Cyanosis

Published on 21/03/2015 by admin

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Chapter 12 CYANOSIS

Theodore X. O’Connell

General Discussion

Cyanosis is a blue to dusky hue which may be seen in the newborn. Bruising or ecchymosis may look like cyanosis and is differentiated by applying pressure over the skin, which will blanch with cyanosis but not with ecchymosis. Central cyanosis involves the entire body, including the mucous membranes and tongue. Peripheral cyanosis, or acrocyanosis, is limited to the extremities.

Arterial blood oxygen content is normal in peripheral cyanosis, whereas arterial blood oxygen content is decreased in central cyanosis. Although peripheral cyanosis may be seen with exposure to the cold, it may also be the presenting sign of serious conditions such as sepsis, hypoglycemia, or hypoplastic left-sided heart syndrome. Therefore, peripheral cyanosis should not be ignored unless other conditions have been ruled out.

In addition to central and peripheral cyanosis, cyanosis has several other patterns. In differential cyanosis, the upper part of the body remains pink while the lower part of the body remains cyanotic. This pattern is seen in conditions in which there is right-to-left shunt from the pulmonary artery to the descending aorta through a patent ductus arteriosus (PDA). In reverse differential cyanosis, the upper part of the body remains cyanotic, whereas the lower part remains pink. Reverse differential cyanosis may occur in transposition of the great vessels with pulmonary hypertension and shunt through a PDA and total anomalous pulmonary venous return above the diaphragm with shunt through a PDA. Harlequin condition is a unique phenomenon in which one quadrant or one half of the body may become cyanotic while the rest of the body remains pink. This condition is thought to result from vasomotor instability.

During the assessment of cyanosis in the newborn, it is important to identify the cause of cyanosis on a physiologic basis. The two most common causes of cyanosis are cardiac and pulmonary conditions. Cyanosis also may result from abnormalities in the oxygen carrying states of the hemoglobin, metabolic causes, central nervous system (CNS) conditions, and sepsis. Other causes are outlined below.

Because most causes for cyanosis are attributable to cardiopulmonary problems, it is important to differentiate between cardiac and pulmonary causes. The hyperoxia test, described below, can help differentiate between cardiac and noncardiac causes. Respiratory disease is more likely in newborns who are tachypneic and using accessory muscles of respiration.

Cyanotic congenital heart defects that are not detected in the newborn nursery will present during the first 2 to 3 weeks of life when the ductus arteriosus closes. Echocardiogram is indicated in these patients.

Causes of Cyanosis

Cardiac Causes

CNS Causes

• Vocal cord paralysis or paresis

Miscellaneous Causes

Key Historical Features

Onset of Cyanosis

Onset at birth may result from transient tachypnea of the necoborn (TTN), respiratory distress syndrome, pneumothorax, meconium aspiration syndrome, CDH, or CCAM

Onset several hours after birth may be related to cyanotic congenital heart disease, postnatal aspiration syndromes, or TEF

Maternal History

Maternal diabetes increases the risk of TTN, HMD, and hypoglycemia

Asthma increases risk of TTN

Narcotic use may lead to narcotic withdrawal, often 36 to 48 hours after birth

Pregnancy-induced hypertension increases risk of polycythemia and hypoglycemia

Labor and Delivery History

Prolonged rupture of membranes increases the risk of sepsis and pneumonia

Intrapartum fever increases the risk of infection in the newborn

Narcotic analgesia or anesthesia increases the risk of newborn cyanosis

Nonreassuring fetal heart-rate tracings and perinatal hypoxic depression at birth increase the risk of hypotension, metabolic acidosis, and cerebral edema in the newborn

Cesarean section deliveries without labor are associated with a higher risk of TTN and persistent pulmonary hypertension

Difficult vaginal delivery may cause an Erb palsy with associated phrenic nerve paralysis, leading to respiratory distress

Prenatal History That May Increase Risk of Polycythemia and Hypoglycemia

Oligohydramnios may lead to pulmonary hypoplasia

Polyhydramnios may be associated with TEF, neurologic conditions, or anatomic abnormalities of the gastrointestinal (GI) tract

Family History

A sibling with a history of early onset invasive group B streptococcal (GBS) disease confers a higher risk of early onset GBS infection

A family history of congenital heart disease increases the risk of recurrence

A sibling with a history of surfactant protein B deficiency increases the risk of recurrence

Key Physical Findings

Vital Signs

Blood pressure measurement in all four extremities

Determination of whether cyanosis is peripheral or central

Head and neck examination for nasal flaring: holding the bell of the stethoscope over the nostrils may help identify nasal obstruction from choanal atresia

Cardiac examination for heart rate, heart sounds, and murmurs; location of the apical impulse and presence of a precordial thrill

Evaluation of respirations for respiratory rate, retractions, and grunting

Evaluation of the shape of the chest

Pulmonary examination for equal air entry bilaterally, presence of breath sounds in all lung fields, rales, and rhonchi

Abdominal examination for distension, hepatosplenomegaly, and bowel sounds

Assessment of perfusion by capillary refill time

Palpation of both brachial and femoral pulses with assessment of the quality and volume of the pulses

Neurologic examination for hypotonia or Erb palsy

Suggested Work-up

Pulse oximetry monitoring	If there is severe cyanosis with respiratory distress, the pulse oximeter should be placed over the right hand and a lower extremity to detect the gradient across the ductus arteriosus
Hyperoxia test	Indicated if the infant’s pulse oximeter reading is less than 85% on both room air and 100% oxygen
	An arterial blood gas (ABG) is obtained on room air, the infant is placed on 100% oxygen for 10 to 15 minutes, then the ABG is repeated. If the cause of cyanosis is pulmonary, the Pao₂ should increase by 30 mm Hg. If the cause is cardiac, there should be minimal improvement in the PaO₂. The initial ABG should be obtained with co-oximetry because methemoglobinemia can also cause cyanosis
Chest radiograph	To determine the locations of the stomach, liver, and heart to evaluate for dextrocardia and situs inversus. To evaluate the size and shape of the heart; pulmonary vascular markings, lung volumes, and interstitial markings; pneumothorax, pleural effusion, infiltrates, or elevated hemidiaphragms. To evaluate the bony thoracic cage and to look for fractures of the ribs, humerus, or clavicles
Electrocardiogram (ECG)	To evaluate for arrhythmias
Echocardiogram	To evaluate for congenital cardiac lesions and pulmonary hypertension
CBC with differential count	To evaluate for polycythemia, anemia, neutropenia, leukopenia, abnormal immature-to-total neutrophil ratio, and thrombocytopenia
Blood culture	If sepsis is suspected
Spinal tap	If sepsis is suspected

Additional Work-up

Serum electrolytes	To evaluate for electrolyte abnormalities contributing to heart block if the infant’s heart rate does not increase appropriately with stimulation
Serum calcium and magnesium	Should be obtained in newborns in whom other causes are ruled out
Ultrasound	To evaluate for pleural effusion or paradoxical motion of the diaphragm
Computed tomography (CT) scan of the chest	May be helpful if the diagnosis is not clear and in detecting congenital abnormalities and tumors of the mediastinum, lungs, and heart
Upper GI contrast study	To evaluate for severe gastroesophageal reflux and esophagitis when cyanosis occurs with feeding
Metabolic screening of urine and drug screening of urine and meconium	If clinically indicated