Newborn Exam Flashcards
When is Newborn Exam done?
1st exam 72h
2nd exam 6-8w, latest 10w
What are you looking for in the exam?
Congenital HD
Developmental dysplasia of hip
Morphological abnormalities
Undescended testes
Important postnatal changes
Increased systemic vascular resistance with separation from low-resistance placental vasculature
Closure of L to R shunts (foramen ovale and DA)
Rapid lowering of pulmonary vascular resistance with onset of ventilation
Clearance of fluid away from airway pressure due to ventilation
Increased metabolic rate leading to higher glucose needs
Increased catecholamine levels to support BP
Foramen Ovale
1st postnatal breath causes pulmonary vascular resistance to decrease dramatically
Due to ventilation and increased O2 exposure
Pressure withing L atrium then increases because of distal aortic pressure and greater amount of blood returning to L atrium
L atrium pressure > R atrium pressure = flap across foramen ovale closes
Ductus arteriosus
Reversal of flow across DA with a L to R flow = greater pulmonary flow
Oxygenation of DA further leads to increased Ca channel activity/inhibition of potassium channel activity = closure
Surfactant
Surfactant secretion into foetal lungs is stimulated by labour
Alveolar stretch as a result of initiation of ventilation further increases secretion of surfactant
Surfactant lowers surface tension in lungs so can inflate at lower pressures
Clearance of foetal lung fluid
Begins before birth, increased in labour and mostly done by 2 hours old
Spontaneous labour and immediately after birth - resp epithelium changes from active fluid secretion to active fluid absorption - uses sodium transport in interstitium
Regulation of active fluid absorption is believed to be regulated by increased cortisol and thyroid hormone levels
Postnatal haematological changes
After birth, production of foetal Hb decreases and there is increase in haemoglobin B chain production
Normal adult levels of Hb achieved by 4-6m
Exposure to increased oxygenation of extrauterine environment leads to decreased erythropoeitin, leading to lower rates of erythropoeisis in neonate
Postnatal metabolic changes
Foetus has low metabolic rate
Maintain blood glucose - surge in catecholamines and glucagon levels and decrease in insulin amounts
Gluconeogenesis and glycogenolysis
Ketone bodies and lactate provide additional energy for brain
Cortisol and thyroid hormones activate sodium channel activity that drives resorption of lung fluid
Increased production and release of catecholamines renin-angiotensin and ADH - CO, plasma glucose and free fatty acids
Postnatal temperature regulation
Babies emerge covered in fluids = heavy heat loss via evaporation
Newborns not held skin-to-skin or wrapped up then hypothermia can ensue because of conduction, convection and radiant heat losses
Brown adipose tissue lipolysis triggered by noradrenaline can generate heat and peripheral vasoconstriction can minimise heat loss
What can you use to predict preterm birth?
Transvaginal USS of the cervix and measurement of foetal fibronectin
Positive foetal fibronectin from 22-37 weeks means increased risk of premature birth within 7 days
Maternal characteristics which increase risk of preterm birth
- FHx of preterm birth
- Lows SES
- Low educational attainment
- Maternal age (low or high)
- Ethnicity (non-white race)
- Stress
- Depression
- Tobacco use
- Infections
- Periodontal disease
- Uterine abnormalities
- History of cervical excisional procedures/surgery
Reproductive history risk factors for preterms
- Prior preterm birth/ stillbirth/ pregnancy loss >16w GA
- induced abortion
- cervical insufficiency
Pregnancy risk factors for preterms
- vaginal bleeding
- assisted reprodructive technologies
- multiple gestation
- short cervical length
Causes of preterm labour
- spontaneous preterm labour
- intra-uterine infection
- premature membrane ruptures
- pre-eclampsia/pregnancy induced HTN
- Abruption/anterpartum haemorrhage
- abnormal amniotic fluid volume
- severe BV
- Previous preterm
- Cervical incompetence
- Gestational DM
- high or low BMI
Prediction of LBW
- inadequate weight gain by mother during pregnancy
- inadequate proteins in diet
- previous preterm/LBW
- Anaemic mother
- Passive smoking
Methods to prevent preterm birth and LBW
- Limit maternal RF - smoking cessation
- Treat BV w/ clindamycin - reduce risk of membrane rupture
- Progesterone - short cervix
- Cervical sutures - previous loss from weakness, short cervix or response to dilation
- Reduction of pregnancy number
- Bed rest
- Tocolytic drugs (Atosiban/Ritodrine) can briefly delay labour + allow steroids to be given to reduce lung disease risk
What are complications of pre-term delivery and why? (think systems)
- Immaturity of organ systems (lungs)
- Temp control - heat loss is high due to high SA:V and lack of fat insulation, limited muscle activity
- Blood and circulation - hypotension, easy bruising and bleeding
- Resp system - narrow nasal airway, poor cough reflex, alveolar collapse due to surfactant insufficiency
- GIT - uncoordinated suck/swallow (before 32-34w), regurg
- Active and passive immunity limited
Short term disorders of preemies
- Surfactant deficiency
- Apnoeic attacks
- PDA
- Intracranial lesions
- Necrotising entercolitis
Surfactant deficiency
Features + Mx
- Immaturity of type II pneumocytes
- Lowers surface tension in alveoli and prevents alveolar collapse
- Worse in boys
S+S: Resp distress, tachypnoea, cyanosis, expiratory grunting
Mx: Resolves spontaneously 3-7d as endogenous surfactant produced
- glucocorticoids antenatally for 48hours
- artifical surfactant therapy (Curosurf)
- O2 + assisted ventilation
What does surfactant deficiency look like on xray?
Ground glass appearance
Apneoic attacks
RF
Mx
- periodic respiration with some spells of very shallow breathing or complete cessation of breathing for 20s
RF = Resp distress, hypoxia, sepsis, cranial pathology
Alarms - alert staff is O2 sats reach certain point use physiological stimulation
Caffeine used to prevent apneoia as improves neurodevelopmental outcome
Vent support if severe
Intracranial lesions
RF
Complications
Intracranial haemorrhage into geminal matrix or ventricles
Ischaemia of periventricular white matter
RF: pneumothorax, asphyxia, hypovolaemia, hypotension, hypoxia
Hydrocephalus is late stage complications
Serial intracranial USS used to diagnose
Necrotising Enterocolitis
(what is, aetiology, S+S, Mx)
Necrosis of intestine - distal ileum or proximal colon
Aetiology: preterm birth, IUGR, Polycythaemia, PDA, Asphyxia, early formula milk feeding
S+S: abdo distension, vomiting, bloody stools, AXR - dilated, thick walls, static bowel loops
Mx: Large bore NG tube + parenteral nutrition, penicillin, gentamicin and metronidazole, surgical resection
Long term consequences of preemies
Retinopathy
Chronic Lung disease
Neurodevelopmental problems
Retinopathy of prematurity
Retinas are incompletely vascularised at birth
Can progress to fibrosis, retinal detachments and blindness
All infants weighing <1500g or <32w GA should have eyes screened at 6-8w
Most resolve spontaneously
Laser therapy for severe disease
CLD of prematurity
Prolonged ventilation with high pressure and high concentration
Requiring supplemental O2 after 36w, corrected GA or 28 days of age whichever is later
Positive pressure ventilation causing volutrauma, oxygen toxicity and inflammation - all contribute
Mx of CLD
Assisted ventilation and CPAP
Supplemental O2 as needed
Dexamethasone - helps wean from ventilation but increase risk of neurodevelopment impairment
Strict nutrition
Prophylaxis against RSV - Plaivizumab vaccine
Neurodevelopmental problems
Very LBW infants those with gestation period under 28w are at risk of:
CP
Cognitive delay
Visual impairment
Hearing loss
Seizures
Behavioural problems
Educational difficulties
Types of acyanotic heart disease
ASD
VSD
PDA
Coarctation of aorta
Aortic stenosis
Pulmonary stenosis
What causes acyanotic congenital HD?
Lesions that allow blood to shunt from left to right side of the heart/circulation OR lesions that obstruct the flow of blood by narrowing a valve or vessel
What are the types of ASD?
Ostium primum - occurs lower in atrial septum, often associated with mitral regurg and Downs syndrome
Ostium Secondum (most common) - high in atrial septum, more common in girls, asymptomatic as left to right shunt develops slowly
What are causes of ASD?
Ostium primum - when septum primum doesn’t fuse to endocardial cushion of septum intermedium
Ostium Secondum - excessive apoptosis or resaborption of septum primum or insufficient formation of septum secondum
S+S of ASD
Abnormal RV impulse
Widely split and fixed S2
Tricuspid flow murmur - rumbling mid-diastolic murmur at left sternal edge
Pulmonary flow murmur - soft, ejection systolic murmur in pulmonary area
Sounds like an ejection systolic murmur and a fixed split of S2
Diagnosing an ASD (Signs on scans)
CXR - pulmonary plethora (increased pulmonary perfusion)
ECG - RVH with incomplete RBBB - big R wave
ECHO
Mx of ASD
Transcatheter closure of ASDs, best done between 3-5y
Prevent cardiac failure and arrhythmias later in life
Risk factors for VSD
Foetal alcohol syndrome and Down’s syndrome
Commonest type of CHD
VSD
Causes of VSD
Muscular ridge grows up from apex of heart and membranous region grows down from endocardial cushion = 2 chambers
If leaves a gap/don’t fuse = VSD
Majority caused by defect in membranous region
What happens in VSD?
Blood flows from high - low pressure so right side of heart functions normally as has lower pressure
L side of heart has higher pressure so some blood flows into RV = L to R shunt
Leads to higher O2 sats in RV and pulmonary artery
If pressure increases in R side increases (e.g Cor Pulmonale) to being more than L shunt can swap to be R to L = deoxygenated blood into systemic circulation = cyanosis
Eisenmenger Syndrome
Pressure in R side increases to being more than L shunt can swap to be R to L - deoxygenated blood in circulation = cyanosis
S+S of VSD
Pulmonary HTN - shunt means more blood volume in R side
Cyanosis - shunt swaps to R to L = Eisenmengers syndrome
Ductus arteriosus
Connects aorta to L pulmonary artery to bypass lungs and usually closes by 4th day of life
Kept open by prostaglandin E2
When is PDA diagnosed?
Pathophysiology of PDA
Complications of PDA
If doesn’t close 1 day after life
After birth, R side of heart functions normally as is lower pressure area so blood flows to lungs as normal
L side = higher pressure, blood flows high - low, some is shunted back to lower pressure side - back to lungs
No deoxygenated blood travels round systemic circulation = acyanotic
Increased RV can lead to pulmonary HTN pressure in R > L so then shunts to L and then deoxygenated blood travels systemically = Eisenmengers
RF for PDA
Preterm infants
Down’s syndrome
High altitudes
Maternal rubella
S+S of PDA
Asymptomatic
Bounding pulses - wide pulse pressure
Murmur - continuous machinery
What do you seen on scan with a PDA?
Similar on ECG and CXR to VSD
Large PDA - increased pulmonary markings are seen
Shown on ECHO
Ductal shunt confirmed by US
Mx of PDA
Indomethacin = NSAID inhibits protaglandin E so can shut
If large, may be closed at 1-3 months
Closed in cardiac catheter lab at 1y
Coarctation of aorta
Obstructive lesion caused by narrowing or constriction in a portion of aorta
Preductal or postductal
Forces heart to pump harder to get blood through aorta and circulation
Preductal coarctation of aorta
(definition. presentation, mx)
Abnormal circulation often diagnosed antenatally
Present as a sick neonate with absent femoral pulses
Whilst DA is open - RV can maintain adequate CO to systemic circulation
Prostaglandin infusion given to maintain ductal patency
Transfer to cardiac centre for surgery
Postductal coarctation of aorta
(s+s, mx)
normally asymptomatic
leg pains or headaches
HTN in arm, weak or absent femoral pulses
Ejection click (bicuspid valve) and ejection systolic murmur
Balloon dilatation
Resection of coarcted segment with end-end anastamosis