ANAESTHESIA FOR PREMATURE AND EX-PREMATURE BABIES
MODERATOR: DR. PRASANNA
DR. SANTHALAKSHMI DR. KANCHAN
DEFINITION
Preterm: Born before 37 weeks GA
INCIDENCE
• 10-12 % of Indian Babies
• 5-7 % in the West
CAUSES OF PRETERM DELIVERY
SpontaneousPoor socio-economic status
Systemic maternal disease
APH
Cervical incompetence
Infection
Past history
Smoking
Threatened Abortion
Stress
Sexual activity
Trauma
Uterine malformations
Multiple pregnancy
InducedMaternal DM
Placental dysfunction
Eclampsia
Fetal hypoxia
APH
Iso-immunization
HOW TO RECOGNISE A PRETERM BABY?Head circumference < 33cm
>3cm greater than chest circumference
Poor activity, sluggish reflexes
Extended posture due to poor tone
Sutures widely separated, fontanel large
Shallow orbit, absent buccal fat
Ear catilage- poor recoil
Hair- fuzzy, separate strands
Skin- thin, gelatenous, shiny, abundant lanugo, very less vernix caseosa
Edema +/-
Deficient Subcutaeous fat
Breast nodule small/ absent
Sole creases ill-defined
Testes undescended
Labia majora widely separated
PHYSIOLOGICAL HANDICAPS
CNS
• Lethargy
• Poor cough reflex
• Incoordinated sucking and swallowing in babies <35 weeks GA
More resistant to toxic effects of hypoxia compared to term babies
Intraventricular-periventricular hemorrhage, leucomalacia
↓ Vit K
Capillary fragility
RESPIRATORY SYSTEM
28-36 weeks: Terminal air sacs and capillaries
36 weeks GA to 18 months of age: Alveolar phase
Type II pneumocytes identifies after 22-26 weeks GA
but the osmophilic lamellar bodies (surfactant) prominent only after 34 weeks
< 26 Weeks Cuboidal alveolar lining
Resuscitation difficulties at birth
Large Deadspace/ tidal volume ratio
Diaphragmatic breathing (more fatiguable)
Periodic
Intercostal-recessions
RESPIRATORY SYSTEM
Response to Hypoxia
The sensitivity of an infant's ventilatory response to carbon dioxide increases with postnatal and gestational age
Hyaline Membrane Disease/ RDS
Onset < 6hours
Tachypnea
Retractions
Grunting
Oxygen desaturation
RDS Chest X ray
Diffuse reticulonodular pattern with air bronchogram
Uncomplicated clinical course
Peak by 2-3 days
Resolution begins at ~72 hours
Surfactant Administration
Intra-tracheal
<28 weeks
2nd Dose 12 hours later
3rd Dose if required in mechanically ventilated patients
Chronic Lung Disease
RDS Repair process• Parenchymal fibrosis
• Chronic inflammation
• Airway epithelial metaplasia
• Smooth muscle hypertrophy
Bronchopulmonary Dysplasia
Mechanical ventilation during >3 days during the 1st week of life
Persistence of O2 dependence after 28 days
Radiographic abnormalities characterized by patchy density with areas of hyperlucency
Non-homogenous lung parenchyma Densities secondary to volume loss due to fibrosis Cystic emphysema, Hyperinflation
Chronic Lung Disease
BPD and Chorioamnionitis
Yoon and others (1999) noted that chorioamnionitis was easily detected in 92% of the placentas from preterm infants who developed BPD and 62% of those who did not
IL-1β, IL-6, and IL-8 were in the amniotic fluid within 5 days of preterm delivery
BPD and Mechanical Ventilation
The influx of granulocytes into the alveoli of preterm infants after mechanical ventilation has been measured as soon as 1 hour of age; these infants have a higher incidence of BPD ( Ferreira et al., 2000 )
New BPD
Causes:
Premature stage of lung development
Artificial surfactant and prenatal steroid less severe RDS
Later oxygen dependance, CLD
Abnormal growth of alveoli and vasculature
Characteristic firbroproliferative BPD pattern NOT seen
NEW BPD•Fine, hazy, uniform parenchymal pattern
•Modest hyperinflation
•Arrested development
CVSDelayed DA closure
• 1/3 of patients <34 weeks GA +/- CHF• ↑ in patients with HMD, Protracted Hypoxia
Thrombo-embolic complications due to indwelling venous and arterial catheters
Iatrogenic anemia due to repeated blood sampling
GASTROINTESTINAL SYSTEM
Poor, incoordinated suckling
Regurgitation, Aspiration
Small Stomach
Incompetent cardioesophageal junction
Necrotising enterocolitis
NEC• Preterm baby weighing less than 2500 g• Infants with NEC may be acidotic, hypoxic, hypothermic, and in shock• Bowel perforation surgery
THERMOREGULATION
Reduced or absent subcutaneous fat
Reduced or absent BROWN fat
Greater body surface area for heat loss
Immature thermostat
FLUID AND ELECTROLYTES
Impaired urine concentrating ability: hypotonicity of the renal medulla
Dehydration
Hyponatremia: prolonged glomerulotubular imbalance
GFR is high relative to tubular capacity to reabsorb Na+
Hypocalcemia: related to decreased PTH secretion
PERINATAL PROBLEMS ACCORDING TO INFANTS’
GESTATIONAL AGE
Near-Term Infants (35 to 37 weeks gestation)
Delay in establishing full feeds
Hyperbilirubineamia
IDM- Pulmonary immaturity
30 to 34 Weeks Gestation
RDS/ HMDPneumothoraxIntestitial emphysemaChronic Lung Disease Iatrogenic blood loss (sampling)
New BPDVariations of CLD
Temperature instability
Hypoglycemia
Hypocalcemia
NEC (esp. with co-existing PDA)
PDA (20-30%)
Intracerebral bleed
Apnea
27 to 29 Weeks Gestation
Fragile skin
Absent subcutaneous fat
Transcutaneous fluid loss
Perioperative Apnea
Less Than 26 Weeks Gestation
“on the edge of survivability”
Intracranial haemorrhage
Pulmonary insufficiency, Apnea
THANK YOU!