Very Low and Extremely Low
INTRODUCTION and DEFINITIONS:
Low birth weight infants are those born weighing less than 2500 g. These are further
- Very Low Birth Weight (VLBW): Birth
weight <1,500 g
- Extremely Low Birth Weight (ELBW): Birth
weight <1,000 g
Obstetrical history (LMP,
sonographic dating), newborn physical examination, and
examination for maturational age (Ballard or Dubowitz) are
critical data to differentiate premature LBW from more mature
growth-retarded LBW infants. Survival statistics for ELBW
infants correlate with gestational age. Morbidity statistics for
growth-retarded VLBW infants correlate with the etiology and the
severity of the growth-restriction.
CAUSES: The primary causes of VLBW are
premature birth (born <37 weeks gestation, and often <30 weeks)
and intrauterine growth restriction (IUGR), usually due to
problems with placenta, maternal health, or to birth defects.
Many VLBW babies with IUGR are preterm and thus are both
physically small and physiologically immature.
NEONATAL COMPLICATIONS are markedly
increased in VLBW, and especially ELBW, infants. Because most
VLBW infants are also premature, it may be difficult to
differentiate problems due to prematurity from those due to very
small size. In general, the lower a baby's birthweight, the
greater are the risks for complications. However, some
complications of prematurity (e.g., risk of RDS) are
lessened by the stress of mild to moderate intrauterine growth
restriction. Clinical problems associated with VLBW and ELBW
1. Hypothermia: LBW infants have higher
body surface area: body weight ratios, decreased stores of brown
fat and glycogen, and may not be able to conserve or generate
body heat. Clinical problems associated with hypothermia include
hypoglycemia, apnea, increased O2
consumption and metabolic acidosis. Prevention of
hypothermia increases survival of the infants. Methods of
preventing heat loss include:
- Drying the infant at birth to prevent
evaporative heat loss
- Warmed blankets or plastic wrap to
prevent convective and radiant heat loss during transport.
- Swaddling to preserve body heat in larger
infants, and radiant heater or a heated incubator to
maintain a neutral thermal environment for smaller infants.
2. Hypoglycemia due
to decreased stores of glycogen and fat. Hypothermia and
hypoxia aggravate this due to increased metabolic demands and
3. Perinatal asphyxia, especially among growth retarded
infants because of compromised O2 delivery in utero.
4. Respiratory problems:
- Respiratory Distress Syndrome, due to
- Apnea of prematurity
5. Fluid and electrolyte
imbalances due to increased insensible
water loss (due to
weight, thin skin), impaired renal function. They are at risk
for dehydration, fluid overload, hypernatremia, hyponatremia,
hyperkalemia (especially ELBW), hypocalcemia, hypermagnesemia
(iatrogenic from maternal treatment). Compromised renal function
may impair tolerance of free water, bicarbonate resorption,
potassium secretion, or urinary concentrating capacity.
RBC survival, hepatic immaturity,
delayed enteric feedings and
gut motility. With IUGR, risk
factors may include infection and/or polycythemia.
Direct (conjugated) hyperbilirubinemia as
a complication of parenteral nutrition.
7. Anemia due to:
- Phlebotomy for laboratory tests and small
total blood volume
- Anemia of prematurity
8. Impaired nutrition,
feeding difficulties and slow rates of weight gain due to:
risk of necrotizing
Delayed enteric feeding due to
respiratory disease, PDA, indomethacin treatment
Infants <32-34 weeks gestation are
developmentally not ready to nipple feed
Increased caloric needs (↑surface
- Gut immaturity with decreased motility,
enzyme deficiencies and
Risks are increased because of immunologic
immaturity, prolonged invasive treatments (e.g.,
endotracheal tube, intravascular catheters, parenteral nutrition
and prolonged, recurrent treatment with antibiotics.
10. Neurological problems
11. Ophthalmologic complications
- Retinopathy of prematurity (ROP)
- Strabismus and refractive errors
12. Hearing deficits
- Prematurity itself
- Ototoxic drugs
13. Sudden infant death
syndrome (SIDS): Premature infants are
at increased risk, but home monitoring has not been shown to be
an effective preventive measure. Home monitoring is not
recommended in absence of other risk factors (e.g.. twin
sibling with SIDS, two siblings with SIDS, obstructive airway
problems, or craniofacial anomalies posing risks for obstructed
Because of the increased risk for multiple
problems, these infants require meticulous attention to all
facets of their care. The following are but a brief summary of
certain aspects of the care of these fragile infants:
2. Respiratory Care:
The majority of
ELBW (i.e., <1,000 g) will require intubation at birth
(to assist in their cardiopulmonary adaptation to
extra-uterine life) and assisted ventilation for a prolonged
period. They require close attention with frequent measurements
of pH and blood gas tensions. In addition to surfactant
deficiency, they are at risk for respiratory failure because of:
Decreased central respiratory drive
- Weak chest wall
- Weak muscles of respiration
- Smaller alveoli (
Most VLBW and almost all ELBW infants will
require an umbilical arterial catheter for blood sampling and
blood pressure measurement.
Hypotension is common.
The most effective therapy is dopamine (usual starting
dose is 5 mcg/kg/min). Do not automatically give fluid boluses
for “decreased perfusion,” acidosis, or hypotension. Excess
fluid will worsen pulmonary function and give excess Na+.
Reserve volume expansion for situations where there are signs of
3. Oxygen therapy:
in range of 85-92%. If SpO2
is > 94%, arterial oxygen tension
may be high (>100 mmHg) because of the inaccuracy of the pulse
oximeter at high saturations. This puts the infants at
risk for ROP.
Do not write titration orders for oxygen.
1st day of life, preterm
infants should receive restricted fluids (e.g., 60-80 mL/kg/d).
for ELBW infants, fluid intake
should be higher (e.g., 100-125 mL/kg/d.
Follow intake and output closely, at least q12h for the first
several days. VLBW Infants
5. Electrolytes: On the 1st day, do not give Na+ or K+.
To avoid hypocalcemia, start Ca gluconate
at 200 mg/kg/d. Follow serum electrolytes closely.
Feedings on the 1st day of life are unusual for VLBW infants. Do
feeds on the 1st
day of life in ELBW
infants. Trophic (gut stimulation) feedings
for several days facilitate later advance of feedings. Consider
early institution of TPN. Do not give IV lipids
for 3-5 d, especially if there is severe pulmonary disease.
Obtain CBC and blood culture at birth. If there
are any risk factors, begin antibiotic therapy (48 h of
treatment until culture results are known).
Maintain blood glucose
mg/dL. Initial IV fluid should be D10W. Some ELBW infants may
become hyperglycemic and require lower glucose intake and/or
Assume all ELBW and many VLBW infants will need
at least 1 transfusion. Obtain parental consent in advance,
discussing option for designated donor blood. Type and cross
match packed cells in small volume aliquots to minimize number
of donors. Start erythropoietin as described in Guidelines for
Use of Erythropoietin.
11. Intraventricular hemorrhage
12. Ophthalmology examination
commencing at age 1 mo for infants born < 32 weeks.