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For laboring women with thick meconium staining of amniotic fluid, amnioinfusion did not reduce the risk of perinatal death, moderate or severe meconium aspiration syndrome, or both. The study was adequately powered at the 80% level to detect a decrease in the expected outcome from 5% to 2.5%. |
Citation/s:
Fraser, WD, et al. Amnioinfusion for the prevention of the meconium aspiration
syndrome. N Engl J Med 2005;353:909-17
Lead author's name and fax:
Three-part Clinical Question: In laboring women with thick meconium
staining of the amniotic fluid, does amnioinfusion of saline into the amniotic
cavity, compared to no amnioinfusion, result in decreased risk of perinatal
death, moderate or severe meconium aspiration syndrome, or both?
Search Terms:
The Study:
Single-blinded randomised controlled trial with intention-to-treat.
The Study Patients: 56 centers in 13 countries; women with thick
meconium staining of amniotic fluid, cephalic singleton fetus at 36 weeks or
more gestation, cervix dilated 2 to 7 cm and no FHT indications for urgent
delivery (late decelerations, etc). Exclusions included fetal anomaly,
chorioamnionitis, vaginal bleeding, infection, and others. 1998 women were
randomized to amnioinfusion or standard care by central computerized
randomization. Stratification by study center, and by the presence of variable
decelerations (3 or more) during the 30 minutes prior to randomization.
Control group (N = 1003; 989 analysed): Oropharyngeal and nasopharyngeal
suctioning after shoulder delivery and again after infant delivery. Oxytocin
augmentation of labor permitted.
Experimental group (N = 995; 986 analysed): Amnioinfusion performed
immediately after randomization: 800 cc sterile saline under force of gravity
at 20 cc per minute x 40 minutes, followed by 2 cc per minute to max of 1500
cc, with IUPC monitoring. Continuous FHT monitoring. Oropharyngeal and
nasopharyngeal suctioning after shoulder delivery, and again after infant
delivery. Oxytocin augmentation of labor permitted in both groups.
Neonatologists (3) were blinded to study group in determining outcomes.
The Evidence:
|
Outcome |
Time to Outcome |
CER |
EER |
RRR |
ARR |
NNT |
|
Primary:
perinatal death, moderate or severe meconium aspiration syndrome or both. |
|
0.035 |
0.044 |
-26% |
-0.009 |
-111 |
|
95% Confidence Intervals: |
-75% to 23% |
-0.026 to 0.008 |
NNT = 124 to INF; NNH = 38 to INF |
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|
Secondary:
perinatal death, other serious morbidity or both, including kApgar score
below 7, umbilical pH below 7.05, trauma or serious maternal morbidity |
|
0.099 |
0.113 |
-14% |
-0.014 |
-71 |
|
95% Confidence Intervals: |
-41% to 13% |
-0.041 to 0.013 |
NNT = 77 to INF; NNH = 24 to INF |
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|
Perinatal death
alone |
|
0.005 |
0.005 |
0% |
0.000 |
INF |
|
95% Confidence Intervals: |
-124% to 100% |
-0.006 to 0.006 |
NNT = 162 to INF; NNH = 162 to INF |
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Comments:
Prophylactic pharyngeal suctioning and tracheal aspiration have not been shown
to reduce the risk of the meconium aspiration syndrome. A previous
meta-analysis of small studies (Cochrane, 2002) suggested that amnioinfusion
might prevent some cases of meconium aspiration syndrome occurring with thick
meconium. This large, carefully done multicenter trial with nearly 2000
patients concludes that this is not the case. Reasons may include that meconium
aspiration occurs before the labor process begins, or that other processes
involving the lungs (indicative of longstanding fetal stress) may already be
present for which intrauterine meconium passage is a marker. Of note,
stratified analysis also showed no effect when decelerations in fetal heart
rate were present at randomization, although the study authors admit that the
study was not powered to detect a difference in this smaller (17% of total)
group. Regarding maternal outcomes, there were no differences in the rates of
cesarean delivery (approx 30%), peripartum fever (3%0, maternal death or
serious morbidity (1.5%), uterine rupture (0.2%), or hemorrhage (1.1%).
Appraised by: CAT author: Linda Olson Douglas, MD JC Leader: Lynne DeSotel,
MD ; Tuesday, December 13, 2005
Email:
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