Introduction
Annually, an estimated 15 million babies worldwide are born before 37 weeks of gestation, and approximately 1 million children die each year due to complications of preterm birth.1 Many babies who survive preterm birth face a lifetime of disabilities. Moreover, preterm births are increasing in almost all countries. Prematurity is the leading cause of death in newborns during the first 4 weeks of life, and it is the second leading cause of death after pneumonia in children under the age of 5.1
Premature babies are at high risk for hypothermia, hypoglycemia, electrolyte imbalance, hyperbilirubinemia, respiratory distress syndrome (RDS), patent ductus arteriosus, infections, necrotizing enterocolitis, and intraventricular hemorrhage (IVH). In the long term, they are at risk for chronic lung disease, cognitive delays, cerebral palsy, and visual and hearing loss. Late-preterm and moderate-preterm babies are at risk for complications such as learning disabilities.2
Being part of the healthcare team caring for infants in the neonatal intensive care unit (NICU) is exciting as well as challenging. As pharmacists, we play a vital role in the pharmacological care of NICU patients just as with any other patient population. We ensure that medications are appropriate for each indication, dosed, filled, and monitored correctly. This is especially vital for NICU patients where the margin for error is much smaller than in adult and pediatric populations.
The drug formulary used in the NICU is rather limited compared with that used in other patient populations. The majority of medications for NICU babies are dosed by weight—sometimes to the tenth and even hundredth of a milligram. Such precise attention to detail cannot be taken lightly and requires a vigilant pharmacist’s careful scrutiny. Timing is crucial. Because of their tiny body mass, infants’ health status can change rapidly. Antibiotics and intravenous (IV) dextrose are just two examples of treatments that need to be implemented quickly to ensure timely treatment in such a delicate patient population.
Many pharmacists shy away from working with NICU patients due to the high risks in this specialized clinical environment. Although it is always good to have a healthy fear regarding the responsibility of caring for any patient population, pharmacists should not be intimidated by the care required in the NICU. This book will equip you with the necessary tools to provide such care. The purpose of this first chapter is to provide an introduction to neonatal care that will aid in effective patient care in a NICU setting.
Definitions
Neonates—babies from birth to the age of 30 days of postnatal life, including both preterm and post-term babies.
Gestational age (GA)—the age from the time of conception to birth.
Postnatal age (PNA)—the age in days of life after birth.
Post-menstrual age (PMA)—also known as corrected gestational age (CGA) the sum of these two ages: PMA = GA + PNA
Appropriate for gestational age (AGA)—babies born at the appropriate weight for their gestational age (10th–90th percentile).
Large for gestational age (LGA)—babies who weigh more than expected for their gestational age. This condition is commonly caused by maternal diabetes (>90th percentile).
Small for gestational age (SGA)—babies who weigh less than expected for their gestational age (<10th percentile).
Intrauterine growth restriction (IUGR)—condition that is often a result of maternal uteroplacental vascular insufficiency, which in turn is caused by preeclampsia, hypertension, or tobacco use and the inherent genetic growth potential of the fetus. SGA is the neonatal manifestation of IUGR, and SGA infants are at increased risk for fetal distress and neonatal hypoglycemia, neonatal complications, and perinatal death.3
Preterm Classifications
Preterm—babies born alive before 37 weeks of pregnancy are completed. There are subcategories of preterm birth based on gestational age.
Moderate-to-late preterm (LPT)—babies who are 32 weeks to less than 37 weeks of gestational age.
Very preterm (VPT)—babies who are 28 weeks to less than 32 weeks of gestational age.
Extremely preterm (EPT)—babies who are less than 28 weeks of gestational age.
Classifications by Birth Weight
Low birth weight (LBW)—less than 2,500 g.
Very low birth weight (VLBW)—less than 1,500 g.
Extremely low birth weight (ELBW)—less than 1,000 g.
Obstetric History Classifications
Obstetric history is expressed in gravida/para/abortus (GPA):
Gravida—the total number of times a woman has been pregnant regardless of whether those pregnancies were carried to term.
Para—the number of viable births.
Abortus—the number of pregnancies that were lost for any reason, including miscarriages.
When a woman has not had any pregnancy loss, history may be expressed simply as gravida/para (GP). For example, a woman who was pregnant three times, who gave birth to two infants and suffered one miscarriage, would be expressed G3-P2-A1. A woman who had four pregnancies and four live births and no abortions or miscarriages would be expressed G4-P4.
Causes of Premature Birth
Delivery of babies prematurely occurs for various reasons. However, a common reason for preterm delivery is the result of early induction of labor or cesarean section birth due to medical reasons. Such reasons include pre-eclampsia, placental abruption, uterine rupture, cholestasis, fetal distress, and fetal growth restriction with abnormal tests.4 Spontaneous preterm labor is another reason. Identified causes of spontaneous preterm labor include multiple pregnancies, infections (e.g., urinary tract infections, bacterial vaginitis, human immunodeficiency virus, syphilis, and infection of the amniotic membrane), chronic maternal health conditions (e.g., diabetes, high blood pressure), being African American, maternal age younger than 16 or older than 35 years, poor nutrition before and during pregnancy, obesity, lack of prenatal care, tobacco or/and alcohol use, and low socioeconomic status.
Prevention of Preterm Labor
To prevent preterm birth for all pregnant women, it is important to identify women at high risk. All pregnant women are screened for signs and symptoms of any infection, including sexually transmitted diseases and nutrition conditions, and educated about identification of early labor.5 Pregnant women who have hypertensive disorder, diabetes, multiple gestations, bleeding, and/or are younger than 16 or older than 35 years are considered to be at higher risk for preterm birth. For mothers at GA of 32 weeks or less, use of corticosteroids (betamethasone 12 mg every 24 hours times two doses or dexamethasone 6 mg every 12 hours times four doses) ensures babies have a lower risk of developing RDS. Some studies suggest that for every 100 women treated with corticosteroids, four cases of neonatal deaths, nine cases of RDS, four cases of IVH, and 12 cases of surfactant use would be avoided.3 If a mother has a history of spontaneous preterm birth less than 37 weeks’ gestation, 17-alpha-hydroxyprogesteron caproate intramuscularly (IM) 250 mcg weekly can be given to maintain pregnancy until 36 weeks’ GA.6
Management of Preterm Labor
The treatment goal of preterm labor is to prolong pregnancy to term because a longer GA reduces complications of premature birth, or even to halt labor long enough to get antenatal steroids administered. Tocolytics are used to inhibit muscle contractions and include magnesium sulfate, terbutaline, nifedipine, nicardipine, and indomethacin.
Assessment of the Infant
One tool used to assess an infant’s condition right after birth is the APGAR scoring system. It is named for Dr. Virginia Apgar who invented this assessment tool in the early 1950s.7 APGAR (Appearance, Pulse, Grimace, Activity, and Respiration) scoring for each category is numerical from 0 to 2, with 0 as the least responsive and 2 as the healthiest response. Appearance includes observations such as color of the extremities and the rest of the body. Grimace refers to response to stimulation, and activity refers to muscle tone. This evaluation is performed on the infant at 1, 5, and 10 minutes of life. A total score ranging from 7 to 10 indicates that the baby’s condition is normal. Scores of 0 to 3 are low and indicate that immediate medical intervention is required.
The Ballard scoring system, developed by Dr. Jeanne Ballard,8 is also widely used to assess a newborn infant’s neuromuscular and physical maturity. This assessment is done at 24 hours of life. Arm recoil; posture; and appearance of skin, eyes, and genitals are examples of criteria measured using the Ballard scoring charts. The scores range from −1 to 5, and the sum of scores helps to determine the gestational maturity of the baby in weeks. A maturity rating chart is part of the Ballard score assessment and helps to determine the infant’s GA.9 For example, a Ballard score of 35 correlates to the maturity rating that indicates the GA of a 38-week infant. This is particularly helpful if the infant’s GA is unknown or if the infant is unusually large or small for the determined age. Determining GA is crucial for accurately dosing medications.
Management of Newborns
Newborn and most late-preterm babies need simple essential care for warmth, breastfeeding, and a clean environment. For younger GA babies, NICUs can provide infection control measures, temperature control, feeding support, safe oxygen use, and respiratory care in addition to medical care by a multidisciplinary team including neonatologists, nurses, respiratory therapists, and pharmacists.
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