Transcript
Page 1: Anaesthesia for Premature and Ex-premature Babies

ANAESTHESIA FOR PREMATURE AND EX-PREMATURE BABIES

MODERATOR: DR. PRASANNA

DR. SANTHALAKSHMI DR. KANCHAN

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DEFINITION

Preterm: Born before 37 weeks GA

INCIDENCE

• 10-12 % of Indian Babies

• 5-7 % in the West

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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

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InducedMaternal DM

Placental dysfunction

Eclampsia

Fetal hypoxia

APH

Iso-immunization

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HOW TO RECOGNISE A PRETERM BABY?Head circumference < 33cm

>3cm greater than chest circumference

Poor activity, sluggish reflexes

Extended posture due to poor tone

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Sutures widely separated, fontanel large

Shallow orbit, absent buccal fat

Ear catilage- poor recoil

Hair- fuzzy, separate strands

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Skin- thin, gelatenous, shiny, abundant lanugo, very less vernix caseosa

Edema +/-

Deficient Subcutaeous fat

Breast nodule small/ absent

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Sole creases ill-defined

Testes undescended

Labia majora widely separated

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PHYSIOLOGICAL HANDICAPS

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CNS

• Lethargy

• Poor cough reflex

• Incoordinated sucking and swallowing in babies <35 weeks GA

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More resistant to toxic effects of hypoxia compared to term babies

Intraventricular-periventricular hemorrhage, leucomalacia

↓ Vit K

Capillary fragility

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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

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< 26 Weeks Cuboidal alveolar lining

Resuscitation difficulties at birth

Large Deadspace/ tidal volume ratio

Diaphragmatic breathing (more fatiguable)

Periodic

Intercostal-recessions

RESPIRATORY SYSTEM

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Response to Hypoxia

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The sensitivity of an infant's ventilatory response to carbon dioxide increases with postnatal and gestational age

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Hyaline Membrane Disease/ RDS

Onset < 6hours

Tachypnea

Retractions

Grunting

Oxygen desaturation

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RDS Chest X ray

Diffuse reticulonodular pattern with air bronchogram

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Uncomplicated clinical course

Peak by 2-3 days

Resolution begins at ~72 hours

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Surfactant Administration

Intra-tracheal

<28 weeks

2nd Dose 12 hours later

3rd Dose if required in mechanically ventilated patients

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Chronic Lung Disease

RDS Repair process• Parenchymal fibrosis

• Chronic inflammation

• Airway epithelial metaplasia

• Smooth muscle hypertrophy

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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

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Non-homogenous lung parenchyma Densities secondary to volume loss due to fibrosis Cystic emphysema, Hyperinflation

Chronic Lung Disease

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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

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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 )

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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

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NEW BPD•Fine, hazy, uniform parenchymal pattern

•Modest hyperinflation

•Arrested development

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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

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GASTROINTESTINAL SYSTEM

Poor, incoordinated suckling

Regurgitation, Aspiration

Small Stomach

Incompetent cardioesophageal junction

Necrotising enterocolitis

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NEC• Preterm baby weighing less than 2500 g• Infants with NEC may be acidotic, hypoxic, hypothermic, and in shock• Bowel perforation surgery

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THERMOREGULATION

Reduced or absent subcutaneous fat

Reduced or absent BROWN fat

Greater body surface area for heat loss

Immature thermostat

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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

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PERINATAL PROBLEMS ACCORDING TO INFANTS’

GESTATIONAL AGE

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Near-Term Infants (35 to 37 weeks gestation)

Delay in establishing full feeds

Hyperbilirubineamia

IDM- Pulmonary immaturity

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30 to 34 Weeks Gestation

RDS/ HMDPneumothoraxIntestitial emphysemaChronic Lung Disease Iatrogenic blood loss (sampling)

New BPDVariations of CLD

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Temperature instability

Hypoglycemia

Hypocalcemia

NEC (esp. with co-existing PDA)

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PDA (20-30%)

Intracerebral bleed

Apnea

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27 to 29 Weeks Gestation

Fragile skin

Absent subcutaneous fat

Transcutaneous fluid loss

Perioperative Apnea

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Less Than 26 Weeks Gestation

“on the edge of survivability”

Intracranial haemorrhage

Pulmonary insufficiency, Apnea

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THANK YOU!


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