Quick Entonox/nitrous oxide: Oxygen to ease spinal anesthesia in obstetrics

Abstract

Sir, Entonox has been one of the modalities as a part of labor analgesia. It is safe and can be implemented immediately.[1] Although epidural analgesia plays a primary role in the management of labor analgesia, the use of 50:50 oxygen (O2)/nitrous oxide (N2O) is still a useful practice in operation theater (OT) for obstetric surgeries. Not many obstetric patients come to OT from the labor room with an epidural catheter in situ. However, anesthesiologists continue to receive patients for cesarean sections with ongoing labor pain. Nonprogress of labor, cephalopelvic disproportions, maternal requests, and failure of epidural analgesia are some indications for lower segment cesarian section (LSCS) of semi-urgent nature where patients are received with ongoing labor pain. These patients are uncooperative for proper positioning during subarachnoid block (SAB); as a result, there can be an increase in the number of attempts and chances of failure or partial block can be observed. Can Entonox/N2O:O2 help? Three cases of the American Society of Anesthesiologists II obstetric patients were posted for emergency LSCS with no indication of fetal distress with ongoing labor pain. They were subjected to N2O:O2 inhalation in the form of 4 L of O2 and 4 L of N2O on the operation table with anesthesia workstation (Datex Ohmeda) via closed circuit. After 4–6 breaths, the patients were comfortable, quiet, and cooperative. This facilitated the performance of SAB by the anesthesiologist. It helped in performance of the SAB procedure with ease by keeping patients comfortable during positioning. Once SAB was done, the patient was turned supine and 100% O2 was given for 10 min or till delivery of the baby. Entonox in the form of O2 and N2O gas flows in the ratio of 50:50 has been used to supplement patchy blocks of spinal anesthesia or partial failures during cesarean section surgeries.[2] There were no adverse effects on the newborn in our cases and had good Apgar scores. Entonox has been used for labor analgesia either in continuous form or intermittently with the onset of labor pain without any consequences on the neonatal outcome.[34] Orthopedic patients with fractures and obstetric patients are the known categories where compliance in positioning for neuraxial anesthesia might face problems due to pain resulting in failed spinal anesthesia.[5] In these circumstances N2O:O2 combination can be effective for analgesia for acute pain relief. It proves safer in obstetric patients than systemic analgesia which is considered in nonobstetric patients.[5] The duration of use of N2O:O2 to help SAB is ultra short. We suggest the use of Entonox inhalation in the form of N2O:O2/50:50 mixture of gas flow, especially in obstetric patients with ongoing labor pain to facilitate performance of SAB. This will help the mother to cooperate well and facilitates the anesthesiologist to perform SAB. The use of Entonox can ease the anticipated difficult SAB in anxious and hollering obstetric patients promoting a successful SAB. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.