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 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 ) ... 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... 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... 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