Chest x-ray films: Chest x-ray films may reveal pulmonary causes of cyanosis. They can also hint at the presence or absence of cardiac defects and the type of defect.
Arterial blood gases in room air:
Arterial blood gases in room air confirm or reject central cyanosis. An elevated PCO 2 suggests pulmonary or central nervous system problems. A low pH may be seen in sepsis, circulatory shock, or severe hypoxemia.
Hyperoxia test:
To differentiate between Cardiac from Pulmonary cause. Oxygen should be administered through a plastic hood (such as an Oxyhood) for at least 10 minutes to replace the alveolar air completely with oxygen. With pulmonary disease, arterial PO 2 usually rises to> 150 mm Hg. When there is a significant intracardiac right-to-left shunt, the arterial PO 2 does not exceed 100 mm Hg, and the rise is not more than 10 to 30 mm Hg. However in Persistent Pulmonary Hypertension of newborn with a normal heart) PaO 2 may not have a rise in arterial PO 2 to 100 mm Hg. The purpose of positive hyperoxia test helps in ruling out significant cyanotic congenital heart defect but when negative does not differentiate between cyanotic heart and PPHN.
Pre-ductal and Post-ductal saturations:
This helps in differentiating shunting across the ductus in PPHN. The difference of 10% between right upper limb and lower limbs is significant.
ECG may be helpful in cardiac origin of cyanosis. A PaO 2 value in a preductal artery (such as the right radial artery) that is 10 to 15 mm Hg higher than that in a post-ductal artery (an umbilical artery line) suggests a right-to-left ductal shunt.
2-D Echocardiography and a Doppler examination:
It will reveal the cause of the central cyanosis
Treatment: Administration of oxygen is the cornerstone in the therapy of cyanotic neonate except in cyanotic congenital heart defects
If perfusion seems compromised, administer 20 mL/kg of normal saline as an intravenous bolus over 15 minutes. Infants who have respiratory distress should have an orogastric tube and need ventilatory support.
If a ductal-dependant congenital heart disease is suspected (e.g., pulmonary atresia with or without VSD, tricuspid atresia, Hypoplastic left heart syndrome [HLHS], interrupted aortic arch, severe Coarctation), it is advisable to start prostaglandin E-1 infusion at a rate of 0.05 mcg/kg/min. The starting dose is 0.05 to 0.1 mcg/kg per minute, administered in a continuous intravenous drip. Three common side effects of intravenous infusion of prostaglandin E 1 are apnea (12%), fever (14%), and flushing (10%). Antibiotic therapy for sepsis if suspected is initiated.
A systematic approach to the diagnosis, starting with the history, physical examination, work-up (including chest radiograph, EKG, echocardiogram, hyperoxia test), and laboratory tests including blood glucose, calcium, CBC, and septic work-up as indicated, is required.
Management is based on the clinical diagnosis and requires initial stabilization, assuring hemodynamic stability, oxygen administration, and either referral to a neonatal intensive care unit or continued care in a Level II nursery.
Prognosis depends on the diagnosis, but is generally good with prompt recognition and intervention. Key message:
- Early detection of cyanosis in a newborn is crucial and oxygen should be started even before analyzing the cause.
- With improved technology, neonatal ventilation and good supportive care outcome of babies with cyanosis and respiratory distress has improved.
- PGE1 should be started in duct-dependent cyanotic congenital heart lesions.
- Cyanosis with normal or higher PaO 2 is seen in Methemoglobinemia. The pulse oximetry may be higher than the true level of oxyhemoglobin.
