<p>The Median Effective Dose of Oxytocin Needed to Prevent Uterine Atony During Cesarean Delivery in Elderly Parturients</p>

Abstract

Purpose Oxytocin is the first-line agent to prevent and treat uterine atony during cesarean delivery (CD). We compared the effective dose in 50% of the parturients (ED 50 ) of a prophylactic oxytocin bolus during CD in young (<35 years) and old parturients (≥35 years) using Dixon’s up-and-down method. Patients and Methods Twenty-eight young parturients (young group) and 25 old parturients (old group) undergoing CD under combined spinal-epidural anesthesia were enrolled. The initial oxytocin bolus was 0.5 IU, with increments or decrements of 0.25 IU. Maternal adverse effects, requirement for additional uterotonic agents, and estimated blood loss were recorded. Results The ED 50 for oxytocin in the old group was higher than that in the young group (1.41 IU; 95% confidence interval, 0.63–2.19) vs 0.66 IU (0.04–1.29), P < 0.001). The total oxytocin dose in the old group was higher than in the young group (5.9 ± 2.9 vs 4.1 ± 2.1 IU, P = 0.01). The estimated blood loss in the older group and young group was 401.2 ± 204.5 mL and 289.3 ± 104.6 mL, respectively ( P =0.01). The overall prevalence of adverse effects was higher in the old group than in the young group (68.0% vs 21.4%, P < 0.001). Conclusion The initial bolus and total requirement of oxytocin for preventing uterine atony were higher in old parturients than in young parturients during CD. Advanced maternal age may necessitate higher doses of oxytocin.

Effect of aging on the human myometrium at single-cell resolution

“…The simplification/depletion of such CCC networks in the aging myometrium may cause a decline in nerve impulse transmission and decreased contractility essential for pregnancy and labor. Our findings suggest that the decreased contractile potential during myometrial aging may justify why older parturients have longer labors 44 and require higher dosages of oxytocin for third-stage labor to prevent uterine atony 45 .…”

Effect of Aging on the Human Myometrium at Single-Cell Resolution

“…Of note, some prior studies failed to encounter alterations in the contractile ability of myometrial tissues according to age 57 , while others have noted lower responsiveness to oxytocin stimulation 58 or lower electromyographic activity 16 . Clinical studies have reported that older parturients have longer labors 59 , with higher dosages of oxytocin needed for third-stage labor to prevent uterine atony 60 . In this sense, our findings agree with decreased contractile potential during myometrial aging.…”

Advancing understanding of maternal age: correlating epigenetic clocks in blood and myometrium

“…Some prior studies did not find differences in contractile ability in myometrial tissue specimen by maternal age [ 11 , 15 ]; however, others have noted lower responsiveness to oxytocin stimulation [ 42 ] or lower electromyographic activity [ 43 ]. Clinical studies report that older parturients have longer labors [ 44 ] and more often need oxytocin in labor [ 8 ], and higher dosages of oxytocin are needed for third-stage labor to prevent uterine atony [ 45 ]. The specific reasons for the differences observed by studies of vitro contractility studies and clinical outcomes by age prompts further study.…”