Neonatology Flashcards
What cell produces surfactant?
Type II pneumocytes.
What is the role of surfactant?
Reduces surface tension of the fluid in the lungs, increasing lung compliance.
This maximises the surface area of the alveoli, by preventing alveolar collapse.
When does surfactant production begin?
Between 24 and 34 weeks gestation.
Pre-term babies therefore have problems associated with reduced pulmonary surfactant.
How is neonatal respiratory effort induced after birth?
The stress of labour stimulates the release of adrenaline and cortisol, which induces respiratory effort.
Outline the closure of foramen ovale after birth.
The first breaths the baby takes expands the alveoli, reducing pulmonary vascular resistance.
This causes a fall in pressure in the right atrium, to below the pressure in the left atrium. This causes a functional closure of the foramen ovale.
The foramen ovale then structurally closes and becomes the fossa ovalis.
Outline the closure of ductus arteriosus after birth.
Increased blood oxygenation after birth causes a drop in circulating prostaglandins, causing a closure of ductus arteriosus. This then becomes ligamentum arteriosum.
Outline the closure of ductus venosus after birth.
Immediately after birth, the ductus venosus stops functioning because the umbilical cord is clamped and there is no flow in the umbilical veins.
The ductus venosus structurally closes a few days later, becoming the ligamentum venosum.
Outline the consequences of hypoxia in neonates.
Normal labour and delivery leads to hypoxia, as powerful contractions disable the placenta from carrying out gaseous exchange.
Extended periods of hypoxia leads to anaerobic respiration and consequent bradycardia.
Further hypoxia leads to reduced consciousness and a drop in respiratory effort, in turn worsening hypoxia.
Extended hypoxia leads to hypoxic-ischaemic encephalopathy (HIE), with life-long consequences in the form of cerebral palsy.
What are the common obstacles to neonatal resuscitation?
- large SA:V ratio, so get cold very easily
- born wet, so loose heat rapidly
- babies born through meconium may have this in their mouth or airway
What are the general principles of neonatal resuscitation?
- warm the baby
- calculate APGAR score
- stimulate breathing
- inflation breaths
- chest compressions
How can a baby be warmed in neonatal resuscitation?
- get baby dry as quickly as possible (vigorous drying)
- warm delivery rooms and management under a heat lamp
What is the APGAR score?
An indicator of progress over the first minutes after birth, helping to guide neonatal resuscitation efforts.
Appearance
Pulse
Grimmace
Activity
Respiration
How can a baby’s breathing be stimulated in neonatal resuscitation?
- virgorously drying with a towel
- head in a neutral position to keep airway open
- check for airway obstruction and consider aspiration
Principles of inflation breaths in neonatal resuscitation.
- Two cycles of five inflation breaths to stimulate breathing and heart rate.
- If there is no response and bradycardic, 30 seconds of ventilation breaths are given.
- If there is no response, chest compressions can be used, coordinated with the ventilation breaths (3:1).
Principles of chest compressions in neonatal resuscitation.
- start compressions if HR<60bpm despite resuscitation and inflation breaths.
- chest compressions are performed at a 3:1 ratio with ventilation breaths.
What is the rationale behind delayed umbilical cord clamping?
After birth, there is still a significant volume of fetal blood in the placenta. Delayed umbilical cord clamping provides time for this blood to enter the circulation of the baby.
This is known as placental transfusion.
What are the benefits of delayed umbilical cord clamping?
Placental transfusion:
- improves haemoglobin
- improves iron stores
- improves blood pressure
- reduces intraventricular haemorrhage
- reduces necrotising enterocolitis
What are the negatives of delayed umbilical cord clamping?
Increase in neonatal jaundice, potentially requiring more phototherapy.
Resuscitation Council UK recommends umbilical cord clamping after how long in the following situations?
a) uncompromised neonates
b) neonates requiring resuscitation
a) a delay of at least one minute to allow for placental transfusion
b) immediate clamping - priority is resuscitation, not delayed clamping
What actions should be taken immediately after birth of a baby?
- skin to skin contact
- clamp the umbilical cord (delayed where possible)
- dry the baby
- keep the baby warm with a hat and blanket
- vitamin K
- label the baby
- measure the weight and length
Describe the administration of vitamin K to babies following birth.
Babies are born with vitamin K deficiency.
IM injection of vitamin K is given in the thigh shortly after birth, which can help to stimulate the baby to cry and expand the lungs.
What is the role of vitamin K in babies?
Important co-factor for clotting factors II, VII, IX and X.
Prevents bleeding, particularly intracranial, umbilical stump and gastrointestinal bleeding.
What are the benefits of skin to skin contact?
- helps warm the baby
- improves mother and baby interaction
- calms the baby
- improves breast feeding
Out of the delivery room, how is a baby usually cared for?
- initiate breast feeding or bottle feeding as soon as the baby is alert enough
- delay first bath until warm and stable
- newborn examination within 72 hours
- blood spot test
- newborn hearing test