What is the definition of preterm? Define the different levels of severity.
Preterm: babies born alive <37 weeks of gestation
- Moderate-late preterm: 32-37 weeks
- Very preterm: 28-32 weeks
- Extremely preterm: <28 weeks
(According to the lecture, extreme prematurity = <30 weeks)
It is for this reason that induction of labour or C/S should not be planned <39 weeks unless medically indicated to prevent iatrogenic prematurity.
What is the definition of low birth weight? Define the levels of severity.
- Low birth weight (6%): <2500g
- Very low birth weight (1%): <1500g
- Extremely low birth weight (<1%): <1000g
What is the definition of term?
37-42 weeks of maturity
What are the factors of PPROM?
- Ascending infection
- Cervical incompetence
What are the risk factors for preterm labour?
- Maternal age <15 yeras of >40 years
- Low body weight
- History of preterm delivery
- Extra-uterine infections
- Social causes: alcohol, smoking, drugs, domestic violence, stress etc.
>> Overdistension from fibroids, multiple gestation or polyhydramnios
>> Uterine abnormalities
>> Uterine trauma
>> Multiple gestation
>> Chromosomal abnormalities
>> Congenital abnormalities
>> Cervical incompetence
>> Cervical trauma/surgery
What are the risk factors for chorioamnionitis?
- Prolonged rupture of membranes (>24 hours)
- Preterm labour with or without ROM
- GBS carriage of the mother
- Bacterial vaginosis of the mother
What are the complications of prematurity to the baby?
>> Respiratory distress syndrome
>> Apnea of prematurity
- Patent ductus arteriosus
- Necrotizing enterocolitis
- Intraventricular hemorrhage
- Hypoglycemia, hypocalcemia and electrolyte disturbances
- Bronchopulmonary dysplasia
- Retinopathy of prematurity (ROP)
- Post-NEC complications: short bowel syndrome
- Periventricular leukomalacia >> quadriplegic cerebral palsy
- Post-hemorrhagic hydrocephalus
- Developmental delay
- Osteopenia of prematurity
What is the presentation of respiratory distress syndrome?
Features of respiratory distress (tachypnea >60, tachycardia, nasal flaring, expiratory grunting, use of accessory muscles, intercostal and subcostal insucking) within 4 hours of delivery with difficulty waning off oxygen
What are the typical CXR findings of RDS?
- Ground-glass appearance of fine reticular, homogenous shadows
- Hazzing out of the cardiac shadow
- Air bronchogram
How does one manage a case of RDS?
1. Stabilize the patient: ABC, fluid resuscitation if necessary
2. Look out for anemia and malnutrition
3. Nasal CPAP
4. IPPV/HFOV (intermittent positive pressure ventilation, high frequency oscillation ventilation)
>> Prolonged and frequent apnea
>> Severe hypoxemia
>> CO2 retention
>> Respiratory fatigue
5. Surfactant replacement with exosurf VS. survanta
>> Maternal steroids given 24-48 hours prior to delivery helps prevent RDS
Most patients with ?RDS also receive antibiotics since congenital pneumonia and RDS are clinically and radiologically indistinguishable.
What is necrotizing enterocolitis?
Intestinal inflammation associated with focal or diffuse ulceration and necrosis, primarily affecting the terminal ileum and colon
Mucosal damage and enteral feeding --> bacterial growth --> bowel necrosis, gangrene and perforation
What are the risk factors for NEC?
- Enteral feeding with formula (breast milk can be protective)
- Asphyxia, shock, sepsis
How does NEC present?
- Poor feeding
- Bile-stained vomiting
- Frank/occult blood in stool
- Abdominal distension
- Diminished bowel sounds
- Signs of bowl perforation
What are the typical AXR findings for NEC?
- Intramural gas: pneumatosis intestinalis
- Distended bowel loops
- Fixed bowel loops
- Thickened bowel wall
- Portal tract gas
- Free gas ("Football sign")
How does one manage a case of NEC?
Prevention in pre-emies
- Cautious feeding regime
- Early treatment for PDA and polycythemia
- NPO with parenteral nutrition
- Vigorous IV fluid resuscitation
- Decompression with NG tube
>> Ampicillin, gentamicin +/- metronidazole x 7-10 days)
- Supportive ventilation and circulation
- Serial AXRs to detect early perforation
- Surgical resection of necrotic bowel, perforation and strictures
- Intestinal obstruction
- Short gut syndrome
What is intraventricular hemorrhage?
Hemorrhage in the periventricular subependymal germinal matrix, usually occurring within 72 hours of delivery
How common is RDS?
14% of all LBW infants
How common is IVH?
~25% of lal LBW infants
What are the risk factors for IVH?
- Prematurity <32 weeks
- BW <1500mg (very low birth weight)
- Need for vigorous resuscitation at birth
- Respiratory distress syndrome
- Hemodynamic instability
How may IVH present?
Most are asymptomatic
- Altered level of consciousness
- Bulging fontanelle with separation of sutures
What are the complications of IVH?
- Post-hemorrhagic hydrocephalus
- Post-hemorrhagic infarction
- Cyst formation
- Extension of bleed
- Cerebral palsy
- Visual and hearing impairment
- Developmental delay
- Intellectual disability
Routine head USG screening for all preterm infants <32 weeks or <1500g throughout NICU stay to screen for IVH -- In Canada.
What is retinopathy of prematurity (ROP)?
- Nasal retina vascularization completion: 36 weeks
- Temporal retina vascularization completion: 40 weeks
- Due to high oxygen exposure after birth, disrupting the vascularization process
>> The most common cause of blindness in preterm infants
>> Treatment: laser, cryotherapy
Hwo does ROP present?
- Retinal hemorrhage
- Retinal fibrosis and detachment
Weekly screening by ophthalmologist in infants born at <32 weeks of gestation or <1500g birth weight for RETINOPATHY OF PREMATURITY.
~10% of infants with respiratory distress syndrome treated with ventilation with develop pneumothorax as a complication.
What is apnea of prematurity
Episodic central apnoea of >20 second in premature infants due to an immature central respiratory control; often associated with bradycardia and desaturation
How does one manage a case of apnoea of prematurity?
1. Gentle physical stimulation
2. Respiratory stimulant: caffeine (methylxanthine)
3. CPAP +/- intermittent positive pressure ventilation (IPPV)
>> Apnea of prematurity is NOT PATHOLOGICAL.
What is bronchopulmonary dysplasia?
A chronic lung disorder of prematurely that is clinically defined as oxygen dependence at 36 weeks' postmenstrual age
- Barotrauma from prolonged mechanical ventilation
- Oxygen toxicity
What are the CXR findings for bronchopulmonary dysplasia?
Widespread area of opacification, cystic changes and lung collapse
What are the complications of bronchopulmonary dysplasia?
- Feeding problems from prolonged intubation
- Recurrent wheezing episodes
- Recurrent respiratory infections
- Pulmonary hypertension
- Right-sided heart failure
- Growth and developmental delay
How does one manage a case of bronchopulmonary dysplasia?
- Optimize nutrition
- Supplemental O2 PRN
- CPAP with gradual weaning from ventilator
- Corticosteroid therapy (short-term): decrease inflammation and encourage weaning
Premature infants have proportionally more fluid in the ECF than in ICF ---- therefore they are EASIER TO DEHYDRATE
What are the fluid requirements for a premature baby?
First day of life: 60-90mL/kg
Subsequently increase by 20-30mL/kg/day until you reach 150-180mL/kg
What is the normal rate of growth in term infants?
- Double of birth weight: 4.5 months
- Triple of birth weight: 1 year
What is the normal rate of growth/target rate of growth for premature infants?
- Double of birth weight: 6 weeks
- Triple of birth weight: 12 weeks
Both IRON and IgG ANTIBODIES are transferred to the fetus during the 3rd trimester.
BREAST MILK is the best choice for enteral feeding in premature infants due to the INCREASED RISK FOR NEC and DECREASED PROTECTION AGAINST INFECTION associated with formula milk.
What are the long-term follow-up items for prematur einfants?
1. Growth and nutrition
2. Neurodevelopmental delay and learning difficulties
3. Bronchopulmonary dysplasia
4. Retinopathy of prematurity
5. Gastroesophageal reflux (associated with BP)
>> Pavalizumab for RSV prophylaxis