Neonatal and Perinatal Medicine Flashcards
Features of necrotising enterocolitis on xray - what is pneumotosis
Portal venous gas pneumotosis coli “ train tract” - intraluminal gas - sub mucosal and subserosal gas (nitrogen and hydrogen produced by gas forming bacteria)
Classical triad of NEC
Abdominal distension, bloody stools, bilious aspirates
Causes of NEC
Multifactorial - immaturity / very low birth weight - poor barrier function – bacterial translocation and mucosal damage –> NEC Ischaemia, infection, formula feeding, anaemia, toxins, bacterial overgrowth (microbial dysbiosis)
Good postnatal bacteria (Term babies)
Lactobacilli, bifidobacteria
Bad postnatal bacteria
Gram negatives - E.coli, Klebsiella, clostridia - major determinant of necrosis, ischaemia
Why do we give probiotics to preterm babies
Non-pathogenic bacteria to improve outcome Bifidobacterium + lactobacillus reduced incidence of NEC (0.26-0.93) CI ANZ studies Also reduce mortality
Who needs NEC surgery?
20-50% require surgery Perforation, abdominal mass Form ileistomy + closure 4-6 weeks - contrast pre-closure
How much bowel does a term baby have?
Length of small intestine doubles in 3rd trimester - adapts and rapidly evolves 2.5M of small bowel in term baby
Minimum bowel lengths required for survival post neonatal bowel resection? - + outcome predictions in babies with short gut syndrome
>25cm with ileocaecal valve (slows down transit time) >40cm without ileocaecal valve Outcome predicted by residual length, % of calories tolerated enterally at 12 weeks cGA and presence/abscence of ileocaecal valve
What is the strongest stimulus for postnatal closure of the ductus arteriosis in a term infant?
Increased systemic oxygen saturation
In utero, what percentage of the RV output goes through the lungs?
13%
In utero, what does the right ventricle mainly supply?
lower 2/3 of the body with low O2 blood (70%) through pulmonary artery and ductus arteriosis to the descending aorta
In utero, what does the Left ventricle mainly supply?
Upper 1/3 of the body (brain) with higher oxygenated blood shunted from umbilical vein through ductus venosis into IVC, across RA through foramen ovale into LA –> LV –> aortic arch (sO2 ~80%)
What is the strongest stimulus for postnatal closure of the ductus arteriosis in a term infant?
Increased systemic oxygen saturation + reduced flow through shunt due to decreased pulmonary vascular resistance
Causes of prolonged jaundice
Breast-feeding jaundice (Dx of exclusion) - prolonged when over 14 days - FBC, SBR
Signs of congenital hypothyroidism (x 5)
Prolonged jaundice Poor feeding / suck Bradycardia Constipation Large anterior fontanelle
What cause of hypothyroidism is missed on newborn screening?
* NBST only detects elevated TSH, won’t detect central hypothyroidism *
Effect of caffiene in preterm neonates
Reduces central apnoea Decreases incidence of chronic lung disease Increases disability - free survival reduces severe ROP Reduced cerebral palsy and cognitive delay No long term significant
What is the sats target for preterm babies for overall survival?
91-95% (any higher or lower may cause increased death)
Effect of caffeine in preterm neonates
Reduces central apnoea Decreases incidence of chronic lung disease Increases disability - free survival reduces severe ROP Reduced cerebral palsy and cognitive delay No long term significant
What is the sats target for preterm babies for overall survival?
91-95% (any higher or lower may cause increased death) - more likely to have ROP with higher sats, more likely to need O2 at 36 weeks, BUT - high sats are good for NEC and treatment of PDA
Late preterm (34-36 weeks) - risk of CP
Associaed with worse neurodevelopmental milestones at 2 yrs - brain doesn’t finish developing (very ruggaed at term) - 3 x greater risk of CP than term babies
What kind of ventilation should you use in babies with congenital diaphragmatic hernia?
Ventilate as gently as possible - use conventional mechanical ventilation initially - lung hypoplasia
Characteristics of Refeeding syndrome
Hypophophataemia Hypokalaemia Hypercalcaemia More likely in pre-term and SGA due to placental insufficiency Usually in first 5 days +/- Thiamine deficiency Increases risk of death, worse in SGA, under 1000g Constellation of fluid and electrolyte dysregulation that occurs on initiation of enteral / parenteral nutrition following a period of malnutrition / starvation
Which vitamin is usually involved in refeeding syndroem?
Thiamine !!
Should naloxone be given in NAS babies?
No - will start withdrawing +++
Do opiates or benzodiazepines cause MORE teratogenicity?
Opiates - less teratogenic All others +++
Is breastfeeding contraindicated in NAS infants?
No - alleviate withdrawal - If hypotonic, would not feed PO anyway
What percentage of infants born to mothers born taking methadone develop NAS
70% - not all need treatment
Is hypotonicity characteristic of NAS?
No - Hypertonic ++, last thing to recover.
What is the main differential diagnosis of NAS?
Hyperthyroidism - also causes tremors, low grade fevers, incessant crying - Need to check maternal TRABs
Characteristics of RSD on X-ray
Ground glass appearance, no clear heart border ETT in situ (just below clavicles) 2 x vascular lines - arterial
Ground glass throughout No heart border
*Add xray R) pneumothorax
R) pneumothorax with tension and not much collapse due to stiff lung
Bilateral chest x-rays Pneumomediastinum Short NGT
Overexpanded left lung - secondary to pulmonary interstitial emphysaema Mediastinal shift to right L) chest drain RUL consolidation
Patchy areas of collapse and consolidation, over inflation and underinflation Developing chronic lung disease
Over expansion of bases Fibrosis of apices - chronic lung disease - eventually form bullae ET too low (at carina
What pushes oxygen dissociation curve to right? (reduced affinity)
Adult Hb
What pushes oxygen dissociation curve to right? (reduced affinity)
Adult Hb High 2-3 DPG (eg - in anaemia due to chronically reduced O2) Higher temperature High H+++
Characteristics of Human Milk Oligosaccharides (x 6)
- Only present in breast milk - Not well absorbed - largely metabolised by gut bacteria and excreted in faeces - NOT a pre-biotic - Glycans competitively block pathogen biidning to epithelial cells - GBS unable to proliferate in presences of HMO, anti-adhesive effects (also agains rotavirus) - Specific to each mother
What is the major whey protein in breast milk?
Lactoferrin
Mechanism of action of lactoferrin
Iron transporter - binding iron and enabling passage across mucosal barrier 6 x higher concentration in colostrum than mature milk Gut trophic, anti-inflammatory
Does lactoferrin prevent NEC?
No but may prevent late onset sepsis
What effect do high concentrations of lactoferrin in colostrum have on gut permeability?
decreases gut permeability
How does lactoferrin work in immune function?
Bacteriostatic - sequesters iron thereby inhibiting viral and bacterial replication
Facts about gentamicin in the new born ( x )
Bacteriocidal (at high concentrations) - through ribosomal inactivation (irreversible) 24 hour dosing decreases adaptive resistance Toxicity increases with use of loop diuretics Generally useful again gram negative (except pseudomoas) pH dependent (not so good in lungs due to low pH)