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breathing, the infant will remain well appearing and without signs of respiratory
distress. In contrast, apneic spells last greater than 20 seconds OR are associated
with cyanosis or bradycardia. Apneic events are never a normal finding, and
should be further evaluated (see Chapter 14 Apnea ).
Tachypnea can result from systemic changes, such as fever, hyperthyroidism,
metabolic acidosis, cardiac disease, or pulmonary disease. It is often the only
presenting sign of congestive heart failure. Tachypnea can be a presenting sign
for a number of metabolic disorders, particularly urea cycle defects, as well as
renal disorders, where the body is compensating for metabolic acidosis.
Tachypnea is common with respiratory illnesses, such as bronchiolitis or
pneumonia, but also in premature infants with chronic lung disease, or infants
with a history of congenital pulmonary lesions such as congenital diaphragmatic
hernia. The underlying disease causing tachypnea should be addressed prior to the
development of hypoxia and respiratory failure.
For more details on clinical considerations and management of respiratory rate
anomalies in the neonate, see Section: Neonatal Respiratory and Airway
Problems.
Pulse Oximetry
At sea level, normal pulse oximetry saturation values are greater than 94%; 89%
and higher are acceptable at higher elevations, such as in Denver and Salt Lake
City. Pulse oximetry saturation (POS) values in healthy newborns normalize
within the first few hours of life, with a mean value 97% by 24 hours. POS values
increase incrementally with gestational age, and show variability with infant state.
Crying neonates are more likely to have lower values compared to quiet or
sleeping infants.
Pulse oximetry should be used for any infant with tachypnea, dyspnea, or any
signs of cardiorespiratory illness. Cyanosis may be absent in the face of
significant hypoxemia if the hemoglobin is low (see Section: Color Changes). It
is important to note that acrocyanosis is a common neonatal finding in healthy
infants that can persist for several days to weeks, particularly in cool
environments. This is in contrast to infants with central cyanosis, which should

always be evaluated with pulse oximetry and arterial blood gas measures of
oxygenation.
Hypoxia is never normal in the term newborn, and may be due to respiratory or
cardiac anomalies. Increasingly, pulse oximetry has been used as a screening
method for critical congenital heart diseases (CHDs) that produce hypoxemia.
CHD screening should be completed after 24 hours of life to decrease the


incidence of false positives, but within the first week. Importantly, the pulse
oximetry screen for CHD does not detect nonhypoxic heart disease (e.g.,
coarctation of the aorta, single ventricle, or double outlet right ventricle). The
American Academy of Pediatrics (AAP) and the CDC endorse screening for
critical CHD for all newborns ( Fig. 96.1 ). An infant who fails the initial screen
should be referred for an echocardiogram.
Hypoxia without respiratory distress, specifically without signs of grunting,
retractions, or accessory muscle use, is more common in cardiac disease than
respiratory disease. To better distinguish the etiology of hypoxemia, the clinician
can perform the hyperoxia test. To complete the test, the infant is given 100%
oxygen to breathe for 5 to 10 minutes. Serial pulse oximetry or arterial blood gas
measurements are obtained on room air and after the infant has breathed 100%
oxygen. If there is little to no increase in oxygenation, the hypoxia can be
attributed to extrapulmonary causes of right-to-left shunting. Extrapulmonary
right-to-left shunting occurs in persistent pulmonary hypertension and in cardiac
disease. To distinguish between the two, the clinician can perform the
hyperventilation test. In this circumstance, hyperventilating to a PaCO2 of 25 to
30 mm Hg in conjunction with 100% oxygen is more likely to elicit an increase in
PaO2 levels (typically >100 mm Hg) in persistent pulmonary hypertension of the
newborn (PPHN) due to relaxation of the pulmonary bed. Infants that continue to
have low PaO2 despite hyperoxia and hyperventilation are more likely to have a
fixed, intracardiac right-to-left shunting. In either circumstance, an

echocardiogram is the definitive study to differentiate between the two.


FIGURE 96.1 Congenital heart disease screening algorithm. (Reproduced with permission
from Kemper AR, Mahle WT, Martin GR, et al. Strategies for implementing screening for
critical congenital heart disease. Pediatrics 2011;128(5):e1259–1267. Copyright © 2011
American Academy of Pediatrics.)

Supplemental oxygen should be administered to infants with suspected or
confirmed respiratory disease. Hypoxic premature infants with lung disease
should be administered oxygen judiciously, particularly if they have not corrected
to term gestation. Hyperoxia is associated with retinopathy of prematurity,
increased risk of pneumonia, and exacerbations of chronic lung disease. Target
saturations for this population should be discussed with a neonatologist.
Similarly, oxygen administration to infants with CHD can alter pulmonary


vascular resistance and influence the direction and degree of intracardiac shunts,
potentially leading to congestive heart failure. Target saturations for this
population should be discussed with a cardiologist.
It is important to note that pulse oximetry measures are dependent on adequate
pulse pressure, and so any low perfusion state may lead to falsely low pulse
oximetry readings. Pulse oximetry is also unable to detect significant hyperoxia
or severe hypoxemia. The presence of other hemoglobin forms, such as
methemoglobin or carboxyhemoglobin, may not be detected by pulse oximetry. In
any of these circumstances, arterial blood sampling for PaO2 and cooximetry for
carboxyhemoglobin or methemoglobin may be needed to better understand the
infant’s respiratory physiology.
Blood Pressure
Blood pressure monitoring in the newborn requires specific equipment and

interpretation. Most commonly, indirect blood pressure monitoring utilizes an
occlusive cuff device that functions identically to pediatric and adult cuffs.
Neonatal blood pressure cuff width should measure approximately 50% of the
extremity circumference. A cuff that is too loose can result in inaccurate
measurement of blood pressure. To increase accuracy, the cuff should be placed at
the same level as the heart, typically in the upper extremity. Normal ranges for
blood pressure increase within the first few hours to days of life and are
dependent on the infant’s weight and gestational age at birth, and should be
interpreted accordingly ( Figs. 96.2 and 96.3 ).