Asphyxia Neonatorum Health Article

Definition

Asphyxia neonatorum is respiratory failure in the newborn, a condition caused by the inadequate intake of oxygen before, during, or just after birth.

Description

Asphyxia neonatorum, also called birth or newborn asphyxia, is defined as a failure to start regular respiration within a minute of birth. Asphyxia neonatorum is a neonatal emergency as it may lead to hypoxia (lowering of oxygen supply to the brain and tissues) and possible brain damage or death if not correctly managed. Newborn infants normally start to breathe without assistance and usually cry after delivery. By one minute after birth most infants are breathing well. If an infant fails to establish sustained respiration after birth, the infant is diagnosed with asphyxia neonatorum. Normal infants have good muscle tone at birth and move their arms and legs actively, while asphyxia neonatorum infants are completely limp and do not move at all. If not correctly managed, asphyxia neonatorum will lead to hypoxia and possible brain damage or death.

Demographics

According to the National Center for Health Statistics (NCHS), in 2002, infant mortality caused by asphyxia neonatorum amounted to 14.4 deaths per 100,000 live births in the United States, representing the tenth leading cause of infant mortality. Worldwide, more than 1 million babies die annually from complications of birth asphyxia. According to the World Health Organization, asphyxia neonatorum is one of the leading causes of newborn deaths in developing countries, in which 4 to 9 million cases of newborn asphyxia occur each year, accounting for about 20 percent of the infant mortality rate.

Causes and symptoms

There are many causes of asphyxia neonatorum, the most common of which include the following: prenatal hypoxia (a condition resulting from a reduction of the oxygen supply to tissue below physiological levels despite adequate perfusion of the tissue by blood), umbilical cord compression during childbirth, occurrence of a preterm or difficult delivery, and maternal anesthesia (both the intravenous drugs and the anesthetic gases cross the placenta and may sedate the fetus). High-risk pregnancies for asphyxia neonatorum include:

• maternal age of less than 16 years old or over 40 years old
• low socioeconomic status
• maternal illnesses, such as diabetes, hypertension, Rh-sensitization, severe anemia
• mothers with previous abortions, stillbirths, early neonatal deaths, or preterm birth
• lack of prenatal care
• abnormal fetal presentation or position
• alcohol abuse and smoking by the mother
• severe fetal growth retardation
• preterm labor

The symptoms of asphyxia neonatorum are bluish or gray skin color (cyanosis), slow heartbeat (bradycardia), stiff or limp limbs (hypotonia), and a poor response to stimulation.

When to call the doctor

Pregnant women who are at high risk of delivering newborns with asphyxia neonatorum should arrange for a close follow-up of their pregnancy with their obstetrician.

Diagnosis

Diagnosis can be objectively assessed using the Apgar score—a recording of the physical health of a newborn infant, determined after examination of the adequacy of respiration, heart action, muscle tone, skin color, and reflexes. Normally, the Apgar score is of 7 to 10. Infants with a score between 4 and 6 have moderate depression of their vital signs while infants with a score of 0 to 3 have severely depressed vital signs and are at great risk of dying unless actively resuscitated.

Treatment

The treatment for asphyxia neonatorum is resuscitation of the newborn. All medical delivery rooms have adequate resuscitation equipment should an infant not breathe well at delivery. Between 1970 and 2000, neonatal resuscitation has evolved from disparate teaching methods to organized programs. The most widely used procedure is the Neonatal Resucitation Program, supported by the American Academy of Pediatrics (AAP) and the American Heart Association (AHA).

If stimulation fails to initiate regular respiration in the newborn, the attending physician attempts resuscitation. He may decide first to gently suction the oropharynx—the area of the throat at the back of the mouth, with a soft catheter. When stimulation and a clear airway do not result in adequate respiration, the physician may give 100 percent oxygen via a face mask. If the infant is still not breathing, some form of artificial ventilation is then required. The usual method is to use mask ventilation with a resuscitator. The mask is applied tightly to the infant's face. If this procedure fails, the infant can be intubated with a endotracheal tube to which the resuscitator can then be connected. The more severe the fetal asphyxia, the longer it will take before the infant starts to breathe spontaneously. If the infant does not breathe despite adequate ventilation, or if the heart rate remains below 80 beats per minute, the physician can give an external cardiac massage using two fingers to depress the lower sternum at approximately 100 times a minute while continuing with respiratory assistance. Adrenaline may also be administered to increase cardiac output. Once the infant starts breathing, he or she is transferred to a nursery for observation and further assessment. Temperature, pulse and respiratory rate, color, and activity are recorded, and blood glucose levels checked for at least four hours.

Treatment may also include the following:

• giving the mother extra amounts of oxygen before delivery
• medications to support the baby's breathing and sustain blood pressure
• extracorporeal membrane oxygenation (ECMO)

ECMO is a technique similar to a heart-lung bypass machine, which assists the infant's heart and lung functions with use of an external pump and oxygenator.