Complications of Prematurity

Neonatal mortality

Causes of neonatal death in Cambridge Maternity Hospital

1982 - 89 1990 - 94

Respiratory distress syndrome 137* 38

Infection 24 13

Birth asphyxia 15 14

Extreme prematurity 14 44

Pulmonary hypoplasia 10 19

Other causes 10 0

Total non-malformed neonatal deaths 210 128

Malformations 84 46

Total neonatal deaths 294 174

* 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 maturationIncrease 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 inhibitionof surfactant

by serum proteins

Epithelial damage occurs through suction effect of gasping

Depleted surfactant

Decreased FRCIncreased dead spaceAlveolar collapse

Reducedcompliance

Increased workof breathing

Reduction in compliance

Histology

RDSNormal

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

SuperoxideDismutase (SOD)

cell

O2,H2O2

O2

Pressures

High pressures – damage walls

High volumes – over inflation

Large swings – cyclic collapse