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

Chang Na Wei,1,2,* Jia Li Deng,1,2,* Jin Hua Dong,3 Ze Peng Ping,3 Xin Zhong Chen1,2 1Department of Anesthesia, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou 310006, People’s Republic of China; 2Department of Anesthesia, Jiaxing University Affiliated Women and Children Hospital, Jiaxing 314000, People’s Republic of China; 3Department of Obstetrics, Jiaxing University Affiliated Women and Children Hospital, Jiaxing 314000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Xin Zhong ChenDepartment of Anesthesia, Women’s Hospital, Zhejiang University School of Medicine, Xueshi Road 1, Hangzhou 310006, People’s Republic of ChinaTel +86 13575738058Email chenxinz@zju.edu.cnPurpose: 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 (ED50) 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 ED50 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.Keywords: maternal age, drug delivery, bolus, postpartum haemorrhage prevention