Complications of Prematurity

Neonatal mortality Causes of neonatal death in Cambridge Maternity Hospital Respiratory distress syndrome137*38 Infection Birth asphyxia 1514 Extreme prematurity1444 Pulmonary hypoplasia1019 Other causes10 0 Total non-malformed neonatal deaths Malformations8446 Total neonatal deaths * The majority of these babies had a periventricular haemorrhage

Gestational age and RDS

Predisposing factors Gender Caesarean section Asphyxia Maternal diabetes Multiple birth Hypothermia IUGR (IntraUterine Growth Restriction)

Role of antenatal steroids Structural maturation Increase in lung volume Epithelial barrier function

RDS pathophysiology Alveolar damage Formation of exsudate from leaky capillaries Inflammation Repair

Surfactant deficiency - “vicious cycle” Respiratory acidosis Severe hypoxia Further inhibition of surfactant by serum proteins Epithelial damage occurs through suction effect of gasping Depleted surfactant Decreased FRC Increased dead space Alveolar collapse Reduced compliance Increased work of breathing

Reduction in compliance

Histology RDS Normal

Atelectasis

Patent Ductus Arteriosus (PDA) Premature infants at risk Duct does not respond to “close” signals Leads to symptoms of congestive heart failure Oxygen requirements are high Exacerbates RDS

Pulmonary haemorrhage Rare Bleeding into the lungs Increases the need for ventilatory support Occurs mainly 2-4 days after birth Predisposing factors include mechanical ventilation, immaturity and PDA

Pneumothorax

Bronchopulmonary dysplasia Simple definition 5-20% of ventilated neonates with RDS Oxygen requirement at 36 weeks post conceptional age

Lung damage Barotrauma Volutrauma Oxygen toxicity Inflammation (Biotrauma)

Oxygen free radicals Superoxide Dismutase (SOD) cell O 2,H 2 O 2 O2O2

Pressures High pressures – damage walls High volumes – over inflation Large swings – cyclic collapse