Perinatology & Neonatology Flashcards
Early term
37 0/7 weeks of gestation through 38 6/7 weeks
Full term
39 0/7 weeks of gestation through 40 6/7 weeks
Late term
41 0/7 weeks of gestation through 41 6/7 weeks
Post term
42 0/7 weeks of gestation and beyond)
Perinatal Period:
After 28 weeks gestation up to 28 days following birth
Neonatal Period:
First 28 days (4 weeks) of life
Ductus venosus
O2 rich blood from maternal placenta enters
circulation (bypasses liver) via inferior vena cava
* Connects umbilical vein to
inferior vena cava
Ductus arteriosus
~90% of blood bypasses the pulmonary
vasculature directly to the aorta
* Connects the pulmonary
artery & aorta
Foramen ovale
O2 rich blood from the Right Atrium directly
to the Left Atrium (right-to-left shunting)
* Opening between the two atria of the fetal heart
Median closure time of ductus arteriosus
13.5 hours
Clamping the umbilical cord ___ preload to the left ventricle & ___ cardiac output = _____
↓; ↓ ; bradycardia
Delayed cord clamping =
After the lungs have aerated
- 30-60 seconds
- Cardiac output should not fall
- Delayed cord clamping should be performed in preterm & term newborns not requiring resuscitation at birth
Delayed umbilical cord clamping in term infants
↑ Hgb levels at birth
↑ iron stores during infancy
↑ neurodevelopment at 4 yo
Delayed umbilical cord clamping in pre-term infants
↓ need for blood transfusion
↓ intraventricular hemorrhage
↓ necrotizing enterocolitis
When to not delay cord clamp
- Resuscitation is required
- Placental circulation is disrupted by:
* Abruption
* Cord avulsion
* Bleeding placenta previa
* Vasa previa
Neonates are sensitive to
heat loss & retention
How do neonates thermoregulate at birth?
- Temperature has been tightly regulated for 9 months
- Now dependent mainly on metabolic heat from brown adipose tissue
Limited, esp. preterm
When is surfactant produced?
3rd trimester (28-40 weeks)
Surfactant
- Phospholipid & protein substance ↓ surface
tension at the liquid-air interface - Produced by Alveolar type II cells
- Without surfactant, ↑ pressure is required
to inflate & ventilate the lungs
–Without surfactant → alveoli collapse - Production minimally sufficient by 34 weeks gestation
Following birth, the neonate MUST transition from placental to pulmonary
gas exchange, meaning these things must occur:
- Pulmonary vascular resistance must ↓
- Pulmonary perfusion must ↑
- Fetal vascular shunts must close to separate systemic & pulmonic circulation
- Patent Ductus arteriosus & Foremen Ovale
At term, fetal lungs contain _____ of fluid
~90 mL (~3 1/8 oz)
How is the fluid from fetal lungs removed?
- Uterine contractions & vaginal birth
squeeze this from the lungs
~1/3 of fluid through nose & mouth - Fetal adrenaline stimulates pulmonary
epithelial cells to stop secreting & start
reabsorbing lung fluid via Na+ channel
activation
-Lung aeration changes the transpulmonary
pressure gradient & the remaining fluid is
reabsorbed via capillaries & lymphatics
T/F Pre-mature neonates &/or cesarean born do not experience the “vaginal squeeze” &
experience greater respiratory difficulty
T
Neonatal breathing begins within ____
seconds of birth & should be sustained
by ____ seconds
30; 90
Steps for newborn resuscitation
- Dry infant & place under radiant heat, monitor temp.
- Position infant to open airway, gentle suction of mouth/nose
- Assess respiratory effort (apneic v. gasping v. regular)
- Assess heart rate (>100 or <100 beats/min)
* ↓ HR is the MOST RELIABLE indicator for resuscitation - Gently stimulate (back rub, heel flick) if HR <100 or irregular respiration
- If stimulation fails within a few seconds begin bag & mask ventilation
* More to come in Pediatric Advanced Life Support
How many newborns need resuscitation?
~10% require active resuscitation & 1% need extensive care
The APGAR Score
- Time honored method in evaluating the
newborn infant at time of delivery - NOT predictive of long-term outcomes
- Description of the severity of perinatal
depression & the need for & response to
resuscitative efforts
APGAR Levels
Assessed at 1 & 5 minutes following birth
7-10 = stable infant
<7 = resuscitative measures continue &
scores assigned q 5 minutes until infant
stabilized
<7 after 3-4 intervals = consider ICU
Ophthalmia neonatorum
- Mucopurulent conjunctivitis of
newborns
12% of neonates
Gonococcal & Chlamydial
infections = MOST COMMON - 1% Silver Nitrate solution or
0.5% erythromycin ointment
First immunization a newborn will recieve
Routine immunization against
hepatitis B
Standard practice prior to d/c for all
medically stable newborns with
birthweights >2000 g
What if the mother is seropositive
for Hepatitis B surface antigen?
Neonate is also passively
immunized with Hep
B immune globulin
Vitamin K supplementation in newborns
- Single, IM dose of Vitamin K 0.5 - 1 mg given within 1 hour of birth
Prevents Vitamin K dependent hemorrhagic disease of the newborn
3 part newborn screening for rare disorders includes
- Blood sample (heel stick) collected on filter paper
- Pulse Oximetry
- Hearing Screen
60+ asymptomatic conditions including:
Phenylketonuria (PKU), galactosemia,
hemoglobinopathies, hypothyroidism, cystic fibrosis,
hearing,
Consequences for failure to screen for PKU
Phenylketonuria (PKU) → inability to break down the amino acid phenylalanine
Left untreated, PKU → brain damage or death