1
Q
define a foetus
A
An unborn human, in-utero
2
Q
Define a newly born infant
A
- The first minutes to hours following birth
* AV use ‘up to 24 hours’ as their definition
3
Q
Define neonate?
A
• From birth up to 28 days of age
4
Q
Define Infant?
A
• From birth up until 1 year of age
5
Q
What is the normal newborn weight?
A
3.5 kg
6
Q
What is the normal newborn blood volume?
A
80ml/kg
7
Q
What is the normal newborn HR?
A
110-170
8
Q
What is the normal newborn RR?
A
25-60
9
Q
What is the normal newborn temp?
A
36.5-37.5
10
Q
What is the normal newborn BGL?
A
2.6-3.2
11
Q
When does the foetal heart begin beating?
A
4 weeks after fertilisation
12
Q
what are the 4 shunts in the foetal cardiovascular system?
A
Ductus venosus
Foramen Ovale
Ductus arteriosus
Umbilical circulation
13
Q
What does the ductus venosus do?
A
allows blood to pass from the umbilical vein to the right atrium. Closes at birth to become ligamentus venous
14
Q
What does ductus arteriosis do?
A
allows blood to pass from pulmonary trunk to the aorta. Closes after borth to become the ligamentum arteriosum.
15
Q
What is the ductus venosus?
A
- Narrow vessel with high velocity blood passing through
- Shunts a portion of the left umbilical vein blood flow directly to the inferior vena cava
• Some blood oxygenates the liver –the rest pass through to the IVC • The degree of shunting in the fetus: • 30% at 20 weeks • which decreases to 18% at 32 weeks
16
Q
What is the foramen ovale?
A
- Physiological defect in the atrial septum
- Allows blood to enter the left atrium from the right atrium
- In most individuals, the foramen ovalecloses at birth
- Oxygenated blood from the placenta travels through the umbilical cord to the right atrium of the fetal heart. As the fetal lungs are non-functional at this time, it is more efficient for the blood to bypass them
- It later forms the fossa ovalis in adulthood
17
Q
What is the ductus arteriosus?
A
- A blood vessel connecting the main pulmonary artery to the proximal descending aorta
- Allows bulk of the blood from the right ventricle to bypass the foetus’slungs (at this stage is fluid filled and as we know doesn’t function)
- After birth it starts to constrict until it closes.
- In adults it becomes the ligamentum arteriosum
- Failure of the DA to close after birth results in a condition called patent ductus arteriosus (PDA) and the generation of a left-to-right shunt. If left uncorrected, patency leads to pulmonary hypertension and possibly congestive heart failure and cardiac arrhythmias.
18
Q
What is the circulatory composition of the umbilical cord?
A
2 x umbilical arteries
1 x umbilical vein
19
Q
What do the umbilical arteries do?
A
- Normally two umbilical arteries
- Carries de-oxygenated blood away from the neonate
- Branch from the internal iliac arteries
- Pressure normally 50mmHg
20
Q
What does the umbilical vein do?
A
- Normally single umbilical vein
- Carries oxygenated and nutrient rich blood toward the neonate
- Connects to portal circulation where blood is shunted back to IVC via ductus venosus
- Pressure normally 20mmHg
21
Q
What is the physiology of the foetal lungs?
A
- Fluid filled until birth (fluid production stops and is absorbed at birth)
- No air to breathe
- Lung almost completely deflated
- Leads to high PVR in lungs
- Surfactant production begins around 30 weeks gestation
- Surfactant production normally adequate by 35 weeks gestation
22
Q
explain the process of gas exchange for the foetus?
A
- Before birth, all the oxygen used by the foetus diffuses across the placental membrane from the mother’s blood.
- The foetallungs do not function as a source of oxygen or as a route to excrete carbon dioxide.
- Blood flow to the lungs is minimal (~8%) so pulmonary vascular resistance is high.
- Foetal SpO2 is 40-60%.
23
Q
Explain the physiology of the foetal nervous system
A
- Earliest system to begin developing and one of the last to complete
- Most reflexes present by 3-4 months of pregnancy
- Cerebral cortex development still relatively immature at birth
24
Q
Explain the physiology of the foetal GIT
A
- Primitive gut is present by the end of the 4thweek of gestation
- Consists of foregut, midgut and hindgut –each of these eventually develop into all the organs we know an associated with the GIT system
- 2ndtrimester foetus begins to consume amniotic fluid
- 3rdtrimester foetus begins to form meconium which may be passed prior to birth
25
Explain the physiology of the foetal renal system
* 2ndtrimester foetus begin to excrete urine into the amnion
* Accounts for 70-80% of amniotic fluid at birth
* Kidney abnormalities may present as oligohydramnios (low amniotic fluid levels)
26
What is the process for a newborn tranistioning to breathing?
* Most newborns will respond to the cold air on their face as they are born by crying, moving and breathing.
* Normal newborns make vigorous efforts to inhale air into their lungs.
27
Explain the process of the newborns first breaths?
* There is a reduction in the pulmonary artery pressures in order to allow an increased blood flow to the lungs
* The hydrostatic pressure created by crying assists foetallung liquid to move out of the alveoli and into the surrounding tissue.
* The lung liquid is replace by air over several breaths. Fluid is cleared by lymphatics of over the first few hours post birth
* Once the blood is being oxygenated by the lungs the ductus arteriosus can close
28
What happens in the newborn once effective breathing occurs?
* Oxygen tension rises.
* Pulmonary blood flow increases and pulmonary vascular resistance decreases.
* Systemic vascular resistance (SVR) increases as the cord is clamped and cut.
* As PVR decreases and SVR increases, the pressure gradient across the ductus arteriosus reverses, resulting in reverse shunting of blood from (L) to (R) into the pulmonary circulation.
29
What causes closure of the ductus arteriosus?
• The rise in PaO2 causes smooth muscle constriction of the ductus arteriosus (DA) which then closes.
30
What causes closure of the ductus venosus?
* Blood flow through umbilical vein ceases
* Most blood continues to divert through ductus venosuswith minimal flow to liver
* 1-3 hours post birth the smooth muscle of the ductus venosus contracts which stops flow through the duct. Blood flow then proceeds through the normal portal system (Liver)
31
What causes closure of the foramen ovale?
* Reversal (or correction) or pressure gradient
* Low right atrial pressure
* High left atrial pressure
* Small valve on left atrial side is held closed
32
How long does it take for a newborn to achieve 90% spo2 after birth?
7-10 mins
33
what are S&S of a healthy newborn?
* Cry vigorously
* Have a heart rate over 100 bpm within a minute after birth
* Be fully flexed: both arms and legs
* Become centrally pink by 7-10 minutes of age
34
What are the signs of successful transition?
* Quiet alertness
* Large gazing eyes
* Reaction to his or her surroundings
* Interested in sound, light & moving objects
* Will grasp in response to touch
* Will suck if offered the breast
35
Why is there a greater risk of hypothermia in a newborn?
* A large surface area-to-body mass ratio
* Decreased subcutaneous fat (half of what adults have)
* Greater body water content
* Immature skin leading to increased evaporative water and heat losses
* Poorly developed metabolic mechanism for responding to thermal stress (e.g. no shivering)
* Altered skin blood-flow (e.g. peripheral cyanosis)
* Highly sensitive to temperature changes for the first 24-48 hours –will begin to regulate within the first few weeks
36
What are the 4 causes of heat loss in newborns?
* Evaporation: when amniotic fluid evaporates from the skin.
* Conduction: when the newborn is placed naked on a cooler surface
* Convection: when the newborn is exposed to cool surrounding air
* Radiation: when the newborn is near cool objects, walls, tables, cabinets, without actually being in contact with them.
37
What is the metabolic triangle?
Thermoregulation, oxygenation and glucose
38
How does hypothermia affect the metabolic triangle?
leads to brown fat liposis to restore temp. The process consumes oxygen and glycogen
39
How does hypoglycaemia affect the metabolic triangle?
leads to mobilisation of glycogen stores to restore glucose level. Process of converting glycogen to glucose require oxygen and heat
40
How does hypoxia affect the metabolic triangle?
leads to anaerobic methods of oxygen production. The processes require heat and glucose
41
What are the steps for neonatal management to provide warmth?
* Dry immediately at birth.
* Dry and cover the head (hat, folded towel)
* If vigorous, place skin-to-skin with mum & cover with warm blankets.
* If not vigorous, place onto warm towels on a firm surface to initiate resuscitation interventions.
* Cover the body with warm blankets. Cover the head (not face)
42
What are the S&S of hypothermia?
* Acrocyanosis (blue extremities) and cool, mottled, or pale skin
* Hypoglycaemia
* Transient hyperglycaemia
* Bradycardia
* Tachypnea, restlessness, shallow and irregular respirations
* Respiratory distress, apnoea, hypoxemia, metabolic acidosis
* Decreased activity, lethargy, hypotonia
* Feeble cry, poor feeding
* Decreased weight gain
43
What are the steps to clear the airway in a newborn?
* Vigorous newborns do not require suctioning
* Only suction if obvious blood or meconium
* obstructing the airway: mouth then nose
* Use 10Fg or 12Fg catheter
KEY POINT:
* Suctioning can cause complications:
* Delayed onset of effective breathing
* Laryngospasm & bradycardia
* Trauma to soft tissues
44
what can cause hypoxia prior to birth?
* Any event that compromises placental function or blood flow through the umbilical cord can lead to foetalhypoxia.
* Accidental separation of the placenta from the uterine wall before birth (‘abruption’)
* Cord prolapse
* Cord compression
* Cord being tightly around the neck
* True knot in the cord
45
What are the signs of a compromised newborn?
* Heart rate <100 bpm despite stimulation
* Not breathing or breathing ineffectively
* May be gasping
* ‘Frog posture’ with poor tone
* May be pale or centrally cyanosed despite vigorous stimulation
* “Floppy” no tone, response, reflex etc
46
What are some common birth injuries?
* Caput succedaneum:
* Cephalhaematoma:
* Fractured clavicle:
* Facial paralysis:
* Erb’spalsy:
47
What is Caput succedaneum
Caput succedaneum: is an oedemaof the scalp at the neonate’s presenting part of the head. It often appears over the vertex of the newborn’s head as a result of pressure against the mother’s cervix during labor
48
What is Cephalhaematoma
Cephalhaematoma: It is a collection of blood betweenthe periosteum of a skull bone and the boneitself. It occurs in one or both sides of the head
49
What is Fractured clavicle
Fractured clavicle: Common in large newborns. Potential complication of shoulder dystocia management e.g. Rubin 1 (suprapubic pressure)
50
What is Facial paralysis
Facial paralysis: From pressure on cranial nerve during delivery. Affected side doesn’t move while crying.
51
what is Erb’spalsy
Erb’spalsy: Associated with stretching or pulling head away from shoulder during delvery
52
What causes neonatal jaundice?
Post birth foetal haemoglobin is broken down and replaced with adult haemoglobin. The neonates liver is relatively immature post birth and this often leads to a build of bilirubin in the blood or hyperbilirubinemia.
53
What is a NecrotisingEnterocolitis
Neotnatal infection is characterised by necrosis of the intestinal wall
* Is a condition where a portion of the bowel dies. More common in premature or otherwise unwell neonates.
* Symptoms may include poor feeding, bloating, decreased activity, blood in the stool, or vomiting of bile.
54
What is neonatal sepsis?
* Systemic bacterial infections of newborn infants are termed as neonatal sepsis
* Immature neutrophils and complement system poor bacterial killing ability
* They are one of the most common cause of neonatal deaths
* This is ageneric term which incorporates conditions such as meningitis, pneumonia, pyelonephritis, or gastroenteritis
55
What are the S&S of neonatal sepsis?
* Often vague and nonspecific, demanding a high degree of suspicion for early diagnosis
* Any alterations in feeding patterns
* Active baby suddenly becoming lethargic
* Hypothermia or Fever
* Diarrhoea, vomiting and abdominal distension
* Jaundice
* Episodes of apnoea
* Check axillary temperature –most accurate (not the ear)
56
What are the 3 regions of the foetal skull?
The vault
The face
The base
57
What is the Vault of the foetal head?
The vault is the most important part of the fetal skull as it contains the brain and is usually the part of the skull that will be felt during internal examinations to assess
progress in labour.
58
What are the bones of the vault of the foetal skull?
* The frontal bone, which is divided into two halves
* Two parietal bones
* Two temporal bones
* The occiput.
59
What are the sutures of the vault on the foetal skull?
* The frontal suture – located between the two halves of the frontal bone
* The sagittal suture – located between the parietal bones
* The coronal suture – located between the frontal and parietal bones
* The lambdoidal suture – located between the occiput and the parietal bones.
60
What are the fontanelles of the vault on the foetal skull?
* The anterior fontanelle or bregma – located at the junction of the coronal, frontal and sagittal sutures. This fontanelle is diamond shaped and measures 2.5 × 1.25 cm
* The posterior fontanelle or lambda – located at the junction of the lambdoidal and sagittal sutures. This fontanelle is triangular.
61
What are the landmarks of the vault of the foetal skull?
* The lambda
* The bregma
* The parietal eminences – a raised area in the middle of each parietal bone where ossification started
* The occipital protuberance – the raised area in the centre of the occiput where ossification started.
62
What are the landmarks of the face of the foetal skull?
The landmarks of the face are:
• The glabella – the bridge of the nose
• The mentum or chin.
63
What are the areas of the foetal skull?
* The vertex – the area enclosed by the anterior and posterior fontanelles and the two parietal eminences. This is the part of the skull that will present in the majority of cephalic presentations
* The brow or sinciput – the area between the coronal suture and the ridge above the eyes
* The occiput
* The suboccipital region – the area below the occipital protruberance.
PAR3031 - MATERNITY
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