Transcript Elective Cesarean Delivery, Neonatal Intensive Care Unit Admission

Elective Cesarean Delivery,
Neonatal Intensive Care Unit
Admission, and Neonatal
Respiratory Distress
楊明智
Introduction
• GA of elective C/S vs risk of neonatal respiratory
distress → guidelines recommending elective
cesarean delivery at term (39 weeks or later).
• 4–5% of neonates will still develop signs of
respiratory distress → labor before caesarean
delivery is associated with a lower rate of neonatal
respiratory distress.
• The mechanism of this effect is unknown, but it is
postulated to be secondary to activation of epithelial
sodium channels in the fetal lung.
• Glucocorticoids appear to be a potent upregulator of the expression of epithelial
sodium channel genes and are secreted in
increasing amounts by the fetal adrenal gland
at term.
• Fetal hypothalamic-pituitary-adrenal axis
maturation and adrenal glucocorticoid
production are also felt to be possible triggers
for the onset of labor at term.
• Adrenal production of glucocorticoids may
both initiate labor and prepare the fetus for
extra-uterine life.
• It has been postulated that the rates of respiratory
distress could be reduced further if elective cesarean
delivery is delayed until the onset of labor or ruptured
membranes.
• Most of the studies that reported a protective effect of
labor included women who had cesarean delivery
after prolonged labor and not just women having an
elective repeat cesarean delivery shortly after the
onset of labor.
• The lower rates of respiratory distress observed
following cesarean delivery after the onset of labor
may simply reflect that these fetuses were more likely
to be truly at a term gestation.
• It is not clear whether the short duration of labor
before elective repeat cesarean delivery is protective.
Intent of the Study
• To estimate whether the risk of neonatal
intensive care unit (NICU) admission and
neonatal respiratory distress was lower in
women undergoing cesarean delivery after
spontaneous rupture of membranes or the
onset of labor
• To confirm the relationship between
gestational age at cesarean delivery and risk
of respiratory distress
Materials and Methods
• All elective cesarean deliveries done in the Calgary Health
Region, Calgary, Alberta, Canada
• March 1, 2004, to April 30, 2005
• 13,360 deliveries, C/S rate: 26.4% 9 (3527)
• GA ≧ 37 wks, BW ≧ 2500 g, Elective C/S
• Maternal data: age, gravidity, parity, antepartum risks
Intrapartum factors including rupture of membranes, presence of
contractions, and duration of labor
• Antepartum or intrapartum maternal medications, postpartum
complications, and length of stay
• Labor before cesarean delivery was defined as the presence of
symptomatic contractions or rupture of membranes before
cesarean delivery.
Materials and Methods
• Newborn data: birth weight, gender, Apgar scores,
cord pH, resuscitation parameters, treatment
provided if admitted to NICU, diagnoses, and length
of stay.
• Twin A was included only (higher risk in twin B).
• Definition of respiratory distress: tachypnea, with
respiratory rate of more than 60 breaths per minute,
retractions, grunting, nasal flaring, and cyanosis in
room air, or requiring treatment with any of the
following: supplemental oxygen, nasal continuous
positive airway pressure, endotracheal intubation, or
exogenous surfactant.
Results
• 1,193 paired maternal-infant charts matched
the criteria of study (≥ 36 wks GA, ≥ 2500 g).
• The mean (standard deviation) maternal age
was 32.1±4.8 years.
• Spontaneous onset of labor before cesarean
delivery occurred in 225 of 1,193 women
(18.9%), of whom, 142 reported symptomatic
contractions, and 104 had spontaneous
rupture of membranes.
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Results
• Previous cesarean delivery (89%)
Breech (6.5%), twins (1.9%), placenta previa
(1.1%), primary elective (0.8%), and previous
uterine surgery (0.4%), others (0.3%)
• A third of the mothers were more than 35
years of age, and 13–15.9% were obese,
correlating with 7.1–8.0% having dietmanaged diabetes, with no difference
between mothers whose infants had
symptoms of respiratory distress and those
who did not .
Results
• The mean (± standard deviation) gestational
age of the infants at time of elective cesarean
delivery was 271.4±6.7 days or 385/7 weeks.
• The mean birth weight was 3,397±480 g.
• Fifty-two percent were male infants.
• Twenty-three (1.9%) infants were from twin
sets, and the gestational age of these infants
ranged from 254 to 268 days (362/7 to 382/7
weeks). Five of these infants were at a
gestational age of less than 259 days (370/7
weeks). From the 23 twin infants, three were
admitted to NICU.
Results
• Overall, 156 (13.1%) infants delivered by
elective cesarean were admitted to NICU.
• 126 infants were identified to have respiratory
distress, although only 118 (9.9%) of these
infants were admitted to NICU.
• Two thirds of the infants admitted to the
NICU with symptoms of respiratory
distress had short stays, with a mean of
6.4 hours, but the remaining third had a
mean length of stay of 1.9 days. Several
infants with other diagnoses had lengths
of stay beyond 7 days (Table 3).
Fig. 2. Smoothed fit of relationship between respiratory
distress and gestational days. Points on the Y axis
indicate respiratory distress=1 and no respiratory
distress=0.
Discussion
• In this study, the risk for admission to NICU and
development of neonatal respiratory distress were
significantly associated with gestational age at time of
elective cesarean delivery and male gender.
• In this population studied, if elective cesarean
delivery were planned for beyond 270 days (384/7
weeks) of gestation, the risk of respiratory distress
could be reduced by 50%, and NICU admission could
be reduced by approximately 40% in these neonates.
• It was anticipated that not all cases will
be appropriate for delay of delivery until
384/7 weeks and that the risk of
respiratory distress and neonatal
admission will be one of the factors in
considering the optimal time of delivery.
• Numerous studies have identified similar
relationships between respiratory morbidity, need
for NICU admission, and gestational age. The
recommendation from these studies is that
cesarean delivery at 39 weeks or later
significantly reduces the risk of respiratory
morbidity. These recommendations are stated in
the American College of Obstetricians and
Gynecologists (ACOG) Committee Opinion 98,
published in 1991.
Conclusion
• In the final model, elective cesarean
occurring beyond 270 days of gestation
(384/7 weeks) significantly reduced the
risk of NICU admission and the risk of
respiratory distress, but again the
presence of pre–cesarean delivery
contractions or rupture of membranes
did not further reduce this risk.
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