Asphyxia neonatorum

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.

Alternative treatment

If an inadequate supply of oxygen from the placenta is detected during labor, the infant is at high risk for asphyxia, and an emergency delivery may be attempted either using forceps or by cesarean section.

Prognosis

The prognosis for asphyxia neonatorum depends on how long the new born is unable to breathe. For example, clinical studies show that the outcome of babies with low five-minute Apgar scores is significantly better than those with the same scores at 10 minutes. With prolonged asphyxia, brain, heart, kidney, and lung damage can result and also death, if the asphyxiation lasts longer than 10 minutes.

Prevention

Anticipation is the key to preventing asphyxia neonatorum. It is important to identify fetuses that are likely to be at risk of asphyxia and to closely monitor such high-risk pregnancies. High-risk mothers should always give birth in hospitals with neonatal intensive care units where appropriate facilities are available to treat asphyxia neonatorum. During labor, the medical team must be ready to intervene appropriately and to be adequately prepared for resuscitation.

KEY TERMS

Adrenaline —Another name for epinephrine, the hormone released by the adrenal glands in response to stress. It is the principal blood-pressure raising hormone and a bronchial and intestinal smooth muscles relaxant.

Anemia —A condition in which there is an abnormally low number of red blood cells in the bloodstream. It may be due to loss of blood, an increase in red blood cell destruction, or a decrease in red blood cell production. Major symptoms are paleness, shortness of breath, unusually fast or strong heart beats, and tiredness.

Anesthesia —Treatment with medicine that causes a loss of feeling, especially pain. Local anesthesia numbs only part of the body; general anesthesia causes loss of consciousness.

Apgar score —The results of an evaluation of a newborn's physical status, including heart rate, respiratory effort, muscle tone, response to stimulation, and color of skin.

Asphyxia —Lack of oxygen.

Asphyxia neonatorum —Respiratory failure in the newborn.

Bradycardia —A slow heart rate, usually under 60 beats per minute.

Cyanosis —A bluish tinge to the skin that can occur when the blood oxygen level drops too low.

Hemoglobin —An iron-containing pigment of red blood cells composed of four amino acid chains (alpha, beta, gamma, delta) that delivers oxygen from the lungs to the cells of the body and carries carbon dioxide from the cells to the lungs.

Hypotonia —Having reduced or diminished muscle tone or strength.

Hypoxia —A condition characterized by insufficient oxygen in the cells of the body

Neonatal —Refers to the first 28 days of an infant's life.

Oropharynx —One of the three regions of the pharynx, the oropharynx is the region behind the mouth.

Respiratory failure —Inability to rid the body of CO₂ or establish an adequate blood oxygen level.

Resuscitation —Bringing a person back to life or consciousness after he or she was apparently dead.

Parental concerns

Women at risk for asphyxia neonatorum pregnancies should receive focused prenatal care from an obstetrician skilled at preventing and detecting problems such as anemia that may contribute to asphyxia neonatorum. While prenatal care will not necessarily prevent newborn asphyxia, it can help ensure that both the mother and her baby are as healthy as possible at the time of birth.

See also Hypotonia.

Resources

BOOKS

Birth Asphyxia and the Brain: Basic Science and Clinical Implications. Edited by Steven M. Donn et al. Malden, MA: Futura Publishing Co., 2002.

PERIODICALS

Cheung, P. Y., and C. M. Robertson. "Predicting the outcome of term neonates with intrapartum asphyxia." Acta Paediatrica 89, no. 3 (March 2000): 262–264.

Clark, R., and J. A. Carcillo. "Is it time to revisit a role for antithrombotic therapy in asphyxia neonatorum?" Pediatric Critical Care Medicine 5, no. 2 (March 2004): 198–199.

Wiswell, T. E. "Neonatal resuscitation." Respiratory Care 48, no. 3 (March 2003): 288–294.

ORGANIZATIONS

American Academy of Pediatrics (AAP). 141 Northwest Point Blvd., Elk Grove Village, IL, 60007. Web site: <www.aap.org>>

WEB SITES

Dave Woods. "Neonatal resuscitation." International Association for Maternal and Neonatal Health. Available online at <www.gfmer.ch/Medical_education_En/PGC_RH_2004/Neonatal_asphyxia.htm> (accessed October 11, 2004).

Monique Laberge, Ph.D.