PrematurityPrematurity

Dr Varsha Atul Shah

Dept of Neonatal and Developmental Medicine

Singapore General Hospital

Extremes of Extremes of Birth WeightBirth Weight

Neonatal Neonatal HypoglycaemiHypoglycaemiaa

PrematurityPrematurity

Preterm

• Gestational age assessment– Obstetric information

• LMP, ultrasound, others (quickening, etc)

– Newborn information• Neurological, physical

– Dubowitz Score, New Ballard Score

• Direct ophthalmoscopy of the lens

Definition:: < 37< 37 completed Gestational weeks

Dubowitz Score

New Ballard Score

Assessment of maturity by examination of anterior vascular capsule of the lens

Hittner et al

Incidence

Singapore• Preterm births: 5-8 % of all births

Associated Factors• Maternal

– Low socioeconomic status– Lack of prenatal care– Substance abuse, smoking– Maternal age < 16yrs or > 35yrs– Maternal illness e.g. renal, heart, lung, HPT, DM, etc– Multiple gestation– Prior preterm delivery– Obstetric factors e.g. uterine malformations, cervical

incompetence, polyhydramnios, premature rupture of membranes, infection (e.g. chorioamnionitis), placenta praevia, abruptio, etc

– Abdominal trauma / surgery

• Foetal– Foetal distress, IUGR, etc

Problems of Prematurity

• Related to difficulty in extrauterine adaptation due to immaturity of organ systems

• Degree of immaturity– Appearance, behaviour, problems, clinical

course

– Mildly preterm (35 - 36 wks)– Moderately preterm (32 - 34 wks)– Severely preterm (< 32 wks)

Management

• Prevention– Obstetric Mx: maternal illness, infection– Inhibition of preterm labour– Steroids to facilitate lung maturation

Problems & Management:• Initial, acute• Long term

Initial Problems & ManagementImmediate postnatal

management

Temperature regulation

Respiratory

Neurologic

Cardiovascular

Haematologic

Gastrointestinal & Nutritional

Metabolic

Renal

Fluid & electrolyte

Infection

Ophthalmologic

Osteopenia

Liver

Surgical conditions

Immunisation

Social

Immediate Postnatal Management

• Delivery– Appropriately equipped & staffed

• Resuscitation & stabilisation

Temperature Regulation

• Poor temperature control– Hypothermia, hyperthermia

1. Immature heat regulatory centre2. Impaired heat production

brown fat, poor muscular activity, poor 02 consumption

3. Increased heat loss subcutaneous fat, surface area (large

surface area to body weight, extended position)

Management• Achieve neutral thermal zone

i.e. environmental T0 at which O2 consumption is minimal yet sufficient to maintain body T0

• Yet exposed to facilitate observation• Heat shield, plastic wrap, cap• Overhead radiant warmer

– Infant accessibility, rapid T0 response

• Closed incubator insensible H2O loss, barrier to infection

Overhead radiant warmer

Closed incubator

Respiratory

• Asphyxia– Poor adaptation to air breathing– Perinatal depression at delivery

• Periodic breathing - jerky, irregular

• Apnoea– Immature respiratory centre– Small nasal passages & airways– Weak respiratory muscles– Compliant thoracic cage

• Respiratory distress syndrome (HMD)

• Aspiration pneumonia– Regurgitate easily– Uncoordinate suck & swallow– Weak gag, cough reflex

• Chronic lung disease– Acute & continued lung injury (surfactant

deficiency, pulmonary oedema, O2 exposure,

mechanical ventilation, inflammation) with abnormal repair

• Subglottic stenosis

Hyaline membrane disease

Subcostal retractions

Management• Assisted ventilation

– Tracheal intubation & mechanical ventilation– CPAP (Continuous Positive Airway Pressure)

– O2 therapy

• Medication– Surfactant– Aminophylline, caffeine– Diuretics, steroids

Intubated

CPAPIntranasal oxygen

Neurologic

• Hypotonic• Perinatal depression• Cerebral ischaemia & intracranial

haemorrhage– Germinal layer vascular with little

supporting tissue– Prone to hypoxia– Impaired ability to regulate cerebral blood

flow

Cardiovascular

• Hypotension– Hypovolaemia, cardiac dysfunction,

vasodilation (sepsis)

Management– Fluid resuscitation– Inotropes

• Patent ductus arteriosus (PDA), CCF

Management– Usually only requires conservative Mx

• Adequate oxygenation, fluid restriction

– Medical Mx: Prostaglandin antagonist (indomethacin, ibuprofen)

– Surgical Mx: PDA ligation

Haematologic

• Anaemia– Iatrogenic losses– Haemorrhage, haemolysis– Inadequate production

Management• Minimizing blood loss• Transfusion• Iron supplement• Misc: erythropoietin

susceptibility to hyperbilirubinaemia & kernicteruskernicterus1. bilirubin production

rbc lifespan, haemorrhage & haemolysis

2. bilirubin excretion• impaired uptake & conjugation by liver,

excretion via bile

3. bilirubin binding capacity serum albumin, hypothermia, acidosis

4. Permeable blood brain barrier

Management– Careful monitoring of bilirubin levels– Phototherapy– Exchange transfusion

Phototherapy, preterm infant, on CPAP, incubator

Gastrointestinal & Nutritional

• Many preterm infants are unable to suck & swallow effectively– Coordination of suck with swallow only

occurs ~ 32 - 34 wks

• Feed intolerance intestinal motility

• Necrotising enterocolitis

NEC

Gross abdominal distension

Shiny, oedematous, anterior abdominal wall with distended vessels

Management– Specific attention to type (expressed breast

milk & human milk fortifiers, preterm formula), amount & route of feeding

– Gavage feeding– Parenteral nutrition– Multivitamin

Long line for TPN

Tube feeding

Metabolic

• Glucose (hypoglycaemia) • Calcium (hypocalcaemia)

Renal

• Immature kidneys– Low GFR & inability to handle water, solute

& acid loads– Drug dosage adjusted

Fluid & Electrolyte

Fluid & electrolyte management difficult:

• High insensible H2O losses– Skin loss, ventilation

• Renal function

• Aim– Normal glucose, electrolyte & fluid balance

Infection

• Increased susceptibility1. resistance– Impaired humoral & cellular response– Skin barrier

2. opportunity for infection– Natural defense bypassed - lines,

procedures (e.g. Staphylococcal infection)– Prolonged hospitalisation, with other infants– Use of antibiotics– Nosocomial infection, fungal infection

Increased risk for nosocomial infection

Ophthalmologic• Retinopathy of prematurity

– Disorder of developing retinal vasculature

Osteopenia• Deficiency of calcium, phosphate & vit D

Liver

• Cholestatic jaundice– TPN, infection

Surgical Conditions

• Inguinal hernia

Immunisation

• Immunised according to chronological age

• No contraindication in infants with stable neurologic condition

Social

• Financial

• Psychosocial & Emotional

Mortality Rates

Gestational Age Mortality• > 30wks < 5%• 27 - 30wks 5 - 10%• 25 - 26wks 10 - 50%• 23 - 24wks 50 - 90%• < 23wks > 97%

Survival Rates

Birth Weight Survival• < 1000g 80%

• < 1500g 90%

• > 1500g 99%

Long Term Problems & Management

Long Term Problems

• Preterm infants are vulnerable to wide spectrum of morbidity

• Severe impairment occurs in a small population

• Prevalence of lesser morbidities less clearly defined

Developmental Disability

• Major handicaps– Cerebral palsy, mental retardation

• Sensory impairments• Hearing loss, visual impairment

• Minimal cerebral dysfunction– Language disorders, learning disability,

hyperactivity, attention deficits, behavioural disorders

Medical Problems

• Chronic lung disease– Increased severity respiratory infections

• Hydrocephalus, epilepsy• Poor growth• Increased rates of postneonatal illness

& rehospitalisation• SIDS

Social

• Increased risk of child abuse & neglect• Financial• Psychosocial & Emotional• Marital discord

• Parent support groups• Light Weight Club• Club Rainbow

Long Term Disability Rates

BW CP MR Sensory impr

• < 1500g 5 - 15% 5 - 8% 0.5 - 6%

• < 1000g 8 - 15% 8 - 15% 4 - 12%

• < 750 - 800g 3 - 14% 3 - 28% 4 - 15%

Management

• Multidisciplinary team– Neonatologists– Nurses– Therapists– Psychologists– Medical specialists: ophthalmologist,

otolaryngologist, cardiologist, paediatric surgeon, plastic surgeon

– Medical social worker

Extremes of Extremes of Birth WeightBirth Weight

Neonatal Neonatal HypoglycaemiHypoglycaemiaa

PrematurityPrematurity