Pediatrics Neo-Nephro Module Respiratory Distress in the NB

Pediatrics Neo-Nephro Module Respiratory Distress in the NBDr. Josie Niu-Kho

Five Common Signs of RD

Tachypnea respiratory rate that exceeds 60 breaths per minute Retractions folding of the skin inwards in the chest wall nasal flaring

grunting expiratory sound made a baby w/ a collapsed lungs; breathing w/ a closed glottis

cyanosis bluish discoloration

Differential Dx in Neonatal Respiratory Distress

Pulmonary D/o

RDS

Transient tachypnea

Meconium aspiration syndrome

Pneumonia

Air leak syndrome

Pulmonary hypoplasia

Systemic D/o

hypothermia

metabolic acidosis

anemia/polycythemia

hypoglycemia

pulmonary hypertension

congenital heart dse closest differential

Anatomic Problems compromising the Respiratory Sys

upper airway obstruction

airway malformations

space occupying lesions

rib cage anomalies

phrenic nerve injury

neuromuscular disease

Respiratory Distress Syndrome (RDS I)

most common initial problem in the NICU

incidence is inversely related to gestational age and birth weight

34-35 weeks AOG enough surfactant already

less than 34-35 wk AOG -> high risk for RDS

Signs & Sx

difficulty initiating normal respiration

sternal and subcostal retractions

nasal flaring

rapid respiration

expiratory grunting

cyanosis

Etiology

primary absence or deficiency of a highly surface active alveolar lining layer (pulmonary surfactant)

fig:

type 2 alveolar cell

lamellar body -> air space -> tubular myelin -> layer of phospholipid (surfactant) -> dec surface tension of alveoli & airways -> expansion -> recycling of phospholipids

main component of surfactant -> reabsorbed by vesicles -> endocytosis -> multivesicular body -> lamellar body formation

Surfactant

70-80% phospholipids (sat phosphatidylcholine)

10% protein

SP-A, B,C,D

10% neutral lipid primarily cholesterol

phosphatidylglycerol

Surfactant Protein A

water soluble collectin

required for tubular myelin formation

contributes to the biophysical porp of surfactant

regulates surfactant secretion and catabolism

major function is as a non immune host defense protein and regulator of inflammation in the lung

not present in sysnthetic surfactant used for RDS treatment

Surfactant Protein B small hydrophobic protein

facilitates surface absorption of lipids and the devt of low surface tension on surface area compression

lack of SP-B causes a loss of lamellar bodies in type II cells

genetic absence of SP-B leads to a lethal form of RDS after term birth

Surfactant Protein C also a small hydrophobic protein

cooperates w/ SP-B for lipid absorption

main role is to spread phospholipids on alveolar surface

Surfactant Protein D

hydrophilic protein w/ structural similiatities to SPA

binds pathogens and facilitates clearance

Phsyiologic Abnormalities dec lung compliance

large areas of lung not ventilated (v/Q)

large areas of lung not perfused (V/q)

dec alveolar ventilation and inc work of breathing

reduced lung volume (dec FRC)

Pathologic Findings

Anatomic

gross: collapsed lung, firm, dark red and liver like

microscopic: alveolar collapse, pink staining membrane on alveolar ducts (hyaline membrane), thickened arteriolar wall

EM: disappearance of lamellar bodies, damage and loss of type II pneumocytes

Biophysical and Biochemical

deficient or absent pulmonary surfactant

abnormal pressure volume curve

X-Ray reticulgranular, ground glass appearance (homogenous & bilateral)

bronchogram

diffuse haziness

white out lungs in severe RDS

General Preventive Measures

prolongation of pregnancy / inhibit premature labor

induction of pulmo surfactant w/ maternal steroids (Bethamethasone)

Clinical Management

Specific Treatment

exogenous surfactant administration

assisted ventilation

Principles of Basic Care thermoregulation

provision of fluid and caloric requirements

maintainance of adequate oxygenation

non invasive monitoring of vital signs

* ensure survival with minimal risk of chronic morbidity

Bronchopulmonary Dysplasia

chronic lung disease of the newborn

a complication of HMD, results from lung injury in infants requiring mechanical ventilation and inc oxygen concentration

defined as a need for supplemental O2 36 wks after conception

CXR radiolucent areas alternating w/ areas of irregular density resembling a sponge

Treatment nutritional support, fluid restriction, O2 support, infection control (infxn worsen pulmonary fxn), drug therapy (diuretics, bronchodilators, dexamethasone postnatal steroid given directly to the baby to help lessen degree of bronchopulmonary dysplasia)

Fig: Bronchopulmonary Dysplasia CXR

sponge like

honey combing

areas of lucencies, white densities

very patchy in lower areas of the lungs

Transient Tachypnea of the NB

follows an uneventful delivery at or near term

major presenting symptom

persistently high RR

other symptoms

mild insignificant cyanosis, good air exchange, minimal respiratory distress

X-Ray confirm Dx

central perihilar streaking

hyperaeration

fluid in the minor fissure

increase in the vascular markings

Pathophysiology

delayed resorption of fetal lung fluid -> distress

inc risk

cesarean delivery w/o labor fluid resorption starts during labor

infants of diabetic mothers

self limited course, resolves within 72 hours

Neonatal Pneumonia

route of transmission

ascending infection from the genital tract

transplacental passage

predisposing factor

prolonged rupture of membranes 18 hours

Group B Strep

major pathogen producing pneumonia

Other bacteria

E. coli most common in the Phil

Listeria

Klebsiella

Enterococcus

Clinical Course

signs of RDS

tachypnea

retractions

cyanosis

non specific signs

apneic spells

thermal instability

jaundice (E. coli)

X-Ray

streaky densities

confluent opacified areas

diffusely granular appearance w/ air bronchograms

Dx

high index of suspicion starting from maternal hx

labs

CBC high or low WBC

Blood culture bacterial growth

Isolated pneumonia usually negative

Tracheal aspirate culture

Treatment

Penicillin (Group B Strep) and aminoglycoside (E. coli)

late onset

Staphylococcus Oxacillin / Vancomycin

Chlamydia erythromycin

Fungi ampothericin B

Duration of treatment 10 days

Air Leak Syndromes: Pneumothorax

spontaneous pneumothorax in 1% of all live births

should be suspected in any NB w/ respiratory distress or in an infant on a respirator whose condition suddenly worsens

increased risk in the following

vigorous resuscitation at birth overinflate the lungs RDS pathologic lungs MAS (meconium aspiration syndrome) read! Pulmonary hypoplasia collapsed lungs usually secondary to barotraumasPathophysiology

air from ruptured alveolus dissects up the vascular sheath into the mediastinum and into the pleural space

Clinical Findings unilateral pneumothorax should be able to dx on PE alone!

cardiac impulse shifted contralaterally

decreased ipsilateral breath sounds

distended abdomen

Diagnosis

transillumination of the chest CXR

Hyperluscent area

Shifting of midline structures to contralateral side

Diaphragm may be pushed down -> distended abdomen

Fig: Massive tension pneumothorax

tension -> medical emergency

decreased venous return to the heart

decreased in cardiac output

babies are hypotensive and bradycardic -> may die

Management nonspecific therapy for asymptomatic pneumothorax

thoracentesis

thoracostomy tube placement left until there is healing of the alveoli

Pneumomediastinum

may be asymptomatic

degree of respiratory distress depends on the amount of trapped air

subcutaneous emphysema is pathognomonic

diagnosis is confirmed by CXR: air in the anterior mediastinum

Mx close observation, may progress to pneumothorax

Fig: Pneumomediastinum

lungs being compressed

lobulated -> accumulation of air in the mediastinum

Pulmonary Interstitial Emphysema

rupture of air from alveoli or small airways into the perivascular tissues of the lung

primary a radiographic diagnosis

seen predominantly in the preterm who requires prolonged assisted ventilation w/ high pressures

presence of PIE signals barotraumas

associated w/ subsequent bronchopulmonary dysplasia

fig: pulmonary interstitial emphysema

multiple lucencies

Extrapulmonary Causes of Respiratory DistressApproach

Hx: pregnancy, delivery, neonatal transition

PE

May not always help but one will have to do a good PE bec there are conditions that will give dx based on PE alone

Analysis of simple laboratory data: blood gases (hypoxemia), blood sugar (hypoglycemia can give RD), CBC (rule out infection), radiographic studies

High index of suspicion!

CNS

most commonly secondary to cerebral edema or hemorrhage

medications administered to mother (narcotics)

Demerol

Tx: give Naloxone

Neuromuscular

Werdnig-Hoffmann disease (Infantile Spinal Muscular Atrophy)

Myasthenia gravis

Hypotonia and respiratory insufficiency

Airway Obstruction

location of obstruction

larynx and upper trachea -> stridor

laryngomalacia, tracheomalacia

mediastinal trachea -> wheezing

will require auscultation

Choanal Atresia

obstruction of nasal passage by a membrane

cyanosis relieved w/ crying of the infant

dx established by inability to pass a catheter through the nose

quiet -> blue; crying -> pink

Laryngomalacia

most common cause of stridor in an infant

stridor lessens in the prone position; tends to exacerbate during agitation

fiberoptic nasolaryngoscopy

Cystic Hygroma

anomalous devt of lymphatic channels in the neck

surgical excision

Proteinaceous exudates

Respiratory Distress Syndrome

Impaired endothelial and epithelial integrity

Pulmonary vasoconstriction

Respiratory + metabolic acidosis

USTMEDB2007

Atelectasis

Structural lung immaturity

surfactant

V/Q inequality

hypoxemia

hypoventilation

hypercarbia

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