Respiratory Disorders Presenting in the Newborn Period

Chapter2B Respiratory Disorders Presenting in the Newborn Period

Content and Objectives

Transient Tachypnea of the Newborn 2B-3

Meconium Aspiration Syndrome 2B-7

Neonatal Pneumonia 2B-10

Neonatal Chylothorax 2B-15

Continuing Nursing Education Test CNE-1 Objectives: 1. List four typical x-ray findings for the infant with transient tachypnea of the newborn (TTN). 2. Describe the appearance of the chest x-ray of the infant with meconium aspiration sydrome (MAS). 3. Identify the most common organisms that cause neonatal pneumonia. 4. Outline the common radiographic findings in neonatal pneumonia. 5. Identify the most common x-ray findings for pleural effusion. 6. Describe the chest x-ray of an infant with chylothorax.

Neonatal Radiology Basics Respiratory Disorders Presenting in the Newborn Period 2B-1 2B-2 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics Chapter 2B Respiratory Disorders Presenting in the Newborn Period

Editor Carol Trotter, PhD, RN, NNP-BC

fetal lung liquid clearance. Now, these are thought to play a Transient Tachypnea minor or negligible role in lung liquid clearance. The actual process is much more complex.3 of the Newborn The fetal lung produces a large volume of fluid, 3–5 mL/kg/hour. This fluid is distinct in composition from ransient tachypnea of the newborn (TTN), a condition amniotic fluid. It is produced, eliminated through the trachea, Talso known as retained lung fluid in the newborn, was swallowed by the fetus, and adds to the amniotic fluid pool. first described as a syndrome by Mary Ellen Avery in 1966.1 One of the primary driving forces for this liquid production is Other names that have been applied to this problem are wet active chloride secretion. Active transport of the chloride ion lung syndrome and respiratory distress syndrome Type II. across pulmonary epithelium generates an electrical potential Swischuk describes this as retained fluid syndrome.2 It is a difference, causing a shift of liquid from the microcircula- diagnosis of exclusion and is generally a benign, self-limiting tion to the interstitium and into the alveoli. Near the time condition of the term or near-term neonate lasting 24 to 48 of birth and prior to labor, lung liquid secretion slows, and hours and occasionally up to 72 hours. It is not a true disease, absorption begins as the pulmonary epithelium changes from but a condition caused by retained fetal pulmonary fluid.2 The a chloride-secreting to a sodium-absorbing barrier. This tran- most prominent findings are tachypnea with respiratory rates sition is influenced by neurohumoral factors, catecholamines, as high as 120 per minute, grunting, nasal flaring, minimal to steroids, and vasopressin. Labor increases lung liquid absorp- no retractions, minimal cyanosis, and mild hypoxemia. The tion. In studies using fetal lambs, lung liquid was reduced onset of clinical findings appears soon after birth or at birth. from 21 mL/kg at the beginning of labor to 6 mL/kg at the Both the clinical and x-ray findings resolve within 72 hours. time of delivery.3 The process of normal lung liquid clearance continues for several hours after birth, with the majority of LUNG LIQUID CLEARANCE MECHANISMS fluid entering the microcirculation. Air inflation at birth shifts It has been proposed that the cause of this syndrome is fluid from the alveoli to the interstitium and the perivascular a disturbance in normal pulmonary adaptation resulting in spaces around large blood vessels and airways. With sponta- delay in clearance of lung liquid. Despite the common occur- neous respiration, intrathoracic pressure drops and lymphatic rence of retained lung fluid, the exact mechanisms and patho- drainage increases. The flow of lung liquid out of the alveoli is physiology of absorption of lung liquid have not been fully facilitated by the higher protein content and osmotic pressure explained. Abnormalities of or lack of labor, cesarean deliv- of blood and lymph fluid. The potential pathways of lung ery, abnormal circulatory adaptation after delivery, pulmo- liquid clearance after birth include the blood vessels, lym- nary artery hypertension, and poor left ventricular function phatics, pleural space, mediastinum, and upper airway. are thought to contribute to the occurrence of retained lung In term fetal lambs, lymphatic flow doubles after breath- fluid. It was previously thought that the chest compression ing is initiated. The concentration of protein in lymph also produced by vaginal delivery and the subsequent evacuation drops, suggesting a shift of low-protein lung liquid to the of fluid from the trachea and mouth were a major factor in interstitium and lymphatics. As low-protein lung fluid enters

Neonatal Radiology Basics Respiratory Disorders Presenting in the Newborn Period 2B-3 FIGURE 2B-1 n Marked perihilar streaking is present bilaterally, FIGURE 2B-2 n Chest x-ray of a three-hour-old neonate obtained extending out into the lung fields. for persistent tachypnea with normal oxygen saturation. This neonate presented at 2 hours of age with tachypnea, flaring, and grunting. She required 28 percent oxygen for 24 hours. Clinical The perihilar area shows prominent markings more apparent in the findings resolved at 36 hours of age, and chest clearing mirrored upper than lower lung fields. The intercostal spaces are wide, and clinical improvement. the heart is of normal size.

barrier as a pathophysiologic component of retained lung fluid. It also supported the role of labor in the normal transition process. the lymphatics, the concentration of the lymph protein is Lung function in this disorder has been studied. Compared diluted. When the lung fluid leaves the lymphatics and enters with normal healthy neonates, those with retained lung fluid the bloodstream, the protein content of the lymph fluid were found to have high total ventilation, high breathing returns to normal. About 10 percent of lung liquid is esti- frequency, low tidal volume, high dead space, prolonged mated to leave the lungs via the lymphatics by way of the thoracic duct and drainage into the superior vena cava. Most lung liquid enters the pulmonary microcirculation or seeps FIGURE 2B-3 n This chest x-ray reveals perihilar streaking, into the mediastinum, with subsequent absorption into the wide intercostal spaces, and hyperaeration with bloodstream. expansion to the ninth thoracic vertebrae on the As noted earlier, factors that delay resorption of lung right and the tenth on the left. liquid are cesarean delivery, lack of labor or prolonged labor, The neonate’s diagnosis is retained lung fluid. increased lung microvascular pressure from hypoxemia, increased left ventricular pressure, and low plasma protein concentration. Krantz studied 4,659 neonates and found an increase in retained lung fluid in neonates delivered by cesarean section.4 Rupture of membranes or uterine contractions prior to cesarean section decreased the incidence of retained lung fluid in full-term neonates. Neonates with low Apgar scores also had higher incidence rates.5 Halliday examined neonates with retained lung fluid by serial echocardiography and found that mild left ventricular failure and myocardial dysfunction were present in this group.5 Gowen evaluated the electrical potential difference and ion transport across the nasal epithelium in term neonates as an index of ion transport across the pulmonary epithelium.6 This study supported the role of epithelial ion transport dysfunction in retained lung fluid and the delay in transition of the epithelium from a chloride-secreting to a sodium-absorbing

2B-4 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics FIGURE 2B-4 n Frontal view of lung lobes and fissures. FIGURE 2B-5 n Minor vascular engorgment, more prominent on the right than on the left, and fluid in the minor, or horizontal, fissure are findings present in this chest x-ray of a tachypneic neonate.

Key: mF = minor (or horizontal) fissure; MF = major (or oblique) fissure. nitrogen clearance, and low dynamic compliance.7 The pattern of abnormal lung function is consistent with small reason for this asymmetrical presentation is unknown, but it is airway disease with high functional residual capacity and low also sometimes seen in congestive heart failure, with changes lung compliance. Swischuk describes the abnormal lungs as appearing more prominently in the right lung than in the left. stiff or splinted, which inhibits ventilation until the fluid is cleared. Fluid clearance typically occurs by 24 hours but may Hyperaeration require 48 hours.2 Mild to moderate hyperaeration, or hyperinflation, with wide intercostal spaces and flatter diaphragms at the ninth CHEST X-RAY FINDINGS or tenth thoracic vertebrae are also findings consistent with The typical chest x-ray findings that have been described in retained lung fluid (Figure 2B-3). Hyperaeration results from retained lung fluid are: the partial airway obstruction caused by fluid in the intersti- 1. Prominent perihilar markings or streaking tium, and it is consistent with the lung function findings of 2. Mild to moderate hyperaeration high functional residual capacity. 3. Fluid visible in the fissures 4. Occasional cardiomegaly and pleural effusions Fluid in the Fissures Fluid visible in the interlobar fissures is common in the Perihilar Markings newborn and occurs secondary to increased lung liquid The perihilar streaking seen with retained lung fluid content.2 The fissures become more apparent when distended is generally symmetrical and is due to engorgement of the with fluid. On a frontal film, the minor, or horizontal, fissure pulmonary vessels and lymphatics (Figures 2B-1 and 2B-2). of the right lung may be visible (Figures 2B-4 and 2B-5). White or more opaque lines are seen radiating out from the The horizontal fissure separates the right upper lobe from the hilar region. These vessels are more dense than the air-filled right middle lobe, and because it is parallel to the x-ray beam, alveolar background and are therefore visible. They radiate it can be seen on x-ray. On a lateral chest x-ray, the oblique out over the middle section of the lung fields in many cases. (major) and horizontal (minor) fissures of the right lung can Although observation of hilar vessels is normal in the neona- sometimes be seen, along with the oblique fissure of the left tal chest x-ray soon after birth, those seen in neonates with lung. (Figure 2B-6) The position of the horizontal fissure is retained fluid are more prominent, are greater in number, and variable; the smaller the middle lobe, the lower the horizontal extend farther out into the lung fields. Occasionally, these fissure will be. Usually, it is seen between the fourth and sixth findings are seen predominantly over the right lung field. The thoracic vertebrae.

Neonatal Radiology Basics Respiratory Disorders Presenting in the Newborn Period 2B-5 FIGURE 2B-6 n Lateral view of the major, or oblique, fissures FIGURE 2B-7 n This neonate’s clinical presentation, course, and of the right and left lung and the minor, or history were all consistent with retained lung horizontal, fissure of the right lung. fluid. The chest xray shows hilar densities that are not symmetrical and have the appearance of infiltrates.

Cardiomegaly The etiology of the cardiomegaly seen in retained lung fluid is unclear. It may be a result of myocardial insuffi- ciency due to perinatal asphyxia, hypoxemia, or abnormal pulmonary vascular transition. Infiltrates or pleural effusions occur at times and represent a pattern of alveolar fluid collec tion that is more consolidated in certain areas of the lung (Figure 2B-7). At one hour of age, the neonate’s respiratory rate had risen to 80 to 90 per minute, and nasal flaring was present without Other Findings retractions or grunting. Re-examination at this time revealed If the initial chest x-ray is taken very early in the neona- clear breath sounds; slight duskiness of the mucous mem- tal course, it may show a pattern of reticulogranularity not branes; normal pulses; no murmur; a normal S1 and S2; and unlike that seen in respiratory distress syndrome. This is normal reflexes, tone, and alertness. Pulse oximetry revealed due to the retained fluid still within the alveoli. The x-ray, an oxygen saturation of 87–88 percent, and the neonate was however, shows normal to increased lung expansion rather placed in 27 percent oxygen, at which time the oxygen satu- than the decreased lung expansion typical of respiratory dis- ration rose to 95 percent. A radial artery gas was obtained tress syndrome. after oxygen therapy had been initiated, and revealed a pH

As was mentioned earlier, retained lung fluid is a diagno- of 7.39, a PCO2 of 38, a PaO2 of 65, and a bicarbonate level sis of exclusion. Pneumonia may mimic the x-ray findings of 24. A complete blood count was obtained and revealed of retained lung fluid. The vascular engorgement seen with a white count of 14,000/mm3 with 47 percent PMNs, 7 congestive heart failure secondary to congenital heart defects percent bands, 2 percent eosinophils, 1 percent basophils, 7 may also be confused with the perihilar streaking of retained percent monocytes, 36 percent lymphocytes, a platelet count lung fluid. It is essential to consider the history and the clini- of 180,000/mm3, and a hemoglobin of 18 gm/dL with a cal, laboratory, and chest x-ray findings before arriving at the hematocrit of 53 percent. The smear was normal. diagnostic impression of retained lung fluid. X-Ray Evaluation (Figure 2B-8) CASE STUDY Indication for the initial x-ray was tachypnea and mild A 40-week-gestation, 3.5 kg AGA male neonate was deliv- hypoxemia in a term neonate at one hour of age. ered by repeat cesarean section to a 29-year-old, gravida 3, Penetration: appears to be normally exposed. para 2 mother. Prenatal care was initiated in the first trimester, Rotation is slight, to the right. and no problems of pregnancy occurred. The cesarean section The soft tissues of the neck, chest, and extremities are of was a scheduled repeat without labor. The neonate’s Apgar normal thickness and without emphysema. Skin folds are scores were 8 and 9 at one and five minutes. The delivery noted at the left shoulder. room examination was normal. On admission to the nursery, The bony framework is intact, with 12 ribs bilaterally. a respiratory rate of 70 was recorded with clear breath sounds, Clavicles are intact; humeri and vertebral bodies are without equal bilaterally. Nursery admission vital signs were tempera- abnormality. ture 36.5°C (97.7°F), heart rate 140 bpm, respiratory rate The trachea shows a straight air column. 70 breaths per minute, and capillary refill time two seconds.

2B-6 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics FIGURE 2B-8 n Chest x-ray for a 40-week AGA neonate with retained lung fluid. Meconium Aspiration See “X-Ray Evaluation” for discussion of findings. Syndrome

econium staining of amniotic fluid is present in Mapproximately 8–10 percent of all deliveries.8 It usually affects the fetus who is 37 weeks gestation or greater, post- mature and/or growth retarded, and has experienced some degree of fetal distress. However, meconium-stained fluid may be present in the premature fetus with Listeria sepsis.9

PATHOPHYSIOLOGY Fetal respiratory activity is a normal physiologic process that causes lung fluid to move from within the tracheobronchial tree out into the amniotic fluid. This movement of fluid during each fetal “breath” is minimal but consistent with a steady movement outward from the trachea.10 Under normal conditions, amniotic fluid does not enter the tracheobronchial tree. When fetal distress occurs, apnea resulting in fetal gasping allows amniotic fluid into the larger airways of the tracheobronchial tree. Fetal distress can also trigger the passage of meconium from the fetal intestine secondary to vagal activity, which results in hyperperistalsis and sphincter relaxation. In this situation, the The hilum shows bilateral radiating vascular markings. The fetus may aspirate amniotic fluid along with meconium and heart is at 62.5 percent of the thoracic diameter, which is other debris (such as vernix and squamous cells). enlarged. No distinctive abnormality in heart shape is present. In the neonate, when meconium has penetrated below the The diaphragms are at the tenth thoracic vertebrae, consis- vocal cords and into the trachea and large airways, it causes tent with hyperaeration and an inspiratory film. partial and/or total occlusion of terminal airways and air sacs. The pleura reach the edges of the bony thorax. The right is This results in atelectasis distal to the areas of total occlusion less visible due to an overlaying electrode. The costophrenic and gas trapping with alveolar overdistension in the areas of angle on the left is normal. partial occlusion. Gastric air is present on the left. In this situation, the meconium in the airway acts like a The intercostal spaces appear wide. ball-valve mechanism. On inspiration, air moves in around The lung fields show increased vascular markings, more the meconium debris. On expiration, when airways constrict prominent on the right than on the left and radiating into the around the meconium particles, air is trapped distally. This mid- and outer lung fields. The minor fissure is present on the results in overdistension of airways and terminal saccules right. The overall appearance of the right lung field is one of leading to alveolar rupture and air leaks. more opacity than the left. This finding may also be due to Because the aspirated meconium and amniotic debris are the slight rotation to the right. foreign substances introduced into the lung parenchyma, No indwelling lines or tubes are visible. clearing of these substances by the ciliary apparatus is often Impression: Review of the history and the clinical and labo- inadequate. This causes an inflammatory process in the ter- ratory findings supports a diagnosis of retained lung fluid. minal airways and air sacs.10 Inflammation results in unsta- This clinical diagnosis is supported by the chest x-ray findings ble alveoli causing alveolar collapse, which in turn results in of hyperaeration, increased vascular markings in the hilum an abnormal ventilation-to-perfusion (V˙/Q˙ ) ratio. Figures and lung fields, minimal cardiomegaly, and fluid in the hori- 2B-9a and 2B-9b summarize the pathophysiology of meco- zontal fissure. nium aspiration syndrome.

Revised and updated from: Carey BE, and Trotter C. 1994. Neonatal SIGNS AND SYMPTOMS Network: 13(4): 65–69. Used with permission of Springer Publishing Company, LLC, www.springerpub.com/nn. Clinically, the infant with meconium aspiration syndrome (MAS) may be quite depressed at birth, demonstrating pallor, cyanosis, tachypnea, grunting, and retractions. Because of gas trapping and alveolar overdistention, a barrel chest appearance

Neonatal Radiology Basics Respiratory Disorders Presenting in the Newborn Period 2B-7 R ADIOLOGY BASICS

FIGURE 9 2B-9I Effectsa n Pathophysiology of meconium on of pulmonary meconium function: aspiration (A) normal FIGURE 102B-10I Term n Term neonate neonate with with meconium meconium aspiration aspiration syndrome. alveolarsyndrome. function and gas exchange, (B) complete Notesyndrome. the diffuse, bilateral, dense infiltrates as well as obstruction with atelectasis and intrapulmonary shunt- the right pleural effusion. The heart size is within nor- ing, (C and D) ball valve effect, (C) partial obstruction on Note the diffuse,mal bilateral, limits. The dense tip infiltratesof the endotracheal as well as the tube right is properlypleural effusion. The heart size is within normal limits. The tip of the inspiration and air entry, (D) airway collapse on expira- located between the clavicles and the carina. endotracheal tube is properly located between the clavicles and tion and air trapping plus distention and impingement the carina. on vasculature, (E) overdistention and rupture with air leak, (F) surfactant displacement and atelectasis.

Endotracheal tube tip Pleural effusion

From: Miller MJ, Fanaroff AA and Martin RJ. 2006. The respiratory system, Part 5: Respiratory disorders in preterm and term infants. In Neonatal–Perinatal Medicine: Diseases of the Fetus and Infant, 8th ed., Martin RJ, Fanaroff AA, and Walsh MC, eds. St. Louis: Mosby, 1123. Reprinted by permission. UVC Tip L1-T12

n FIGURE 2B-9FIGUREb 2B-9bPathophysiology Alveolar function of meconium in aspiration meconiumsyndrome. aspiration. UAC tip: L4

Normal function From: Turnage CS. 1989. Meconium aspiration syndrome. Journal of Perninatal and Neonatal Nursing 3(2): 72. Reprinted by permission of Aspen Publishers, Inc.

Complete obstruction In the(atelectasis neonate, and when pulmonary meconium shunting) has penetrated below the vocal cords and into the trachea and large airways, it causes partial and/or total occlusion of terminal airways and air sacs. may be quite depressed at birth, demonstrating pallor, This results in atelectasis distal to the areas of total occlusion cyanosis,may be observed. tachypnea, Rales grunting, and rhonchi and retractions. may be auscultatedBecause of gason and gas trapping with alveolar overdistension in the areas of trappingphysical exam.and alveolar overdistension, a barrel chest appear- Partial obstruction partial occlusion. •Inspiration anceDepending may be observed. on the severity Rales and of meconiumrhonchi may aspiration, be auscultated both In this situation, the meconium in the airway acts like a onrespiratory physical andexam. metabolic acidosis can develop due to hypox- ball-valve mechanism. On inspiration, air moves in around the emiaDepending and hypercarbia. on the severity The hypoxemia of meconium and aspiration,hypercarbia both are meconium debris. On expiration, when airways constrict respiratorysecondary toand the metabolicV ˙/Q˙ mismatching acidosis can described develop above. due to Acidosis hypox- •Expiration of any origin can increase the risk for and/or potentiate per- around the meconiumball valve effe ctairparticles,way air is trapped distally. This emia and hypercarbia. The hypoxemia and hypercarbia are results in overdistensioncollapse on expi ofration airways traps and terminal saccules lead- secondarysistent pulmonary to the V ˙/Qhypertension˙ mismatching (PPHN). described above. Acidosis air, distends alveolus, can ing to alveolar af rupturefect pulmonary and ci airrculation leaks (Figure 9). of any origin can increase the risk for and/or potentiate per- Because the aspirated meconium and amniotic debris are sistentCHEST pulmonary X-RAY hypertension FINDINGS (PPHN). foreign substances introduced into the lung parenchyma, Infiltrates clearing of these substances by the ciliary apparatus is often CHESTComplete X-RAY occlusion FINDINGS of the airway results in atelectasis. •Overdistention and rupture inadequate. This causes an inflammatory process in the termi- Atelectatic areas on x-ray film appear more gray/white than nal airways and air sacs.15 Inflammation results in unstable the air-filled normal alveoli.Infiltrates This is because atelectatic areas alveoli causing alveolar collapse, which in turn results in an haveComplete a greater occlusion density thanof the air-filled airway resultsalveoli inand atelectasis. therefore abnormal ventilation-to-perfusion (V˙/Q˙ ) ratio. Atelectaticblock the beamareas fromon x-ray reaching film appear the x-ray more cassette. gray/white This thanpro- •Atelectasis results due to theduces air-filled an x-ray normal film alveoli.with bilateral, This is becausediffuse, atelectaticpatchy, fluffy, areas or SIGNS AND loss of surfSYMPTOMSactant havenodular a greater (more dense,density gray/white than air-filled areas) alveoli infiltrates and thereforeand asym- Clinically, the infant with meconium aspiration syndrome blockmetric areasthe beam of opacity. from These reaching infiltrates the x-ray may presentcassette. in aThis focal or generalized manner (Figure 2B-10).

N EONATAL N ETWORK 2B-8 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics32 R ADIOLOGY BASICS TABLE 2B-1 n Chest X-Ray Findings in Infants with Meconium FIGURE 2B-11 n A 41-week-gestation male with history of Aspiration Syndrome FIGURE 11 I A 41-week-gestationmeconium aspiration male withsyndrome. history of meconium FIGURE 12 I A 40-week-gestation male with history of meconium 1. Diffuse, patchy/nodular infiltrates: focal or general, asymmetric or This admissionaspiration chest x-ray syndrome. film demonstrates This admission a right chest tension x-ray film aspiration syndrome. This admission chest film has a symmetric pneumothorax.demonstrates The heart aand right mediastinal tension pneumothorax. structures are shifted The heart very characteristic pattern of diffuse, patchy infiltrates. to the left. Heavyand mediastinal infiltrates arestructures noted in are the shifted upper toand the lower left. lungHeavy 2. HyperinflationThe of lucencies lung fields on the right mediastinal and right sub- fields. infiltrates are noted in the upper and lower lung fields. 3. Air leaks pulmonic areas most likely represent free air. 4. Pleural effusion Lung 5. Cardiomegaly margin Right edge of mediastinum Areas of shifted to left Cardiomegalylucency Cardiomegaly may be noted on the chest x-ray of a neonate Free air with MAS. Cardiomegaly is a result of intrauterine asphyxia associated with meconium aspiration and/or the frequent hypoxemia associated with the disease process postnatally. These events cause a cardiomyopathy and decreased cardiac contractility that results in an enlarged heart. The chest x-ray findings of infants with MAS are summarized in Table 2B-1. Right heart border CASE STUDY A 40-week-gestation,Cardiomegaly 3.9 kg, AGA male was delivered by Cardiomegalycesarean section may due beto breechnoted positionon the chestto a 30-year-old, x-ray of a neonategravida 2,with para meconium 0 mother. aspiration The pregnancy syndrome. was Cardiomegaly complicated isby a upper result respiratoryof intrauterine infections asphyxia during associated the first with and meconium third tri- producesInfiltrates an x-ray may filmalso withoccur bilateral, as a result diffuse, of inflammation patchy, fluffy, of orthe aspirationmesters; the and/or mother the was frequent treated hypoxemia with ampicillin associated and antihista with the- nodularairways and(more air dense,sacs. With gray/white inflammation, areas) infiltratesthe linings and of asym-the air diseasemines early process in the postnatally. third trimester. These events cause a cardiomyopa- metricsacs become areas of injured, opacity. predisposing These infiltrates them may to presentcellular innecrosis. a focal thyLabor and decreasedbegan spontaneously cardiac contractility with rupture that resultsof amniotic in an orCellular generalized necrosis manner causes (Figure fluid accumulation10). within the alveoli, enlargedmembranes heart. four The hours chest prior x-ray to findings delivery. of Lightinfants meconium with MAS- resultingInfiltrates in atelectasis. may also occur Cellular as a damage result of to inflammation capillary walls of alsothe arestained summarized fluid was in notedTable at1. that time. Apgar scores were 6 and airwaysresults fromand airinflammation, sacs. With inflammation, leading to pulmonary the linings edemaof the andair 9 at one and five minutes. sacspleural become effusions injured, secondary predisposing to leaky them capillary to cellularbeds. necrosis. CASEThe babySTUDY was intubated and suctioned at delivery with Cellular necrosis causes fluid accumulation within the alveoli, onlyA a40-week-gestation, scant amount of meconium 3.9 kg, AGA fluid male aspirated. was delivered Stimulation by resulting in atelectasis.Hyperinflation Cellular damageand Air toLeaks capillary walls also cesareanand continuous section positive due to airwaybreech pressureposition by to facea 30-year-old, mask were resultsPartial from occlusion inflammation, of the airwayleading andto pulmonaryair sacs by edemameconium and gravidaprovided 2, topara elicit 0 mother. respirations. The pregnancy Physical wasexam complicated was normal by pleuraldebris causeseffusions air secondary trapping. toPartial leaky occlusioncapillary beds. can be demon- upperexcept respiratoryfor dark staining infections of the duringumbilicus the and first the and develop third- strated by hyperinflation of the lungs, which is seen in the trimesters;ment of respiratory the mother distress was treated shortly with after ampicillin birth. The and neonate antihis- flattening of theHyperinflation diaphragm andalong Air with Leaks generalized inter- taminesdemonstrated early in mild the thirdretractions, trimester. grunting, and tachypnea and spersedPartial radiolucency. occlusion of This the airwaymay also and cause air sacs overdistention by meconium of requiredLabor free-flow began spontaneously oxygen to remain with pink. rupture of amniotic debrisairways causes and terminal air trapping. air saccules, Partial occlusionwhich can can lead be to demon- alveo- membranesUpon admission four hours to priorthe NICU,to delivery. the Lightbaby meconium-was placed stratedlar rupture. by hyperinflation Free air dissects of theinto lungs, the pleural which space,is seen causing in the stainedin 100 fluidpercent was oxygennoted at per that oxyhood. time. Apgar A radialscores arterialwere 6 andgas flatteningpneumothoraces of the (Figurediaphragm 2B-11). along with generalized inter- 9revealed at one anda mild five respiratoryminutes. acidosis: pH of 7.33, PCO2 of spersed radiolucency. This may also cause overdistension of 50,The and babyPaO2 wasof 111. intubated A sepsis and evaluation suctioned was at performed, delivery with and airways and terminal Pleuralair saccules, Effusions which can lead to alveolar onlyantibiotics a scant were amount initiated. of meconium fluid aspirated. Stimulation rupture.Pleural Free effusions, air dissects which representinto the fluidpleural in thespace, pleural causing space and continuous positive airway pressure by face mask were pneumothoraces(usually over the (Figurelung bases), 11). may be present in the neonate with MAS (see Figure 2B-10). Pleural effusions result from TABLE 1 I Chest X-Ray Findings in Infants with Meconium the inflammatory processPleural set Effusions up by meconium in the lungs. Aspiration Syndrome InflammationPleural effusions, causes which cellular represent necrosis fluid and in theatelectasis, pleural spacewhich 1. Diffuse, patchy/nodular infiltrates: (usuallyprevents overthe theairways lung andbases), air maysacs befrom present clearing in the lung neonate fluid focal or general, asymmetric or symmetric witheffectively. meconium aspiration syndrome (MAS) (see Figure 10). 2. Hyperinflation of lung fields Pleural effusions result from the inflammatory process set up 3. Air leaks by meconium in the lungs. Inflammation causes cellular 4. Pleural effusion necrosis and atelectasis, which prevents the airways and air 5. Cardiomegaly sacs from clearing lung fluid effectively.

Neonatal Radiology Basics N EONATALRespiratoryN ETWORK Disorders Presenting in the Newborn Period 2B-9 33 R ADIOLOGY BASICS

n FIGURE 11 I A 41-week-gestation male with history of meconium FIGURE 122B-12I A 40-week-gestationA 40-week-gestation male male with withhistory history of meconium of aspiration syndrome. This admission chest x-ray film aspirationmeconium syndrome. aspiration This admissionsyndrome. chest film has a Neonatal Pneumonia demonstrates a right tension pneumothorax. The heart This admissionvery chest characteristic film has a very pattern characteristic of diffuse, pattern patchy of infiltrates.diffuse, and mediastinal structures are shifted to the left. Heavy patchy infiltrates.The lucencies The lucencies on the on right the mediastinalright mediastinal and right and rightsub- eonatal pneumonia occurs in approximately one infiltrates are noted in the upper and lower lung fields. subpulmonicpulmonic areas most areas likely most represent likely represent free air. free air. Npercent of term neonates and ten percent of preterm neonates. The mortality rate for perinatally acquired pneu- Lung monia varies and has been estimated to be 20 percent, with margin Right edge of a higher mortality rate of 50 percent for postnatally acquired mediastinum Areas of pneumonia.11 In one recent review of perinatally acquired shifted to left lucency infection, the overall mortality was 10 percent.12 This decline was attributed to increased use of perinatal antibiotics. The Free air most common bacterial cause of neonatal pneumonia is Group B Streptococcus, mainly serotypes I and II, followed by Gram-negative enteric bacilli. Neonates requiring prolonged hospitalization in the neonatal intensive care unit are at risk for developing pneumonia from hospital-acquired organisms. These organisms are mainly Gram-negative—Pseudomonas, Right heart Klebsiella, Escherichia coli, and Serratia marcescens—but may border also include Staphylococcus aureus, Staphylococcus epidermidis, Cardiomegaly and Candida. Less commonly, prenatally acquired viral infections such as herpes, cytomegalovirus, varicella-zoster, as well Cardiomegaly mayX-Ray be notedEvaluation on the chest x-ray of a An admission x-ray examination (Figure 2B-12) was indi- as syphilis may present with neonatal pneumonia. neonate with meconium aspiration syndrome. Cardiomegaly cated because of respiratory distress consisting of grunting, Perinatally acquired infectious agents can cause pneumo- is a result of intrauterine asphyxia associated with meconium retracting, tachypnea, and an oxygen requirement. Findings nia later in the neonatal intensive care setting, presenting produces an x-ray film with bilateral, diffuse, patchy, fluffy, or aspiration and/or the frequent hypoxemia associated with the were as follows: in the neonate at 4–11 weeks of age.13 Organisms causing nodular (more dense, gray/white areas) infiltrates and asym- disease process postnatally. These events cause a cardiomyopa- Penetration: appears to be normally exposed. this later onset of pneumonia following perinatal acquisition metric areas of opacity. These infiltrates may present in a focal thy and decreased cardiac contractility that results in an No significantrotation is noted. include Chlamydia trachomatis, Ureaplasma urealyticum, or generalized manner (Figure 10). enlarged heart. The chest x-ray findings of infants with MAS The soft tissues of the neck, chest, and extremities are of Mycoplasma ominis, and Pneumocystis carinii.13 Community Infiltrates may also occur as a result of inflammation of the are summarized in Table 1. h normal thickness and without emphysema. acquired viral infections may also be seen in the neonatal airways and air sacs. With inflammation, the linings of the air The bony framework is intact, with 12 ribs bilaterally and intensive care setting with viral spread from caregivers or sacs become injured, predisposing them to cellular necrosis. CASE STUDY normal vertebrae. Clavicles are intact. family members. Respiratory syncytial virus (RSV), entero- Cellular necrosis causes fluid accumulation within the alveoli, A 40-week-gestation, 3.9 kg, AGA male was delivered by The trachea shows a straight air column. virus, adenovirus, and parainfluenza viruses are examples of resulting in atelectasis. Cellular damage to capillary walls also cesarean section due to breech position to a 30-year-old, The hilar area on the left is difficult to distinguish because these. Table 2B-2 summarizes by type organisms that may results from inflammation, leading to pulmonary edema and gravida 2, para 0 mother. The pregnancy was complicated by of patchy infiltrates. cause neonatal pneumonia. pleural effusions secondary to leaky capillary beds. upper respiratory infections during the first and third The heart is of normal configuration, location, and size. trimesters; the mother was treated with ampicillin and antihis- The thymus is present. PATHOPHYSIOLOGY Hyperinflation and Air Leaks tamines early in the third trimester. The diaphragm is between the ninth and tenth ribs bilaterally. Predisposing factors for the development of infection and Partial occlusion of the airway and air sacs by meconium Labor began spontaneously with rupture of amniotic Gastric air is present on the left. pneumonia include immune system immaturity, colonization debris causes air trapping. Partial occlusion can be demon- membranes four hours prior to delivery. Light meconium- The intercostal spaces are normal in size. of the maternal genital tract with potential pathogens, mater- strated by hyperinflation of the lungs, which is seen in the stained fluid was noted at that time. Apgar scores were 6 and The lung fields demonstrate bilateral, diffuse, patchy infil- nal urinary tract infection, amnionitis, prolonged rupture of flattening of the diaphragm along with generalized inter- 9 at one and five minutes. trates. The areas of lucency on the right represent a pneumo- membranes, prematurity, and the need for neonatal intensive spersed radiolucency. This may also cause overdistension of The baby was intubated and suctioned at delivery with thorax in the right subpulmonic area and the right lower lobe. care. Bacterial infection can occur secondary to hematoge- airways and terminal air saccules, which can lead to alveolar only a scant amount of meconium fluid aspirated. Stimulation There may also be free air located at the right mediastinal nous spread from the mother to the fetus in utero. Infection rupture. Free air dissects into the pleural space, causing and continuous positive airway pressure by face mask were area, although a lateral film may be required to distinguish it. may occur by the ascending route from the maternal vaginal pneumothoraces (Figure 11). The history, clinical, laboratory, and x-ray data tract during labor, from aspiration of organisms during deliv- TABLEImpression: 1 I Chest X-Ray Findings in Infants with Meconium Pleural Effusions support theAspiration diagnosis Syndrome of meconium aspiration with a small ery, and postnatally from inhalation of infected respiratory right pneumothorax. droplets. Neonates requiring intensive care are at high risk Pleural effusions, which represent fluid in the pleural space 1. Diffuse, patchy/nodular infiltrates: focal or general, asymmetric or symmetric of colonization of the upper respiratory tract with potentially (usually over the lung bases), may be present in the neonate Revised and updated from: Moore CS. 1994. Meconium aspiration 2. Hyperinflation of lung fields pathogenic organisms and the passage of pathogens from with meconium aspiration syndrome (MAS) (see Figure 10). syndrome. Neonatal Network 13(7): 57–60. Used with permission of caregivers or contaminated equipment. Pleural effusions result from the inflammatory process set up Springer3. Air leaks Publishing Company, LLC, www.springerpub.com/nn. In bacterial pneumonia, alveolar involvement is often by meconium in the lungs. Inflammation causes cellular 4. Pleural effusion more intense than in viral infection. Proteinaceous fluid necrosis and atelectasis, which prevents the airways and air 5. Cardiomegaly may partly or completely fill alveoli. This is followed by an sacs from clearing lung fluid effectively. influx of polymorphonuclear leukocytes and red blood cells.

EONATAL ETWORK N N2B-10 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics 33 During resolution, alveolar macrophages enter the alveoli TABLE 2B-2 n Pathogenic Organisms That May Produce Neonatal and remove intra-alveolar debris, restoring normal lung func- Pneumonia (partial listing) tioning. Staphylococcus aureus and Klebsiella organisms cause Bacteria: Gram-positive Mycoplasma more severe damage to alveoli and can destroy lung tissue Group B beta-hemolytic Ureaplasma urealyticum by causing necrosis of the septum between alveoli. In some Streptococcus Mycoplasma hominis cases, abscess formation occurs. Streptococcus (other types) Viruses Viruses and Mycoplasma may also be acquired transplacen- Staphylococcus aureus Herpes simplex tally, during the labor and delivery process, or postnatally. Viral Staphylococcus epidermidis Cytomegalovirus and mycoplasmal pneumonias involve the bronchi and peri- Listeria monocytogenes Rubella bronchial interstitium more than the alveoli. These organisms Bacteria: Gram-negative Varicella can cause loss of epithelial ciliary appendages and sloughing Escherichia coli Respiratory syncytial into the airways. The end result is stasis of mucus and mucus Klebsiella Influenza secretion, as well as bronchial obstruction with atelectasis, Enterobacter Adenovirus usually around the hilum. A secondary inflammatory reaction Pseudomonas aeruginosa Enterovirus is characterized by mononuclear infiltration into the submu- Serratia marcescens Other cosa and perivascular areas. This further narrows the airway Haemophilus influenzae Treponema pallidum (syphilis) lumen. Smooth muscle constriction, a response to the inflam- Fungi Chlamydia trachomatis matory process, leads to increasing airway obstruction and Candida albicans Pneumocystis carinii bronchospasm. In severe cases of viral and mycoplasmal infection, inflammatory exudate extends into the alveoli.14 Fungal infection, of which Candida is the most common, may be acquired in utero, during the birth process, or post- is obtained; the etiology of the pneumonia; and the presence of natally. Congenitally acquired pneumonia can be diffuse other respiratory disease, such as respiratory distress syndrome as a result of an established inflammatory process at birth. or bronchopulmonary dysplasia. Pneumonia acquired in utero Candida causes tissue invasion in the pharynx and larynx. is likely to be better established than pneumonia acquired Fungi proliferate and may form a thick layer of hyphae, which during delivery. In some neonates, minimal or no abnormal- line the upper and lower respiratory tract. Ulceration of the ity may be apparent on the first x-ray if it is taken soon after pharynx, larynx, and lower respiratory tract can be seen. As initial clinical signs, but follow-up x-rays 24 hours later may the invasive process extends, secondary inflammation occurs, demonstrate the pneumonia. Serial x-rays are more valuable in and the lungs become consolidated and hemorrhagic. Fungal making the diagnosis than is one isolated x-ray, and they are thrombi from infected central lines are another cause of pneu- helpful in following the course of the disease. monia. Emboli from the fungal thrombus shower the lungs, Lung disease has been divided radiologically into two cate and the result may be a diffuse pneumonia.15 gories: air space, or alveolar, disease and interstitial disease. The two may be seen separately, but they may also coexist. CLINICAL PRESENTATION Additionally, interstitial disease frequently progresses to The clinical findings in neonatal pneumonia vary, depend- involve the alveoli, often making it difficult to separate the ing on the infecting organism and the timing of its acqui- two categories of lung disease. Air space disease involves the sition. Acute respiratory distress is frequently present with alveoli, which fill with fluid or exudate that displaces air. This intrauterine and intrapartum-acquired ascending infection. may occur in small, discrete areas or in multiple areas, which The neonate may also have poor Apgar scores, temperature can coalesce and appear as white or dense lung fields. In inter- instability, and poor tone and activity. Overall, the clini- stitial disease, the disease pattern is distributed throughout the cal signs of pneumonia in the early neonatal period may be lung tissue, usually bilaterally, and produces linear strands of indistinguishable from those of respiratory distress resulting density and granularity in the hilar and peribronchial areas.16 from hyaline membrane disease, TTN/retained lung fluid, or Pulmonary patterns described in neonatal pneumonia sepsis. Late-acquired pneumonia may have a gradual or an include (1) infiltrative patterns, (2) changes in lung volume, abrupt onset, depending on the causative agent. Respiratory and (3) pleural effusions. Table 2B-3 lists x-ray findings in deterioration, apnea, and temperature instability may be the pneumonia resulting from various pathogens. presenting findings. Infiltrative Patterns CHEST X-RAY FINDINGS Infiltrative patterns are summarized in Table 2B-4. Chest x-rays are required to support the diagnosis of pneu- Consolidation results when alveoli fill with inflammatory fluid monia and distinguish the infection from other causes of respi- or exudate and may involve the lobe of a lung or a segment ratory distress. The appearance of pneumonia on x-ray varies, of a lobe (Figure 2B-13). Initially, consolidation begins in the depending upon the duration of infection at the time the x-ray periphery and then progresses to the entire lobe of a lung. As

Neonatal Radiology Basics Respiratory Disorders Presenting in the Newborn Period 2B-11 TABLE 2B-3 n Etiology of Pneumonia and Radiologic Picture TABLE 2B-4 n Radiologic Findings That May Be Present in Neonatal Pneumonia Bacteria Radiologic Picture Lung field infiltrates Group B ß-hemolytic Diffuse reticulogranularity or opacification; patchy Streptococcus infiltrate; pleural effusion Consolidation Streptococcus pneumoniae Patchy lobar consolidation; pleural effusion Patchy alveolar Hilar, peribronchial Staphylococcus aureus Diffuse infiltrate; nodular or miliary pneumatocele Reticular, reticulogranular Staphylococcus epidermidis Hazy lung fields or infiltrates Miliary, nodular Listeria monocytogenes Coarse bilateral patchy infiltrates Opacification Escherichia coli Consolidation in one or more lobes; pneumatocele Distribution: Can be bilateral, unilateral, diffuse, Klebsiella Bilateral consolidation; lung abscess; pneumatocele localized, lobar, patchy, scattered, basalar, apical Loss of heart border (silhouette sign); consolidation; Pseudomonas and Serratia Parenchymal consolidation (patchy area or over lung bases) pneumatocele atelectasis Haemophilus influenzae Nonspecific; may mimic RDS or Group B ß-hemolytic Lung volume changes Streptococcus Hyperaeration Viruses Atelectasis Shift of the mediastinum Herpes Perihilar infiltrates; streaky, lobar consolidation; later pleural effusion Pleural effusions Cytomegalovirus Nonspecific, perihilar streaking; hazy lung fields; infiltrates; opacification Rubella Interstitial infiltrates; hazy lung fields Respiratory syncytial Hyperexpansion; patchy consolidation contact with the left heart border. Disease in this portion of the lung results in loss of visualization Adenovirus, enterovirus Hyperexpansion; patchy consolidation of the heart border. Fungi Patchy infiltratescan be scattered through- Candida albicans Diffuse granularity; opacification; coarse infiltrates out both lung fields or localized to one lobe. Mycoplasma They have poorly defined borders and reflect Ureaplasma urealyticum Fine reticular pattern progressing to air space alveolar disease. When localized to one lung, opacification and consolidation they are usually the result of bacterial or myco- Mycoplasma hominis Diffuse reticular pattern; opacification; pleural plasmal infection. They may also be seen sec- effusion ondary to segmental atelectasis occurring with Other viral and mycoplasmal infection. Treponema pallidum Diffuse opacification; consolidation Hilar and peribronchial infiltrates occur as (syphilis) the inflammatory process spreads from the hilum Chlamydia trachomatis Hyperinflation, with streaky infiltrates outward, thickening the bronchial tissue and Pneumocystis carinii Diffuse haziness; granularity; opacity causing partial atelectasis. The hilar area appears smudged or ragged, and opaque streaks radiate Adapted from: Christensen RD, Thibeault DW, and Hall RT. 1986. Neonatal bacterial and fungal pneumonia. In Neonatal Pulmonary Care, Thibeault DW, and Gregory outward following the bronchi (Figure 2B-15). GA, eds. Norwalk, Connecticut: Appleton-Century-Crofts, 593–608; and Murphy A reticular or reticulogranular pattern of T. 1986. Respiratory syncytial virus and miscellaneous agents. In Neonatal infiltrates occurs when the alveoli and termi- Pulmonary Care, Thibeault DW, and Gregory GA, eds. Norwalk, Connecticut: Appleton-Century-Crofts, 624–638. nal bronchioles are air-filled and seen against a background of alveoli that are partially filled with fluid or exudate or are atelectatic. This is a consolidation occurs, air bronchograms (air in the bronchi) can be seen. fine, bubbly pattern similar to that of respiratory Most lobar consolidations are associated with bacterial infection. There is distress syndrome and often seen with Group B usually no change in the volume of the involved lobe because the alveoli beta-hemolytic streptococcal pneumonia (Figure contain fluid or exudate. The affected lobe can be determined by attempt- 2B-16). Nodular or miliary infiltratesshow up ing to visualize the heart border. Because the anterior segments of the as a larger bubbly pattern than that of reticular right upper lobe and the right middle lobe are in contact with the right infiltrates. Nodules of 2–4 mm are seen against heart border, consolidation in these areas will result in loss of visualiza- a background of black, hyperaerated lungs and tion of the heart border (Figure 2B-14). If right lower lobe consolida- represent alveolar and interstitial disease with air tion has occurred, the area will appear more dense or opaque than other trapping. This pattern has been reported in staph- areas of the lung, but the heart border will remain visible. The upper lobe ylococcal pneumonia and some Gram-negative of the left lung has two lower segments, called the lingula, that are in bacillary pneumonias, such as Pseudomonas.17 If

2B-12 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics R ADIOLOGY BASICS

FIGURE 13 I Consolidation of the right middle lobe, resulting in loss FIGURE 15 I Neonate with herpes virus pneumonia. of the right heart border, in a neonate with X-ray shows parahilar streaking in the right upper lobe, right middle lobe Pseudomonas pneumonia. infiltrate, and infiltrate in the left lingula (i.e., the lower segments of the left upper lobe). Note blunting of the bilateral costophrenic angles as a result of pleural effusions.

FIGURE 132B-13I Consolidation n Consolidation of the of rightthe right middle middle lobe, lobe,resulting resulting in loss FIGURE 14152B-14I RightNeonate n Right upper withupper lobe herpes lobe consolidation virusconsolidation pneumonia. in a neonate in a neonate with in loss of the right heart border, in a neonate with Escherichia coli pneumonia. of the right heart border, in a neonate with X-ray shows parahilarEscherichia streaking coli pneumonia.in the right upper lobe, right middle lobe Pseudomonaswith Pseudomonas pneumonia. pneumonia. infiltrate, and infiltrate in the left lingula (i.e., the lower segments of the left upper lobe). Note blunting of the bilateral costophrenic angles as a result of pleural effusions.

interpleural space, separating the visceral and parietalN EONATAL pleura. N ETWORK Effusions appear dense or white on x-ray and may occur bilat- alveoli and terminal bronchioles are air-filled and seen against 37 anecrosis background of alveolar of alveoli walls occurs,that are progression partially filled to pneumatocelewith fluid or erally or unilaterally. A significant amount of fluid can depress exudatecan be seen or are as aatelectatic. larger cystic This collection is a fine, of bubbly lucent pattern air. similar the diaphragm. A small amount of fluid may cause blunting to Hazythat of lung respiratory fields result distress from syndrome mild atelectasis and often or seen alveolar with or loss of the normal costophrenic angle. Pleural effusions fluid dispersed throughout the lung fields (Figures 2B-17 and Group B β-hemolytic streptococcal pneumoniaADIOLOGY (Figure 16). BASIC Nodular2B-18). Opaqueor miliary lungs infiltrates can be theshow result up Rofas severea larger pneumo bubbly- S patternnia resulting than inthat diffuse of reticular atelectasis infiltrates. or exudate Nodules (Figure of 2–4 2B-19). mm Hazy lung fields result from mild atelectasis or alveolar areFIGUREBoth seen collapsed 13 againstI Consolidation and a background fluid-filled of the right of alveoli black, middle havehyperaerated lobe, the resulting same inlungs diffuse loss fluidFIGURE dispersed 152B-15I Neonate n throughoutNeonate with with herpes theherpes virus lung virus pneumonia. fields pneumonia. (Figures 17 and 25 anddensity represent to theof alveolar thex-ray right beam.and heart interstitial border,Air-filled in disease a neonatebronchi with with (air air trapping.broncho- 18).X-rayX-ray shows showsOpaque parahilar parahilar lungs streaking streakingcan inbe inthe the right right result upper upper of lobe, severelobe, right right middlepneumonia middle lobe Thisgrams) pattern may be Pseudomonashas seen been outlined reported pneumonia. against in staphylococcal the opaque background. pneumonia infiltrate,lobe infiltrate, and infiltrate and infiltrate in the left in thelingula left (i.e.,lingula the (i.e., lower the segments lower of the andWith some extensive Gram-negative opacification, bacillary heart borders pneumonias, may not besuch clearly as leftsegments upper lobe). of the Note left upperblunting lobe). of the Note bilateral blunting costophrenic of the bilateral angles as a FIGUREresultcostophrenic of16 pleuralI Bilateral angles effusions. aslung a result fields of show pleural reticulogranularity effusions. and air visible because26 air density is replaced by tissue density. If the Pseudomonas. If necrosis of alveolar walls occurs, progres- bronchograms in a neonate with Group B β-hemolytic sionpredominant to pneumatocele change iscan atelectasis, be seen as the a larger lung cysticvolume collection will be streptococcal pneumonia. ofreduced. lucent air.Differentiating this x-ray pattern from that of severe respiratory distress syndrome may be difficult. FIGURE 14 I Right upper lobe consolidation in a neonate with EscherichiaChanges coli pneumonia. in Lung Volume Changes in lung volume include hyperaeration and atelectasis. Hyperaeration is seen when partial airway obstruction occurs from bronchiolar narrowing as a result of inflammation or when partial mucus plugging occurs. Bronchioles dilate on inspiration and narrow on expiration. Airway narrowing from mucus or edema further limits the airway lumen and results in air trapping. Atelectasis occurs when bronchioles are completely occluded and trapped air is reabsorbed. Lung volume is reduced as indicated by decreasing lung expansion on x-ray. If significant atelectasis occurs primarily in one lung, the mediastinum shifts or is displaced in the direction of the alveoliatelectatic and lung.terminal bronchioles are air-filled and seen against a background of alveoli that are partially filled with fluid or exudate or are atelectatic.Pleural This Effusions is a fine, bubbly pattern similar to Pleuralthat of effusionsrespiratory can distress be seen syndrome in neonatal and pneumonia. often seen Theywith Grouprepresent B βfluid-hemolytic from thestreptococcal inflammatory pneumonia process (Figure entering 16). the Nodular or miliary infiltrates show up as a larger bubbly pattern than that of reticular infiltrates. Nodules of 2–4 mm Hazy lung fields result from mild atelectasis or alveolar are seen against a background of black, hyperaeratedN EONATAL lungs NfluidETWORK dispersed throughout the lung fields (Figures 17 and Neonatal Radiology Basics Respiratory Disorders Presenting in the Newborn Period 2B-13 and represent alveolar and interstitial disease with air trapping. 18).25 Opaque lungs can be the result of severe pneumonia37 This pattern has been reported in staphylococcal pneumonia and some Gram-negative bacillary pneumonias, such as I 26 FIGURE 16 Bilateral lung fields show reticulogranularity and air Pseudomonas. If necrosis of alveolar walls occurs, progres- bronchograms in a neonate with Group B β-hemolytic sion to pneumatocele can be seen as a larger cystic collection streptococcal pneumonia. of lucent air.

FIGURE 14 I Right upper lobe consolidation in a neonate with Escherichia coli pneumonia.

N EONATAL N ETWORK 37 R ADIOLOGY BASICS

alveoli and terminal bronchioles are air-filled and seen against a background of alveoli that are partially filled with fluid or exudate or are atelectatic. This is a fine, bubbly pattern similar to that of respiratory distress syndrome and often seen with Group B β-hemolytic streptococcal pneumonia (Figure 16). Nodular or miliary infiltrates show up as a larger bubbly pattern than that of reticular infiltrates. Nodules of 2–4 mm Hazy lung fields result from mild atelectasis or alveolar are seen against a background of black, hyperaerated lungs fluid dispersed throughout the lung fields (Figures 17 and and represent alveolar and interstitial disease with air trapping. 18).25 Opaque lungs can be the result ofR severeADIOLOGY pneumonia BASICS This pattern has been reported in staphylococcal pneumonia R ADIOLOGY BASICS and some Gram-negative bacillary pneumonias, such as FIGUREFIGURE 17 162B-16II HazyBilateral n Bilateral lung lung fields lung fields in fields a show neonate show reticulogranularity with reticulogranularity cytomegalovirus and air FIGURE 182B-18I Hazy n Hazy lung lung fields fields in a neonatein a neonate with withStaphylococcus Pseudomonas.26 If necrosis of alveolar walls occurs, progres- and air bronchograms in a neonate with Group Staphylococcus epidermidis pneumonia. FIGURE 17 I Hazypneumonia.bronchograms lung fields in in a a neonate neonate with with Group cytomegalovirus B β-hemolytic FIGURE 18 I Hazyepidermidis lung fieldspneumonia. in a neonate with Staphylococcus B ß-hemolytic streptococcal pneumonia. sion to pneumatocele can be seen as a larger cystic collection pneumonia.streptococcal pneumonia. epidermidis pneumonia. of lucent air.

FIGURE 14 I Right upper lobe consolidation in a neonate with Escherichia coli pneumonia.

bilaterally or unilaterally. A significant amount of fluid can dysplasia can result in patchy atelectasis, which must be differ- bilaterallydepress the or diaphragm. unilaterally. A A small significant amount amount of fluid of may fluid cause can entiated from atelectasis resulting from infection. resulting in diffuse atelectasis or exudate (Figure 19). Both col- depressblunting the or diaphragm.loss of the normalA small costophrenicamount of fluid angle. may Pleural cause resultinglapsed and in fluid-filleddiffuse atelectasis alveoli orhave exudate the same (Figure diffuse 19). densityBoth col- to bluntingeffusions mayor loss be seenof the with normal bacterial, costophrenic fungal, and, angle. more Pleural rarely, may be seen with bacterial, fungal, and, more rarely, viral or lapsedthe x-ray and beam. fluid-filled Air-filled alveoli bronchi have (airthe bronchograms)same diffuse density may beto effusionsviralCASE or mycoplasmal STUDY may be seen pneumonia. with bacterial, fungal, and, more rarely, mycoplasmal pneumonia. A 36-week-gestation, 3 kg, AGA female was delivered vag- theseen x-ray outlined beam. against Air-filled the opaquebronchi background.(air bronchograms) With extensive may be viral or mycoplasmal pneumonia. inally to a 34-year-old gravida 4, para 3 mother. The mother seenopacification, outlined heartagainst borders the opaque may not background. be clearly Withvisible extensive because DIFFERENTIAL DIAGNOSIS N EONATAL NDIFFERENTIALETWORK DIAGNOSIS had received intermittent prenatal care for a total of three opacification,air density is heartreplaced borders by tissue may notdensity. be clearly If the visible predominant because DIFFERENTIALThe chest x-ray must DIAGNOSIS be reviewed with the patient’s histo- The chest x-ray must be reviewed with the patient’s history,37 visits. Rupture of membranes occurred 36 hours prior to airchange density is atelectasis, is replaced the by lung tissue volume density. will Ifbe the reduced. predominant If exu- ry, Theclinical chest information, x-ray must beand reviewed laboratory with datathe patient’sin mind. histo- The clinical information, and laboratory data in mind. The varied changedate or fluidis atelectasis, from inflammation the lung volume fills the will alveoli, be reduced. lung expansion If exu- ry, clinical information, and laboratory data in mind. The chest x-ray presentations of neonatal24 pneumonia may mimic I datemay orinitially fluid from appear inflammation near normal. fills theGroup alveoli, Blung β-hemolytic expansion FIGURE 19 Bilateral opacification in a 30-day-old premature the reticulogranularity and opacification of respiratory distress neonate with Candida albicans sepsis and pneumonia. Streptococcus,may initially appear Haemophilus near normal. influenzae24 Group, BCandida, β-hemolytic and FIGURE 19 2B-1I 9Bilateral n Bilateral opacification opacification in a 30-day-old in a 30-day-old premature premature syndrome and the patchy infiltrates and perihilar streaking of Streptococcus,mycoplasmal pneumonias Haemophilus may present influenzae with this, Candida,chest x-ray andpat- The left hemithoraxneonateneonate is more with opacified with Candida Candida than albicans the albicans right.sepsis Air andsepsis bronchograms pneumonia. and retained lung fluid and meconium aspiration syndrome. Mucus are visible on the pneumonia.right. mycoplasmaltern. Differentiating pneumonias this x-ray may patternpresent fromwith thatthis chestof severe x-ray respi- pat- The left hemithorax is more opacified than the right. Air bronchograms plugging in the airways of neonates with bronchopulmonary are visible on the right. tern.ratory Differentiating distress syndrome this mayx-ray be pattern difficult. from that of severe respi- The left hemithorax is more opacified than the right. Air ratory distress syndrome may be difficult. R ADIOLOGYbronchograms BASIC areS visible on the right. Changes in Lung Volume FIGUREChanges 172B-17I inHazy n lungHazy Changeslung volume lung fields fields inin include aLung neonatein a neonate Volumehyperaeration with withcytomegalovirus and atelec- FIGURE 18 I Hazy lung fields in a neonate with Staphylococcus tasis.ChangesHyperaeration inpneumonia. lungcytomegalovirus volumeis seen include when pneumonia. partialhyperaeration airway obstructionand atelec- epidermidis pneumonia. tasis.occursHyperaeration from bronchiolaris seen narrowing when partial as a result airway of obstruction inflamma- occurstion or from when bronchiolar partial mucus narrowing plugging as aoccurs. result ofBronchioles inflamma- tiondilate or on when inspiration partial and mucus narrow plugging on expiration. occurs. BronchiolesAirway nar- dilaterowing on from inspiration mucus or and edema narrow further on expiration.limits the airway Airway lumen nar- rowingand results from in mucus air trapping. or edema Atelectasis further limitsoccurs the when airway bronchi- lumen andoles resultsare completely in air trapping. occluded Atelectasis and trappedoccurs air whenis reabsorbed. bronchi- olesLung are volume completely is reduced occluded as indicatedand trapped by airdecreasing is reabsorbed. lung Lungexpansion volume on x-ray. is reduced If atelectasis as indicated occurs primarily by decreasing in one lung,lung expansionthe mediastinum on x-ray. shifts If atelectasis or is displaced occurs in primarily the direction in one of lung, the theatelectatic mediastinum lung.17 shifts or is displaced in the direction of the atelectatic lung.17 Pleural Effusions Pleural effusions canPleural be seen Effusions in neonatal pneumonia. They representPleural fluideffusions from can the be inflammatory seen in neonatal process pneumonia. entering They the representinterpleural fluid space, from separating the inflammatory the visceral process and parietal entering pleura. the interpleuralEffusions appear space, denseseparating or white the visceral on x-ray and and parietal may pleura.occur Effusions appear dense or white on x-ray and may occur bilaterally or unilaterally. A significant amount of fluid can depress the diaphragm. A small amount of fluid may cause resulting in diffuse atelectasis or exudate (Figure 19). Both col- blunting or loss of the normal costophrenic angle. Pleural N EONATAL N ETWORK lapsed and fluid-filledRespiratory alveoli Disorders have the Presenting same diffuse in the density Newborn to Periodeffusions may be seen with bacterial, fungal, and, more rarely, 2B-14 Neonatal Radiology Basics38 the x-ray beam. Air-filled bronchi (air bronchograms)N EONATAL may be NviralETWORK or mycoplasmal pneumonia. seen outlined against the opaque background. With extensive 38 opacification, heart borders may not be clearly visible because DIFFERENTIAL DIAGNOSIS air density is replaced by tissue density. If the predominant The chest x-ray must be reviewed with the patient’s histo- change is atelectasis, the lung volume will be reduced. If exu- ry, clinical information, and laboratory data in mind. The date or fluid from inflammation fills the alveoli, lung expansion may initially appear near normal.24 Group B β-hemolytic FIGURE 19 I Bilateral opacification in a 30-day-old premature Streptococcus, Haemophilus influenzae, Candida, and neonate with Candida albicans sepsis and pneumonia. mycoplasmal pneumonias may present with this chest x-ray pat- The left hemithorax is more opacified than the right. Air bronchograms tern. Differentiating this x-ray pattern from that of severe respi- are visible on the right. ratory distress syndrome may be difficult.

Changes in Lung Volume Changes in lung volume include hyperaeration and atelectasis. Hyperaeration is seen when partial airway obstruction occurs from bronchiolar narrowing as a result of inflammation or when partial mucus plugging occurs. Bronchioles dilate on inspiration and narrow on expiration. Airway narrowing from mucus or edema further limits the airway lumen and results in air trapping. Atelectasis occurs when bronchioles are completely occluded and trapped air is reabsorbed. Lung volume is reduced as indicated by decreasing lung expansion on x-ray. If atelectasis occurs primarily in one lung, the mediastinum shifts or is displaced in the direction of the atelectatic lung.17

Pleural Effusions Pleural effusions can be seen in neonatal pneumonia. They represent fluid from the inflammatory process entering the interpleural space, separating the visceral and parietal pleura. Effusions appear dense or white on x-ray and may occur

N EONATAL N ETWORK 38 delivery, and the mother delivered 40 minutes after hospital admission. The neonate’s Apgar scores were 5 and 7 at one Neonatal Chylothorax and five minutes. She required oxygen for cyanosis and was retracting and grunting in the delivery room. She was transferred to the NICU. An arterial blood gas following admis- Barbara E. Carey, MN, RN, NNP-BC sion revealed respiratory acidosis and mild metabolic acidosis. Mild hypotension was present and corrected. The neonate chylothorax is an accumulation of lymphatic fluid was intubated and placed on mechanical ventilation. A sepsis A that collects in the pleural space. It is the most common workup was initiated and antibiotics begun. The admission cause of a large pleural effusion in the newborn.18,19 Estimated x-ray is shown in Figure 2B-16. incidences vary from 1 in 10,000 deliveries to 1 in 2,000 admissions to the NICU.19,20 Chylothorax may be unilateral X-Ray Evaluation or, infrequently, bilateral and can occur spontaneously or be The indication for this film was admission to the NICU with acquired secondary to trauma or surgical procedures. The respiratory distress and the admission diagnosis of “rule out right lung is more commonly affected than the left. respiratory distress syndrome; rule out sepsis.” Penetration: appears to be normal. ETIOLOGY Rotation is present to the right. Spontaneous chylothorax is thought to occur secondary to The soft tissues appear normal. overdistention, rupture, or tear in the thoracic duct during the The bony framework is intact. Twelve ribs are present bilat- birth process as a result of transient elevated central venous erally. The vertebrae are normal, and the clavicles are intact. pressure. Other possible contributory factors may include The trachea is deviated to the right because of rotation. The birth trauma leading to tearing of the duct and congenital tracheal air column is straight, indicating an inspiratory film. abnormality of the duct predisposing it to rupture. Another The tip of the endotracheal tube is located just below the first etiology that has been suggested is the occurrence of major thoracic vertebra (T1). The tracheal bifurcation is visible at fistulas, which form because of the failure of some channels the fourth thoracic vertebra (T4), and the right mainstem to connect with the lymphatic network, allowing free move- bronchus is visible. ment of chyle into the pleural space. Cases have been found The hilar area appears normal in size. to be associated with congenital defects such as extralobar The diaphragm is at the ninth thoracic vertebra (T9) sequestration and Noonan, Turner’s, and Down syndromes. bilaterally. It has been estimated that 70 percent of fats are absorbed The pleura reach the edges of the bony thorax, and the cos- into the lymphatic system via the gastrointestinal system and tophrenic angles are visible bilaterally. are transported into the venous blood via the thoracic duct. The gastric bubble is visible on the left. The major thoracic duct crosses from the right to the left The intercostal spaces appear more narrowed on the right posterior mediastinum at the fifth thoracic vertebra (T5) than on the left because of rotation. They appear normal and ascends to drain into the junction of the left subclavian in size. and the internal jugular veins. This is why a right-sided chy- The lung fields reveal a diffuse bilateral reticulogranular lothorax generally occurs when an injury or abnormality is pattern, with air bronchograms visible bilaterally. The right below the level of T5 and a left chylothorax when an injury lung appears more opaque than the left because of rotation. or abnormality is above T5.20 The endotracheal tube sits just below the first thoracic ver- Thoracic and cardiovascular surgeries are the most common tebra (T1). An umbilical artery catheter is positioned at the predisposing iatrogenic causes for chylothorax. Surgery 12th thoracic vertebra (T12) and was subsequently reposi- requiring open repair and manipulation of the aortic arch, tioned between the third and fourth lumbar vertebrae. such as coarctation, patent ductus arteriosus, or subclavian- Impression: The history, clinical presentation, and x-ray pulmonary artery shunt procedures, have a higher incidence are consistent with neonatal pneumonia. However, because of chylothorax than cardiac surgeries not involving the aortic this neonate is 36 weeks gestational age and prenatal care and arch. In one study, thoracotomy and ligation of a patent pregnancy dating are poor, respiratory distress syndrome is ductus arteriosus was found to be the single most common also a possibility. Tracheal cultures and blood cultures taken antecedent to chylothorax, complicating 1 percent of cases.21 following admission to the NICU were positive for Group B Superior vena caval (SVC) obstruction has been reported to beta hemolytic Streptococcus. predispose to chylothorax because of the high central venous pressure that it produces. SVC obstruction usually occurs sec- Revised and updated from: Carey BE, and Trotter C. 1997. Neonatal ondary to thrombosis from indwelling catheters.2 pneumonia. Neonatal Network 16(5): 65–71. Used with permission of Springer Publishing Company, LLC, www.springerpub.com/nn.

Neonatal Radiology Basics Respiratory Disorders Presenting in the Newborn Period 2B-15 TABLE 2B-5 n Chylothorax: Chest X-Ray Findings TABLE 2B-6 n Possible Etiologies of Opaque Hemithorax with Mediastinal Shift to the Opposite Lung Field on X-Ray Location Findings Chest X-Ray Affected side Opaque hemithorax with normal lung volume Fluid Chylothorax Loss of or blunting of the costophrenic angle Hemothorax Widened intercostal spaces Hydrothorax Flattened diaphragm Pneumonia Shift of the mediastinum toward the opposite lung field Solid Diaphragmatic hernia Unaffected side Loss of lung volume Cystic hygroma Narrowed intercostal spaces Tumor Atelectasis Cystic adenomatoid malformation Elevated/domed diaphragm

DIAGNOSIS CLINICAL PRESENTATION When radiologic findings lead to a preliminary diagnosis Fifty percent of the neonates with spontaneous chylotho- of chylothorax, the definitive diagnosis is based on aspiration rax are symptomatic within the first 24 hours of life, and the and evaluation of the pleural fluid. remainder presents with findings in the first week of life.19 The time of symptom onset is thought to be related to the Appearance rate of chyle accumulation. Clinically, these neonates present Prior to enteral feeding that contains long-chain fatty acids, with respiratory distress and decreased breath sounds on the chyle is clear and yellow. Following enteral feeding that intro- affected side. The chest wall is dull to percussion. The cardiac duces fat into the system, chyle becomes milky in appearance. point of maximal impulse (PMI) may also shift as fluid accumulates in the affected hemithorax and causes shifting of the Analysis mediastinum. The diagnosis is made when analysis of the fluid reveals 20–50 leukocytes per high-power field, with lymphocytes RADIOLOGY at 90 percent or greater. The triglyceride level is high and Radiologically, chylothorax is classified as a pleural effu- the cholesterol level is low. The protein and electrolyte con- sion, and the most common x-ray presentation is an opaque, tents are similar to plasma. The fluid is sterile, and chylomi- dense, white hemithorax (Table 2B-5). Effusions represent crons are visible on light microscopy. In the rare event that fluid leakage from chyle, blood, or intravenous fluid or, in the doubt remains regarding the diagnosis, a lipophilic green dye presence of pneumonia, fluid from an inflammatory process administered with a high-fat diet will color the chyle.21 that enters the interpleural space and separates the visceral and parietal pleura (Table 2B-6). As fluid accumulates, MANAGEMENT there is loss or blunting of the normal costophrenic angle Some cases respond to a single thoracentesis. As the fluid on the affected side. The diaphragm becomes depressed due is removed and the lung expands, the defect may be tam- to increased volume, and the intercostal spaces widen. The ponaded to prevent further fluid accumulation.18 If there is mediastinum shifts away from the affected lung as significant recurrence or persistence of the chylothorax, a chest tube volumes of chyle accumulate. This in turn reduces expansion is inserted to drain the chyle. Parenteral nutrition may be of the opposite lung, causing atelectasis and decreased lung initiated because long-chain fatty acids in formula enhance volume and narrowed intercostal spaces. The costophrenic lymphatic flow.23 Alternatively, enteral formula with medium- angle on the side of the unaffected lung is normally preserved, chain triglycerides that bypass the lymphatics may be given and the diaphragm is elevated secondary to atelectasis.22 a trial. If pleural fluid reaccumulates despite management Less commonly, when only a small amount of fluid has or nutritional depletion occurs through loss of protein and accumulated in the chest, opacity may be present at the base electrolytes, surgery may be considered. Surgical explora- of the lung or around the mediastinum initially, and the diag- tion and ligation and/or repair of the duct are possible if a nosis may not be clear. Because a lateral decubitus film will localized problem is found. In cases with no localized area of show a fluid level, it can be helpful in making the diagnosis. chyle flow, surgical management may involve a pleural abra- Ultrasound can also be used to confirm the presence of fluid. sion procedure.1 In addition to weight loss, hyponatremia, In the rare case of bilateral chylothorax, the chest x-ray shows and nutritional depletion, the neonate with a chylothorax is bilateral opacification of the lungs with a central area of aera- also at increased risk for infection caused by loss of immune tion. The picture differs from atelectasis causing opacification globulins and lymphocytes in chyle.18, 24 because the lungs are expanded with fluid, not collapsed.

2B-16 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics CASE STUDY FIGURE 2B-20 n Initial chest x-ray following intubation and A 41-week gestation, 3.3 kg, AGA male was born by vaginal umbilical artery line placement. delivery to a 39 year old, gravida 1, para 0, ab 0, VDRL test negative, rubella-immune mother after 27 hours of labor. The mother sought prenatal care at 20 weeks gestation and had only four prenatal visits. She informed her obstetrician that she was healthy and wanted a natural pregnancy without excessive testing or ultrasound. Counseling the mother about the usual monitoring and testing procedures met with resis- tance, and despite documented telephone follow-up, she remained adamant in refusing normal testing for age and stage of pregnancy. Her labor was complicated by shoulder dystocia, and the delivery required forceps. Apgar scores were 6 and 7 at one and five minutes: minus 2 for color and minus 1 each for heart rate and respiratory effort at one minute and minus 2 for color and minus 1 for respiratory effort at five minutes. The neonate was cyanotic and required bag and mask ventilation and oxygen. Breath sounds were decreased on the right. The infant was transferred to the NICU for further evaluation. Clinical exam revealed poor breath sounds bilaterally, more decreased on the right, and PMI shifted to the left. Transillumination was performed to rule out a pneumothorax and was found to be negative. An initial arterial blood gas revealed respiratory acidosis and hypoxemia. The infant was intubated, an umbilical arterial line was placed, and visualize because of atelectasis. The apex appears to be shifted mechanical ventilation was begun. A sepsis workup was done to the left rib margin at intercostal spaces 7 through 9. and antibiotics were administered. The admission diagnosis The diaphragm is not visible on the right and is visible at the was term neonate, respiratory distress, rule out sepsis, rule tenth intercostal space on the left. out pneumonia. The admission chest x-ray is shown in Figure The pleura reaches the edge of the thorax on the left, and the 2B-20. costophrenic angle is present. The right pleural edge cannot be seen clearly, but may be visible at the midclavicular line, X-Ray Evaluation compressed by a pleural effusion. The indication for this film was admission to the NICU Gastric air is present on the left. with respiratory distress requiring intubation and mechanical The right lung field shows linear opacity to approximately ventilation. the midclavicular line. A line of delineation, possibly repre- Penetration appears normal. senting the compressed pleural edge, is seen from the fifth Rotation is not present. The spine lies in the center of the through the ninth intercostal space, with minimal aeration. film, and the clavicles are straight. The mediastinum is shifted to the left. The left lung field The soft tissues are normal in appearance. shows atelectasis and air bronchograms. The bony framework is intact with 12 ribs present bilater- Tubes and lines. The endotracheal tube is visible at the ally. Ribs, vertebrae, and clavicles are intact. The ribs in the third thoracic vertebra, and the umbilical artery catheter tip right lung field are horizontal in appearance, and the ribs in is visible between the seventh and eighth thoracic vertebral the left lung field are downward sloping. bodies. The trachea is slightly deviated to the left. The tracheal air Impression. The changes seen in the right lung are consis- column is straight, indicating an inspiratory film. The tip of tent with a right pleural effusion with mediastinal shift, and the endotracheal tube is located at the third thoracic verte- the clinical presentation is consistent with the diagnosis. bra. The tracheal bifurcation is visible at the fourth thoracic Analysis of fluid aspirated from the right chest was consistent vertebra, and the right and left mainstem bronchi are visible. with chyle. The hilum. The right hilum shows minimal aeration and air bronchograms in the area of the sixth through ninth thoracic Originally published: Carey BE. 2001. Neonatal chylothorax. Neonatal Network 20(2): 53–55. Used with permission of Springer Publishing vertebrae. The left hilum shows air bronchograms in the area Company, LLC, www.springerpub.com/nn. of the fourth through the eleventh vertebrae. The mediastinum is shifted to the left. The cardiac silhouette is difficult to

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2B-18 Respiratory Disorders Presenting in the Newborn Period Neonatal Radiology Basics