Biology Reference
In-Depth Information
developmental GA. This developmental age may differ from the
calendar GA and is based on the level of the infant's physical
development and muscle tone. For example, an infant born with a
GA of 35 weeks may at birth be assessed to have a developmental GA
of 37 weeks. BW is perhaps the most important developmental
characteristic. Neonates that are ''small for GA'' or ''birth restricted''
may be full-term but underweight.
In the medical literature, babies born weighing less than 2500 g (5 lbs,
8 oz) are referred to as LBW infants. Babies weighing less than 1500 g
(3 lbs, 5 oz) are classed as very LBW (VLBW) infants, and it is this VLBW
group for which the risk of health problems and long-term complications
is highest.
Premature infants may face a number of medical complications because
of their LBW and underdeveloped organ systems. For example,
underdevelopment of the lungs and the digestive and nervous systems
presents major health hazards, such as respiratory complications,
difficulty coordinating sucking and swallowing, food intolerance,
susceptibility of bleeding into the brain, and episodes of breathing
cessation (apnea). Infection is another significant threat to premature
infants, because their immature immune system is less able to fight
germs that can cause serious illness. Some infections can be life
threatening, even with early initiation of the most advanced treatments.
For premature babies, hospitals have special neonatal intensive care
units (NICUs). Virtually all NICUs have neonatologists and neonatology
nurses on duty around the clock, as well as ready access to respiratory
therapists, pharmacists, occupational therapists, dietitians, and
anesthesiologists, among other highly specialized medical staff. These
experts provide a full range of neonatal intensive care, from treatment
of infection to complex neurologic surgery.
Approximately 40,000 VLBW infants are born in the United States
annually. Although advances in newborn medical care have greatly
reduced the deaths and disabilities associated with LBW, a small
percentage of survivors are still left with problems, such as mental
retardation, cerebral palsy, and impairments in lung function, sight,
and hearing. Infections such as sepsis (see below) continue to be a major
cause of morbidity and mortality (Tortora and Grabowski [2003]; Gray
et al. [1995]).
II. SEPSIS: MEDICAL OVERVIEW, CLINICAL DIAGNOSIS,
AND DIAGNOSTIC CHALLENGES
Sepsis is a life-threatening illness caused by an overwhelming infection of
the bloodstream by toxin-producing bacteria. According to the American
Academy of Pediatrics (AAP), the incidence of proven sepsis is
