Common Respiratory Disorders of the Neonate Common

Common Respiratory Disorders of the Neonate

Common Pulmonary Causes of Respiratory Distress in Neonates Parenchymal conditions ● Transient tachypnea of the newborn ● Meconium aspiration syndrome and other aspirations ● Respiratory distress syndrome ● Pneumonia ● Pulmonary edema ● Pulmonary hemorrhage ● Pulmonary lymphangiectasia Developmental abnormalities ● Lobar emphysema ● Pulmonary sequestration ● Cystic adenomatoid malformation ● Congenital diaphragmatic hernia ● Tracheoesophageal fistula ● Pulmonary hypoplasia Airway abnormalities ● Choanal atresia/stenosis ● Laryngeal web ● Laryngotracheomalacia or bronchomalacia ● Subglottic stenosis Mechanical abnormalities ● Rib cage anomalies (eg, Jeune syndrome) ● Pneumothorax ● Pneumomediastinum ● Pleural effusion ● Chylothorax

The Neonatal Lung is a Work in Progress n Canalicular phase n Saccular phase n Alveolar phase Agrons Radiographics 2005

Respiratory Distress Syndrome (Hyaline Membrane Disease) n Definition? n 1960 – clinical definition describing respiratory distress and a hyaline membrane lining dilated terminal airspaces n 2006 – clinical definition describing respiratory distress and x-ray findings n There is no “test” for RDS

Surfactant is Amazing A mixture of lipid and protein that lowers surface tension on an air-water interface Jobe Neo. Reviews 2006

A Very Complex Metabolism n Surfactant is made in type II cells, works in the fluid hypophase of the alveoli and is recycled Jobe Neo. Reviews 2005

RDS is Inversely Related to Gestational Age n Incidence in 2006 n 501 -1500 g (42%) n 501 -750 g (71%) n 751 -1000 g (54%) n 1001 -1250 g (36%) n 1251 -1500 g (22%) n More common in males than females Fanaroff and Martin 2006 p 1098

Surfactant Maturation Can Be Accelerated n Corticosteroids n TRH n Inflammation n Heroin

Pathophysiology is Less Complicated Than It Looks Fanaroff and Martin 2006 p 1100

Pathophysiology is Less Complicated Than It Looks Fanaroff and Martin 2006 p 1100

Clinical Manifestations n Symptoms usually within hours of birth n Non-specific: tachypnea, cyanosis, nasal flaring, grunting, retractions, etc n Progressive worsening over 2 -3 days followed by slow recovery n Classic CXR findings Diffuse reticulogranular pattern n Air bronchograms n

Classic RDS

Management 1960 s Style n Supplemental oxygen n High humidity n Antimicrobials n Rocking chair devices n Sternal fixation

Management 2007 Style n Supplemental oxygen and respiratory support n Attention to thermoregulation n Antibiotics n IV fluids n Exogenous surfactant

Exogenous Surfactant n There is no question that it works n Decreases mortality from RDS n +/- decrease in BPD n Surfactant works best when: n Administered shortly after birth n Given rapidly n Followed by distending pressure

Other Surfactant Fun Facts n Components are recycled and “improved” like natural surfactant n May need additional doses n Optimal ventilator strategies following administration are more a matter of opinion than science

Respiratory Support n Goals are to: n Survive the acute phase of the disease n Minimize side effects n Minimize chance of chronic lung disease n Lots of opinion, but no consensus n Conventional ventilation n n Pressure volume n. CPAP n HFV n

First Do As Little Harm As Possible Fanaroff and Martin 2006 p 1100

Chronic Lung Disease is Related to Our Treatments Fanaroff and Martin 2006 p 1100

Ventilator Strategies n Distending pressure n Lower Peak Inspiratory Pressures n Lower Tidal Volumes n Early extubation n Permissive hypercarbia n Permissive hypoxemia

Nasal CPAP? n Some places use it exclusively as their first- line mode of respiratory support n Columbia Univ – 76% success in infants with BW < 1250 g and 50% with BW < 750 g n Requires everyone to buy into the system n Can’t give surfactant unless also intubated n Most places use n. CPAP for less severe symptoms, following extubation or in conjunction with “in-and-out” surfactant

High Flow Nasal Cannula n Nasal Cannula at atypical flows (< 1 LPM) n Usually 2 -8 LPM in our NICU n Used to provide distending pressure in a similar manner as n. CPAP n Does not appear to be equal to n. CPAP in efficacy n ? Increased respiratory infection rate

Complications of RDS and Its Treatment n Air Leak Syndrome

More Complications n Airway injury n Subglottic stenosis (1% < 1. 5 kg) n Infection n PDA n IVH n Long-term outcomes n More related to gestational age and BW n Most with normal exercise tolerance

BPD, a Most Troubling Complication n It begins with the definition: n Supplemental oxygen at 28 days of life following oxygen/ventilator therapy in the first week of life n Supplemental oxygen at 36 weeks PMA following oxygen/ventilator therapy in the first week of life n NIH consensus conference 2000

Now It All Makes Sense? The bottom line is that you will see all three definitions

Pathophysiology of BPD n Lungs are attempting to: n Heal n Grow and develop n Respond to continued insults

CLD is Associated With: n Prematurity n Mechanical trauma n Oxygen toxicity n Infection/inflammation n Pulmonary edema n PDA n ? genetics

The Old and the New BPD

Clinical Features n BPD is a systemic disease n Pulmonary n Respiratory distress n Hypoxemia, hypercarbia n Increased airways resistance n Growth deficiency n Developmental delay n Cardiovascular dysfunction n Systemic hypertension, ventricular hypertrophy n Metabolic derangements n Sodium, calcium, etc

Management n Minimize further harm n Permissive hypercapnea. etc. n Aggressive nutritional support n Conservative fluid management n Caution with diuretics n +/- bronchodilators n Steroids with caution n Minimize and aggressively treat infections n Developmental care

Meconium Aspiration Syndrome n Perinatal aspiration of meconium n Complicates ~4% of deliveries through meconium stained amniotic fluid Fanaroff and Martin 2006 p 1123

MAS n Coarse infiltrates n Widespread consolidation n Hyperinflation n Pneumothorax and pneumomediastinum may be present

Management of MAS n Prevention n Supportive respiratory therapy n ? Higher p. O 2 n Normal p. CO 2 n Nitric oxide and other PPHN therapies n Antibiotics n surfactant

Transient Tachypnea n Described in the 1960 s n Later called RDS Type 2 n Delayed clearance of pulmonary fluid n More common in: n Late preterm n C/S birth n Perinatal depression n Maternal diabetes n Diagnosis of exclusion

Symptoms of TTN n Mild to moderate respiratory distress shortly after birth n Increased central vascular markings ("star -burst") n Evidence of interstitial and pleural fluid n Spontaneous improvement in hours to a few days

Other Aspiration Syndromes n Babies can aspirate blood and amniotic fluid n No specific diagnostic test n May mimic TTN or MAS n Management is the same