Diseases » Wegener's granulomatosis

Respiratory Distress and Apnea

Respiratory Distress and Apnea: Excerpt from The Diagnostic Approach to Symptoms and Signs in Pediatrics

Signs of respiratory distress include tachypnea,dyspnea, nasal flaring, grunting, retractions, and cyanosis. Apneais an extreme form of respiratory distress. Respiratory distress(neonatal and postneonatal) is discussed in the first part of thechapter and apnea in the second part.

Principal Causes of Respiratory Distress (Neonatal)

1. Upperrespiratory tract obstruction
2. Lower respiratory tract disorders
   1. Transienttachypnea of the newborn
   2. Respiratory distress syndrome (hyalinemembrane disease)
   3. Meconium aspiration and other aspirationsyndromes
   4. Pneumonia
   5. Pulmonary air leaks
   6. Pulmonary hemorrhage
   7. Bronchopulmonary dysplasia
   8. Congenital malformations of the lungs,bronchi, diaphragm, and rib cage
      1. Lung agenesis and aplasia
      2. Pulmonary hypoplasia
      3. Pulmonary sequestration
      4. Lobar emphysema
      5. Cystic lung lesions
         1. Bronchogeniccyst
         2. Congenital cystic adenomatoid malformation
         3. Intrapulmonary cysts
         4. Congenital pulmonary lymphangiectasia
      6. Chylothorax
      7. Bronchial malformations
      8. Diaphragm lesions
         1. Congenitaldiaphragmatic hernia
         2. Diaphragmatic eventration
         3. Diaphragmatic paralysis or paresis
      9. Rib cage anomalies
   9. Persistent fetal circulation
3. Cardiac disorders
4. Hematologic disorders
   1. Anemia
   2. Polycythemia
5. Metabolic disorders
   1. Hypothermia
   2. Hypoglycemia
   3. Metabolic acidosis
6. Neurologic and muscle disorders
   1. Braindisorders
   2. Spinal cord injury
   3. Neuromuscular disorders
7. Drugs

Clinical Features and Diagnosis: Respiratory Distress (Neonatal)

Upper Respiratory Tract Obstruction

Disorders that cause upper respiratory tractobstruction are discussed in Chap.63, Stertor, Stridor, and Airway Obstruction.

Lower Respiratory Tract Disorders

Transient Tachypnea of the Newborn

Delayedresorption of lung fluid or mild immaturity of surfactant systemare most probable explanations for this disorder, which usuallyoccurs in term infants soon after birth.

Respiratory rate is commonly 60–80breaths/min but sometimes is >100 breaths/min.Mild intercostal retractions and expiratory grunting also may occur.

Characteristic chest radiographic findingsare prominent perihilar markings, hyperaeration, widening of interlobarfissures, and evidence of interstitial and pleural fluid.

Most infants require <40% supplementaloxygen. Tachypnea usually resolves in 3 or 4 days.

Respiratory Distress Syndrome (Hyaline Membrane Disease)

Respiratorydistress syndrome, which is most common cause of respiratory distress inpreterm infants, is due to inadequate amount of surfactant. Someinfants experience intrapartum asphyxia and fail to expand theirlungs at birth, whereas others develop tachypnea and expiratorygrunting within first 1–2 hrs of life.

Spectrum of disease varies from mild(tachypnea and minimal oxygen requirement) to severe (apnea andrespiratory failure). Crackles may be heard on chest exam.

Characteristic chest radiograph showsdiffuse reticulogranular infiltrates, atelectasis, and air bronchograms.

Diagnosis is clinical and radiographic.

Meconium Aspiration and Other Aspiration Syndromes

Neonateswho aspirate meconium are usually those who have had intrapartumasphyxia.

Thick meconium in upper airway andmeconium staining of skin and nails are usual findings. Airway obstruction,pneumonia, and respiratory failure can occur.

Chest radiography shows irregular distributionof coarse, patchy infiltrates and hyperaeration.

Clinical and radiologic findings arediagnostic.

Aspiration of feedings sometimes occursin normal infants but is more frequent in those with sucking andswallowing disorders (see Chap.65, Sucking and Swallowing Difficulty).

Pneumonia

Pneumoniamay be caused by infections acquired transplacentally, during birthprocess, and postnatally. Viral infections transmitted by transplacentalroute include enteroviruses, adenoviruses, influenza viruses, rubellavirus, varicella-zoster virus, herpes simplex virus, cytomegalovirus,and HIV. Transplacental bacterial infections caused by L. monocytogenes,M. tuberculosis, or T. pallidum are less common than viral infections.

Neonatal pneumonia is most commonlyacquired during birth process. Group B Streptococcus is most commonpathogen; other pathogens (e.g., gram-negative enteric bacteria)are less common. Most common viral agents acquired during birthprocess are herpes simplex virus and cytomegalovirus. C. trachomatisis also acquired during delivery and usually presents at 2–8wks of age with staccato cough and wheezing. History of conjunctivalinfection may or may not exist.

Inadequate hand washing and exposureto respiratory equipment or humidified incubators may contributeto infection, especially with S. aureus and gram-negative entericbacteria.

Other causes of postnatal infectionsinclude respiratory syncytial virus, parainfluenza viruses, influenzaviruses, herpes simplex virus, cytomegalovirus, and fungi (C. albicans).

Infants with pneumonia present withrespiratory distress. Chest radiography shows interstitial or alveolarinfiltrates or consolidation. With suspected bacterial pneumoniain newborns, blood and spinal fluid cultures should be performed,and treatment begun immediately while awaiting culture results.

Diagnosis of viral infections is discussedin other chapters.

Pulmonary Air Leaks

Extrapulmonaryair can accumulate in interstitial spaces of lung (pulmonary interstitialemphysema), mediastinum (pneumomediastinum), pleural space (pneumothorax),and pericardium (pneumopericardium).

Common cause of pulmonary interstitial emphysemais positive-pressure mechanical ventilation.

Pneumomediastinum results from dissectionof air from interstitial space into mediastinum.

Pneumothorax results from mediastinalair rupture into pleural space or rupture of air blebs on surfaceof lung. Most common causes of pneumothorax are respiratory distresssyndrome, meconium aspiration, and high-pressure mechanical ventilation.

Pneumopericardium is produced fromdissection of mediastinal air into pericardium.

Clinical presentation depends on sizeand location of air leak. Significant unilateral pneumothorax collapsesipsilateral lung and shifts heart and mediastinum to opposite sidewith diminished breath sounds on affected side. Significant pneumopericardiummay compromise cardiac filling and cause diminished cardiac output.

Chest radiography is diagnostic ofdifferent types of air leak.

Pulmonary Hemorrhage

Predisposingfactors in neonatal period include perinatal asphyxia, septicemia,and mechanical ventilation, especially in those with respiratorydistress syndrome.

Accompanying respiratory distress isbloody fluid, which oozes from nose, mouth, or endotracheal tube.

Depending on how severe bleeding is,chest radiography may show spectrum of findings ranging from patchyinfiltrates to opacification of lungs.

Bronchopulmonary Dysplasia

This form of chronic lung disease developsin neonates treated with prolonged oxygen therapy and positive-pressureventilation for primary lung disorders. Most infants improve duringfirst 1–2 yrs of life, and with time chest radiograph becomesnormal. However, some of these children continue to have abnormalpulmonary function in childhood. Others with severe disease developcor pulmonale and succumb to their illness.

Congenital Malformations of Lungs, Bronchi, Diaphragm, andRib Cage

Lung Agenesis and Aplasia

Lung agenesisis complete absence of lung or lobe and its branches, whereas lung aplasiais complete absence of lung tissue except for presence of smalllobar bronchus.

Respiratory distress often occurs atbirth with decreased breath sounds on affected side.

Chest radiography shows opaque hemithoraxwith displacement of mediastinum and normal lung toward involvedside.

Bronchoscopy shows absence of mainbronchus in agenesis and presence of small bronchus in aplasia.

Pulmonary Hypoplasia

Pulmonaryhypoplasia refers to smaller than normal lungs. Can be isolatedmalformation or occur in association with space-occupying lesionsof thorax (congenital diaphragmatic hernia, cystic adenomatoid malformation,large pleural effusion), oligohydramnios (renal agenesis, polycystickidney disease), and thoracic and abdominal wall abnormalities (asphyxiatingthoracic dystrophy, large omphalocele).

Respiratory distress, chronic cough,and recurrent infection may occur with unilateral hypoplasia. Thoraxis asymmetric because of underdevelopment of 1 side.

Chest radiography shows small hemithoraxwith displacement of mediastinum toward affected side. When bilateralhypoplasia occurs as isolated malformation, respiratory distressoccurs at birth and chest radiography shows small but clear lungfields.

Pulmonary Sequestration

Mass ofnonfunctioning pulmonary tissue that receives its blood supply fromsystemic circulation.

May occur within or outside a lobe.Intralobar sequestration usually occurs in lower lobe of eitherlung, whereas extralobar sequestration usually occurs just aboveor below diaphragm on left side. Whereas intralobar sequestrationis usually isolated malformation, extralobar sequestration is commonly associatedwith other malformations (e.g., diaphragmatic hernia and pulmonaryhypoplasia).

Clinical findings include respiratorydistress, hemoptysis, and recurrent pneumonia.

Chest radiography shows mass lesion.

Chest CT or MRI is usually diagnostic.

Lobar Emphysema

Overdistensionof lobe of lung (usually upper lobe). Usually congenital but alsomay be acquired secondary to extrinsic or intrinsic airway obstruction.

Respiratory distress occurs with decreasedbreath sounds and hyperresonance on involved side.

Chest radiography shows large distendedlobe or lobes with displacement of mediastinum to opposite sideand compression of contralateral lung. Extension of pulmonary vesselsto periphery of hyperexpanded lung almost always distinguishes lobaremphysema from lung cyst or pneumothorax.

Cystic Lung Lesions

Bronchogenic Cyst

Abnormalbudding or branching of tracheobronchial tree produces bronchogenic cysts,which are found incidentally or because they are infected. Locationcan be above or at carina or adjacent to 1 of main lobar bronchi.

They usually do not communicate withtracheobronchial tree and are usually fluid-filled, but if theycommunicate with airway or esophagus, they may contain air. Airwayor lung compression can cause respiratory distress.

CT or MRI is usually diagnostic.

Congenital Cystic Adenomatoid Malformation

Usuallyconsists of multiple cysts, frequently within 1 lobe of lung.

Size of lesion determines age of presentationand degree of respiratory distress.

Chest CT is usually diagnostic.

Intrapulmonary Cysts

Can be singleor multiple and involve ≥1 lobes of lung.

Respiratory distress may occur duringneonatal period. Older children may develop chronic cough or persistentinfiltrate.

Chest radiography usually shows ovalor round translucent area or areas within pulmonary parenchyma containingair or combination of fluid and air.

Chest CT usually confirms diagnosis.

Congenital Pulmonary Lymphangiectasia

Is the dilatationof lung lymphatics. Can occur as isolated defect, with congenital heartlesions that cause obstruction of pulmonary venous drainage, orwith generalized lymphangiectasia.

Respiratory distress usually beginsat birth.

Chest radiography shows reticular appearanceof lungs with nodular infiltrates and hyperinflation.

Localized form of this disorder, whichis less common, may only involve 1 or 2 lobes of lung and presentlater in life with mild respiratory distress or abnormal chest radiograph.

Lung biopsy confirms diagnosis.

Chylothorax

Presenceof chylous fluid in the thorax. Usually attributed to trauma fromdelivery or congenital abnormalities of thoracic duct system.

Lymph does not become chylous untilingestion of formula or breast milk. If large amount of chyle accumulates,respiratory distress occurs, with decreased breath sounds over affectedthorax.

Chest radiography shows large fluidcollection and shift of mediastinum.

Thoracentesis reveals chyle, whichappears milky and has high protein and fat content.

Bronchial Malformations

Bronchialstenosis usually involves main bronchus with narrowing just distalto carina. Narrowing of lobar bronchus usually results in recurrentinfection or atelectasis of involved lobe. Usual presenting featuresare respiratory distress and recurrent lung infection.

Chest radiography may show hyperinflationof involved lung and evidence of recurrent infection or atelectasis.

Chest CT or bronchoscopy is usuallydiagnostic.

Diaphragm Lesions

Congenital Diaphragmatic Hernia

Congenitaldefect in diaphragm allows herniation of abdominal organs into hemithorax,producing varying degrees of lung hypoplasia. Nearly 90% areon left side.

Severe respiratory distress beginsat birth.

Diagnostic chest radiograph shows air-filledloops of bowel and occasionally liver in thoracic cavity.

Diaphragmatic Eventration

Abnormalhigh position of diaphragm or portion of diaphragm, which is dueto congenital defect of muscularization of diaphragm.

Most children are asymptomatic, butmild respiratory distress can occur.

Diagnosis is usually made by chestradiography or fluoroscopy.

Diaphragmatic Paralysis or Paresis

Occurrenceis usually due to phrenic nerve injury from thoracic surgery.

Respiratory distress and asymmetricchest movement can occur.

Fluoroscopy or U/S that showsparadoxic movement of affected hemidiaphragm during respirationis diagnostic.

Rib Cage Anomalies

Thoracicrib cage anomalies that reduce amount of intrathoracic volume maycause respiratory distress. These include asphyxiating thoracicdystrophy, thanatophoric dysplasia, achondrogenesis, and chondroectodermaldysplasia.

Structural anomalies of rib cage andthorax usually are obvious on physical exam.

Physical exam, chest radiograph, andskeletal survey are usually diagnostic of specific disorder.

Persistent Fetal Circulation

Is the persistenceof high pulmonary vascular resistance after birth with resultinghypoxemia and cyanosis. Affected infants are usually near term,and many have history of perinatal asphyxia.

Soon after birth, respiratory distressoccurs. Hyperoxia test with exposure to 100% oxygen for5–10 mins shows small, if any, increase in partial pressureof arterial oxygen (P_aO₂)(<20 mm Hg). Simultaneous preductal-postductal measurementsof P_aO₂ inright arm and umbilical artery reveal P_aO₂ inright arm that is >15 mm Hg higher than in umbilical artery,which is consistent of right-to-left shunt across patent ductusarteriosus

2-D echocardiogram with Doppler methodsshould be performed to rule out any form of structural cardiac disease.

Cardiac Disorders

Disorders that cause cardiac failure or cyanosismay produce respiratory distress. See Chap.7, Cardiac Failure, and Chap. 12, Cyanosis.

Hematologic Disorders

Anemia

Severe acute or chronic anemia may causerespiratory distress. Pallor usually is evident. Low Hct or Hgbconfirms presence of anemia. Diagnostic approach to anemia is discussedin Chap. 45, Pallor (Anemia).

Polycythemia

Common occurrence in infants who have haddelayed clamping of umbilical cord or in infants of diabetic mothers.Venous Hct is greater than 65%, and mild respiratory distressmay occur.

Metabolic Disorders

Hypothermia

May occur in preterm low-birth-weight infantswho are otherwise normal, or in ill newborns who have bacterialmeningitis, septicemia, or intracranial hemorrhage. Oxygen consumptionis significantly increased, and hypoxemia as well as metabolic acidosismay occur.

Hypoglycemia

Irregularrespirations, apnea, seizures, and alteration of consciousness mayoccur in infants with hypoglycemia.

Low blood glucose is diagnostic (see Chap. 59, Seizures).

Metabolic Acidosis

Increase in minute ventilation is compensatoryresponse to metabolic acidosis and lowered blood pH. Normal aniongap with reduced bicarbonate may occur with diarrhea or renal tubularacidosis. Increased anion gap with accumulation of fixed acid occurswith lactic acidosis (lactate), diabetic ketoacidosis (beta-hydroxybutyrate,acetoacetate), and organic acidemias (organic acids).

Neurologic and Muscle Disorders

Brain Disorders

Respiratory distress and apnea may occurwith intracranial hemorrhage or cerebral edema as consequence ofperinatal asphyxia or birth trauma. Other causes of depressed respirationand apnea include cerebral malformations (Chiari, Dandy-Walker),bacterial meningitis, viral encephalitis, and brain tumors.

Spinal Cord Injury

Injury tospinal cord in neonates may occur with vaginal breech delivery orshoulder dystocia.

Fractures of vertebrae with transectionof the cord may result in irregular respirations and apnea, as wellas absence of spontaneous movements.

Neurologic findings depend on locationand severity of lesion.

Neuromuscular Disorders

Disorders affecting neuromuscular system(spinal muscular atrophy, myasthenia gravis, congenital myopathies)may produce slow and shallow respirations with hypoventilation andrespiratory failure (see Chap.33, Hypotonia and Weakness).

Drugs

Drugs (e.g., magnesium sulfate, morphine,and meperidine) that are given to some mothers during labor cancause neonatal respiratory depression. Neonatal drug withdrawalsyndrome may produce tachypnea as 1 of its manifestations.

Principal Causes of Respiratory Distress (Postneonatal)

1. Upperrespiratory tract obstruction
2. Lower respiratory tract disorders
   1. Bronchiolitis
   2. Asthma
   3. Foreign body
   4. Pneumonia
   5. Cystic fibrosis
   6. Lung abscess
   7. Pleural effusion/empyema
   8. Congenital malformations of the lungs,bronchi, diaphragm, and rib cage
3. Cardiac disorders
4. Noncardiac pulmonary edema
5. Mediastinal masses
   1. Anteriormediastinal masses
   2. Middle mediastinal masses
   3. Posterior mediastinal masses
6. Pulmonary tumors (primary and metastatic)
7. Chest trauma
   1. Pulmonary contusion
   2. Pulmonary laceration
   3. Pneumothorax and hemothorax
   4. Mediastinal emphysema
   5. Chylothorax
   6. Tracheobronchial injuries
   7. Myocardial contusion
   8. Pericardial tamponade
   9. Diaphragmatic rupture
   10. Other injuries
8. Hematologic disorders
9. Metabolic disorders
   1. Hypothermia
   2. Hypoglycemia
   3. Metabolic acidosis
10. Neurologic and muscle disorders
11. Drugs
12. Psychologic disturbance

Clinical Features and Diagnosis: Respiratory Distress (Postneonatal)

Some disorders discussed above can also causerespiratory distress after the neonatal period. This section focuseson disorders that cause respiratory distress in infancy, childhood,and adolescence.

Upper Respiratory Tract Obstruction

Disorders that cause upper respiratory tractobstruction are discussed in Chap.63, Stertor, Stridor, and Airway Obstruction.

Lower Respiratory Tract Disorders

Bronchiolitis, asthma, foreign body, pneumonia,cystic fibrosis, lung abscess, and pleural effusion/empyemaare discussed in other chapters. Malformations of lungs, bronchi,diaphragm, and rib cage are discussed in the previous section.

Cardiac Disorders

Any cause of cardiac failure or cyanosismay produce respiratory distress. These disorders are discussedin Chap. 7, Cardiac Failure,and Chap. 12, Cyanosis.

Noncardiac Pulmonary Edema

Individualswith noncardiac pulmonary edema have respiratory distress.

Chest radiography shows evidence ofpulmonary edema without cardiomegaly.

Possible causes include

Altered permeabilityof lung [influenza virus and S. pneumoniae pneumonia, smoke inhalationwith associated thermal injury, near drowning, aspiration pneumonia,radiation, drug reaction, blood transfusion reaction, acute respiratorydistress syndrome, circulating toxins (e.g., endotoxin and coralsnake venom), disseminated intravascular coagulation]

Decreased plasma oncotic pressure (hepaticfailure, malnutrition, protein-losing enteropathy)

Decreased negative interstitial pressure(croup, supraglottitis)

Other disorders of mixed or unknownetiology (neurogenic pulmonary edema, heroin, high altitude, pulmonaryemboli)

Mediastinal Masses

Mediastinumis anatomic space in thorax that separates the lungs and their visceral pleura.

Horizontal line drawn from sternalangle to fourth intervertebral disk space divides mediastinum intoupper and lower compartments.

On lateral chest radiograph, lowercompartment can be divided into 3 sections. Anterior mediastinumis space from sternum to anterior trachea and pericardium, whereasposterior mediastinum is space between posterior aspect of tracheaand spine. Middle mediastinum is space between anterior and posteriormediastinum and contains trachea, major bronchi, and paratrachealspaces.

Anterior Mediastinal Masses

Usuallyarise from thymus or lymph nodes. Normal thymus can be recognizedby its characteristic scalloped border on chest radiograph.

Lymphoma is most common anterior mediastinalmass found in older children and adolescents. Less common are thymoma,teratoma, lymphangioma, and thyroid tumors.

CT defines location and extent of mass.

Histologic diagnosis is definitive.

Middle Mediastinal Masses

Usuallyenlarged lymph nodes or cysts (bronchogenic or neurenteric). Lymphnode enlargement may occur secondary to bacterial pneumonia, tuberculosis,histoplasmosis, Hodgkin disease, and non-Hodgkin lymphoma.

Combination of chest radiograph andchest CT are useful diagnostically.

Bronchogenic cysts are round or ovalmasses with sharp margins that may contain gastric mucosa. CT locatesand defines extent of mass, and diagnosis is confirmed at surgery.

Neurenteric cysts are usually largerthan bronchogenic cysts and occur in middle or posterior mediastinum.Associated findings include vertebral (spina bifida, hemivertebrae)and spinal cord (tethered cord) anomalies. CT myelography and MRIare useful in evaluation of thoracic and spinal components of neurentericcysts.

Posterior Mediastinal Masses

Neurogenictumors (neuroblastoma, ganglioneuroblastoma, ganglioneuroma) accountfor about 95% of posterior mediastinal masses.

Neuroblastoma is more common than othertumors and usually occurs in children <2 yrs. Intraspinalextension may occur with variable clinical presentation, which mayinclude extremity weakness and impaired bowel and bladder function.CT myelography and MRI define location and extent of tumor. See Chap. 1, Abdominal Masses,for further discussion of neuroblastoma.

Pulmonary Tumors (Primary and Metastatic)

Unusualin children and may involve bronchi, lung parenchyma, or pleura.

Benign bronchial tumors include papillomas,adenomas, hemangiomas, and hamartomas, and are much more commonthan benign parenchymal tumors.

Primary malignant tumors include bronchogeniccarcinoma and various sarcomas.

Common metastatic tumors to the lungare Wilms tumor, osteogenic sarcoma, neuroblastoma, and rhabdomyosarcoma.Pleural tumors include same metastatic tumors as well as primarymesothelioma.

Clinical manifestations of pulmonarytumors include respiratory distress, chronic cough, and hemoptysis.

Mass lesion is seen on chest radiographwith parenchymal tumor. Multiple, round or oval, peripheral or subpleuralnodules may be seen with metastatic disease.

Chest CT is useful in diagnosis ofparenchymal mass lesions and metastatic disease. Histologic diagnosisis definitive.

Chest Trauma

May causesevere bruising and soft tissue injury, fractures of sternum orribs, pulmonary contusion, pulmonary laceration, pneumothorax, hemothorax,mediastinal emphysema, chylothorax, tracheobronchial injuries, myocardialcontusion, pericardial tamponade, diaphragmatic rupture, and other injuries.Significant intrathoracic injuries can present with virtually noexternal physical evidence of trauma.

Control of airway should be assured,and chest radiography performed.

Depending on suspected diagnosis, certaintests are useful in investigation of child with chest trauma: bloodHgb, chest radiography, arterial blood gas, thoracentesis, chestCT, bronchoscopy, and aortic angiography.

Pulmonary Contusion

Occurs within minutes of chest injury andis localized to segment or lobe of lung. Produces homogenous parenchymaldensities on chest radiograph. Chest CT confirms diagnosis.

Pulmonary Laceration

Commonly occurs from penetrating chest traumaor rib fractures. Hemopneumothorax and parenchymal hemorrhage mayoccur. CT confirms diagnosis.

Pneumothorax and Hemothorax

Chest traumamay cause pneumothorax and/or hemothorax.

Respiratory distress and decreasedbreath sounds occur on involved side. Hyperresonance to percussionmay be found with pneumothorax, whereas dullness to percussion mayoccur with hemothorax.

Chest radiograph confirms diagnosisof pneumothorax. Thoracentesis confirms diagnosis of hemothorax.

Mediastinal Emphysema

Dissection of air into mediastinum producespneumomediastinum, whereas dissection of air into soft tissues ofneck and chest produces subcutaneous emphysema with crepitus. Chestradiography is diagnostic.

Chylothorax

Disruptionof thoracic duct with chylothorax may occur from penetrating woundor hyperextension injury of spine.

Chest radiography shows pleural effusion.

Thoracentesis reveals milky white fluidwith high protein and fat content, which confirms diagnosis.

Tracheobronchial Injuries

Trachealtear or fracture produces pneumomediastinum and sometimes hematoma formation,whereas bronchial fracture may produce massive atelectasis followingchest trauma.

Combination of tests, including chestradiography, chest CT, and bronchoscopy, are usually diagnostic.

Myocardial Contusion

May present with chest pain and respiratorydistress. ECG ST- and T-wave changes occur over 24–48 hrs.Elevation of creatine kinase MB fraction indicates myocardial injury.

Pericardial Tamponade

May occurfrom dissection of air into pericardium (producing pneumopericardium) orfrom bleeding into pericardium (producing hemopericardium).

Increasing heart rate, decreasing BP,decreasing pulse pressure, enlarging liver, and pulsus paradoxusof >15 mm Hg suggest pericardial tamponade.

Chest radiography shows enlarged cardiacshadow that may be surrounded by air (pneumopericardium).

2-D echocardiography helps confirmdiagnosis.

Pericardiocentesis is both diagnosticand therapeutic.

Diaphragmatic Rupture

Usuallyoccurs on left side.

Clinical findings include respiratorydistress and chest pain. Stomach may be in thorax, and if so, bowelsounds may be heard in thorax on involved side.

Chest radiography usually confirmsdiagnosis.

Other Injuries

Chest injuriesalso may cause myocardial or septal rupture, valve injury, disruption andthrombosis of coronary arteries, and rupture of aorta. Most commonsite of intracardiac rupture is right ventricle, which lies justbelow sternum. Aortic valve is most common valve damaged in acutechest trauma. Left descending coronary artery may have a tear leadingto occlusion.

ECG usually shows persistent ST- andT-wave changes.

Most consistent sign of lacerated orruptured aorta is widened mediastinum on chest radiography.

Hematologic Disorders

Any cause of severe anemia may produce respiratorydistress. See Chap. 45, Pallor(Anemia).

Metabolic Disorders

Hypothermia

Causes of postneonatal hypothermia includeprolonged exposure to low environmental temperature, sudden immersionin cold water, and septicemia. Severe hypothermia produces lowerBP and heart rate as well as impaired mental status. Respiratorydepression occurs late in course.

Hypoglycemia

See discussion of hypoglycemia above andin Chap. 59, Seizures.

Metabolic Acidosis

Severe metabolic acidosis may cause respiratorydistress, with compensatory increase in minute ventilation. Seediscussion above.

Neurologic and Muscle Disorders

Brain disorders(hypoxic-ischemic encephalopathy, intracranial hemorrhage, bacterialmeningitis, viral encephalitis) may depress respiration and causeslow shallow breathing and apnea.

Anterior horn cell disorders (spinalmuscular atrophy, enteroviral infection) can produce weakness withineffective intercostal muscle function, slow and shallow respirations,and respiratory failure.

Other neuromuscular disorders thatproduce diminished intercostal muscle and diaphragm function andrespiratory failure include Guillain-Barré syndrome, botulism,and some primary muscle diseases.

Drugs

Overdose of morphine or meperidine may depressrespiration and cause slow shallow breathing and apnea. If intravenouslorazepam or diazepam is given too quickly, shallow breathing andapnea may occur.

Psychologic Disturbance

Anxiety or hysteria may produce hyperventilationand respiratory distress. So may pain and fear.

Diagnostic Approach: Respiratory Distress

In preterminfants, most common cause of respiratory distress is respiratorydistress syndrome. In term infants, transient tachypnea, meconiumaspiration, pneumonia, and pneumothorax are most common lower respiratorytract disorders causing respiratory distress. Other nonpulmonarycauses of respiratory distress in neonates are congenital heartdisease, persistent fetal circulation, and septicemia. In infancyand childhood, most common causes of respiratory distress are bronchiolitis,croup, asthma, pneumonia, foreign body aspiration, and congenitalor acquired heart disease with cardiac failure.

History and physical exam suggest mostlikely cause for respiratory distress. Oxygen saturation in roomair indicates degree of hypoxemia. Certain tests should be considereddepending on clinical circumstances:

Airway radiography or endoscopy for upperairway obstruction

Chest radiography for lower respiratorydisorders or cardiac disease

CBC for anemia

Serum electrolytes and creatinine;blood urea nitrogen; and venous/capillary pH for metabolicacidosis

ECG and 2-D echocardiography for cardiacfailure

Chest CT for any airway, lung, or mediastinal mass

Principal Causes of Apnea

1. Physiologiccauses
   1. Apneaof prematurity
2. Pathologic causes
   1. Any causeof severe respiratory distress
   2. Upper airway obstruction
   3. Infection
      1. Septicemia
      2. Meningitis
      3. Pertussis
      4. Bronchiolitis
   4. Neurologic
      1. Cerebral malformations
      2. Intracranial hemorrhage
      3. Seizures
      4. Brain tumor
      5. Neuromuscular disorders causing weakness
   5. Cardiovascular
      1. Shock
      2. Arrhythmia
   6. Gastroesophageal reflux
   7. Metabolic disorders
      1. Hypothermia
      2. Hypoglycemia
      3. Metabolic acidosis
   8. Drugs
   9. Abnormal control of ventilation
      1. Congenitalcentral hypoventilation syndrome
      2. Alveolar ventilation with extreme obesity
   10. Sudden infant death syndrome
   11. Munchausen by proxy
   12. Unknown

Clinical Features and Diagnosis: Apnea

Apnea isusually defined as absence of respiration for >20 secsor for briefer time if associated with bradycardia or cyanosis.Can be central (absence of air flow), obstructive (breathing movementsbut no air flow), or mixed.

Any disorder that causes respiratorydistress may result in apnea. However, apnea may be the only signof respiratory distress and this is the focus of the following discussion.

Physiologic Causes

Apnea of Prematurity

A feature of most infants <1,000g in birth weight. Occurrence decreases with advancing gestationalage. Occasionally, may be seen in infants up to 42 wks' gestationalage.

Pathologic Causes

The following causes of apnea are discussedin previous section or in other chapters: any cause of severe respiratorydistress, upper airway obstruction, infection (sepsis, meningitis,pneumonia, pertussis, bronchiolitis), neurologic (cerebral malformations,intracranial hemorrhage, seizures, brain tumor, neuromuscular disorderscausing weakness), cardiovascular (shock, arrhythmia), gastroesophagealreflux, metabolic disorders (hypothermia, hypoglycemia, metabolicacidosis), and drugs. In addition, there are unknown causes of apnea.

Abnormal Control of Ventilation

Congenital Central Hypoventilation Syndrome

Failureof autonomic respiratory drive occurs in this uncommon disorderof unknown cause. Usually presents in neonatal period or early infancy.

Some children with mild disorder haveadequate ventilation while awake but hypoventilate during sleep.Those with more severe disease hypoventilate while awake and asleep.

Diagnosis is based on establishingpresence of primary respiratory acidosis (hypoventilation).

Most persistent finding is low respiratoryrate during sleep, which leads to hypoventilation and sometimesapnea.

Alveolar Hypoventilation with Extreme Obesity (PickwickianSyndrome)

Extreme obesity may be associated with alveolarhypoventilation and apnea. Repeated apneas and awakening from sleeplead to excessive sleepiness during day.

Sudden Infant Death Syndrome

Sudden deathof any infant or young child that is unexplained by history, physicalexam, and thorough postmortem exam is called sudden infant deathsyndrome (SIDS).

Most cases occur during sleep at 2–4mos of age. By 6 mos of age, 90% of cases have occurred.

Although cause still remains uncertain,recent research has shown association between prone sleep positionand SIDS. Rate of SIDS has decreased markedly when infants havebeen positioned on their backs for sleep.

Munchausen by Proxy Syndrome

This syndromedescribes a disturbance in the parent-child relationship. The motheris usually the person who fabricates a history of illness in herchild or harms the child to create an illness.

Apnea is 1 of the most common occurrencesin victimized children. Other common manifestations are vomiting,diarrhea, and factitious fever.

Warning signs that may alert physicianto its presence are recurrent serious illness where satisfactoryexplanation cannot be found, failure of illness to respond to usualtherapeutic interventions, fabrication of any aspect of illnessby parent or guardian, history of unexplained illness or death inchild's siblings, and inappropriate affect of parent orguardian when child is seriously ill.

Confirmation of fabrication of illnessby independent observer is crucial, and strict surveillance of suspectedpersons in hospital is of critical importance.

Diagnostic Approach: Apnea

It is importantto distinguish periodic breathing from apnea. Periodic breathingis a normal phenomenon and is common in both preterm and term infants.Defined as respiratory pause of ≥3 secs followed by breathingperiod of ≤20 secs and occurring ≥3 times.

Once it has been determined that infanthas apnea, clinical status of infant, time of onset, and severitydetermine timing and extent of evaluation.

History and physical exam provide cluesto suspected cause of apnea.

Most common cause of apnea in preterminfants is apnea of prematurity. In newborn with significant apneicepisode, serious acute disease must be excluded (e.g., upper airwayobstruction, parenchymal lung disease, pneumothorax, meningitis,septicemia, or intracranial hemorrhage). ABCs of resuscitation shouldbe performed until infant is stable.

Certain tests should be consideredin any apneic infant: CBC with differential; serum glucose, electrolytes,calcium, magnesium, creatinine, and ammonia; blood urea nitrogen;spinal fluid, blood, and urine cultures; pulse oximetry; neck andchest radiography, and head U/S. Electroencephalography (EEG)should be performed when seizure is suspected.

Other tests to consider in neonatalperiod and in infancy are cervical spine radiography (spinal cordinjury); upper GI radiographic series and esophageal pH studies(gastroesophageal reflux); ECG and Holter monitoring (arrhythmia);CT or MRI (structural brain or cervical spine lesion); nasal washfor respiratory syncytial virus; and capillary partial pressureof CO₂ (hypoventilation).

Most of the time, clinical observationcan distinguish obstructive from nonobstructive apnea. In unusualcircumstances or where a question exists, sleep study with thermistorpneumogram may be useful to distinguish them. This test measureschest wall movement and nasal airflow. Chest wall movement withoutnasal airflow occurs with obstructive apnea, whereas neither chestwall movement nor nasal airflow occur with central apnea. In somecases, both obstructive and central apnea occur.

Recurrent apnea as an isolated findingmay rarely be the only manifestation of a seizure disorder. In neonates,eye deviation, eyelid fluttering, or abnormal lip, sucking, andswallowing movements suggest that seizures are occurring. InterictalEEG may be normal, whereas ictal EEG may show paroxysmal focal orgeneralized discharges.

References

1. Avery GB, et al., eds. Neonatology: pathophysiologyand management of the newborn, 5th ed. Philadelphia: LippincottWilliams & Wilkins, 1999.
2. Behrman RE, et al., eds. Nelson textbook of pediatrics,16th ed. Philadelphia: WB Saunders, 2000.
3. Brazy JE, et al. Central nervous system structurallesions causing apnea at birth. J Pediatr 1987;111:163–175.
4. Chernick V, Boat TF, eds. Disorders of the respiratorytract in children, Philadelphia: WB Saunders, 1998.
5. Fleisher GR, Ludwig S, eds. Textbook of pediatric emergencymedicine, 4th ed, Philadelphia: Lippincott Williams & Wilkins,2000.
6. Jones KW. Thoracic trauma. In: Mayer TA, ed. Emergencymanagement of pediatric trauma. Philadelphia: WB Saunders, 1985:254–271.
7. Kirks DR. Practical pediatric imaging: diagnostic radiologyof infants and children, 3rd ed. Philadelphia: Lippincott-Raven,1998.
8. Long SS, Pickering LK, Prober CG, eds. Principles andpractice of pediatric infectious diseases. New York: Churchill Livingstone,1997.
9. Oren J, et al. Long-term follow-up of children withcongenital central hypoventilation syndrome. Pediatrics 1987;80:375–380.
10. Rudolph AM, ed. Rudolph's pediatrics, 20thed. Stamford, CT: Appleton & Lange, 1996.
11. Southall DP, et al. Covert video recordings of life-threateningchild abuse: lessons for child protection. Pediatrics 1997;100:735–760.
12. Task Force on Infant Positioning. Positioning and suddeninfant death syndrome (SIDS): update. Pediatrics 1996;98:1216–1218.
13. Walsh JK, et al. Gastroesophageal reflux in infants:relation to apnea. J Pediatr 1981;99:197–201.

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Book Source Details

• Book Title: The Diagnostic Approach to Symptoms and Signs in Pediatrics
• Author(s): Paul S. Bellet
• Year of Publication: 2006
• Copyright Details: The Diagnostic Approach to Symptoms and Signs in Pediatrics, Copyright © 2006 Lippincott Williams & Wilkins.

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