Premature Infant

Premature Infants Neonatal Outcome 25-26 weeks gestation = 40% survival without malformation / disability 30-32 weeks gestation = 95% survival without malformation / disability Nutrition Poor suckling response à use NG tube, Can be functional ileus for a few days Nutritional Deficiency High catch up rate à vitamin deficiencies (Fe, Ca, PO4 & Vit D supplements) Necrotising Enterocoloitis Commonest in the smallest babies (2-5% risk) S&S: Bilious vomiting, distended abdomen, blood & mucus in stool AXR: shows thickened bowel wall with intramural gas Treatment: – stop oral feeds, give Abx, ? surgical resection Liver Immaturity High incidence of physiological jaundice Preterm brain is more susceptible to high bilirubin Rx: Blue light (450nm) Thermal High SA:vol ratio, low sub-cut fat and high transdermal water loss for 1st few days Cant shiver & little brown adipose means no non-shivering thermogenesis Hypothermia à increases O2 requirement, decreased surfactant and decreased survival Fluid balance Prems have high transepidermal fluid loss (increased by phototherapy) 80% of term baby body wt = water (more in prem) After delivery renal function improves à loss of up to 5% body wt as urine Respiratory Apnoeic Attacks Common in prems (& sick neonates) due to varying respiratory drive CPAP or intubation required if prolonged Idiopathic Respiratory Distress Syndrome (surfactant deficiency) Surfactant production stimulated by maternal ill health, uterine contractions, or steroids. Decreased by hypothermia, acidosis, Surfactant hypoxia, hypovolaemia & meconium 80% DPPC Lungs sticking together then pulled apart à Remainder Carbohydrate + Protein Damage à hyaline membrane Amphipathic = hydrophilic head & hydrophobic tail 60-80% of 28/40 Proteins SP-A and SP-D are hydrophobic parts 10-30% of 32-36/40 Half life = 2hrs 5% in > 37/40 Diagnosis: symptoms + CXR = diffuse ground glass with air bronchogram Treatment: Where possible give steroids before birth, ET tube and give surfactant May require CPAP / IPPV (repeat blood gas every 4 hrs) Complications: CLD, ROP, Pneumothorax, infection, Intracranial bleeds, PDA Chronic Lung Disease a.k.a bronchopulmonary dysplasia (BPD) Definition: O2 requirements and CXR changes by 28 days old Causes: due to barotraumas & volutrauma (from ventilation) & O2 toxicity CXR – patchy collapse & fibrosis with areas of distension & cystic change Many will outgrow lung damage NB: increased risk of RSV Prevention: steroids, surfactant, allow 91% O2 sats on ventilation, wean asap from ventilator using steroids, optimum nutrition, diuretics, Retinopathy of prematurity Caused by O2 toxicity on developing blood vessels in prem’s retina Complications: Can à retinal detachment & blindness Treatment: check @ 6-8 weeks, laser/cryotherapy, milder may resolve Pneumothorax Causes: Can be spontaneous or occur with ventilation for RDS Suspect if baby worsens on ventilator Diagnose by CXR or trans-illumination with cold light, asymmetrical sounds Treatment: Aspirate air with syringe & place chest drain CNS Brain injury in Prems Risk factors < 32/40 Haemodynamic instability Pulmonary haemorrhage Pneumothorax Bleeding diathesis Chorioamnionitis Sx Sudden deterioration, Drop in Hb, Tense fontanelle (rare) Ix Imaging (C-USS, MRI / CT) e.g. Early cysts in ventricles – CMV / Rubella, Trisomy, Metabolic e.g. copper metabolism e.g. later cysts may be resolving bleed / cystic PVL e.g. Porencephalic cyst = IVH Gr 4 à communicates with ventricle Intraventricular Haemorrhage Uncommon after 35 weeks Bleed into germinal layer lining the lateral ventricles à ruptures into ventricles / choroid plexus 33% incidence in <1500g infants Risk factors: prem, RDS, IPPV, hypercapnia, metabolic acidosis, coag disorder. All à altered cerebral flow autoregulation Features: Minimal – 60% no major signs. Subtle changes in tone, tight popliteal angle, roving eye movements Intermittent deterioration – increasing apnoeas, bradycardias, metabolic acidosis & seizures over days Massive collapse – coma, shock, seizures Diagnosis - Assess with USS through fontanelles Grade 1 – subependymal haemorrhage Grade 2 – IVH with no ventricular dilatation Grade 3 – IVH with distended ventricle due to blood Grade 4 – intraparenchmal haemorrhage Periventricular Leucomalacia (Ischaemia / infarct of brain) Can resolve or lead to cyst formation à spastic cerebral palsy Hypoxic Ischaemic Encephalopathy Perinatal O2 deficiency à multiorgan failure Renal à low UO à low Na, high K, acidosis, high Ur & Cr MI à low CO Liver à coagulopathy GI à increased NEC risk CNS damage is permanent