Neonatology Flashcards
SGA
small for gestational age
used for neonates with a birth weight less that the 10th centile or 2 standard deviations from the population norm
o This definition only considers the birthweight without any consideration of the in-utero growth or physical characteristics at birth
o Severe SGA is birthweight <3rd centile
IUGR
IUGR is used for neonates with clinical features of malnutrition and growth restriction, irrespective of birth weight centile
o It is a failure to fulfil growth potential with faltering growth in-utero
Maternal Causes of IUGR
Malnutrition Low BMI Maternal substance abuse inc. smoking Chronic disease Hypertensive disorders Anti phospholipid syndrome Previous SGA Material age <16 or >35 Nulliparity or grand multiparity
Foetal Causes of IUGR
Chromosomal abnormalities Genetic syndromes Major congenital abnormalities Congenital infections Metabolic disorders
Placental causes of IUGR
Pre-eclampsia
Abruption
Classification of IUGR
- Symmetrical IUGR is due to a cause early in pregnancy (foetal factors above). The head circumference, length and weight are all reduced
- Asymmetrical IUGR is due to a cause later in pregnancy. The weight is reduced but other factors are normal
IUGR Investigations
Undergo serial growth scans (plotted customised growth charts) every 2 weeks from 28 weeks’ gestation to assess the following
- Foetal head circumference, abdominal circumference, and femur length
- Liquor volume
- Uterine artery Doppler
o Where this shows reversal or absent diastolic flow, delivery of the foetus is indicated. If preterm, give steroids
o If it shows reduced pulsatility/notching, continue surveillance - Occasionally CTG is also performed
For severe IUGR consider serological testing for TORCH infections, or pre-natal diagnosis with karyoptyping
Why does oligohydramnios occur in IUGR
o Oligohydramnios occurs in IUGR as there is shunting of blood to the head to protect the developing brain. This deceases renal perfusion, lowering urine output
How to manage previous mothers with previous SGA
they should be commenced on 75mg aspirin OD from booking
- Where women have anti-phospholipid syndrome they should take clexane alongside aspirin from booking
Complications of IUGR
- Asphyxia
- Hypothermia
- Hypoglycaemia
- Jaundice
- Pre-term delivery
- Perinatal mortality (death in utero after 24 weeks, or death in the first 7 days postnatal)
In the longer term these infants are prone to poor growth and neurodevelopmental outcomes. They may also demonstrate the thrifty phenotype, and develop metabolic disorders.
Circulation in Utero
foetus is dependent on the umbilical vein, providing oxygenated blood from the maternal circulation via the placenta. Some of this blood passes to the foetal liver (into the hepatic sinusoids) through the portal sinus, but the majority passes into the ductus venosus and bypasses the liver
Blood in the ductus venosus travels to the inferior vena cava, which also drains the lower limbs, abdomen, and pelvis. This blood then passes into the right atrium, alongside deoxygenated blood returning from the head and arms
- Some of this blood will pass out of the pulmonary trunk. However, due to high pressure within the lungs, most of it will pass through the ductus arteriosus into the descending aorta
- The rest of the blood from the right atrium will pass through the foramen ovale and into the left atrium, passing out of the left ventricle to the ascending and descending aorta to pefuse the body
The deoxygenated blood will then flow to the placenta through the two umbilical arteries. The blood is oxygenated in the placenta and then passes back into the foetus through the umbilical vein.
Changes at Birth with Circulation
At birth, when maternal circulation is removed and the lungs become filled with air, major changes to the foetal circulation must take place
During labour the fluid filling the lungs is drained, and at birth with the first breath, the remaining fluid is absorbed. This decreases the pulmonary vascular resistance dramatically as the lungs can expand
What happens as a result of reduced pulmonary vascular resistance
Blood can then flow from the right ventricle into the pulmonary circulation, returning to the left atrum
o This increase in left atrial pressure, coupled with a decrease in right atrial pressure, closes the foramen ovale by pushing the septum primum against the septum secundum
How are baby’s lungs able to expand with their first breath
The ability for the lungs to expand in the first breath is reliant on the presence of sufficient lung surfactant
- Surfactant production occurs from around 20 weeks and is complete at term
- Surfactant is a form of interstitial fluid that reduces alveolar surface tension (secreted by type II alveolar cells), increasing lung compliance
What happens to foetal circulation after birth?
The umbilical arteries, umbilical vein, and ductus venosus close in response to thermal and mechanical stimuli
o After around 3 months’ post-partum these will be obliterated
- The ductus arteriosus closes almost immediately after birth by muscular contraction in response to bradykinin due to oxygenated blood flow
o Anatomical closure follows this physiological closure after a few days
Why might a neonate not take their first breath spontaneously
Several reasons for this, and almost all relate to a respiratory rather than cardiac arrest
- Asphyxia, where the foetus experiences a lack of oxygen during labour
- Deprivation of oxygen in utero e.g. cord prolapse/ abruption, meaning that the foetus attempts to breathe in utero and apnoea follows
- Birth trauma
- Maternal analgesics or anaesthetics
- Prematurity and lack of surfactant
- Congenital lung malformation
Where an infant does not take their first breath, immediately transfer them to a neonatal resuscitation trolley
Infant Resuscitation Algorithm
Dry the baby, remove wet towels, and wrap the baby in a new towel. Cover their head with a hat
- Start the clock
- Assess the baby’s heart rate (auscultation), chest movement, colour, and tone
What is the first thing that must be achieved in resuscitation?
The first thing that must be achieved is aeration of the lungs, which can only be confirmed when the chest is seen to passively move.
- Open the airway by placing the head into neutral position
- Give 5 inflation breaths over 30 seconds
o Inflation breaths are best given using a neopuff device with mask (or bag-valve-mask) using air, at 30 cmH2O for 3 seconds per breath
- Re-assess heart rate, chest movement, colour, and tone
What happens if chest has not expanded and HR has not increased after inflation breaths?
re-check the head position and call for help
- Give 5 further inflation breaths
- If these measures have failed to expand the lungs, apply an SpO2 monitor to the right hand to gain a pre-ductal saturation recording. Try 5 inflation breaths after each of the following manoeuvres
o Move on to two-person airway control, with a jaw thrust manoeuvre
o Look inside the mouth and suction anything visible, insert a guedel airway
o If there is someone competent present, consider tracheal intubation
- Ensure to re-assess the baby every 30 seconds
What happens if you intubate but heart rate does not increase and chest does not expand
consider DOPE - Displaced ET tube - Obstructed ET tube - Patient o Tracheal obstruction o Lung disorders o Shock o Upper airways obstruction - Equipment failure
What happens after chest movement is seen and HR improves after intubation ?
you can assume that the lungs have been aerated. The baby will usually breathe for themselves at this point. If the baby does not start to breathe on their own, move on to ventilation breaths
- Give 30 ventilation breaths at 30 cmH2O for 1 second per breath
- Repeat this in 30 second cycles, with re-assessment of the baby between cycles, until it starts to breathe on its own
What do you do if the chest starts moving after ventilation breaths but heart rate is not improving?
give 5 further inflation breaths with good passive chest movement and re-assess. If heart rate is still <60, commence chest compression
- Grip the chest with both hands so that the thumbs can press on the lower third of the sternum
- Give 3 compressions to one inflation breath
- Re-assess heart rate every 30 seconds, stop when heart rate >60
What drugs should you use if HR is less than 60 despite adequate ventilation and chest compression
Adrenaline Bicarbonate Dextrose Saline Drugs should be given via an umbilical venous catheter
Definition of neonate
Infant <28 days old
Hypoxic Ischaemic Encephalopathy
HIE is injury to the brain occurring due to perinatal asphyxia, significant hypoxic events immediately before and during labour have many potential causes
- Placental failure e.g. abruption, uterine rupture
- Cord failure e.g. cord prolapse, shoulder dystocia
- Inadequate maternal placental perfusion
- Failure of cardiorespiratory adaptation at birth
Clinical Manifestation of HIE
tend to become apparent within the first 48 hours of life
In mild cases there may be irritability and trouble feeding
- In more severe cases there may be abnormalities in tone and movement, seizures, and multi-organ failure
o Encephalopathy, persistent pulmonary hypertension, myocardial dysfunction, metabolic derangements, DIC, and renal failure
APGAR Measurements
Evaluates newborn baby on five criteria, and is designed to see if a child needs immediate intervention
A Appearance, this is skin colour
P Pulse, this measures heart rate and is measured through a stethoscope
G Grimace, this is a measurement of reflex irritability in response to mild stimulation e.g. a pinch
A Activity, this is muscle tone
R Respiration
APGAR Scoring
Each of the five criteria is scaled from 0 to 2, therefore the maximum score is 10. Different score bandings are summarised below
- <3 is critically low
- 4 – 6 is fairly low
- 7 – 10 is generally normal
APGAR score is taken at 1 and 5 minutes after birth (and later if necessary). It is not able to predict the need for long term care
- However, a score <3 beyond 5 minutes increases the risk of the child developing neurological damage e.g. cerebral palsy
Physical Examination of the Newborn
carried out within 72 hours of birth
involves a ‘top to toe’ physical assessment, alongside several specific screening tests
- Auscultation of heart and examination of pulses
- Hip movement in all planes to detect congenital hip dysplasia
- Ophthalmoscopy of eyes to check for congenital cataracts
- Check for undescended testes. If the testes have not descended by 1 – 2 years, an operation may be advised
Physical Examination of the Newborn: General Appearance
- Do they look particularly small or large?
- Look for pallor, cyanosis, and jaundice
- Assess movements and tone of the four limbs. Are they moving equally, and in a flexed position?
Physical Examination of the Newborn: Cardiorespiratory + General
The position of the heart should be assessed by palpating the apex beat. The doctor should then auscultate for any murmurs, and measure the heart rate (should be 100 – 160). Femoral pulses should be measured
- Lungs should be auscultated for added sounds, and the respiratory rate measured (30 – 60)
- Abdominal examination should look for any herniae, organomegaly, and the general shape of the abdomen
Physical Examination of the Newborn: Head
head circumference is then measured, as well as an assessment of the overall shape, sutures, and fontanelles. Observe the face and the ears
- Look for accessory skin tags or preauricular sinuses. These are usually normal, but additional hearing tests are recommended
- Assess the face for syndromic or dysmorphic features
Physical Examination of the Newborn: Eyes and Vision
In high risk infants e.g. premature, family history of eye problems, permanent squint, the doctor should check that the infant is being seen by an opthalmologist
- An opthalmoscope is used to check for the red reflex
- This may absent in retinoblastoma, corneal scarring or congenital cataracts (more common in Down’s, rubella, and galactosaemia)
- The pupils and alignment of the eyes are noted, as well as the completeness of the iris
Physical Examination of the Newborn: Mouth
Look in the mouth for cyanosis, dentition, and the completeness of the palate
- Digitate the palate, but also ensure to look at it when the baby is crying
- Epstein’s pearls may be present in the midline, and are a normal variant
Physical Examination of the Newborn: Limbs
Assess the limbs, looking at the palms and counting the fingers, and then the feet and toes.
Physical Examination of the Newborn: Genitalia and Anus
Genitalia should be examined
- In boys check for hypospadias, hydrocele, hernia and undescent of testes
- In girls, the labia should be parted to check for ambiguous genitalia e.g. 5α-reductase deficiency, CAH
The anus should be checked for patency and position
- Passage of meconium does not necessarily indicate a perforate anus
Physical Examination of the Newborn: Spine and Hip
The spine should be checked (inspection and palpation) for any deformities or surface changes.
Examination of the hip can follow. The infant should be placed supine on a flat surface with the hip partially abducted and fully flexed to 90 degrees. Hold each leg with one hand, grip the femur so that the middle finger is over the greater trochanter, the index is over the lesser trochanter, and the thumb is just medial to the knee
Physical Examination of the Newborn: Hip Findings
- Abduct the hip by pressing outwards on the greater trochanter. If the hip is dislocated it will relocate with a clunk = Ortolani positive
- Adduct the hip and push posteriorly, trying to push the head of the femur out of the acetabulum. If the hip is dislocatable it will clunk over the posterior edge of the acetabulum = Barlow positive
Physical Examination of the Newborn: Reflexes
check for Moro reflex
- Place the infant supine on a flat surface. Flex the infants head on to the body, and then release the head
- The infant should abduct their arms at the shoulders and flex the elbows and wrists, the hands will be open; this may be followed by adduction of the shoulders. The baby will usually cry
When is the heel prick test carried out
5 – 8 days
What diseases does the heel prick test detect
- Sickle cell disease
- Cystic fibrosis
- PKU
- Congenital hypothyroidism
- MCADD
- Homocysteinuria
- Maple syrup urine disease
- Gutaric aciduria type 1
- Isovaleric acidaemia
Hearing Scan
The hearing scan is performed in hospital, by a health visitor, or at the GP. This should usually take place within 2 weeks of birth
Which two hearing tests can be used?
- The automated otoacoustic emission (AOAE). This places a probe in the ear, which will emit clicks, acoustic energy will be produced in response to this if the cochlea is normal, this acoustic energy is detected
- The automated auditory brainstem response (AABR). This presents a stimulus to the child’s ear and detects electrophysiological responses from the brainstem using scalp electrodes.
The benefit of this is that it can detect deafness due to the pathway from the cochlea to the brainstem, as well as problems with the cochlea itself
Neither test can detect problems from the brainstem to the auditory cortex
Abnormal Findings: Benign
- Peripheral cyanosis of hand and feet is common in day one, and not necessarily worrying
- Traumatic cyanosis can also occur, usually from cord around baby’s neck or from face/brow presentation
- Swollen eyelids and distortion of shape of head from delivery, including caput succedaneum
- Subconjunctival haemorrhages from delivery
- Epstein pearls along the midline of the palate
- Cysts of gums or floor of moth (epulis or ranula)
- Breast enlargement ± lactation
- White vaginal discharge or small withdrawal bleed
- Umbilical hernias are common, especially in afro-caribbean infants, and will usually resolve
- Positional talipes, indicated as the foot can be fully dorsiflexed to touch the leg. This requires simple physiotherapy exercises
Abnormal Findings: Significant Abnormalities
- Natal teeth should be removed to prevent aspiration
- Polydactyly and syndactyly should be referred to plastics
- Heart murmurs are usually not worrying and resolve in the first few days, but as some are caused by congenital heart disease there should be referral to cardiology
- Midline abnormality over spine or skull will need further investigation with USS to rule out spinal bifida occulta
- Palpable bladder can be an indication of urinary outflow obstruction
Oesophageal Atresia +/- trachea oesophageal fistula: Presentation
Oesophageal atresia can be detected at many different stages
- Polyhydramnios in utero
- Persistent salivation and drooling from the mouth at birth
- Coughing and choking during feeding ± cyanosis
Oesophageal Atresia +/- trachea oesophageal fistula: Diagnosis + Management
Diagnosis is made on the basis of x-ray, with a radio-opaque tube passed to see if it reaches the stomach
Early surgery is essential, with continuous suctioning applied to a tube placed into the oesophageal pouch to prevent aspiration prior to this.
Oesophageal Atresia +/- trachea oesophageal fistula: :VACTERL
Almost half of patients with oesophageal atresia have associated syndromes These are known by the mnemonic VACTERL - Vertebral defects - Anorectal malformations - Cardiovascular defects - Tracheo-oesophageal fistula - Renal anomalies - Limb deformities
Neonatal Small Bowel Obstruction: Causes
- Duodenal atresia/stenosis. This will show a ‘double bubble’ sign on x-ray, and is commonly associated with Down’s syndrome
o This can also occur in the jejunum and ileum - Malrotation with volvulus
- Meconium ileus, usually in cystic fibrosis
Neonatal Large Bowel Obstruction: Causes
- Hirschprung disease
- Rectal atresia
- Imperforate anus
Ventral Body Wall Defects: Omphalocele
Exomphalos is centrally placed, and consists of the abdominal organs herniating through the umbilicus. The viscera are covered with a membrane
- The baby is usually stable at birth
- It is associated with a number of congenital anomalies
o Trisomy 13, 18, 21
o Cloacal extrophy e.g. meningomyelocele, bladder extrophy
o Beckwith-Wiedemann syndrome
Ventral Body Wall Defects: Gastroschisis
congenital defect of the abdominal wall, the organs have no covering membrane
- There is a higher risk of dehydration and collapse
- Associated conditions are less common but can include cleft lip, ASD, diaphragmatic hernia, and scoliosis
Respiratory Distress in New-born: Features
- Respiratory rate >60
- Laboured breathing e.g. chest wall recession (particularly sternal and subcostal), nasal flaring
- Expiratory grunting
- Cyanosis may be present in severe cases
Respiratory Distress in New-born: Pulmonary Causes
Transient tachypnoea of the newborn Infection Meconium Aspiration Persistent pulmonary hypertension Congenital Anomalies: diaphragmatic hernia, pulmonary hypoplasia, trachea-oesophageal fistula Milk Aspiration Pneumothorax
Respiratory Distress in New-born: Non-Pulmonary
Congenital Heart Disease Intracranial birth trauma HIE Severe anaemia Metabolic Acidosis
Respiratory Distress in New-born: Investigations
- Blood gases
- Pulse oximetry
- CXR
- Echocardiogram
- Blood and surface cultures
Broad-spectrum antibiotics are usually started early until the results of infection screen are available.
Transient Tachypnoea of the Newborn
commonest cause of respiratory distress in term infants
- It is caused by a delay in the resorption of lung fluid, and is therefore more common in infants born via C-section (particularly elective C-section where there have been no contractions)
This usually settles rapidly and without intervention. Additional ambient oxygen may be required
Meconium Aspiration
During labour the passage of fresh meconium (dark green, sticky, and lumpy) is a sign of foetal distress
- Asphyxiation leads infants to start gasping, and inhale the thick meconium
- Commence CTG monitoring and ensure obstetric review
Aspiration of meconium results in a chemical and mechanical pneumonitis. There is plugging of the airways, leading to patches of over-inflation and consolidation. Later complications include sepsis
- Babies born with meconium staining should be observed 2-hourly for 12 hours
o If there is any evidence of respiratory distress, pyrexia, or circulatory compromise there should be referral to neonatology
Persistent Pulmonary Hypertension of the Newborn
life-threatening condition usually associated with birth asphyxia, meconium aspiration, sepsis, or respiratory distress syndrome
- High pulmonary vascular resistance leads to right-to-left shunting within the lungs, atrial, and ductus arteriosus
These infants will be cyanotic however cardiac auscultation and echocardiography will indicate that congenital heart disease is not present
Most infants will require mechanical ventilation alongside inhaled vasodilators e.g. sildenafil, nitric oxide
Respiratory Distress Syndrome (RDS)
Developmental insufficiency of pulmonary surfactant production + structural immaturity; 1% of newborn infants, Most common cause of death of newborns
o Surfactant (secreted by type II pneumocytes, contains phospholipids and proteins) normally lowers surface tension of alveolar epithelium
o Leads to widespread alveolar collapse – Reduced surface area for gaseous exchange
• The more preterm the infant, the higher risk of RDS; common if <28wks gestation, more severe in boys than girls
o Rare at term; May occur in diabetic mothers or genetic conditions
