PREPARATION FOR THE PROCEDURE
Initial Evaluation
Someone other than the obstetrician should evaluate and resuscitate
the neonate. If intrauterine asphyxia is known to exist or is strongly suspected
( Table 59-2
), at least two
additional people are required to resuscitate the neonate: one to ventilate the
lungs and the other to insert an umbilical artery or venous catheter, or both, and
correct acid-base and blood volume abnormalities. A plan for the resuscitation of
each neonate should be developed and understood by everyone in the delivery room
before the neonate's birth. There should be at least one person immediately available
who is skilled in neonatal resuscitation. A second person should be designated as
backup and should be available in a reasonable amount of time to assist in the resuscitation.
After breathing is established and the umbilical cord has stopped
pulsating, the cord is cut and the neonate is taken to the resuscitation table.
Holding the neonate below the introitus of the mother increases blood volume and
causes polycythemia.[57]
Raising the neonate above
the level of the introitus or clamping the umbilical cord early decreases blood volume.
[58]
Stripping blood from the umbilical cord to the neonate increases
blood volume,[59]
respiratory rate,[60]
lung water,[61]
pulmonary artery pressure, and PaCO2
.
[62]
Lung compliance, FRC, and PaO2
[63]
decrease. Figure
59-6
shows the effects of early and late cord clamping on placental blood
volume. The larger the placental blood volume, the smaller is the neonate's blood
volume. Early cord clamping can deprive neonates of up to 30 mL of blood per 1 kg
of body weight.[58]
If the neonate is flaccid, pale, limp, or cyanotic, the umbilical
cord should be clamped and cut and the neonate handed off to be resuscitated. However,
when this is done, there is a high likelihood that the neonate will be hypovolemic
because the umbilical cord was clamped early.
The neonate should be placed in a radiantly heated resuscitation
bed with the head slightly lower than the body, and the airway should be cleared
of secretions and blood by gently suctioning the mouth and nose with a bulb syringe.
Prolonged suctioning can cause vomiting and arrhythmias, the most common of which
is bradycardia, but ventricular arrhythmias occur in 10% to 20% of neonates who are
suctioned vigorously while hypoxic.
If the respiratory pattern and color are normal, nothing more
is required except to dry the neonate with a towel and quickly insert a suction catheter
into the posterior pharynx through each nostril to rule out choanal atresia. The
same catheter is then passed through the mouth into the stomach to rule out esophageal
atresia and small bowel atresia and to empty the stomach of its contents.
TABLE 59-2 -- Disorders frequently associated with asphyxia at birth
|
Maternal Conditions |
|
Elderly primigravida (>35 years of age) |
|
Diabetes |
|
Hypertension |
|
Toxemia |
|
Maternal treatment with any of the following |
|
Glucocorticoids |
|
Diuretics |
|
Antimetabolites |
|
Reserpine, lithium |
|
Magnesium |
|
Ethyl alcohol |
|
β-Adrenergic drugs (to stop premature labor) |
|
Abnormal estriol levels |
|
Anemia (hemoglobin level less than 10 g/100 mL) |
|
Blood type or group isoimmunization |
|
Previous birth of child with a hereditary disease |
|
Current maternal infection or infection during pregnancy with
rubella, herpes simplex, or syphilis |
|
Abruptio placentae |
|
Placenta previa |
|
Antepartum hemorrhage |
|
History of previous infant with jaundice, thrombocytopenia, cardiorespiratory
distress, or congenital anomalies |
|
Narcotic, barbiturate, tranquilizer, or psychedelic drugs |
|
Ethyl alcohol intoxication |
|
History of previous neonatal death |
|
Prolonged rupture of membranes |
|
Conditions of Labor and Delivery |
|
Forceps delivery other than low elective |
|
Vacuum extraction delivery |
|
Breech presentation and delivery or other abnormal presentation |
|
Cesarean section |
|
Prolonged labor |
|
Prolapsed umbilical cord |
|
Cephalopelvic disproportion |
|
Maternal hypotension |
|
Sedative or analgesic drugs given intravenously within 1 hour
of delivery or intramuscularly within 2 hours of delivery |
|
Fetal Conditions |
|
Multiple births |
|
Polyhydramnios |
|
Meconium-stained amniotic fluid |
|
Abnormal heart rate or rhythm |
|
Acidosis (fetal scalp capillary blood) |
|
Decreased rate of growth (uterine size) |
|
Premature delivery |
|
Amniotic fluid surfactant test negative or intermediate within
24 hours of delivery |
|
Neonatal Conditions |
|
Birth asphyxia |
|
Birth weight (inappropriate for gestational age) |
|
Meconium staining of the skin, nails, or umbilical cord |
|
Signs of cardiorespiratory distress |
Figure 59-6
The effects of early and late cord clamping on placental
blood volume. (Adapted from Ogata ES, Kitterman JA, Phibbs RH, et al: The
effect of time of cord clamping and maternal blood pressure on placental transfusion
with cesarean section. Am J Obstet Gynecol 128:197, 1977.)
Bilateral choanal atresia may be lethal because the airway becomes completely obstructed
when he or she closes the mouth. When the mouth is open, the neonate is pink; when
the mouth is closed, the neonate continues to make breathing efforts, but no gas
movement into or out of the lung can take place. To alleviate the airway obstruction,
the physician inserts an oral airway or an endotracheal tube to prevent the tongue
from making a tight seal with the pharyngeal wall. If the diagnosis of choanal atresia
is made, the neonate should be seen by a nose and throat surgeon who specializes
in pediatric surgery, and the obstruction should be relieved surgically.
The 1-minute Apgar score can be used to guide resuscitation, but
it is only a guide. The physician should not wait until 1 minute has passed before
initiating resuscitation. The primary purpose of Apgar scoring
is to ensure that each neonate is closely evaluated during the first few minutes
of life.
