Review – Kaplan Pediatrics: Respiratory Disease

Dec 5, 2019 admin NHI KHOA 0

Review – Kaplan Pediatrics: Respiratory Disease

Croup

  • Parainfluenza types 1, 2, 3
  • Age 3 months–5 years; most common in winter; recurrences decrease with increasing growth of airway
  • Inflammation of subglottis
  • Course: prodrome (URI) 1–3 days, then barking cough, hoarseness, inspiratory stridor; worse at night, gradual resolution over 1 week
  • Hypoxia only when obstruction is complete
  • Clinical diagnosis; x-ray (steeple sign) not needed
  • Supportive treatment: Nebulized epinephrine, followed by corticosteroids

Epiglottitis

  • Agents:
    • Haemophilus influenzae type B (HiB) no longer number one (vaccine success)
    • Now combination of Streptococcus pyogenes, Streptococcus pneumoniae, Staphy- lococcus aureus, Mycoplasma
    • Risk factor—adult or unimmunized child
  • Inflammation of epiglottis and supraglottis
  • Course: dramatic acute onset
    • High fever, sore throat, dyspnea, and rapidly progressing obstruction
    • Toxic-appearing, difficulty swallowing, drooling, sniffing-position
    • Stridor is a late finding (near-complete obstruction)
  • Diagnosis
    • Clinical first (do nothing to upset child), controlled visualization (laryngoscopy) of cherry-red, swollen epiglottis; x-ray (thumb sign) not needed; followed by immediate intubation
  • Treatment
    • Establish patent airway (intubate)
    • Antibiotics to cover staphylococci, HiB, and resistant strep (antistaphylococcal plus third-generation cephalosporin)

Croup and Epiglottitis

Feature Croup Epiglottitis
Etiology Parainfluenza 1,2,3 S. aureus
S. pneumonia,
S. pyogenes
H. influenza type B
Age Preschool Toddler-young school age
Timing Cool months Year round
Diagnosis Key Words Barking cough
Inspiratory stridor
If the patient gets worse: Inspiratory stridor, then expiratory stridor, then stridor at rest		 Acute onset
Extremely sore throat
Cannot swallow
High fever
Sniffing position
Drooling
Inspiratory stridor later
Best Initial Test Clinical Dx
CXR not needed-but shows steeple sign		 Laryngoscopy
Most Accurate Test PCR for virus
Not needed clinically		 C and S from tracheal aspirate
Best Initial Treatment None or nebulized epinephrine if severe Airway (intubation)
Definitive Treatment (If Needed) IM Dexamethasone once → observation Airway (tracheostomy if needed) + broad- spectrum antibiotics
Then per sensitivities

Laryngomalacia

  • Most common laryngeal airway anomaly and is the most frequent cause of stridor in infants and children.
  • Collapse of supraglottic structures inward during inspiration stridor; less in prone position
  • Starts in first 2 weeks of life, and symptoms increase up to 6 months of life; typically exacerbated by any exertion
  • Diagnosis—Clinical suspicion is confirmed with laryngoscopy, bronchoscopy (for associated anomalies).
  • Treatment—with most, supportive care if significant, surgery (supraglottoplasty may prevent tracheostomy)

Congenital Subglottic Stenosis

  • Second most common cause of stridor
  • Common presentation—recurrent/persistent croup, i.e., stridor (no difference supine prone position)
  • Diagnosis—airway x-rays; confirm with laryngoscopy
  • Treatment—surgery (cricoid split or reconstruction), may avoid tracheostomy

Vocal Cord Paralysis

  • Third most common cause of stridor
  • Often associated with meningomyelocele, Chiari malformation, hydrocephalus
  • May be acquired after surgery from congenital heart defects or tracheoesophageal fistula (TEF) repair
  • Bilateral—airway obstruction, high-pitched inspiratory stridor
  • Unilateral—aspiration, cough, choking, weak cry and breathing
  • Diagnosis—flexible bronchoscopy
  • Treatment—usually resolves in 6–12 months; may require temporary tracheostomy

Bronchiolitis

  • Infective agents—respiratory syncytial virus (RSV) (50%), parainfluenza, adenovi- rus, Mycoplasma, other viruses
  • Typical age—almost all children infected by age <2 years, most severe at age 1–2 months in winter
  • Inflammation of the small airways (inflammatory obstruction: edema, mucus, and cellular debris) → (bilateral) obstruction → air-trapping and overinflation
  • Signs and symptoms:
    • Mild URI (often from household contact), decreased appetite and fever, irrita- bility, paroxysmal wheezy cough, dyspnea, and tachypnea
    • Apnea may be more prominent early in young
    • Wheezing, increased work of breathing, fine crackles, prolonged expiratory phase
    • Lasts average of 12 days (worse in first 2–3 days)
  • Complications—bacterial superinfection, respiratory insufficiency and failure (worse in infants with small airways and decreased lung function)
  • Diagnosis
    • Clinical
    • Chest x-ray (not routine)—hyperinflation with patchy atelectasis (may look like early pneumonia)
    • Immunofluorescence of nasopharyngeal swab (not routine); PCR
  • Treatment
    • Supportive care; hospitalize if respiratory distress; may give trial of beta-2 agonist nebulization
    • No steroids
    • Ribavirin not routinely used; may prevent need for mechanical ventilation in severe cases
  • Prevention—hyperimmune RSV IVIG or monoclonal antibody to RSV F protein (preferred: palivizumab) in high-risk patients only

 PNEUMONIA

  • Definition—inflammation of the lung parenchyma
  • Epidemiology
  • Viruses are predominant cause in infants and children younger than 5 years of age
  • Major pathogen—RSV
  • Others—parainfluenza, influenza, adenovirus
  • More in fall and winter
    • Nonviral causes more common in children older than 5 years of age
  • Most— pneumoniae, and C. pneumoniae (not trachomatis)
  • pneumoniae most common with focal infiltrate in children of all ages
  • Others in normal children— pyogenes and S. aureus (no longer HiB)

Clinical Findings in Viral Versus Bacterial Pneumonia

Viral Bacterial
Temperature ↑ ↑ ↑ ↑
Upper respiratory infection ++ ¾
Toxicity + +++
Rales Scattered Localized
WBC Normal to ↓ ↑ ↑ ↑
Chest x-ray Streaking, patchy Lobar
Diagnosis Nasopharyngeal washings Blood culture, transtracheal aspirate (rarely done)

 Clinical findings

  • Viral:
    • Usually several days of URI symptoms; low-grade fever
    • Most consistent manifestation is tachypnea
    • If severe—cyanosis, respiratory fatigue
  • Examination—scattered crackles and wheezing
  • Difficult to localize source in young children with hyper-resonant chests; difficult to clinically distinguish viral versus nonviral
  • Bacterial pneumonia:
  • Sudden shaking chills with high fever, acute onset
  • Significant cough and chest pain
  • Tachypnea; productive cough
  • Splinting on affected side—minimize pleuritic pain
  • Examination—diminished breath sounds, localized crackles, rhonchi early; with increasing consolidation, markedly diminished breath sounds and dullness to percussion
  • Chlamydia trachomatis pneumonia:
    • No fever or wheezing (serves to distinguish from RSV)
    • 1–3 months of age, with insidious onset
    • May or may not have conjunctivitis at birth
    • Mild interstitial chest x-ray findings
  • Staccato cough
  • Peripheral eosinophilia
  • Chlamydia pneumoniae and mycoplasma pneumoniae
    • Cannot clinically distinguish
    • Atypical, insidious pneumonia; constitutional symptoms
    • Bronchopneumonia; gradual onset of constitutional symptoms with persis- tence of cough and hoarseness; coryza is unusual (usually viral)
    • Cough worsens with dyspnea over 2 weeks, then gradual improvement over next 2 weeks; becomes more productive; rales are most consistent finding (basilar)
  • Diagnosis
    • Chest x-ray confirms diagnosis:
  • Viral—hyperinflation with bilateral interstitial infiltrates and peribronchial cuffing
  • Pneumococcal—confluent lobar consolidation
  • Mycoplasma—unilateral or bilateral lower-lobe interstitial pneumonia; looks worse than presentation
  • Chlamydia—interstitial pneumonia or lobar; as with Mycoplasma, chest x-ray often looks worse than presentation
  • White blood cells:
    • Viral—usually <20,000/mm3 with lymphocyte predominance
    • Bacterial—usually 15,000–40,000/mm3 with mostly granulocytes
    • Chlamydia—eosinophilia
  • Definitive diagnosis:
    • Viral—isolation of virus or detection of antigens in respiratory tract secretions; (usually requires 5–10 days); rapid reagents available for RSV, parainfluenza, influenza, and adenovirus
  • Bacterial—isolation of organism from blood (positive in only 10–30% of chil- dren with pneumoniae), pleural fluid, or lung; sputum cultures are of no value in children. For mycoplasma get IgM titers.
    • Treatment
      • Based on presumptive cause and clinical appearance
      • Hospitalized—parenteral cefuroxime (if aureus suspected, add vancomycin or clindamycin)
      • If suspect viral (outpatient, mild)—may withhold treatment if mild and no respiratory Up to 30% may have coexisting bacterial pathogens; dete- rioration should signal possible secondary bacterial infection and should start empiric treatment.
      • Chlamydia or Mycoplasma—erythromycin or other macrolide
Feature Bacterial Viral C. trachomatis M. pneumoniae or

C. pneumonia
Etiology •      S. pneumoniae

•      HIB

•      S. aureus

 •      RSV

•      Parainfluenza

•      Influenza

•      Adenovirus

 C. Trachomatis •      M. Pneumoniae

•      C. Pneumonia
Age •      Any age

•      Most common reason for lobar is

S. pneumoniae

 Most common form <5 years Age 1–3 months Most common form age >5 years
Timing More in cold months Cold months All year All year; more in winter
Diagnosis Key Words •      Acute

•      Severe

•      Productive cough

•      Dyspnea

•      High fever

•      Chest pain

•      Rhonchi

•      Rales

•      Decreased breath sounds

•      May have empyema

 •      Insidious

•      Often worsening URI

•      Lower temperature

•      Wheeze

•      Cough

•      Mild dyspnea

 •      May have had conjunctivitis as newborn

•      Afebrile

•      No wheeze

•      Staccato cough

 •      Insidious

•      URI symptoms with persistence of cough worsening over 2 weeks

•      Rales most consistent finding (lower lobe uni- or bilateral)
Best Initial Test •      CXR = lobar consolidation •      CXR = bronchopneumonia, interstitial

•      Hyperinflation with increased peribronchial markings

 •      CXR = mild interstitial •      CXR most unilateral lower lobe interstitial

•      Classically looks worse than symptoms
Most Accurate Test •      Sputum C and S (cannot rely on in child)

•      Blood culture

•      Pleural fluid culture

 Respiratory secretions for viral or antigen isolation (would not do routinely) Sputum PCR (but not needed = classic clinical diagnosis) PCR of NP or throat swab (but not usually needed)
Best Initial Treatment and Definitive Treatment •      Admit for IV cefuroxime

•      Then change if needed based on C and S

 •      No treatment of viral pneumonia

•      If uncertain, give oral amoxicillin

 Oral macrolide Oral macrolide

CYSTIC FIBROSIS (CF)

A 3-year-old white girl presents with rectal prolapse. She is noted to be in the less than 5th percentile for weight and height. The parents also note that she has a foul-smelling bulky stool each day that “floats.” They also state that the child has developed a repetitive cough over the last few months.

 

  • Most common life-limiting recessive trait among whites
  • Major cause of severe chronic lung disease and most common cause of exocrine pancreatic deficiency in children
  • Primary pathogenic feature is dysfunction of epithelialized surfaces; obstruction and infection of airways; maldigestion
  • Genetics
    • Autosomal recessive; CF gene most prevalent among northern and central Europeans
    • All of the gene mutations occur at a single locus on long arm of chromosome
    • Codes for CF transmembrane regulator (CFTR—ion channel and regulatory functions)
  • Expressed mostly on epithelial cells of airways, gastrointestinal tract, sweat glands, genitourinary (GU) system
  • Not all children with CF can be identified by DNA testing; may need to sequence CFTR gene
    • Pathogenesis and pathology
      • Membranes of CF epithelial cells unable to secrete Cl– in response to cyclic ade- nosine monophosphate–mediated signals:
    • Failure to clear mucous secretions; paucity of water in mucous secretions
    • Increased salt content of sweat and other serous secretions
    • Manifestations:

} Bronchiolar obliteration, bronchiectasis (end-stage; severe destructive disease)

} Opacified paranasal sinuses

} Large nasal polyps

} Pancreatic dysfunction; fat and fat-soluble vitamin malabsorption

} Intestinal glands distended with mucous secretions; focal biliary cirrhosis

} Endocervitis

} Body and tail of epididymis, vas deferens, seminal vesicles obliterated or atretic in males

  • Clinical presentation
    • Intestinal tract—usually first presentation:
  • 10% of newborns with meconium ileus

} X-ray shows dilated loops, air–fluid levels, “ground-glass” (bubbly appear- ance) material in lower central abdomen

} Gastrografin enema → reflux into ileum may clear; if not, then surgery

  • Most with malabsorption from pancreatic exocrine insufficiency → frequent, bulky, greasy stools and failure-to-thrive.
°      Fat-soluble vitamin deficiency—ADEK
  • Hepatobiliary—icterus, ascites, hepatomegaly, cholelithiasis, varices
  • Pancreas—increased incidence of diabetes mellitus, acute pancreatitis
  • Rectal prolapse—most in infants with steatorrhea, malnutrition, and cough
  • Respiratory tract:
    • Rate of progression of lung disease is chief determinant of mortality and morbidity—easy in life—nontypable influenzae and S. aureus, then coloni- zation with P. aeruginosa, then later colonization with Burkholderia cepacia: associated with rapid deterioration and death (end-stage)
    • Cough, purulent mucus—early in first year, extensive bronchiolitis, then pulmonary function test (PFT) abnormalities, dyspnea; finally, cor pulmonale, respiratory failure, and death; high risk for pneumothorax
    • Examination:

} Increased A-P diameter

} Hyper-resonance, rales, expiratory wheezing

} Clubbing, cyanosis (late)

} Sinuses almost always opacified

  • Genitourinary tract:
    • Delayed sexual development
    • Almost all males with azoospermia
    • Increased incidence of hernia, hydrocele, undescended testes
    • Females: secondary amenorrhea, cervicitis, decreased fertility
  • Sweat glands:
    • Excessive loss of salt → salt depletion, especially with hot weather or gastroenteritis (serum–hypochloremic alkalosis)
°      Salty taste of skin
  • Diagnosis
    • See Table 8-4.

 

 

Table 8-4. Diagnosing CF
Any of the Following Plus Any of the Following
•    Typical clinical features

•    History of a sibling with CF

•    Positive newborn screen

 •    Two increased sweat chlorides on 2 separate days

•    Identification of 2 CF mutations (homozygous)

•    Increased nasal potential difference

 

  • Sweat test (best test):
    • Difficult in first weeks of life
    • Confirm positive results
    • Diagnosis: >60 mEq/L
  • If sweat test is equivocal:
    • Increased potential difference across nasal epithelium
    • Pancreatic function—72-hour fecal fat collection, stool for trypsin, pancreozy- min-secretin stimulation, serum immunoreactive trypsinogen (↑ in neonates)
  • X-rays:
  • Hyperinflation of chest
  • Nodular densities, patchy atelectasis, confluent infiltrates, hilar nodes
  • With progression—flattening of diaphragm, sternal bowing, narrow cardiac shadow; cysts, extensive bronchiectasis
    • Pulmonary function tests:
  • By 5 years—obstructive pulmonary disease
°      Then restrictive (fibrosis)
  • Microbiologic—finding in sputum of aureus first, followed by P. aeruginosa

(mucoid forms) is virtually diagnostic (also B. cepacia, but is usually late finding)

  • Genetic:
  • Antenatal diagnosis by mutational analysis in family previously identified by birth of child with CF
  • Test spouse of carrier with standard panel of probes
  • Newborn screen—determination of immunoreactive trypsinogen in blood spots and then confirmation with sweat or DNA testing; does not improve pulmonary and therefore long-term outcome
    • Treatment
      • Clear airway secretions and control infections:
°      Aerosol treatment; albuterol/saline
  • Daily dose of human recombinant DNAse (mucolytic)
  • Chest physical therapy with postural drainage: 1–4 times per day
    • Antibiotics:
  • For acute infections (change in baseline condition)
  • Most frequent is aeruginosa (also non-typable H. influenzae, S. aureus,
  1. cepacia)
  • Must base choice on culture and sensitivity
  • Aerosolized antibiotics—tobramycin
    • Hospitalization:
  • Progressive despite intensive home measures
  • Typical 14-day treatment
  • Two-drug regimens to cover pseudomonas, g., piperacillin plus tobramycin or ceftazidime
    • Nutritional:
°      Pancreatic enzyme replacement with meals/snacks
  • Vitamin supplementation (ADEK)
    • Adequate fluid replacement when exercising or hot weather

SUDDEN INFANT DEATH SYNDROME (SIDS)

A  2-month-old  term  infant  born  without  any  complications  via  spontaneous vaginal delivery is brought to the emergency center via ambulance with CPR in progress.  According  to  the  mother,  the  patient  was  in  his  usual  state  of  good health until 4 a.m. when she found the patient cyanotic and not breathing. The mother states that at midnight the infant was fed 4 ounces of formula without any difficulty. After the feeding, the child was placed to sleep in a crib. At 4 a.m. the mother returned to check on the infant and found the child unresponsive. She immediately  called  Emergency  Medical  Services  and  began  CPR.  The  child  was pronounced dead on arrival to the emergency department.

 

  • Definition—sudden death of an infant, unexplained by history; unexplained by thor- ough postmortem examination including autopsy, investigation of death scene, and review of medical history
  • Before 1992, incidence was constant at 4 in 1,000; then with Back to Sleep cam- paign, down to 0.45 in 1,000
  • Differential diagnosis
    • Explained at autopsy: infections; congenital anomaly; unintentional injury; trau- matic child abuse; other natural causes
    • Not explained: SIDS; intentional suffocation
  • Pathology
    • No findings are pathognomonic and none are diagnostic (Markers for pre-existing, chronic, low-grade asphyxia): petechial hemorrhages; pulmonary edema
  • Environmental risk factors
    • Nonmodifiable:
      • Low socioeconomic status
      • African American and Native American
      • Highest at 2–4 months of age; most by 6 months
      • Highest in winter, midnight to 9 a.m.
      • Males > females
    • Modifiable:
      • Shorter interpregnancy interval
      • Less prenatal care
      • Low birth weight, preterm, intrauterine growth retardation
°      Maternal smoking
  • Postnatal smoking
  • Sleep environment
    • Higher incidence related to prone sleeping
    • Supine position now better than side-lying
    • No increased problems in supine, e., aspiration
    • Higher incidence with soft bedding/surfaces
    • Higher incidence with overheating
    • Pacifier shown to consistently decrease risk
  • Other risk factors
    • Episode of an apparent life-threatening event (ALTE)
    • Subsequent sibling of SIDS victim
    • Prematurity—inverse with gestational age and birth weight
•      Home monitors do not decrease risk.
  • Reducing risk
–            Supine while asleep
  • Use crib that meets federal safety standards
  • No soft surfaces (sofas, waterbeds, )
  • No soft materials in sleep environment
  • No bed-sharing
  • Avoid overheating and overbundling
  • Use prone position only while infant is awake and observed
  • No recommendation for home monitoring for this purpose
  • Expand national Back to Sleep campaign (up to 45% of infants still sleep prone).

 

 

 

 

 

 

 

 

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