Desflurane analgesia for vaginal delivery. Neonatal neurobehavioral effects of inhalation analgesia for vaginal delivery. Comparison between nitrous oxide and methoxyflurane for obstetrical analgesia. Enflurane as an analgesic in labour. Entonox for labor pain: a randomized placebo controlled trial. Nitrous oxide in early labor. Safety and analgesic efficacy assessed by a double-blind, placebo-controlled study. Self-administered intermittent nitrous oxide analgesia for labour. Enhancement of effect with continuous nasal inhalation of 50 per cent nitrous oxide (Entonox). [Methoxyflurane (Penthrane) or nitrous oxide as agents of analgesia in childbirth?]. Clinical study on labor pain relief using the combined spinal-epidural analgesia and inhaling nitrous oxide. Methoxyflurane and nitrous oxide as obstetric analgesics. I. A comparison by continuous administration. Enflurane analgesia in obstetrics. Analgesia with sevoflurane during labour: ii. Sevoflurane compared with Entonox for labour analgesia. Self-administered isoflurane in labour. A comparative study with Entonox. [Application of nitrous oxide in labor analgesia]. Self-administered mixture of Entonox and isoflurane in labour. Effectiveness of transcutaneous electric nerve stimulator for pain relief in labour.
The use of subanaesthetic concentration of inhalational anaesthetic for vaginal delivery offers many advantages to the mother and newborn. Desflurane, with the characteristics of rapid onset and minimal metabolism, may provide better analgesia and safety for labour pain control. Eighty healthy parturients were randomly assigned to receive either desflurane 1.0-4.5% and oxygen (n = 40) or nitrous oxide 30-60% in oxygen (n = 40). Analgesia was assessed using a score from 0 (no relief) to 4+ (excellent analgesia), amnesia for the delivery, blood loss were recorded. Neonates were evaluated by Apgar scores and neurologic and adaptive capacity scores (NACS). Data were analyzed for statistical significance using Student's t-test or Chi-square when appropriate. Analgesia scores were similar for both groups with more amnesia in desflurane group (23% vs 0% P < 0.05). Blood loss did not differ significantly, 364 ml for the desflurane group and 335 ml for the nitrous oxide group. There were no significant differences for neonatal Apgar score at 1 min or at 5 min or the NACS at 2 hr or 24 hr between the two groups. We conclude that desflurane in subanaesthetic doses is safe and effective inhalation agent for normal delivery but might be associated with amnesia. The authors studied the neonatal neurobehavioral effects of nitrous oxide:oxygen and enflurane:oxygen inhalation analgesia for vaginal delivery. Parturients were assigned randomly to receive no inhalation agent (Group 1, n = 21); enflurane, 0.3 to 0.8 per cent, and oxygen (Group 2, n = 22); or nitrous oxide, 30 to 50 per cent, and oxygen (Group 3, n = 18). Infants were tested at 15 min, 2 h, and 24 h of age using the Neurologic and Adaptive Capacity Score (NACS); and at 2 and 24 h using the Early Neonatal Neurobehavioral Scale (ENNS). No significant differences in neurobehavioral status occurred. For all groups, scores tended to be lowest at two hours of age. We conclude that neither enflurane nor nitrous oxide analgesia adversely affects neonatal neurobehavioral status at 15 min, 2 h, or 24 h of age. nan A comparison of the analgesic efficacy of enflurane 1% in air with Entonox (50% nitrous oxide in oxygen) was performed in 20 consenting women during the first stage of labour. The two drugs were given in a random sequence to each woman, who also acted as her own control. Pain scores were significantly lower with enflurane than Entonox, although drowsiness scores were higher. No untoward effects were reported with either agent. The use of enflurane as an analgesic in the first stage of labour warrants further investigation. This study aims to investigate the effectiveness of nitrous oxide on pain of labor contractions and on maternal SaO2. The patients were randomized to receive either a pre-prepared mixture of 50% nitrous oxide and oxygen or 50% oxygen by a coin. Study drugs started as early as the onset of pain with each contraction. The patient herself administered gases via a facemask connected to the uni-directional valve which enables the patients to breathe fresh gas in each inspiration. The gas administration was continued to the end of contraction pain at which the patient breathed the room air. Variables such as SaO2, blood pressure, pain and side effects were recorded. 534 ASA I and II parturients, aged from 16 to 35 years, scheduled for elective labor from September 2004 to 2006 were evaluated. Four patients were lost from the study. The mean age of patients was 25.5+/-4.3 years. During the first three measurements, the SaO2 was significantly higher in control group. In addition, the mean arterial pressure was comparable between groups except two first measurements in which the control group was higher. All the Visual Analogue Scale (VAS) values were significantly lower in nitrous oxide group. There were no significant differences in 1st and 5th min apgar scores between groups. All of the side effects were significantly higher among patients in nitrous oxide. In conclusion, our data indicate that using nitrous oxide 50% provides significant pain relief. Nonetheless, it is associated with few side effects, nitrous oxide can be quickly implemented during advanced painful labor. Intermittent self-administered nitrous oxide has long had widespread use as an analgesic in labor, but its efficacy has not been adequately established. Questions about its effect on maternal oxygenation between labor contractions also have been raised.
                Twenty-six women were recruited to participate in a randomized, double-blind, cross-over, placebo-controlled study to assess the effect of intermittent nitrous oxide inhalation on labor pain and maternal hemoglobin oxygen saturation (SPO2) during the first stage of labor. Visual analog scale pain scores for each of five consecutive labor contractions were measured after administration of either nitrous oxide or compressed air.
                Mean visual analog scale pain scores for five contractions were 5.1, 5.2, 5.7, 5.2, and 5.6 (nitrous oxide) and 4.9, 5.2, 6.1, 5.6, and 5.7 (compressed air). There were no statistically significant differences in pain when nitrous oxide as compared with compressed air was administered. Pain scores did not differ significantly over time as a function of inhaled substance (F = 0.41, P = 0.53). The mean lowest SPO2 observed between these contractions after self-administration of nitrous oxide and air were 97, 97, 97, 97, and 97% (nitrous oxide) and 97, 96, 96, 96, and 96% (compressed air). SPO2 was significantly higher after nitrous oxide administration (F = 8.8, P = 0.007).
                While intermittent self-administered 50% nitrous oxide in oxygen does not appear to predispose parturient women to hemoglobin oxygen desaturation, its analgesic effect has yet to be clearly demonstrated. nan nan To study the pain relief effectiveness of the combined spinal-epidural analgesia (CSEA) and the inhalation of nitrous oxide, and the influences on the mothers and infants.
                The 300 cases of pregnant women were randomly divided into 3 groups: CSEA group, nitrous oxide group and control group. The nitrous oxide group was that pregnant women inhaled nitrous oxide premixed with oxygen (50%:50%), the pregnant women of the CSEA group were injected fentanyl and bupivacaine in the subarachnoid and epidural space, analgesic was not used in the control group. The degree of labor pain, duration of the labor, way of delivery, bleeding volume, rate of anoxia of newborn, blood gas analysis to maternal radius artery and fetal umbilical blood among 3 groups were observed.
                The effect for analgesia labor of the CSEA group was much better than that of the nitrous oxide group (P < 0.01). In the first stage of labor and total stage of labor, the CSEA group was shorter than the others (P < 0.05), but there was no difference between the nitrous oxide group and the control group (P > 0.05). In the second stage of labor, the 3 groups were alike to each other. The bleeding volume of caesarean section (373 +/- 77) ml in the nitrous oxide group was much more than the other 2 groups, there was no difference between the CSEA group (259 +/- 78) ml and the control group (239 +/- 89) ml. The rate of obstetric forceps of CSEA group was higher than the control group (P < 0.01), and the rate of caesarean section of the nitrous oxide group was much higher than the CSEA group. The blood gas analysis to maternal radius artery and fetal umbilical blood and the rate of anoxia of newborn of 3 groups revealed no significant difference.
                The effectiveness of the combined spinal-epidural analgesia CSEA for analgesia labor is confirmed and has rarely side-effect, and it can be the first choice, and the inhalation of nitrous oxide can safely provide effective labor analgesia, too. Methoxyflurane and nitrous oxide have been compared as obstetric analgesics. The inhaled concentrations of these agents, given continuously, were adjusted by an anaesthetist to maintain each patient at the optimum state between reaction to pain and consciousness. Assessments were made continuously.Though the anaesthetist's assessment showed no difference between the mean results, a greater proportion of the methoxyflurane patients were "satisfactory" for 90-100% of the time than of the nitrous oxide patients, particularly in regard to objective pain relief. The midwives' opinion of those who had "complete" pain relief supported this. Nausea was significantly less among methoxyflurane patients, and vomiting during labour occurred only in patients who had nitrous oxide. It is concluded that nitrous oxide and methoxyflurane given in a continuously adjusted concentration are almost equally effective as obstetric analgesics, though there are certain features which favour methoxyflurane. The effects of enflurane analgesia (approximately 0.5%) were studied in 55 patients during the second stage of normal vaginal delivery and were compared with effects of nitrous oxide (approximately 40%) in 50 similar patients. The enflurane and oxygen mixture was rated satisfactory by 89% of the mothers and 80% of the anesthesiologists. These ratings did not differ significantly from those for nitrous oxide. Obstetricians, however, rated the enflurane and oxygen mixture superior. The newborns of mothers receiving both agents wee vigorous and comparable when assessed by Apgar scores and cord blood gas tensions. The estimate of blood loss was similar in both groups. Serum inorganic fluoride concentrations in the mother after anesthesia were not significantly increased from preanesthetic levels with either agent. There was no biochemical evidence of renal toxicity. In neonates of mothers given enflurane, the mean umbilical cord concentration of serum inorganic fluoride ions was 2.4 +/- 0.2 micromoles/L, a value well below that associated with nephrotoxicity. We determined the optimal inspired sevoflurane concentration for use during labour as 0.8% in our previous study. This study compared sevoflurane at a concentration of 0.8% and Entonox((R)) (nitrous oxide 50%: oxygen 50%) for analgesia during labour in 32 healthy parturients.
                Each mother underwent two open-label, three-part sequences in random order, Entonox-sevoflurane-Entonox or sevoflurane-Entonox-sevoflurane. In each part the agent was self-administered during 10 contractions. A 100 mm visual analogue scores for pain relief and sedation was completed immediately after each contraction.
                Two patients withdrew during administration of sevoflurane (because of its odour) and five during Entonox (requesting epidural analgesia). Of the remaining women, data were available for analysis from 29 participants: median (IQR [range]) pain relief scores were significantly higher for sevoflurane 67 (55-74 [33-100]) mm than for Entonox 51 (40-69.5 [13-100]) mm (P<0.037). Nausea and vomiting were more common in the Entonox group [relative risk 2.7 (95% CI 1.3-5.7); P=0.004]. No other adverse effects were observed in the mothers or babies. There was significantly more sedation with sevoflurane than with Entonox {74 (66.5-81 [32.5-100]) and 51 (41-69.5 [13-100]) mm, respectively; P<0.001}. Twenty-nine patients preferred sevoflurane to Entonox and found its sedative effects helpful.
                We conclude that self-administered sevoflurane at subanaesthetic concentration (0.8%) can provide useful pain relief during the first stage of labour, and to a greater extent than Entonox. Although greater sedative effects were experienced with sevoflurane, it was preferred to Entonox. Entonox (50% nitrous oxide in oxygen) and isoflurane (0.75% in oxygen) were compared as analgesics in the first stage of labour in 32 consenting women. The drugs were self-administered and given in random sequence, each during five consecutive uterine contractions. Each patient acted as her own control. Linear analogue pain scores were significantly lower (p less than 0.001) with isoflurane than with Entonox, but scores for drowsiness were higher for isoflurane. Further study is needed to assess the effects of more prolonged use of isoflurane in labour. Labor analgesia with nitrous oxide was studied in 34 parturients, and another 50 women taking no drug as the control group. The analgesic effect was satisfactory. By Mulleetr's pain in labor score, 91.18% women had score of 0-1, and their respiratory and circulatory functions were not affected. During inhalational analgesia the parturients remained conscious. Uterine contraction, progress of labor and neonatal Apgar score were not interferred, and postpartum bleeding was not increased. There was no complications in the treatment group. This study suggests that nitrous oxide with enough oxygen inhalation is one of the good drug for obstetric analgesia, but its concentration must be strictly controlled. Entonox (50% nitrous oxide premixed in oxygen) was compared with a mixture of Entonox and approximately 0.25% isoflurane (Entonox-isoflurane) for pain relief in the first stage of labour in 39 mothers. An Oxford Miniature Vaporizer was incorporated as the draw-over vaporizer for adding isoflurane to Entonox. The mixture was self-administered via the Entonox on-demand valve. The two mixtures were given in random sequence for five consecutive contractions of labour to each patient. Linear analogue pain relief scores were significantly higher (P=0.001) with Entonox-isoflurane. Fourteen patients continued using Entonox-isoflurane until delivery. No adverse effect from prolonged use was noted. Entonox-isoflurane is considered worthy of further investigation. The effectiveness of transcutaneous electric nerve stimulation (TENS) for pain relief in labour was compared to inhalation analgesia consisting of 50% nitrous oxide and 50% oxygen (ENTONOX). In the first part of the study 101 patients in early labour were allocated to using TENS (Group A) or ENTONOX (Group B) for pain relief. Our results did not show any beneficial effect on pain relief in labour with the use of TENS over ENTONOX; 18.8% of patients in Group A went through labour without any further form of analgesia as opposed to 17.0% in Group B. In the second part of the study 20 nulliparous patients having induced labour were randomly allocated to use TENS (Group C) or ENTONOX (Group D) as the first modality of pain relief. A switchover was made when labour pains were no longer tolerable. The results showed that both TENS and ENTONOX could be used in early labour up to 5-6 cm cervical dilatation till the frequency of contractions was nearly 5 in 10 min or the first 3-4 hr from the time patients first requested pain relief in labour when frequency of contractions was nearly 4 in 10 min. TENS could be used in early labour for patients who wish to be ambulant and is as effective as ENTONOX. Either modality of pain relief was not adequate for pain relief throughout labour.
Inhaled analgesia appears to be effective in reducing pain intensity and in giving pain relief in labour. However, substantial heterogeneity was detected for pain intensity. Furthermore, nitrous oxide appears to result in more side effects compared with flurane derivatives. Flurane derivatives result in more drowsiness when compared with nitrous oxide. When inhaled analgesia is compared with no treatment or placebo, nitrous oxide appears to result in even more side effects such as nausea, vomiting, dizziness and drowsiness. There is no evidence for differences for any of the outcomes comparing one strength verus a different strength of inhaled analgesia, comparing different delivery systems or comparing inhaled analgesia with TENS.