The Effects of Entonox and Epidural Analgesia on Arterial Oxygen Saturation of Women in Labour

The arterial oxygen saturation of 60 mothers in the first stage of labour was monitored using pulse oximetery. Half the mothers received epidural analgesia and the other half inhaled Entonox for pain relief. Eight women in epidural group had at least one episode of significant arterial oxygen desaturation (SpO2 < 90%) as compared to twelve women in Entonox group (P 0.273). There was little difference in the number of hypoxic episodes experienced by either group, there were 22 periods in epidural group as compared to 36 periods in Entonox group, although their mean duration of these hypoxic episodes was longer in women of Entonox group that is (12 – 72 seconds) while in epidural group that (12 – 36 seconds) (P = 0.002). The severity of these hypoxic episodes was greater in the Entonox group than the epidural group (P = 0.02)