Antenatal Assessment/Changes at birth

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RSPT 2353 – Neonatal/Pediatric Cardiopulmonary Care

Changes at Birth

Lecture Notes

Reference & Reading: Chapter 3

I.

Terms that are heard in L&D: a.

Para/Gravida/Abortions

Para (P) – Pregnancy

Gravida (G) – Live births

Abortions (A) – Either elective, or spontaneous

Example: P3 G1 A1 b.

Type of delivery

Vaginal

Cesarean section

VBAC c.

a.

Current situation with mom and/or baby

II.

Maternal History

Risk Factors

Incompetent cervix

Toxic habits

HTN

Diabetes Mellitus

Infectious Diseases – GBS, HSV, HBV

III.

Problems from Labor and/or Delivery a.

b.

Dystocia – prolonged difficult labor

The longer the labor the more problems may arise c.

Causes include:

Uterine dysfunction

Abnormal Presentation

Excessive fetal size

Hydrocephalus

Abnormality in size or shape of birth canal

IV.

Problems with the placenta, umbilical cord, & fetal membranes a.

Fetal membranes b.

Premature Rupture of Membranes (PROM)

No longer sterile;

risk of fetal infection

 

fetal fluid sac

Placenta Previa – placenta implants in lower portion of the uterine cavity

Low

Partial

Total

c.

d.

Abruptio Placentae –

A normally attached placenta separates prematurely from uterine wall

Most common cause is Preeclampsia or eclampsia (PIH)

Many risks involve for both mother, fetus & at delivery

Umbilical Cord Problems

Prolapsed cord – the umbilical cord presents in the cervix into the birth canal before the baby

Nuchal cord – the umbilical cord wraps around the baby’s neck

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Cord knot – also called a true knot; a knot is made in the umbilical cord

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V.

Problems with Amniotic fluid (AFI) a.

b.

c.

Fluid within Amnion

Dynamic – constantly being replenished & absorbed

After 24-26 weeks gestation fluid is swallowed and replenished with fetal urine d.

e.

P

OLYHYDRAMNIOS

– too much amniotic fluid present

CNS malformations

Orogastric malformations

Down syndrome

CHD

IDM

O

LIGOHYDRAMNIOS

– scant or decreased amount of fluid

Defect in urinary system – usually renal dysplasia or urethral stenosis

Potter’s syndrome

Implications include: lung Hypoplasia, asphyxia, and significant skeletal deformities

Presentation later in gestation – umbilical cord compression

VI.

Mode of Delivery a.

b.

c.

Vaginal most common

Forceps/ vaccum extraction

C-section – there are several risks involved:

Accidental cutting

TTN

VII.

Multiple Gestation – more than one fetus present

a.

b.

Higher incidence of premature labor

Fraternal twins – separate placentas c.

Identical twins – shared placenta

VIII.

Antenatal Assessment a.

Ultrasound b.

Amniocentsis – Performed to run for a variety of tests

Routinely done on mothers over 35

Not common practice because of risks involved

Tests that can be performed:

1.

2.

L/S ratio – a.

Determines lung maturity b.

compares amount of lecithin to sphingomyelin in amniotic fluid c.

lungs considered mature when L/S ration reaches 2:1

Shake test – a.

b.

Amniotic fluid mixed with ethanol

15 minutes later if there is a ring of bubble present, there is enough protein – lungs are mature c.

d.

e.

3.

Alpha-fetoprotein a.

Alpa-fetoprotein peaks in 12 th

week and then b.

decreases

If there is a break in fetal skin AFP will be c.

d.

present

High level usually indicates neural defect

Low level indicates Down Syndrome

Nonstress Test and Contraction stress test

FHR is monitored with fetal movement (NST) or with induced contractions (CST)

Reactive NST - FHR

with movement or contraction

CST

1.

2.

3.

Negative – no late decals

Positive – late decals w/ each contraction

Suspicious – some late decals w/ some contractions

Biophysical Profile (Table 3-1)

Determines fetal risk

Tests: fetal breathing, fetal movement, fetal limb tone, NST, amniotic fluid volume

Fetal Heart Rate Monitoring

Important reading along with variability

Good indicator of what is going on with fetus during labor

Three ways to monitor:

1.

2.

External abdominal transducer

Electrodes on abdomen

3.

Spiral electrode

Uterine contractions are monitored with a tocodynamometer

Fetal Heart Patterns

1.

2.

Baseline

Variability – changes with CNS depression, fetal sleep,

3.

narcotic or sedative use, etc.

Bradycardia - <100bpm or a maintained 20 bpm drop from baseline

4.

5.

6.

Tachycardia – consistenly above 180 bpm; usually maternal fever

Accelerations – FHR exceeds 160 bpm for <2 minutes; good sign

Decelerations – FHR drops below 120 bpm for <2 minutes a.

b.

Early (Type I) drops during contraction – benign

Late (Type II) don’t follow contractions – c.

uretoplacental insufficiency during contractions

Variable (Type III) independent of contractions

– secondary to umbilical cord compression

IX.

High risk conditions a.

Premature labor – Prevention is better!

Tocolysis – process of stopping labor

1.

Identification of risks for premature labor

Bedrest-

1.

2.

3.

Pharmacological –

β

-sympathomimetic (terbutaline & ritodine); anti-convulsant (magnesium sulfate)

Light-duty

Bedrest (home or hospital)

Trendelenburg b.

Postterm Pregnancy

Increased risk for:

1.

Large size

2.

3.

Meconium aspiration

Obstetrical trauma

Labor often induced

X.

Adaptation to Extrauterine Life a.

The first breath – Three things that influence the initiation of the first breath

Chemoreceptors detect changes in PaO2 & PaCO2 stimulate the baby to breathe

Thoracic recoil and baby leaves vaginal canal

Abrupt change in environment b.

Change from fetal to adult circulation

Changes in circulatory Pressures

1.

Umbilical cord is clamped, forcing blood to lower extremities, raising arterial blood pressure

2.

Initial breathing causes ↓ pulmonary vascular resistance (FRC & ↑PaO2)

Closure of fetal shunts

1.

With ↑ pressures in L heart foramen ovale closes

2.

3.

4.

Ductus arteriosus closes with the absence of prostaglandins (smooth muscle constricts)

Umbilical arteries & veins constrict & become ligaments

Ductus venosus also constricts & becomes ligament

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