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 26 -52 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 - week36Increased 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 surfactantSurfactant Function• Decreases surface tension• Maintains compliance and FRCTests 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

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 10-24 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 BornResuscitation of New Born

30 sec

Approximate Time

BirthBirth

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 warmthPositionClear Airway(as necessary)Dry, stimulateReposition,Give O2

Provide warmthPositionClear Airway(as necessary)Dry, stimulateReposition,Give O2

NO

Routine CareProvide warmthClear AirwayDry

Routine CareProvide warmthClear AirwayDry

Evaluate:RespirationsHeart rateColor

Evaluate:RespirationsHeart rateColor

SupportiveCare

SupportiveCare

Breathing

HR >100Pink

PPVPPV

Apnea orHR<100

Ongoing careOngoing care

HR >100Pink

Ventilating

30 sec

HR >60

HR <60

PPVChest 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