Approach to cyanosis (newborn): Clinical sciences

Newborn cyanosis refers to blue or purple skin discoloration that results from poor circulation or inadequate blood oxygenation and indicates a potentially life-threatening condition. Peripheral cyanosis involves the distal extremities only, while central cyanosis also involves the face, trunk, mucous membranes, and tongue. Possible causes of central cyanosis include cyanotic congenital heart disease, pulmonary hypertension, respiratory depression, upper airway obstruction, pulmonary disease, sepsis, and hemorrhagic shock.

Here's a high-yield fact! Acrocyanosis describes bluish-purple discoloration that is isolated to the hands and feet. Unlike central cyanosis, this is a common, transient, and benign finding in the immediate newborn period and is caused by immature vascular tone.

When evaluating a newborn patient with cyanosis, first perform an ABCDE assessment to determine if they are stable or unstable. Newborns with cyanosis are considered unstable, so stabilize their airway, breathing, and circulation; and intubate if needed. Next, obtain IV or IO access, place your patient on continuous vital sign monitoring, and provide supplemental oxygen.

Once you’ve initiated acute management, obtain a focused history and physical exam. The perinatal history might reveal maternal infection or opioid use, meconium-stained amniotic fluid, a complicated birth, or a cesarean or preterm delivery. On physical exam, you’ll notice a blue or purple discoloration of the skin of the extremities and trunk, as well as the mucous membranes and tongue. This finding confirms the presence of central cyanosis. Keep in mind that a visual assessment of cyanosis isn’t always reliable in newborns with deeply pigmented skin, so check areas where the skin is thinnest or has the least amount of pigment, like the oral mucosa, conjunctiva, or nail beds, where cyanosis can sometimes present as grayish-blue!

Now that you’ve identified cyanosis, you should consider the possibility of critical congenital heart disease. Next, obtain pulse oximetry measurements on the right hand, which measures pre-ductal saturation; and either foot, which measures post-ductal saturation. These measurements allow you to compare oxygenation of the systemic circulation before and after the ductus arteriosus inserts into the aorta. If pre-ductal saturations are significantly higher than post-ductal saturations, this means that deoxygenated blood is being shunted from the pulmonary artery to the aorta through an open ductus arteriosus. This is called differential cyanosis and suggests the presence of congenital heart disease.

Next, assess the criteria for performing an echocardiogram. These include an oxygen saturation below 90% in the right hand and foot; an oxygen saturation below 95% in the right hand and foot on three separate occasions; or a difference of 3% or higher between the pre- and post-ductal oxygen saturations on three separate occasions.

Now, if any of these criteria are met, order an echocardiogram to evaluate your patient for congenital heart disease.

Here’s a high-yield fact! If an echocardiogram is unavailable, a hyperoxia test can help distinguish congenital heart disease from pulmonary conditions. To perform this test, obtain arterial blood gases before and after administering 100% oxygen. The PaO2 will rise by 150 mmHg or more after hyperoxia if the newborn has pulmonary disease, but there will be little to no improvement in cyanotic heart lesions with a right-to-left intracardiac shunt.

Let’s discuss newborns with cyanotic congenital heart disease. History might reveal a cardiac defect on prenatal ultrasound or a family history of cyanotic congenital heart disease. The physical exam may demonstrate a murmur, a loud S2, or hepatosplenomegaly. Additionally, the echocardiogram will confirm the presence of a heart defect with a right-to-left intracardiac shunt; and depending on the lesion, there could be pulmonary over or under circulation.

These findings confirm the diagnosis of cyanotic congenital heart disease, which can be categorized according to their characteristic circulatory patterns, including increased or decreased pulmonary blood flow, decreased systemic blood flow, or inadequate pulmonary-systemic mixing. Congenital heart lesions associated with increased pulmonary blood flow include truncus arteriosus and total anomalous pulmonary venous return with obstruction. On the other hand, lesions associated with decreased pulmonary blood flow include tetralogy of Fallot, tricuspid atresia, pulmonary atresia with intact ventricular septum, and Ebstein anomaly. Finally, hypoplastic left heart syndrome is associated with decreased systemic blood flow and signs of shock; while transposition of the great vessels is associated with inadequate pulmonary-systemic mixing.

Here’s another clinical pearl! Heart failure can also cause central cyanosis in the absence of congenital heart defects; for example, conditions like myocarditis and arteriovenous anomalies such as vein of Galen malformation can also be associated with cyanosis.

Let’s move on to persistent pulmonary hypertension of the newborn, which occurs when pulmonary vascular resistance remains elevated after birth. The perinatal history might reveal preterm or cesarean delivery or meconium aspiration, And the exam commonly demonstrates a systolic murmur and loud S2. An echocardiogram will confirm elevated pulmonary artery pressure, with right-to-left shunting at the ductus arteriosus. These findings indicate persistent pulmonary hypertension of the newborn. This condition can be idiopathic, but in some cases, it’s caused by underlying conditions like meconium aspiration syndrome, pneumonia, and neonatal respiratory distress syndrome.

Now let’s switch gears and discuss your steps if the echocardiogram is normal, or if your patient didn’t meet the criteria for an ECHO. In this case, assess your patient’s respirations.

If your patient demonstrates shallow, slow, or absent respirations, consider conditions associated with respiratory depression. The perinatal history might reveal maternal sedative or opioid use, intrauterine distress, or birth trauma. Some newborns may have had postnatal lethargy or seizures, and the exam might demonstrate hypotonia. Next, consider a head ultrasound or CT scan of the head, which might reveal an intracranial hemorrhage. With these findings, diagnose respiratory depression, which can be caused by maternal sedative or opioid use; intrauterine or birth-related asphyxia; hypoxic-ischemic encephalopathy; or intracranial hemorrhage.