neonatal diseases rc 290. respiratory distress syndrome (rds) also known as hyaline membrane disease...
TRANSCRIPT
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 birthsGreatest occurrence is in the premature and low birth weight infant
Etiology & Predisposing Factors
PrematurityImmature lung architecture and surfactant deficiency
Fetal asphyxia & hypoxiaMaternal diabetes
Increased chance of premature birthPossible periods of reflex hypoglycemia in the fetus causing impaired surfactant production
PathophysiologySurfactant deficiency
Decreased FRCAtelectasisIncreased R-L shuntIncreased 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 gruntingHelps 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 oxygenationO2 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-sectionThese infants do not have the fluid expelled from their airways as occurs in vaginal delivery
Maternal DiabetesIncreased chance of C-section due to LGA
Cord Compression
Anesthesia
TTN Pathophysiology
Primary problem = retained lung fluidFluid not expelled from airways because of C-sectionPoor absorption of remaining fluid by pulmonary capillaries and lymphaticsIf retained fluid is in interstitial spaces, compliance and TC are decreasedIf retained fluid is in airways,airway resistance and TC are increasedTTN 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 pneumoniaOften initial diagnosis
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
PrematurityD.A. not as sensitive to increasing PaO2
HypoxiaDecreasing 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-opensThen shunting occurs between the pulmonary artery and the aortaThe 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 borderMurmur is loudest when D.A. just starts opening or when it is almost closed
Clinical Signs (cont.)ABGs – hypoxemia with respiratory acidosisIf 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 resistanceCXR – 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
MedicalL-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 airMoist cracklesABGs – hypoxemia with combined acidosisCXR – coarse, patchy infiltrates with areas of atelectasis and areas of hyperinflation
May see flattened diaphragms if obstruction is severe
M.A.S. TreatmentAmnioinfusion – artificial
amniotic fluid infused into uterus to dilute meconium
Proper resuscitation at birth(clear meconium from trachea before stimulating respiration)
Oro-gastric tubeNTEO2
NaHCO3 if severe metabolic acidosis
Broad spectrum antibioticsBronchial hygieneMay need mechanical
ventilationSlow rates and wide I:E ratios because of increased TCLow level of PEEP may help prevent check valve effectMay 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-
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
PathophysiologyPrimary 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 PaO2Hypoxemia with combined acidosis
CXR usually OK when compared to infants condition
PPHN Treatment
NTE and O2
Nitric OxideOften 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 bleedingEspecially 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 lifeNo 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 11-5 weeks after birthDiffuse areas of atelectasis and hyperinflation
Stage 21-5 months after birthCystic (hyperinflated) areas coalesce and cause flattening of the diaphragms
Stage 35-24 months after birthCystic 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 NTESome 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 StagesStage 1
Acute phase of RDS
Stage 24-10 days after the onset of RDSAreas of atelectasis and hyperinflation
Stage 32-3 weeks after RDSHyperinflated areas start to coalesceFibrosis starts to develop
Stage 41 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
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/electrolytesDiuretics if needed to prevent fluid overload and heart failure
Possibly vitamin E
Prognosis & Complications
Good if infant survives to age 250% 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
PathologyUsually occurs during the 8-10th week of gestation80% occur on the left at the Foramen of BochdalekAbdominal viscera enters thorax and compresses developing lungAs baby attempts to breathe after birth, the stomach and bowel fill with air and cause further compression of the lung
Severe restriction!
Clinical SignsCyanosisSevere respiratory distress with retractions and nasal flaringBowel sounds in chestUneven chest expansionDecreased breath sounds on affected sideABGs – profound hypoxemia with combined acidosisCXR – 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 tubeNo 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 TypesPneumothorax PneumomediastinumPneumopericardiumPIE (Pulmonary Interstitial Emphysema)
Gas from ruptured alveoli dissects along perivascular and interstitial spacesCauses airway compression (obstruction) and alveolar compression (restriction)May lead to pneumothorax, pneumomediastinum, or pneumopericardium
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
Transillumination
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 catheterBacterial colonization after ischemia starts necrosisEarly formula feeding may provide substrate needed for further bacterial growth and further necrosis
Clinical SignsAbdominal distentionPoor feedingBlood in fecal materialLethargyHypotensionApneaDecreased urine outputBile stained emesisCXR – bubbles in intestinal wall
NEC Treatment
NPO and NG suction
IV hydration and hyperalimentation
Broad spectrum antibioticsAmpicillin, Gentamycin
Minimum pressure on abdomenNo 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 ventricleR-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%
