
• With high hemoglobin concentrations (normal relative polycythemia, 14-20g/dl) seen in normal infants, cyanosis becomes apparent at higher PaO2 (partial pressure of oxygen) compared to the setting of severe anemia where a far lower PaO2 would lead to clinically recognizable cyanosis from very low hemoglobin concentration. Therefore, cyanosis depends on the concentration of deoxygenated hemoglobin and not merely oxygen saturation. As an example, a neonate with a hemoglobin concentration of 24g/dl exhibits signs of central cyanosis at 88% arterial saturation (SaO2) while cyanosis isn't clinically obvious in an anemic infant until SaO2 falls to about 62%.
• Oxygen binding capabilities differ between fetal and adult hemoglobin. If a newborn has mostly adult hemoglobin, cyanosis would be observed at an elevated PaO2 42-53mmHg which is comparable to an SaO2 of 75%-85% as opposed to predominantly fetal hemoglobin(PaO2 of 32-42mmHg); infants have varied proportions of adult and fetal hemoglobin. Therefore, a major reduction in PaO2 would have set in before cyanosis becomes apparent in a newborn with elevated fetal hemoglobin, a setting that shifts the oxygen-hemoglobin dissociation curve to the left.
• Several changes occur in the newborn from the first breath. Blood flow resistance decreases within the pulmonary vasculature as a result of a rise in oxygen tension; this increase in oxygen tension and pulmonary circulation causes functional closure of the patent ductus arteriosus (PDA). Raised left atrial pressures closes the foramen ovale. The events resulting in the closures of those shunts invariably abolishes the right-to-left shunts of the precedent fetal circulation. The first breath also causes a net absorption of the fluid from the lungs, causing its expansion and successfully initiates the gaseous exchange. Furthermore, removal of the low-pressure placental bed causes a rise in blood flow resistance of the systemic vasculature. These are the traditional physiological changes observed within the normal neonate after birth.
• Deviations from these may result in pathological conditions requiring immediate interventions; infants, especially those born prematurely would require medical assistance for this phenomenal transition.
• In peripheral cyanosis, there's normal SaO2 with a rise in oxygen uptake by tissues leading to a wide arteriovenous difference within the venous aspect of the capillaries. Vasoconstriction could be a cause. This kind of cyanosis is seen majorly at the extremities.

Causes

• A systematic way of classifying the common causes of cyanosis in newborns is by using the ABC which stands for Airway, Breathing, and Circulation.

Epidemiology and Demographics

• Persistent pulmonary hypertension of the newborn and Congenital heart diseases (CHD) are the common causes of newborn cyanosis. Common in older kids are respiratory diseases.
• Tetralogy of Fallot (TOF) followed closely by the Transposition of Great Arteries (TGA) are the commonest causes of CHD.

Age

• Newborns are more prone to cyanosis due to the peculiarities of birth and the changes that occur during the transition from fetal to neonatal life and/or due to congenital or acquired disorders.

Gender

• No documented evidence of gender predilection.

Race

• No particular racial tendency for cyanosis in newborns.

Risk Factors

• Common risk factors in the development of cyanosis in newborns are evident in the pregnancy and labor period.
• Pregnancy-related risk factors are:
  • Advanced age of the mother
  • Pregnancy-induced hypertension
  • Gestational diabetes
  • Intake of Lithium (Ebstein's anomaly)
  • Oligohydramnios
  • Polyhydramnios
• Labor and birth-related risk factors are:
  • Cesarean section
  • Preterm/prematurity
  • Use of anesthetic drugs and/or sedatives
  • Premature rupture of membranes (PROM)
  • Meconium aspiration
  • Difficult/assisted vaginal delivery

Natural History, Complications and Prognosis

• Potential complications seen in these patients can include:
  • Stroke
  • Sudden Cardiac Arrest
  • Repeated respiratory tract infections in infants with unrepaired heart defects which can be severe.
  • Developmental delays ranging from motor to cognitive
  • Various forms of disabilities
  • Arrhythmias
  • Heart failure
• Prompt recognition, and administration of treatment modalities, with appropriate referral to the ideal hospital setting equipped to manage the diagnosis, can improve prognosis.
• Mortality is high in newborns with critical CHD however, there has been an encouraging improvement in one-year survival to 75% following advances in treatment. 69% of these babies can survive to the age of 18 years.

Diagnosis

Symptoms

• Primary symptom is the bluish/dark colored lips, mucous membranes, and/or hands and feet.
• Other symptoms include the following:
  • Breathing difficulties such as:
    • Nasal flaring
    • Chest retractions
    • Fast breathing
    • Slow breathing
    • Irregular breathing
    • History of momentary cessations of breathing
  • Pausing/excessive sweating or crying while feeding
  • Small volume of feeds
  • Small for age/poor weight gain
  • Large for age
  • Fixed/immobile arms suggesting paralysis from birth trauma
  • Increasing head cicumference with\without scalp injuries from a difficult delivery
  • Hypo/hyperactive child

Physical Examination

• Patients usually appear cyanotic
• Other examination findings relates to the etiology which can include:
  • Lethargy
  • Conjunctival injection
  • Features of shock
  • Tachypnea
  • Periodic breathing
  • Apneic spells
  • Use of accessory muscles of respiration
  • Flaring of the alar nasa
  • Tube or catheter carefully inserted into the nasal cavity if suspicion is high for Choanal atresia
  • Tachycardia
  • Abnormal heart sounds/murmurs
  • Weak peripheral pulses especially femoral
  • Fine crackles in lower lung fields
  • Hepatomegaly
  • Scaphoid abdomen(in diaphragmatic hernia)
  • Erb's paralysis
  • Scalp injuries
  • Seizures

Laboratory Findings

• Complete blood count and differentials
  • ↑Packed cell volume(PCV)- Polycythemia
  • ↑White cell count- Septicemia
• Complete metabolic panel- electrolyte imbalance (metabolic acidosis)
• Serum glucose- hypo or hyperglycemia
• Hyperoxia Test- differentiates pulmonary from a cardiovascular cause. An increase in PaO2 to 100mmHg or more after administering 100% oxygen suggests a pulmonary etiology. Seldom used due to the availability of echocardiography.
• Arterial Blood Gases (ABGs)
  • PaCO2, ↑ suggests hypoventilation of CNS, pulmonary or cardiac etiology.
  • PaO2, ↓ confirms cyanosis
  • PH, a ↓ suggests hypoxemia, sepsis
  • 'Chocolate-brown' color of blood with normal levels of PaO2 and reduced SaO2 Methemoglobinemia

Electrocardiogram

• It is seldom used however, may be helpful in the diagnosis of arrhythmias and dextrocardia to show a left axis deviation seen in Tricuspid atresia due to left ventricular hypertrophy.
• It could give a normal reading in very serious heart defects like TGA.

X-ray

• Can identify:
  • Pulmonary causes like pulmonary hypoplasia
  • Increased lung vascular markings in pulmonary edema, bronchopneumonia
  • Reduced pulmonary markings in pulmonary atresia, Pulmonary stenosis, and persistent pulmonary hypertension of newborns
  • Location of abdominal contents in diaphragmatic hernia
  • Elevation of the affected hemidiaphragm in phrenic nerve injury
  • Cystic adenomatoid malformation
• Characteristic features of some congenital heart diseases can be observed like:
  • 'Snowman' or 'Figure 8' in TAPVR
  • 'Boot-shaped heart' in TOF
  • 'Egg-on-string' in TGA
  • Cardiomegaly in Ebstein's anomaly

Boot-shaped heart in Tetralogy of Fallot. [1]

Echocardiography or Ultrasound

• Can be used when the diagnosis is equivocal or when physical exam findings and/or failed hyperoxia test suggests the presence of congenital heart disease.
• It usually used with doppler to define the direction of shunts.

CT scan

• Used as an adjunct to further define cardiac and other anatomical anomalies in preparation for definitive management.

MRI

• Used as an adjunct to further define cardiac and other anatomical anomalies in preparation for definitive management.

Other Imaging Findings

• Cardiac catheterization and angiography:
  • Sometimes as an adjunct to further define cardiac and other anatomical anomalies in preparation for definitive management.

Other Diagnostic Studies

• Pre-ductal and post-ductal PaO2 measurements

Treatment

Medical Therapy

• The priority in the immediate term will be to optimize the neonate, especially in severe cyanosis. This includes:
  • Establishing assisted ventilation in respiratory distress
  • Keep infant in a radiant warmer
  • Stop all per oral feeds and give intravenous fluids through peripheral or central access like the umbilical vein
  • Give glucose for hypoglycemic infants and monitor serum glucose levels
  • Consult should be sent to the Neonatologist
  • Oxygen administration should be done with caution. Care must be taken not to begin with very high concentrations of 100% due to damage to the lung tissue and pulmonary vessels
  • Prostaglandin E1(PGE1) given as an infusion to keep the ductus patent for pulmonary blood flow in CHDs
  • Definitive treatment can be planned in stages once infant is optimized and a diagnosis has been made.
  • Antibiotics coverage for sepsis if suspected. Give after blood samples are taken for culture and sensitivity, urine samples have been collected.

Surgery

• This a treatment modality for diagnoses associated with anatomic deformities in CHDs or airway obstructions.
• Surgical treatment is tailored to the cause of the cyanosis that requires surgical intervention. An example is a Balloon Atrial Septostomy for acute TGA allowing for blood mixing.

Prevention

• Prevention can be challenging as some of its causes would have been prevalent in-utero before the birth of the child while others occur during the actual labor and birthing process.
• The following preventive measures can be adopted:
• Counsel expectant mothers especially women who are above the age of 35 years.
• Routine prenatal and postnatal care for early detection of congenital anomalies and adequate preparedness for its management during pregnancy, labor, and delivery.
• Early detection and management of gestational diabetes and pregnancy-induced hypertension.
• Parents of a child with congenital malformations should be counseled on the risk of having another child with the same or similar deformities.
• Prophylaxis against Respiratory syncytial virus(RSV).
• Follow up for polycythemia, excessive dehydration, and iron-deficiency anemia.