| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
ORIGINAL RESEARCH |
From the Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson, Mississippi.
 |
Abstract |
|---|
Top
 Abstract Materials and MethodsResultsDiscussionReferences |
|---|
Methods: Patients with repetitive variable decelerations were randomized to an intermittent bolus or continuous amnioinfusion. The intermittent bolus infusion group received boluses of 500 mL of normal saline, each over 30 minutes, with boluses repeated if variable decelerations recurred. The continuous infusion group received a bolus infusion of 500 mL of normal saline over 30 minutes and then 3 mL per minute until delivery occurred. The ability of the amnioinfusion to abolish variable decelerations was analyzed, as were maternal demographic and pregnancy outcome variables. Power analysis indicated that 64 patients would be required.
Results: Thirty-five patients were randomized to intermittent infusion and 30 to continuous infusion. There were no differences between groups in terms of maternal demographics, gestational age, delivery mode, neonatal outcome, median time to resolution of variable decelerations, or the number of times variable decelerations recurred. The median volume infused in the intermittent infusion group (500 mL) was significantly less than that in the continuous infusion group (905 mL, P = .003).
Conclusion: Intermittent bolus amnioinfusion is as effective as continuous infusion in relieving variable decelerations in labor. Further investigation is necessary to determine whether either of these techniques is associated with increased occurrence of rare complications such as cord prolapse or uterine rupture.
Transcervical amnioinfusion is the instillation of a physiologic solution through a transcervical intrauterine catheter to restore amniotic fluid (AF) volume. This procedure has become common in the intrapartum management of the laboring gravida. The advantages of amnioinfusion include correction of repetitive variable decelerations,1,2 a decrease in cesarean delivery rate1,3,4 ( Macri CJ, Schrimmer DB, Greenspoon JS, Strong TH, Paul RH. Amnioinfusion does not alter the length of labor [abstract]. Am J Obstet Gynecol 1992;166:413), and a lower rate of postpartum endomyometritis.4 The proposed reason for the beneficial effects of amnioinfusion in the case of fetal decelerations is that the addition of infusate to the amniotic cavity supplies a fluid cushion (which is normally lost at the time of membrane rupture) for the umbilical cord and facilitates normal fetoplacental circulation.5
Numerous amnioinfusion protocols have been described in the literature. Currently, there appears to be no difference in outcome associated with warming the infusate6 or using normal saline or Ringer’s lactate.7 Published amnioinfusion protocols reviewed by Paszkowski8 in 1994 included intermittent bolus infusions of 250–1000 mL, infusions in which total volumes infused over the first stage of labor were 100–4300 mL, bolus infusions at rates of 10–25 mL/minute, and infusions at maintenance rates of 3 mL/minute. We could identify no study that evaluated whether an intermittent bolus or continuous infusion protocol is superior in maintaining adequate intrauterine volume to alleviate variable decelerations throughout the first and second stages of labor.
Recurrent fetal variable decelerations have been shown to be caused by a decrease in AF volume,9 and amnioinfusion is effective in decreasing the severity and incidence of variable decelerations in labor. Once the amnioinfusion has been instituted, fluid is lost continuously through the cervix throughout the first and second stages of labor. It is not clear whether an intermittent bolus or continuous infusion protocol is more effective in treating variable decelerations in labor.
The primary objective of this investigation was to determine whether intermittent bolus or continuous transcervical amnioinfusion is more efficacious for the treatment and abolition of recurrent variable fetal decelerations in labor; medical costs associated with both protocols also were reviewed. We hypothesized that continuous instillation of the infusate would be more effective in treating repetitive variable decelerations in labor.
|
Materials and Methods |
|---|
|
Top
AbstractMaterials and MethodsResultsDiscussionReferences |
|---|
Patients consenting to participate had a fetal scalp electrode and intrauterine pressure catheter placed if this had not been done already. Randomization schedules had been generated previously by a computerized random number table, and assignments had been placed in envelopes that then were sealed. Patient allocation to either treatment arm was performed by selection of the next numbered, sealed, opaque envelope.
Patients assigned to the intermittent bolus infusion arm were given an initial intra-amniotic bolus of 500 mL of normal saline over 30 minutes. If variable decelerations resolved (ie, if 10 minutes passed without evidence of variable deceleration and with at least three contractions) during the 30-minute infusion, the infusion was completed and amnioinfusion was withheld until repetitive variable decelerations recurred. If the variable decelerations did not resolve, another bolus was infused over an additional 30 minutes. Whenever variable decelerations recurred during labor, this protocol was repeated.
Patients assigned to the continuous infusion arm underwent the initial bolus protocol just described. If variable decelerations persisted, another 500-mL bolus of normal saline was infused. Next, a maintenance infusion of 3 mL/minute of normal saline was begun, and this infusion was continued until delivery.
We reviewed patient records for and otherwise obtained maternal demographic information, neonatal outcome variables, and intrapartum data points including the time from the initial amnioinfusion bolus until resolution of variable decelerations, the number of boluses until resolution of variable decelerations, the total volume infused, and the number of times that variable decelerations recurred. Fetal monitoring strips were reviewed by a single investigator (BKR) to determine the length of time until resolution of variable decelerations. Cost of therapy was estimated using information supplied by the central supply and patient accounts offices at the University of Mississippi Medical Center. All data then were entered into a relational database, and two-tailed analysis was performed using the Student t test, 
2 analysis, the Fisher exact test, and the Kruskal-Wallis test as appropriate. P < .05 was considered statistically significant.
Sample-size analysis performed before initiation of the investigation showed that a total sample size of 64 for the two groups combined would be necessary to determine a mean difference of 1 in the number of times variable decelerations recurred, assuming a power of .80 and P < .05 as statistically significant.
|
Results |
|---|
|
Top
AbstractMaterials and MethodsResultsDiscussionReferences |
|---|
), nor in incidence of cesarean delivery, mean birth weight, incidence of Apgar scores less than 7 at 1 or 5 minutes, or mean cord pH (Table 2). When we examined the time to resolution of variable decelerations and the median number of 500-mL boluses required for resolution of variable decelerations, we found no clinical or statistical differences between the two groups.
|
|
). Patients in the continuous amnioinfusion group received more infusate (median 905 mL) than did patients in the intermittent bolus infusion group (median 500 mL, P = .003). Cost was calculated as cost to the patient. At our institution, a liter of normal saline costs $4.50 and the cost of use of an intravenous (IV) pump is $34.00/day. Costs of IV tubing and intrauterine pressure catheters were not added, because these costs would be the same for all participants. Likewise, costs of nursing care were assumed to be similar, because all patients were cared for in an acute care/labor and delivery setting. The median cost of amnioinfusion was $6.15 for the intermittent infusion group and $42.40 for the continuous infusion group (P < .001).
|
|
Discussion |
|---|
|
Top
AbstractMaterials and MethodsResultsDiscussionReferences |
|---|
This investigation demonstrates that maternal and neonatal outcome are not different with continuous or intermittent amnioinfusion protocols but that the continuous infusion protocol is associated with an increased cost to the patient because of use of greater volumes of infusate and use of IV pumps to control the rate of intrauterine infusion. This investigation was designed to detect a mean increase in the recurrence rate of repetitive variable decelerations as small as 1 in the intermittent bolus infusion group. Given the lack of detectable difference in this rate and the lack of difference in maternal or neonatal outcome, we suggest that amnioinfusion protocols used in the setting of severe fetal heart rate variable decelerations in labor be simplified as much as possible. Intermittent bolus amnioinfusion should be used to avoid the extra cost, including that of increased infusate volume. Because of the study’s small sample size, we could not evaluate rare complications of amnioinfusion such as cord prolapse and uterine hyperdistension or uterine rupture. Nonetheless, no such complications occurred in this study. Use of an intermittent bolus amnioinfusion protocol allows a reduction in health care costs without detrimental effects on patient outcome.
|
Footnotes |
|---|
Received February 28, 2000. Received in revised form April 14, 2000. Accepted April 27, 2000.
|
References |
|---|
|
Top
AbstractMaterials and MethodsResultsDiscussionReferences |
|---|
2. Miyazaki FS, Taylor NA. Saline amnioinfusion for relief of variable or prolonged decelerations: A preliminary report. Am J Obstet Gynecol 1983;146:670–8.[Medline]
3. Nageotte MP, Freeman RK, Garite TJ, Dorchester W. Prophylactic intrapartum amnioinfusion in patients with preterm rupture of membranes. Am J Obstet Gynecol 1985;153:557–62.[Medline]
4. Owen J, Henson BV, Hauth JC. A prospective randomized study of saline solution amnioinfusion. Am J Obstet Gynecol 1990;162: 1146–9.[Medline]
5. Cusick W, Smulian JC, Vintzileos AM. Intrapartum use of fetal heart rate monitoring, contraction monitoring, and amnioinfusion. Clin Perinatol 1995;22:875–906.[Medline]
6. Glantz JC, Letteney DL. Pumps and warmers during amnioinfusion: Is either necessary? Obstet Gynecol 1996;87:150–5.[Abstract]
7. Pressman EK, Blakemore KJ. A prospective randomized trial of two solutions for intrapartum amnioinfusion: Effects on fetal electrolytes, osmolality, and acid-base status. Am J Obstet Gynecol 1996;175:945–9.[Medline]
8. Paszkowski T. Amnioinfusion: A review. J Reprod Med 1994;39: 588–94.[Medline]
9. Gabbe SG, Ettinger BB, Freeman RK, Martin CB. Umbilical cord compression associated with amniotomy: Laboratory observations. Am J Obstet Gynecol 1976;126:353–5.[Medline]
10. Nageotte MP, Bertucci L, Towers CV, Lagrew DL, Modanlou H. Prophylactic amnioinfusion in pregnancies complicated by oligohydramnios: A prospective study. Obstet Gynecol 1991;77:677–80.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
