RSPT 2353 Neonatal Pediatric Respiratory Care STAGES OF FETAL LUNG DEVELOPMENT

Objectives Discuss anatomy and physiology of fetal circulation Compare and contrast fetal circulation to infant circulation Define specialized structures of fetal circulation Discuss normal cardiac circulation (infant and adult) Discuss cardiac defects

Stages of Lung Development Embroynal days development of trachea and major bronchi Pseudoglandular 52 days- week 16 Development of remaining conducting airways Canalicular week 17- week 28 Development of vascular bed and acinus Saccular week 29 - week36 Increased complexity of saccules Alveolar week 36 – Term 40 weeks Development of alveoli sufficient to sustain gas exchange Post Term > 41 weeks

Factors That Limit Normal Lung Growth Hyperoxia Cigarette smoking Diaphragmatic hernia Nutritional deprivation Problems with amniotic fluid Hormonal imbalances Drug abuse ETOH abuse

Surfactant Surfactant Production Type II pneumocytes produces surfactant in the alveoli Alveoli must be formed to make surfactant < 33 weeks the alveoli are insufficient to form surfactant Surfactant Function Decreases surface tension Maintains compliance and FRC Tests for Adequate Surfactant Production Shake test LS Ratio test Amniocentisis

Fetal Lung Fluid What happens to all that fluid that has been filling the lungs for 9 months? Fetal lung fluid is evacuated from the newborns lungs via: Absorption- lymphatic system Clearance- pulmonary capillaries Contraction – birth canal, birth squeeze

Placenta Provides Gas exchange & waste removal. Supplies nutrient to the fetus Placenta is the lung for the fetus

Fetal Circulation

Cardiac development occurs between the 4th and 7th week of gestation. The foramen ovale is a one-way flap in the atrial septal wall. Blood bypasses the lungs because of the high right sided pressures. The ductus arteriosis is a connection between the PA and the Aorta - shunts blood away from the lungs. Fetal PVR is high, within 24hr after birth, PVR should fall to 1/2 SVR The ductus should close within hrs after birth. Fetal CO is very high, therefore tissue hypoxia usually does not occur, even when oxygen saturations are 60-70%

Fetal Circulation Low pressure circuit Gas Exchange occurs in the Placenta Fetal lungs do not participate in gas exchange Roughly 10% of blood goes to lungs for tissue development

Fetal Oxygenation Best-oxygenated blood –Right atrium, Foramen ovale, Left atrium –Supplies the upper body, specifically the brain Less-oxygenated blood supplies the rest of the body via the Ductus Arteriosus

How Does Blood Bypass the Lungs? High PVR in utero creates a desireable R to L shunting Foramen Ovale Ductus Arteriosus Question: Why is a R to L shunt desirable in – utero ?

PaO2 in Fetal Circulation Large gradient between mom’s PaO2 and fetal PaO2 –Promotes the transfer of O2 –Higher Hgb concentration in fetus –Fetal Hgb Greater affinity for O2 Higher SaO2 for the same PaO2 than adult Hgb Left shift of fetal oxyhemoglobin dissociation Curve

Conversion from Fetal to Infant Circulation Cord is clamped - closing low pressure system SVR increases Lungs inflate w/ air (due to several factors, one of which is atmospheric pressure changes) PVR decreases –Lung inflation (only slightly changes it) –Changes in O2, CO2 and pH

Conversion from Fetal to Infant Circulation R to L shunting decreases Increased pressures in LA results in: –Closing of Foramen Ovale –Closing of Ductus Arteriosus PaO2 changes Prostaglandin level changes

Overview of Conversion Umbilical cord is clamped Loose placenta Closure of ductus venosus Blood is transported to liver and portal system Loss of placenta also leads to first breath Lungs expand and fluid is expelled Decreased pulmonary vascular resistance Increased systemic vascular resistance

Overview of Conversion Increased pressure in left atrium Closure of foramen ovale Loss of placenta Increased systemic resistance Pressure in right atrium decreased Change from right to left shunting to left to right blood flow Increased O2 levels in pulmonary circulation Closure of the ductus arteriosus

Fetal vs. Infant Circulation Fetal Low pressure system Right to left shunting Lungs non-functional Increased pulmonary resistance Decreased systemic resistance Infant High pressure system Left to right blood flow Lungs functional Decreased pulmonary resistance Increased systemic resistance

NORMAL HEART

Antenatal Assessment and High-Risk Delivery Fetal and Newborn Assessment in the L and D

Objectives At the completion of this lecture the student will: Be able to discuss relevant points concerning Antenatal Assessment Be able to ID the L and D cases which may present a high-risk delivery Know the parameters on which to base antenatal/perinatal assessments

Antenatal Assessment and High- Risk Delivery Indications of a High-Risk Delivery: Incompetent Cervix Toxic habits in Pregnancy Hypertension and Diabetes Mellitus Preclampsia Severe Preclampsia Infectious Disease Multiple birth

Indications of a High-Risk Delivery: Long cord, Nuchal cord, cord knots Placenta Abruption Placenta Previa Disorders of aminiotoic fluid Abnormalities of Umbilical cord Oligohydraminos, Polyhydraminos Antenatal Assessment and High- Risk Delivery

Antenatal Assessment Antenatal = Around birth time, usually considered prior to L and D Ultrasound Amniocentesis Shake test Fetal Biophysical profile Preterm Pregnancy Less than 37 weeks

Indications of High-Risk Delivery Magnesium sulfate is given to stop contractions Blood gas with Ph less than 7.15 can be an indication of asphyxia Post-term Labor Pregnancy continued beyond 42 weeks Pre-term less than 33 weeks ges age Lack of prenatal care

Neonatal Assessment and Resuscitation Neonatal Resuscitation Considerations While Assessing the Patient Maintain warmth Cold stress increases oxygen consumption Maintain an airway Placing a small roll under the shoulders will correct the position Suction the airway Stimulation Obtain vascular access Provide resuscitative drugs PRN

Assessing the Neonate Vital signs Apgar score Neonatal resuscitation When is Positive pressure ventilation Indicated? When is Intubation Indicated? When are chest compressions indicated? When are Medications indicated?

30 sec Resuscitation of New Born 30 sec Approximate Time Birth Clear of Meconium? Breathing or Crying? Good Muscle Tone? Color Pink ? Term gestation? Clear of Meconium? Breathing or Crying? Good Muscle Tone? Color Pink ? Term gestation? Yes Provide warmth Position Clear Airway (as necessary) Dry, stimulate Reposition, Give O 2 Provide warmth Position Clear Airway (as necessary) Dry, stimulate Reposition, Give O 2 NO Routine Care Provide warmth Clear Airway Dry Routine Care Provide warmth Clear Airway Dry Evaluate: Respirations Heart rate Color Evaluate: Respirations Heart rate Color Supportive Care Supportive Care Breathing HR >100 Pink PPV Apnea or HR<100 Ongoing care HR >100 Pink Ventilating

30 sec HR >60 HR <60 PPV Chest Compressions Administer Epinephrine Time HR < 60

Assessment of Neonatal Patient Vital signs Skin Mottling Irregular areas of dusky skin alternating with pale skin Capillary refill

Respiratory Function Assessment Apnea Periodic breathing Grunting Nasal flaring Retractions Silverman score Stridor X-ray

Nasal Flaring and Sub-sternal Retractions

Nasal Flaring and Substernal Retractions

Silverman score

Cardiac Assessment Heart, how is it working? HR, RR,BP Cardiac murmur – PDA Weak pulse Coarctation of Aorta Hypo plastic Left heart syndrome Adequate MBP= gestational age + 5

Abdomen Diaphramatic hernia Omphalocele Gastroschisis Umblical cord A single umblical artery Congenital anomalies Thin cord Thick cord-diabetics

Head and Neck Assessment Microstomia-small mouth Micrognathia-small jaw T-E fistula Pierre robin syndrome Choanal Artesia Macroglossia

Assess an Infant’s Cry Loud and vigorous- healthy infant Grunting cry- RDS Hoarse cry-laryngeal edema Cat like cry- chromosme abnormality High-pitched cry- neurological deficit

Pediatric Assessment Pedi assessment is focused on different indications: History and assessment Chief complaint Medical history Family history Environmental history

Elements of Pediatric Physical Assessment Assessment Inspection RR Retractions AP diameter Digital clubbing Palpation Tactile fremitus Position of trachea Percussion Auscultation