Background and objectives: Labor pain is a severe form of pain experienced by a woman, leading to tremendous stress. Several routes for labor analgesia have been tried. Entonox is a premixed homogeneous gas mixture of nitrous oxide and oxygen in the ratio of 50:50 providing conscious sedation in obstetrics during labor. It is a safe and effective analgesia for obstetrics use due to its properties of rapid onset, short half-life, and rapidly disappearing symptoms on withdrawal of the gas. Therefore, we aimed to evaluate the effect of Entonox on the severity and relief of labor pain during its various stages and its associated maternal or fetal side effects.
Materials and Methods: A prospective randomized controlled trial (RCT) of 200 term pregnant mothers reporting in labor over a period of 2 months who were randomized into Entonox group and placebo oxygen control group was included in the study. Administration of both gases was done, and the pain scoring was recorded. Maternal and fetal complications were noted.
Results: The intensity of labor pain was significantly lower in Entonox group as evident by lower pain scoring values. The mean duration of the active phase of labor in the Entonox group was comparable to the oxygen group. Maternal and fetal side effects were not significant in both groups. The mode of delivery is also comparable in both groups.
Conclusion: Entonox usage in labor analgesia is a safe, effective, and inexpensive method of relieving labor pain, achieving immense patient satisfaction and making labor a pleasurable experience.
Sharma S, Menia V, Bedi J, et al. Labor analgesia: an unmet right of laboring women in India. J South Asian Federation Obstet Gynaecol 2013;5(1):26–32. DOI: 10.5005/jp-journals-10006-1214.
Reena, Bandyopadhyay KH, Afzal M, et al. Labor epidural analgesia: past, present and future. 2014;28(2):71–81. DOI: 10.4103/0970-5333.132843.
Labor S, Maguire S. The pain of labour. Rev Pain 2008;2(2):15–19. DOI: 10.1177/204946370800200205.
Mittal S, Das B, Khatuja R. Quest for labor analgesia in second stage in resource poor setup. J South Asian Federation Obstet Gynaecol 2018;10(3):194–198. DOI: 10.5005/jp-journals-10006-1588.
Richards W, Parbrook GD, Wilson J. Pioneer of nitrous oxide and oxygen analgesia. Anaesthesia 1976;31(7):933–940. DOI: 10.1111/j.1365-2044.1976.tb11906.x.
King TL, Wong CA. Nitrous oxide for labor pain: is it a laughing matter? Anesth Analg 2014;118(1):12–14. DOI: 10.1213/ANE.0000000000000017.
Agah J, Baghani R, Tabaraei Y, et al. Maternal side-effects of continuous vs. intermittent method of entonox during labour: a randomized clinical trial. Iranian J Pharmaceut Res 2016;15(2): 641–646. PMCID: PMC5018294, PMID: 27642337.
Brown SM, Sneyd JR. Nitrous oxide in modern anaesthetic practice. BJA Education 2016;16(3):87–91. DOI: 10.1093/bjaceaccp/mkv019.
Baker A, Ferguson SA, Roach GD, et al. Perceptions of labor pain by mothers and their attending midwives. J Adv Nurs 2001;35(2):171–179. DOI: 10.1046/j.1365-2648.2001.01834.x.
Turk DC, Wilson HD. Fear of pain as a prognostic factor in chronic pain: conceptual models, assessment, and treatment implications. Curr Pain Headache Rep 2010;14(2):88–95. DOI: 10.1007/s11916- 010-0094-x.
Buhre W, Disma N, Hendrickx J, et al. European society of anaesthesiology task force on nitrous oxide: a narrative review of its role in clinical practice. Br J Anaesth 2019;122(5):587–604.
Richardson MG, Raymond BL, Baysinger CL, et al. A qualitative analysis of parturients’ experiences using nitrous oxide for labor analgesia: it is not just about pain relief. Birth 2019;46(1):97–104. DOI: 10.1111/birt.12374.
Sheyklo SG, Hajebrahimi S, Moosavi A, et al. Effect of Entonox for pain management in labor: a systematic review and meta-analysis of randomized controlled trials. Electron Physician 2017;9(12):6002–6009. DOI: 10.19082/6002.
Attar AS, Feizabadi AS, Jarahi L, et al. Effect of Entonox on reducing the need for pethidine and the relevant fetal and maternal complications for painless labor. Electronic Physician 2016;8(12):3325–3332. DOI: 10.19082/3325.
Agah J, Baghani R, Tali SHS, et al. Effects of continuous use of entonox in comparison with intermittent method on obstetric outcomes: a randomized clinical trial. J Pregnancy 2014;2014. Article ID 245907, 5 p. DOI: 10.1155/2014/245907.
Naddoni DB, Balakundi SK, Assainar KK. The effect of nitrous oxide (entonox) on labour. Int J Reprod Contracept Obstet Gynecol 2017;5(3):835–839. DOI: 10.18203/2320-1770.ijrcog20160594.
Foji S, Moghadam MY, Asl HT, et al. A comparison of the effects of ENTONOX inhalation and spinal anesthesia on labor pain reduction and Apgar score in vaginal delivery: a clinical trial study. BioMedicine 2018;8(3):29–36. DOI: 10.1051/bmdcn/2018080317.
Parsa P, Saeedzadeh N, Ei GR, et al. The effect of Entonox on labour pain relief among nulliparous women: a randomized controlled trial. J Clin Diagn Res 2017;11(3):QC08–QC11. DOI: 10.7860/JCDR/2017/21611.9362.