Neonatal Diseases RC 290

Respiratory Distress Syndrome (RDS) Also known as Hyaline Membrane Disease (HMD)

Occurrence 1-2% of all births 10% of all premature births Greatest occurrence is in the premature and low birth weight infant

Etiology & Predisposing Factors Prematurity Immature lung architecture and surfactant deficiency Fetal asphyxia & hypoxia Maternal diabetes Increased chance of premature birth Possible periods of reflex hypoglycemia in the fetus causing impaired surfactant production

Pathophysiology Surfactant deficiency Decreased FRC Atelectasis Increased R-L shunt Increased W.O.B. Hypoxemia and eventually hypercapnia because of V/Q mismatch

Pathophysiology (cont.) Atelectasis keeps PVR high Increased PAP Lung hypoperfusion R-L shunting may re-occur across the Ductus Arteriosus and the Foramen Ovale

Hypoxia/hypoxemia results in anaerobic metabolism and lactic acidosis This damages the alveolar-capillary membrane causing formation of hyaline membranes. Hyaline membranes perpetuate all of the problems in the lung

The cycle continues until surfactant levels are adequate to stabilize the lung Symptoms usually appear 2-6 hours after birth Why not immediately? Disease peaks at 48-72 hours Recovery usually occurs 5-7 days after birth

Clinical findings: Physical Tachypnea (60 BPM or >) Retractions Nasal flaring Expiratory grunting Helps generate autoPEEP Decreased breath sounds with crackles Cyanosis on room air Hypothermia Hypotension

Clinical Findings: Lab ABGs: initially respiratory alkalosis and hypoxemia that progresses to profound hypoxemia and combined acidosis Increased Bilirubin Hypoglycemia Possibly decreased hematocrit

CXR: Normal

RDS CXR: Ground Glass Effect

RDS CXR: Air Bronchograms & Hilar Densities

Time constant is decreased since elastic resistance is so high Increased elastic resistance means decreased compliance!

RDS Treatment: Primarily supportive until lung stabilizes NTE, maintain perfusion, maintain ventilation and oxygenation O2 therapy, CPAP or mechanical ventilation May require inverse I:E ratios if oxygenation can not be achieved with normal I:E ratio Surfactant instillation!!! May cause a sudden drop in elastic resistance!

Prognosis/Complications Prognosis is good once infant makes it past the peak (48-72 hours) Complications possible are: Intracranial Bleed BPD (Bronchopulmonary Dysplasia) PDA (Patent Ductus Arteriosus)

Transient Tachypnea of the Newborn (TTN) Also known as Type II RDS or Retained Lung Fluid

Occurrence: Similar to RDS More common in term infants!

Etiology & Predisposing Factors C-section These infants do not have the fluid expelled from their airways as occurs in vaginal delivery Maternal Diabetes Increased chance of C-section due to LGA Cord Compression Anesthesia

TTN Pathophysiology Primary problem = retained lung fluid Fluid not expelled from airways because of C-section Poor absorption of remaining fluid by pulmonary capillaries and lymphatics If retained fluid is in interstitial spaces, compliance and TC are decreased If retained fluid is in airways,airway resistance and TC are increased TTN can be restrictive , obstructive, or both! Fluid usually clears by itself after 24-48 hours after birth

Clinical Signs Tachypnea (usually rate is greater than seen in RDS) Minimal (if any) nasal flaring or expiratory grunting ABG’s: mild hypoxemia. PaCO2 depends on whether problem is restrictive or obstructive

TTN CXR Coarse peri-hilar streaks Prominent lung vasculature Flattened diaphragms if fluid is causing obstruction/air-trapping

TTN Treatment: Like RDS, it is primarily supportive Monitoring and O2 therapy Possibly CPAP or mechanical ventilation

Prognosis/Complications Prognosis is very good Main complication is pneumonia Often initial diagnosis

Lab Time!

Patent Ductus Arteriosus -PDA_ Failure of the D.A. to close at birth or a re-opening of the D.A. after birth. Allows shunting between the pulmonary artery and the aorta

Occurrence 1 per 2000 term babies 30-50% of RDS babies

Etiology & Predisposing Factors Prematurity D.A. not as sensitive to increasing PaO2 Hypoxia Decreasing PaO2 allows it to re-open for up to three weeks after birth Thus, a PDA can occur in a premature infant who is NOT hypoxic or in a term baby who is hypoxic Worst case is a premature infant who is hypoxic!

Pathophysiology D.A. fails to close or it re-opens Then shunting occurs between the pulmonary artery and the aorta The direction of the shunt depends on which vessel has the higher pressure A PDA can cause L-R shunting or R-L shunting! Clinically, most PDA’s refer to a L-R shunt

Clinical Signs Tachypnea, bounding pulses, hyperactive pre-cordium Decreased breath sounds and possibly some crackles Possible murmur over left sternal border Murmur is loudest when D.A. just starts opening or when it is almost closed

Clinical Signs (cont.) ABGs – hypoxemia with respiratory acidosis If R-L shunting, the PaO2 in the upper extremities, ie pre-ductal, will be greater than the PaO2 in the umbilical artery, ie post-ductal! TC – decreased if L-R shunting causes pulmonary edema; increased if fluid spills into airways and increases airway resistance CXR – if L-R shunt, butterfly pattern of pulmonary edema with possible cardiomegaly

PDA Treatment Basic – NTE, O2, may require CMV if not already on the ventilator Medical L-R shunt that fails to close: Indomethacin (Indocin) R-L shunt: Priscoline (Tolazoline) to decrease PVR; also nitric oxide Surgical –if medical treatment fails, the PDA may be surgically ligated

Prognosis/Complications Good prognosis when baby responds to medical treatment May develop : Shock CHF Necrotizing Enterocolitis (NEC)

Meconium Aspiration Syndrome -MAS- Syndrome of respiratory distress that occurs when meconium is aspirated prior to or during birth

Occurrence 10-20% of ALL births show meconium staining 10-50% of stained babies may be symptomatic More common in term and post-term babies

Etiology & Predisposing Factors Intra-uterine hypoxic or asphyxic episode Post-term Cord compression

Pathophysiology: Check Valve Effect Causes gas trapping (obstruction) If complete obstruction, then eventually atelectasis occurs Irritating to airways, so edema and bronchospasm Good culture ground for bacteria, so pneumonia possible

Pathophysiology (cont.) V/Q mismatch leads to hypoxia and acidosis which increases PVR TC increases because it increases airway resistance Meconium is usually absorbed in 24-48 hours; there are still many possible complications

Clinical Signs Respiratory depression or distress at birth Hyperinflation Pallor Meconium stained body Possible cyanosis on room air Moist crackles ABGs – hypoxemia with combined acidosis CXR – coarse, patchy infiltrates with areas of atelectasis and areas of hyperinflation May see flattened diaphragms if obstruction is severe

M.A.S. Treatment Amnioinfusion – artificial amniotic fluid infused into uterus to dilute meconium Proper resuscitation at birth(clear meconium from trachea before stimulating respiration) Oro-gastric tube NTE O2 NaHCO3 if severe metabolic acidosis Broad spectrum antibiotics Bronchial hygiene May need mechanical ventilation Slow rates and wide I:E ratios because of increased TC Low level of PEEP may help prevent check valve effect May need HFO

Prognosis & Complications Good prognosis if there are no complications Complications: Pneumonia Pulmonary baro/volutrauma Persistent Pulmonary Hypertension (PPHN)

Persistent Pulmonary Hypertension -PPHN- Also known as Persistent Fetal Circulation -PFC-

Results in R-L shunting across the D.A. and the Foramen Ovale Failure to make the transition from fetal to neonatal circulation or a reversion back to the condition where pulmonary artery pressure exceeds aortic pressure Results in R-L shunting across the D.A. and the Foramen Ovale

Occurrence Usually term and post-term babies Females more often than males Symptoms may take 12-24 hours after birth to develop

Etiology & Predisposing Factors M.A.S – most common Hypoxia and /or acidosis, eg RDS Any condition that causes PVR to increase

Pathophysiology Primary problem is pulmonary artery hypertension Infants arterial walls are thicker and they are more prone to vasospasm If pulmonary artery pressure gets high enough, blood will shunt R-L across the D.A. and Foramen Ovale Remember, conditions that drive up PAP usually make the D.A. open Lung is hypoperfused resulting in refractory hypoxemia and hypercapnia

Clinical Signs Refractory hypoxemia and cyanosis Shock and tachypnea Murmur possible Pre-ductal PaO2 > post-ductal PaO2 Hypoxemia with combined acidosis CXR usually OK when compared to infants condition

PPHN Treatment NTE and O2 Nitric Oxide Often in conjunction with HFO Priscoline, Indocin may also be used If completely unresponsive to therapy ECMO may be tried

Prognosis & Complications Prognosis depends on how well infant responds to treatment Complications Shock Intracranial bleed Internal bleeding Especially a problem if Priscoline is used

Wilson – Mikity Syndrome -Pulmonary Dysmaturity- Respiratory distress that develops after the first week of life and presents with definite CXR changes

Occurrence Usually in <36 weeks gestational age and birth weight <1500 grams After first week of life No prior symptoms

Etiology & Predisposing Factors Exact etiology unknown Appears to be due to immature lung and airways trying to function Not due to O2 toxicity or mechanical ventilation!

Pathology Immature alveoli and T-B tree causes V/Q mismatch Areas of atelectasis and hyperinflation develop

Pathology (cont.) 3 Stages Stage 1 Stage 2 Stage 3 1-5 weeks after birth Diffuse areas of atelectasis and hyperinflation Stage 2 1-5 months after birth Cystic (hyperinflated) areas coalesce and cause flattening of the diaphragms Stage 3 5-24 months after birth Cystic areas start to clear up

Clinical Signs Tachypnea Cyanosis on room air Some retractions and/or nasal flaring Decreased breath sounds with crackles ABGs – respiratory acidosis with hypoxemia CXR consistent with the stage of the disease

Wilson – Mikity Treatment Is purely supportive-there is no medicinal or surgical treatment O2 and NTE Some cases require mechanical ventilation Maintain fluids/electrolytes and caloric intake Watch for infection

Prognosis & Complications Prognosis good if infant survives stage 2 Complications PDA Cor Pulmonale CNS damage

Bronchopulmonary Dysplasia -BPD- A result of RDS and/or its treatment that results in areas of fibrosis, atelectasis, and hyperinflation

Etiology & Predisposing Factors RDS and prematurity Triad of O2, ET tube, and mechanical ventilation

Pathology: 4 Stages Stage 1 Stage 2 Stage 3 Stage 4 Acute phase of RDS 4-10 days after the onset of RDS Areas of atelectasis and hyperinflation Stage 3 2-3 weeks after RDS Hyperinflated areas start to coalesce Fibrosis starts to develop Stage 4 1 month after the onset of RDS Diaphragms start to flatten Interstitial fibrosis evident on CXR PPHN may start to develop O2 dependency develops

Clinical Signs Tachypnea Persistent retractions A-B spells Cyanosis on room air Decreased breath sounds with crackles ABGs – respiratory acidosis (may be compensated) with hypoxemia CXR – consistent with stage of disease

Interstitial fibrosis and flattened diaphragms BPD: Stage 4 CXR Interstitial fibrosis and flattened diaphragms

BPD Treatment Prevention is best! Use the least amount of intervention for the least amount of time! Supportive care O2, NTE, bronchial hygiene, maintain fluids/electrolytes Diuretics if needed to prevent fluid overload and heart failure Possibly vitamin E

Prognosis & Complications Good if infant survives to age 2 50% mortality if PPHN develops Complications PHTN Cor Pulmonale Respiratory Infections CNS damage

Diaphragmatic Hernia Congenital malformation of the diaphragm that allows abdominal viscera into the thorax

Occurrence 1 per 2200 births

Etiology & Predisposing Factors Exact unknown but may be related to vitamin A deficiency

Pathology Usually occurs during the 8-10th week of gestation 80% occur on the left at the Foramen of Bochdalek Abdominal viscera enters thorax and compresses developing lung As baby attempts to breathe after birth, the stomach and bowel fill with air and cause further compression of the lung Severe restriction!

Clinical Signs Cyanosis Severe respiratory distress with retractions and nasal flaring Bowel sounds in chest Uneven chest expansion Decreased breath sounds on affected side ABGs – profound hypoxemia with combined acidosis CXR – loops of bowel in chest with shift of thoracic structures towards unaffected side, eg dextrocardia

Diaphragmatic Hernia CXR

Diaphragmatic Hernia Treatment Immediate ET tube and NG tube No BVM – it will make things worse! Surgical repair Post operative ECMO and/or HFO May need NO with HFO

Prognosis & Complications 50% mortality Complications Pneumothorax PDA Hypoplastic lung

Pulmonary Barotrauma & Air Leak Syndromes

4 Main Types Pneumothorax Pneumomediastinum Pneumopericardium PIE (Pulmonary Interstitial Emphysema) Gas from ruptured alveoli dissects along perivascular and interstitial spaces Causes airway compression (obstruction) and alveolar compression (restriction) May lead to pneumothorax, pneumomediastinum, or pneumopericardium

1-2% of all births (not all are symptomatic) Occurrence 1-2% of all births (not all are symptomatic)

Etiology & Predisposing Factors Positive pressure ventilation Increased airway resistance/airway obstruction RDS

Clinical Signs Sudden cyanosis (except with PIE) Respiratory distress Mediastinal shift Sudden hypotension (except with PIE) Crepitus (if sub-Q emphysema develops) Unequal chest expansion Decreased breath sounds and hyperressonance ABGs – hypoxemia with respiratory acidosis Transillumination

Transillumination Small Pneumothorax

Transillumination Big Pneumothorax

CXR: Pneumothorax

CXR: Pneumomediastinum Note how air does NOT outline the apex of the heart

CXR: Pneumopericardium Note how air completely outlines the heart

CXR: PIE

Air Leak Syndrome Treatment Prevention! Use the least amount of intervention for the shortest time possible! Chest tube for pneumothorax HFO may help prevent and/or resolve PIE

Prognosis and Complications Good as long as shock and/or cardiac tamponade does NOT occur PIE puts infant at risk for BPD

Necrotizing Enterocolitis -NEC- Necrosis of the intestinal mucosa

Occurrence 20% of all premature births Males = Females Most common in low birth weight babies who experience perinatal distress

Etiology & Predisposing Factors Exact cause unknown but seen with the following: Intestinal ischemia Bacterial colonization Early formula feeding

Pathology Intestinal ischemia due to hypoperfusion, eg shock, or vascular occlusion, eg, clot from umbilical artery catheter Bacterial colonization after ischemia starts necrosis Early formula feeding may provide substrate needed for further bacterial growth and further necrosis

Clinical Signs Abdominal distention Poor feeding Blood in fecal material Lethargy Hypotension Apnea Decreased urine output Bile stained emesis CXR – bubbles in intestinal wall

NEC Treatment NPO and NG suction IV hydration and hyperalimentation Broad spectrum antibiotics Ampicillin, Gentamycin Minimum pressure on abdomen No diapers or prone positioning Monitor for/treat sepsis Necrotic bowel may need surgical resection

Prognosis & Complications Mortality is 20-75% Best prognosis if infant does NOT require any surgery Main complication is sepsis Infants who have bowel resection may develop malabsorption syndrome

Congenital Cardiac Anomalies

Tetralogy of Fallot VSD Over-riding aorta Pulmonary valve stenosis Right ventricular hypertrophy Significant cyanosis because of R-L shunt

Complete Transposition of the Great Vessels Pulmonary artery arises from left ventricle and Aorta arises from right ventricle R-L shunt through PDA, ASD, or VSD needs to be present for infant to survive until corrective surgery Balloon septostomy during cardiac catheterization

Truncus Arteriosus Aorta and pulmonary artery are the same vessel Large VSD Requires MAJOR surgical repair Mortality is 40-50%

Case Study Time

Never Stop Being Inquisitive!