Effect of Advanced Maternal Age on Epidural Consumption during Labor

Abstract Number: S-18
Abstract Type: Original Research

Introduction:

The number of parturients of advanced maternal age has increased 3-fold from 4.6% to 14.3% over the last 30 years.(1) In the non-obstetric population, older patients have an increased spread of epidural local anesthetic from the lumbar area [2] as well as a decreased epidural narcotic requirement [3]. Many OB studies have analyzed the effect of advanced maternal age (AMA, >35 y.o.) on labor patterns as well as maternal and fetal complications. However, no study has addressed epidural dose requirements as a function of age in parturients. Therefore, we examined the effect of maternal age on epidural local anesthetic consumption during labor.

Methods:

After IRB approval, a retrospective medical chart review was performed for 2008. Inclusion criteria were primigravid women aged >18 years admitted with a gestational age >36 weeks who delivered vaginally. Advanced maternal age was defined as >35 y.o., with <35 y.o. serving as controls. Epidural medications were calculated as AUC as both infusion and bolus dosing. At our institution epidural analgesia is provided by a 0.2% ropivacaine infusion without narcotic and anesthesiologist administered boluses of either ropivacaine, bupivacaine, lidocaine, or chloroprocaine with or without fentanyl. Epidural boluses were converted to ropivacaine equivalent dose in mg by minimal local anesthetic concentration equivalency. [4] Epidural AUC was divided by the epidural duration, to obtain an hourly ropivacaine equivalency rate, in order to account for differences in duration of epidural use. Unpaired T-Test and regression analysis was performed, p<0.05 was statistically significant.

Results:

A total of 571 parturients met inclusion criteria, with 124 with advanced maternal age and 447 in the control group. The epidural drug consumption during labor was 22.1 ± 6 mg/h in the advanced maternal age group and 22.8±7.7 mg/h in the control group, P=.36. The duration of epidural infusion was 8.8±4.1 h and 8.1±4.7 h P=0.04, and duration of labor 15.3±7.0 h and 13.9±7.0 P=0.05 for AMA and non-AMA groups. To further examine this effect, we used linear regression analysis of age vs. ropivacaine AUC, which was not correlated, R^2 =0.003.

Conclusion:

Advanced maternal age leads to complications of pregnancy including increased cesarean rate, preeclampsia, and hemorrhage. In our study AMA parturients required the same epidural dose per hour, yet with longer labors. Our study is the first large study examining epidural local anesthetic requirements in primiparous AMA parturients completing vaginal delivery. Advanced maternal age parturients do not follow the decreasing epidural requirement pattern seen in non-pregnant older patients. The correct dosing requirements of AMA parturients are important in this group at higher risk for obstetric and anesthetic complications.

References

1) www.cdc.gov/nchs

2) Anesth Analg. 2002 May;94(5):1325-30

3) Anesth Analg 1987;66:1215-8

4) Br J Anaesth 1999;82:371-3

SOAP 2014